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229 <h1>Command-line Options</h1>
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href="command-line-options.html#magnify">‑magnify</a> <span class='bull'> • </span> <a href="command-line-options.html#map">‑map</a> <span class='bull'> • </span> <a href="command-line-options.html#map_stream_">‑map[stream]</a> <span class='bull'> • </span> <a href="command-line-options.html#mask">‑mask</a> <span class='bull'> • </span> <a href="command-line-options.html#mattecolor">‑mattecolor</a> <span class='bull'> • </span> <a href="command-line-options.html#median">‑median</a> <span class='bull'> • </span> <a href="command-line-options.html#metric">‑metric</a> <span class='bull'> • </span> <a href="command-line-options.html#mode">‑mode</a> <span class='bull'> • </span> <a href="command-line-options.html#modulate">‑modulate</a> <span class='bull'> • </span> <a href="command-line-options.html#monitor">‑monitor</a> <span class='bull'> • </span> <a href="command-line-options.html#monochrome">‑monochrome</a> <span class='bull'> • </span> <a href="command-line-options.html#morph">‑morph</a> <span class='bull'> • </span> <a href="command-line-options.html#morphology">‑morphology</a> <span class='bull'> • </span> <a href="command-line-options.html#mosaic">‑mosaic</a> <span class='bull'> • </span> <a href="command-line-options.html#motion-blur">‑motion‑blur</a> <span class='bull'> • </span> <a href="command-line-options.html#name">‑name</a> <span class='bull'> • </span> <a href="command-line-options.html#negate">‑negate</a> <span class='bull'> • </span> <a href="command-line-options.html#noise">‑noise</a> <span class='bull'> • </span> <a href="command-line-options.html#normalize">‑normalize</a> <span class='bull'> • </span> <a href="command-line-options.html#opaque">‑opaque</a> <span class='bull'> • </span> <a href="command-line-options.html#ordered-dither">‑ordered‑dither</a> <span class='bull'> • </span> <a href="command-line-options.html#orient">‑orient</a> <span class='bull'> • </span> <a href="command-line-options.html#page">‑page</a> <span class='bull'> • </span> <a href="command-line-options.html#paint">‑paint</a> <span class='bull'> • </span> <a href="command-line-options.html#path">‑path</a> <span class='bull'> • </span> <a href="command-line-options.html#pause_animate_">‑pause[animate]</a> <span class='bull'> • </span> <a href="command-line-options.html#pause_import_">‑pause[import]</a> <span class='bull'> • </span> <a href="command-line-options.html#pen">‑pen</a> <span class='bull'> • </span> <a href="command-line-options.html#perceptible">‑perceptible</a> <span class='bull'> • </span> <a href="command-line-options.html#ping">‑ping</a> <span class='bull'> • </span> <a href="command-line-options.html#pointsize">‑pointsize</a> <span class='bull'> • </span> <a href="command-line-options.html#polaroid">‑polaroid</a> <span class='bull'> • </span> <a href="command-line-options.html#poly">‑poly</a> <span class='bull'> • </span> <a href="command-line-options.html#posterize">‑posterize</a> <span class='bull'> • </span> <a href="command-line-options.html#precision">‑precision</a> <span class='bull'> • </span> <a href="command-line-options.html#preview">‑preview</a> <span class='bull'> • </span> <a href="command-line-options.html#print">‑print</a> <span class='bull'> • </span> <a href="command-line-options.html#process">‑process</a> <span class='bull'> • </span> <a href="command-line-options.html#profile">‑profile</a> <span class='bull'> • </span> <a href="command-line-options.html#quality">‑quality</a> <span class='bull'> • </span> <a href="command-line-options.html#quantize">‑quantize</a> <span class='bull'> • </span> <a href="command-line-options.html#quiet">‑quiet</a> <span class='bull'> • </span> <a href="command-line-options.html#radial-blur">‑radial‑blur</a> <span class='bull'> • </span> <a href="command-line-options.html#raise">‑raise</a> <span class='bull'> • </span> <a href="command-line-options.html#random-threshold">‑random‑threshold</a> <span class='bull'> • </span> <a href="command-line-options.html#red-primary">‑red‑primary</a> <span class='bull'> • </span> <a href="command-line-options.html#regard-warnings">‑regard‑warnings</a> <span class='bull'> • </span> <a href="command-line-options.html#region">‑region</a> <span class='bull'> • </span> <a href="command-line-options.html#remap">‑remap</a> <span class='bull'> • </span> <a href="command-line-options.html#remote">‑remote</a> <span class='bull'> • </span> <a href="command-line-options.html#render">‑render</a> <span class='bull'> • </span> <a href="command-line-options.html#repage">‑repage</a> <span class='bull'> • </span> <a href="command-line-options.html#resample">‑resample</a> <span class='bull'> • </span> <a href="command-line-options.html#resize">‑resize</a> <span class='bull'> • </span> <a href="command-line-options.html#respect-parentheses">‑respect‑parentheses</a> <span class='bull'> • </span> <a href="command-line-options.html#reverse">‑reverse</a> <span class='bull'> • </span> <a href="command-line-options.html#roll">‑roll</a> <span class='bull'> • </span> <a href="command-line-options.html#rotate">‑rotate</a> <span class='bull'> • </span> <a href="command-line-options.html#sample">‑sample</a> <span class='bull'> • </span> <a href="command-line-options.html#sampling-factor">‑sampling‑factor</a> <span class='bull'> • </span> <a href="command-line-options.html#scale">‑scale</a> <span class='bull'> • </span> <a href="command-line-options.html#scene">‑scene</a> <span class='bull'> • </span> <a href="command-line-options.html#screen">‑screen</a> <span class='bull'> • </span> <a href="command-line-options.html#seed">‑seed</a> <span class='bull'> • </span> <a href="command-line-options.html#segment">‑segment</a> <span class='bull'> • </span> <a href="command-line-options.html#selective-blur">‑selective‑blur</a> <span class='bull'> • </span> <a href="command-line-options.html#separate">‑separate</a> <span class='bull'> • </span> <a href="command-line-options.html#sepia-tone">‑sepia‑tone</a> <span class='bull'> • </span> <a href="command-line-options.html#set">‑set</a> <span class='bull'> • </span> <a href="command-line-options.html#shade">‑shade</a> <span class='bull'> • </span> <a href="command-line-options.html#shadow">‑shadow</a> <span class='bull'> • </span> <a href="command-line-options.html#shared-memory">‑shared‑memory</a> <span class='bull'> • </span> <a href="command-line-options.html#sharpen">‑sharpen</a> <span class='bull'> • </span> <a href="command-line-options.html#shave">‑shave</a> <span class='bull'> • </span> <a href="command-line-options.html#shear">‑shear</a> <span class='bull'> • </span> <a href="command-line-options.html#sigmoidal-contrast">‑sigmoidal‑contrast</a> <span class='bull'> • </span> <a href="command-line-options.html#silent">‑silent</a> <span class='bull'> • </span> <a href="command-line-options.html#size">‑size</a> <span class='bull'> • </span> <a href="command-line-options.html#sketch">‑sketch</a> <span class='bull'> • </span> <a href="command-line-options.html#smush">‑smush</a> <span class='bull'> • </span> <a href="command-line-options.html#snaps">‑snaps</a> <span class='bull'> • </span> <a href="command-line-options.html#solarize">‑solarize</a> <span class='bull'> • </span> <a href="command-line-options.html#sparse-color">‑sparse‑color</a> <span class='bull'> • </span> <a href="command-line-options.html#splice">‑splice</a> <span class='bull'> • </span> <a href="command-line-options.html#spread">‑spread</a> <span class='bull'> • </span> <a href="command-line-options.html#statistic">‑statistic</a> <span class='bull'> • </span> <a href="command-line-options.html#stegano">‑stegano</a> <span class='bull'> • </span> <a href="command-line-options.html#stereo">‑stereo</a> <span class='bull'> • </span> <a href="command-line-options.html#stretch">‑stretch</a> <span class='bull'> • </span> <a href="command-line-options.html#strip">‑strip</a> <span class='bull'> • </span> <a href="command-line-options.html#stroke">‑stroke</a> <span class='bull'> • </span> <a href="command-line-options.html#strokewidth">‑strokewidth</a> <span class='bull'> • </span> <a href="command-line-options.html#style">‑style</a> <span class='bull'> • </span> <a href="command-line-options.html#subimage-search">‑subimage‑search</a> <span class='bull'> • </span> <a href="command-line-options.html#swap">‑swap</a> <span class='bull'> • </span> <a href="command-line-options.html#swirl">‑swirl</a> <span class='bull'> • </span> <a href="command-line-options.html#synchronize">‑synchronize</a> <span class='bull'> • </span> <a href="command-line-options.html#taint">‑taint</a> <span class='bull'> • </span> <a href="command-line-options.html#text-font">‑text‑font</a> <span class='bull'> • </span> <a href="command-line-options.html#texture">‑texture</a> <span class='bull'> • </span> <a href="command-line-options.html#threshold">‑threshold</a> <span class='bull'> • </span> <a href="command-line-options.html#thumbnail">‑thumbnail</a> <span class='bull'> • </span> <a href="command-line-options.html#tile">‑tile</a> <span class='bull'> • </span> <a href="command-line-options.html#tile-offset">‑tile‑offset</a> <span class='bull'> • </span> <a href="command-line-options.html#tint">‑tint</a> <span class='bull'> • </span> <a href="command-line-options.html#title">‑title</a> <span class='bull'> • </span> <a href="command-line-options.html#transform">‑transform</a> <span class='bull'> • </span> <a href="command-line-options.html#transparent">‑transparent</a> <span class='bull'> • </span> <a href="command-line-options.html#transparent-color">‑transparent‑color</a> <span class='bull'> • </span> <a href="command-line-options.html#transpose">‑transpose</a> <span class='bull'> • </span> <a href="command-line-options.html#transverse">‑transverse</a> <span class='bull'> • </span> <a href="command-line-options.html#treedepth">‑treedepth</a> <span class='bull'> • </span> <a href="command-line-options.html#trim">‑trim</a> <span class='bull'> • </span> <a href="command-line-options.html#type">‑type</a> <span class='bull'> • </span> <a href="command-line-options.html#undercolor">‑undercolor</a> <span class='bull'> • </span> <a href="command-line-options.html#unique-colors">‑unique‑colors</a> <span class='bull'> • </span> <a href="command-line-options.html#units">‑units</a> <span class='bull'> • </span> <a href="command-line-options.html#unsharp">‑unsharp</a> <span class='bull'> • </span> <a href="command-line-options.html#update">‑update</a> <span class='bull'> • </span> <a href="command-line-options.html#verbose">‑verbose</a> <span class='bull'> • </span> <a href="command-line-options.html#version">‑version</a> <span class='bull'> • </span> <a href="command-line-options.html#view">‑view</a> <span class='bull'> • </span> <a href="command-line-options.html#vignette">‑vignette</a> <span class='bull'> • </span> <a href="command-line-options.html#virtual-pixel">‑virtual‑pixel</a> <span class='bull'> • </span> <a href="command-line-options.html#visual">‑visual</a> <span class='bull'> • </span> <a href="command-line-options.html#watermark">‑watermark</a> <span class='bull'> • </span> <a href="command-line-options.html#wave">‑wave</a> <span class='bull'> • </span> <a href="command-line-options.html#weight">‑weight</a> <span class='bull'> • </span> <a href="command-line-options.html#white-point">‑white‑point</a> <span class='bull'> • </span> <a href="command-line-options.html#white-threshold">‑white‑threshold</a> <span class='bull'> • </span> <a href="command-line-options.html#window">‑window</a> <span class='bull'> • </span> <a href="command-line-options.html#window-group">‑window‑group</a> <span class='bull'> • </span> <a href="command-line-options.html#write">‑write</a> ] </p>
233 <div class="doc-section">
235 <p>Below is list of command-line options recognized by the ImageMagick <a
236 href="command-line-tools.html">command-line
237 tools</a>. If you want a description of a particular option, click on the
238 option name in the navigation bar above and you will go right to it. Unless
239 otherwise noted, each option is recognized by the commands <a href="convert.html">convert</a>, <a href="mogrify.html">mogrify</a>.</p>
241 <div style="margin: auto;">
242 <h4><a id="adaptive-blur"></a>-adaptive-blur <em class="arg">radius</em>[x<em class="arg">sigma</em>]</h4>
245 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Adaptively blur pixels, with decreasing effect near edges.</td><td style='text-align:right;'></td></tr></table>
247 <p>A Gaussian operator of the given radius and standard deviation (<em
248 class="arg">sigma</em>) is used. If <em class="arg">sigma</em> is not given it
251 <div style="margin: auto;">
252 <h4><a id="adaptive-resize"></a>-adaptive-resize <em class="arg">geometry</em></h4>
255 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Resize the image using data-dependent triangulation.</td><td style='text-align:right;'></td></tr></table>
257 <p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument. The <a href="command-line-options.html#adaptive-resize">-adaptive-resize</a>
258 option defaults to data-dependent triangulation. Use the <a
259 href="command-line-options.html#filter">-filter</a> to choose a different resampling algorithm.
260 Offsets, if present in the geometry string, are ignored, and the <a
261 href="command-line-options.html#gravity">-gravity</a> option has no effect.</p>
263 <div style="margin: auto;">
264 <h4><a id="adaptive-sharpen"></a>-adaptive-sharpen <em class="arg">radius</em>[x<em class="arg">sigma</em>]</h4>
267 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Adaptively sharpen pixels, with increasing effect near edges.</td><td style='text-align:right;'></td></tr></table>
269 <p>A Gaussian operator of the given radius and standard deviation (<em
270 class="arg">sigma</em>) is used. If <em class="arg">sigma</em> is not given it
273 <div style="margin: auto;">
274 <h4><a id="adjoin"></a>-adjoin</h4>
277 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Join images into a single multi-image file.</td><td style='text-align:right;'></td></tr></table>
279 <p>This option is enabled by default. An attempt is made to save all images of
280 an image sequence into the given output file. However, some formats, such as
281 JPEG and PNG, do not support more than one image per file, and in that case
282 ImageMagick is forced to write each image as a separate file. As such, if
283 more than one image needs to be written, the filename given is modified by
284 adding a <a href="command-line-options.html#scene">-scene</a> number before the suffix, in order to
285 make distinct names for each image. </p>
287 <p>Use <a href="command-line-options.html#adjoin">+adjoin</a> to force each image to be written to
288 separate files, whether or not the file format allows multiple images per file
289 (for example, GIF, MIFF, and TIFF). </p>
291 <p>Including a C-style integer format string in the output filename will
292 automagically enable <a href="command-line-options.html#adjoin">+adjoin</a> and are used to specify
293 where the <a href="command-line-options.html#scene">-scene</a> number is placed in the filenames. These
294 strings, such as '<code>%d</code>' or '<code>%03d</code>', are familiar to those
295 who have used the standard <code>printf()</code>' C-library function. As an
296 example, the command</p>
298 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert logo: rose: -morph 15 my%02dmorph.jpg</span></p>
299 <p>will create a sequence of 17 images (the two given plus 15 more created by
300 <a href="command-line-options.html#morph">-morph</a>), named: my00morph.jpg, my01morph.jpg,
301 my02morph.jpg, ..., my16morph.jpg. </p>
303 <p>In summary, ImageMagick tries to write all images to one file, but will
304 save to multiple files, if any of the following conditions exist...
306 <li>the output image's file format does not allow multi-image files,
307 <li>the <a href="command-line-options.html#adjoin">+adjoin</a> option is given, or
308 <li>a printf() integer format string (eg: "%d") is present in the output
313 <div style="margin: auto;">
314 <h4><a id="affine"></a>-affine
315 <em class="arg">s<sub>x</sub></em>,<em class="arg">r<sub>x</sub></em>,<em
316 class="arg">r<sub>y</sub></em>,<em class="arg">s<sub>y</sub></em>[,<em
317 class="arg">t<sub>x</sub></em>,<em class="arg">t<sub>y</sub></em>]</h4>
320 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Set the drawing transformation matrix for combined rotating and scaling.</td><td style='text-align:right;'></td></tr></table>
322 <p>This option sets a transformation matrix, for use by subsequent <a
323 href="command-line-options.html#draw">-draw</a> or <a href="command-line-options.html#transform">-transform</a> options. </p>
325 <p>The matrix entries are entered as comma-separated numeric values either in
326 quotes or without spaces. </p>
328 <p>Internally, the transformation matrix has 3x3 elements, but three of them
329 are omitted from the input because they are constant. The new (transformed)
330 coordinates (<em class="arg">x'</em>, <em class="arg">y'</em>) of a pixel at
331 position (<em class="arg">x</em>, <em class="arg">y</em>) in the original
332 image are calculated using the following matrix equation.</p>
335 <img alt="affine transformation" src="../images/affine.png"/>
338 <p> The size of the resulting image is that of the smallest rectangle that
339 contains the transformed source image. The parameters <em
340 class="arg">t<sub>x</sub></em> and <em class="arg">t<sub>y</sub></em>
341 subsequently shift the image pixels so that those that are moved out of the
342 image area are cut off.</p>
344 <p>The transformation matrix complies with the left-handed pixel coordinate
345 system: positive <em class="arg">x</em> and <em class="arg">y</em> directions
346 are rightward and downward, resp.; positive rotation is clockwise.</p>
348 <p> If the translation coefficients <em class="arg">t<sub>x</sub></em> and <em
349 class="arg">t<sub>y</sub></em> are omitted they default to 0,0. Therefore,
350 four parameters suffice for rotation and scaling without translation.</p>
352 <p>Scaling by the factors <em class="arg">s<sub>x</sub></em> and <em
353 class="arg">s<sub>y</sub></em> in the <em>x</em> and <em>y</em> directions,
354 respectively, is accomplished with the following.</p>
356 <p>See <a href="command-line-options.html#transform">-transform</a>, and the <a
357 href="command-line-options.html#distort">-distort</a> method '<code>Affineprojection</code> for more
361 <p class="crtsnip"> -affine <em class="arg">s<sub>x</sub></em>,0,0,<em
362 class="arg">s<sub>y</sub></em> </p>
364 <p>Translation by a displacement (<em class="arg">t<sub>x</sub></em>, <em
365 class="arg">t<sub>y</sub></em>) is accomplished like so:</p>
368 -affine 1,0,0,1,<em class="arg">t<sub>x</sub></em>,<em class="arg">t<sub>y</sub></em>
371 <p>Rotate clockwise about the origin (the upper left-hand corner) by an angle
372 <em>a</em> by letting <em>c</em> = cos(<em>a</em>), <em>s</em>
373 = sin(<em>a</em>), and using the following.</p>
376 -affine <em>c</em>,<em>s</em>,-<em>s</em>,<em>c</em>
379 <p>The cumulative effect of a sequence of <a href="command-line-options.html#affine" >-affine</a>
380 transformations can be accomplished by instead by a single <a href="command-line-options.html#affine"
381 >-affine</a> operation using the matrix equal to the product of the matrices
382 of the individual transformations.</p>
384 <p>An attempt is made to detect near-singular transformation matrices. If the
385 matrix determinant has a sufficiently small absolute value it is rejected.</p>
387 <div style="margin: auto;">
388 <h4><a id="alpha"></a>-alpha <em class="arg">type</em></h4>
391 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Gives control of the alpha/matte channel of an image.</td><td style='text-align:right;'></td></tr></table>
393 <p>Used to set a flag on an image indicating whether or not to use existing alpha
394 channel data, to create an alpha channel, or to perform other operations on the alpha channel. Choose the argument <em class="arg">type</em> from the list below.</p>
400 <th align="left" style="width: 8%">type</th>
401 <th align="left">Description</th>
405 <td valign="top"><code>Activate</code> or <code>On</code></td>
407 Enable the image's transparency channel. Note normally <code>Set</code>
408 should be used instead of this, unless you specifically need to
409 preserve existing (but specifically turned <code>Off</code>) transparency
413 <td valign="top"><code>Deactivate</code> or <code>Off</code></td>
415 Disables the image's transparency channel. Does not delete or change the
416 existing data, just turns off the use of that data.</td></tr>
419 <td valign="top"><code>Set</code></td>
421 Activates the alpha/matte channel. If it was previously turned off
422 then it also resets the channel to opaque. If the image already had
423 the alpha channel turned on, it will have no effect.</td></tr>
426 <td valign="top"><code>Opaque</code></td>
428 Enables the alpha/matte channel and forces it to be fully opaque.
432 <td valign="top"><code>Transparent</code></td>
434 Activates the alpha/matte channel and forces it to be fully
435 transparent. This effectively creates a fully transparent image the
436 same size as the original and with all its original RGB data still
437 intact, but fully transparent. </td></tr>
440 <td valign="top"><code>Extract</code></td>
442 Copies the alpha channel values into all the color channels and turns
443 '<code>Off</code>' the the image's transparency, so as to generate
444 a gray-scale mask of the image's shape. The alpha channel data is left
445 intact just deactivated. This is the inverse of '<code>Copy</code>'.
449 <td valign="top"><code>Copy</code></td>
451 Turns '<code>On</code>' the alpha/matte channel, then copies the
452 gray-scale intensity of the image, into the alpha channel, converting
453 a gray-scale mask into a transparent shaped mask ready to be colored
454 appropriately. The color channels are not modified. </td></tr>
457 <td valign="top"><code>Shape</code></td>
459 As per '<code>Copy</code>' but also colors the resulting shape mask with
460 the current background color. That is the RGB color channels is
461 replaced, with appropriate alpha shape.
465 <td valign="top"><code>Remove</code></td>
467 Composite the image over the background color.
471 <td valign="top"><code>Background</code></td>
473 Set any fully-transparent pixel to the background color, while leaving
474 it fully-transparent. This can make some image file formats, such as
475 PNG, smaller as the RGB values of transparent pixels are more uniform,
476 and thus can compress better.
481 <p>Note that while the obsolete <code>+matte</code> operation was the
482 same as "<code><a href="command-line-options.html#alpha" >-alpha</a> Off</code>", the <code>
483 >-matte</code> operation was the same as "<code><a href="command-line-options.html#alpha" >-alpha</a>
484 Set</code>" and not "<code><a href="command-line-options.html#alpha" >-alpha</a> On</code>". </p>
487 <div style="margin: auto;">
488 <h4><a id="annotate"></a>
489 -annotate <em class="arg">degrees</em> <em class="arg">text</em><br />
490 -annotate <em class="arg">Xdegrees</em>x<em class="arg">Ydegrees</em> <em
491 class="arg">text</em><br /> -annotate <em class="arg">Xdegrees</em>x<em
492 class="arg">Ydegrees</em> {+-}<em class="arg">t<sub>x</sub></em>{+-}<em
493 class="arg">t<sub>y</sub></em> <em class="arg">text</em></h4>
496 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Annotate an image with text.</td><td style='text-align:right;'></td></tr></table>
498 <p>This is a convenience for annotating an image with text. For more precise
499 control over text annotations, use <a href="command-line-options.html#draw">-draw</a>.</p>
502 <p>The values <em class="arg">Xdegrees</em> and <em class="arg">Ydegrees</em>
503 control the shears with respect to the , respectively, applied to the text,
504 while <em class="arg">t<sub>x</sub></em> and <em
505 class="arg">t<sub>y</sub></em> are offsets that give the location of the text
506 relative to the upper left corner of the image.</p>
508 <p>Using <a href="command-line-options.html#annotate">-annotate</a> <em class="arg">degrees</em>
509 or <a href="command-line-options.html#annotate">-annotate</a> <em class="arg">degrees</em>x<em
510 class="arg">degrees</em> produces an unsheared rotation of the text. The
511 direction of the rotation is positive, which means a clockwise rotation if <em
512 class="arg">degrees</em> is positive. (This conforms to the usual mathematical
513 convention once it is realized that the positive <em>y</em>–direction is
514 conventionally considered to be <em>downward</em> for images.)</p>
516 <p>The new (transformed) coordinates (<em class="arg">x'</em>, <em
517 class="arg">y'</em>) of a pixel at position (<em class="arg">x</em>, <em
518 class="arg">y</em>) in the image are calculated using the following matrix
519 equation.</p> <div class="eqn"><img alt="annotate transformation" src="../images/annotate.png"/></div>
521 <p>If <em class="arg">t<sub>x</sub></em> and <em
522 class="arg">t<sub>y</sub></em> are omitted, they default to 0. This makes the
523 bottom-left of the text becomes the upper-left corner of the image, which is
524 probably undesirable. Adding a <a href="command-line-options.html#gravity" >-gravity</a> option in this
525 case leads to nice results.</p>
527 <p>Text is any UTF-8 encoded character sequence. If <em class="arg">text</em>
528 is of the form '@mytext.txt', the text is read from the file
529 <code>mytext.txt</code>. Text in a file is taken literally; no embedded
530 formatting characters are recognized.</p>
532 <div style="margin: auto;">
533 <h4><a id="antialias"></a>-antialias</h4>
536 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Enable/Disable of the rendering of anti-aliasing pixels when
537 drawing fonts and lines.</td><td style='text-align:right;'></td></tr></table>
539 <p>By default, objects (e.g. text, lines, polygons, etc.) are antialiased when
540 drawn. Use <a href="command-line-options.html#antialias">+antialias</a> to disable the addition of
541 antialiasing edge pixels. This will then reduce the number of colors added to
542 an image to just the colors being directly drawn. That is, no mixed colors
543 are added when drawing such objects. </p>
545 <div style="margin: auto;">
546 <h4><a id="append"></a>-append</h4>
549 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Join current images vertically or horizontally.</td><td style='text-align:right;'></td></tr></table>
551 <p>This option creates a single longer image image, by joining all the current
552 images in sequence top-to-bottom. Use <a href="command-line-options.html#append">+append</a> to
553 stack images left-to-right. </p>
555 <p>If they are not of the same width, narrower images are padded with the
556 current <a href="command-line-options.html#background">-background</a> color setting, and their
557 position relative to each other can be controlled by the current <a
558 href="command-line-options.html#gravity">-gravity</a> setting. </p>
561 <div style="margin: auto;">
562 <h4><a id="attenuate"></a>-attenuate <em class="arg">value</em></h4>
565 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Lessen (or intensify) when adding noise to an image.</td><td style='text-align:right;'></td></tr></table>
567 <p>If unset the value is equivelent to 1.0, or a maximum noise addition</p>
569 <div style="margin: auto;">
570 <h4><a id="authenticate"></a>-authenticate <em class="arg">password</em></h4>
573 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Decrypt a PDF with a password.</td><td style='text-align:right;'></td></tr></table>
575 <p>Use this option to supply a <em class="arg">password</em> for decrypting
576 a PDF that has been encrypted using Microsoft Crypto API (MSC API). The
577 encrypting using the MSC API is not supported.</p>
579 <p>For a different encryption method, see <a href="command-line-options.html#encipher">-encipher</a>
580 and <a href="command-line-options.html#decipher">-decipher</a>. </p>
584 <div style="margin: auto;">
585 <h4><a id="auto-gamma"></a>-auto-gamma</h4>
588 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Automagically adjust gamma level of image.</td><td style='text-align:right;'></td></tr></table>
590 <p>This calculates the mean values of an image, then applies a calculated <a
591 href="command-line-options.html#gamma" >-gamma</a> adjustment so that is the mean color exists in the
592 image it will get a have a value of 50%. </p>
594 <p>This means that any solid 'gray' image becomes 50% gray. </p>
596 <p>This works well for real-life images with little or no extreme dark and
597 light areas, but tend to fail for images with large amounts of bright sky or
598 dark shadows. It also does not work well for diagrams or cartoon like images.
601 <p>It uses the <a href="command-line-options.html#channel" >-channel</a> setting, (including the
602 '<em>sync</em>' flag for channel synchronization), to determine which color
603 values is used and modified. As the default <a href="command-line-options.html#channel"
604 >-channel</a> setting is '<em>RGB,sync</em>', channels are modified
605 together by the same gamma value, preserving colors. </p>
609 <div style="margin: auto;">
610 <h4><a id="auto-level"></a>-auto-level</h4>
613 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Automagically adjust color levels of image.</td><td style='text-align:right;'></td></tr></table>
615 <p>This is a 'perfect' image normalization operator. It finds the exact
616 minimum and maximum color values in the image and then applies a <a
617 href="command-line-options.html#level" >-level</a> operator to stretch the values to the full range of
620 <p>The operator is not typically used for real-life images, image scans, or
621 JPEG format images, as a single 'out-rider' pixel can set a bad min/max values
622 for the <a href="command-line-options.html#level" >-level</a> operation. On the other hand it is the
623 right operator to use for color stretching gradient images being used to
624 generate Color lookup tables, distortion maps, or other 'mathematically'
627 <p>The operator is very similar to the <a href="command-line-options.html#normalize">-normalize</a>, <a
628 href="command-line-options.html#contrast-stretch" >-contrast-stretch</a>, and <a href="command-line-options.html#linear-stretch"
629 >-linear-stretch</a> operators, but without 'histogram binning' or 'clipping'
630 problems that these operators may have. That is <a href="command-line-options.html#auto-level"
631 >-auto-level</a> is the perfect or ideal version these operators. </p>
633 <p>It uses the <a href="command-line-options.html#channel" >-channel</a> setting, (including the
634 special '<em>sync</em>' flag for channel synchronization), to determine
635 which color values are used and modified. As the default <a
636 href="command-line-options.html#channel" >+channel</a> setting is '<em>RGB,sync</em>', the
637 '<em>sync</em>' ensures that the color channels will are modified
638 together by the same gamma value, preserving colors, and ignoring
642 <div style="margin: auto;">
643 <h4><a id="auto-orient"></a>-auto-orient</h4>
646 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>adjusts an image so that its orientation is suitable for viewing (i.e. top-left orientation).</td><td style='text-align:right;'></td></tr></table>
648 <p>This operator reads and resets the EXIF image profile setting 'Orientation'
649 and then performs the appropriate 90 degree rotation on the image to orient
650 the image, for correct viewing. </p>
652 <p>This EXIF profile setting is usually set using a gravity sensor in digital
653 camera, however photos taken directly downward or upward may not have an
654 appropriate value. Also images that have been orientation 'corrected' without
655 reseting this setting, may be 'corrected' again resulting in a incorrect
656 result. If the EXIF profile was previously stripped, the <a
657 href="command-line-options.html#auto-orient" >-auto-orient</a> operator will do nothing. </p>
660 <div style="margin: auto;">
661 <h4><a id="average"></a>-average</h4>
664 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Average a set of images.</td><td style='text-align:right;'></td></tr></table>
666 <p>An error results if the images are not identically sized.</p>
669 <div style="margin: auto;">
670 <h4><a id="backdrop"></a>-backdrop</h4>
673 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Display the image centered on a backdrop.</td><td style='text-align:right;'>[<a href="animate.html">animate</a>, <a href="display.html">display</a>]</td></tr></table>
675 <p>This backdrop covers the entire workstation screen and is useful for hiding
676 other X window activity while viewing the image. The color of the backdrop is
677 specified as the background color. The color is specified using the format
678 described under the <a href="command-line-options.html#fill">-fill</a> option.</p>
680 <div style="margin: auto;">
681 <h4><a id="background"></a>-background <em class="arg">color</em></h4>
684 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Set the background color.</td><td style='text-align:right;'></td></tr></table>
686 <p>The color is specified using the format described under the <a
687 href="command-line-options.html#fill">-fill</a> option. The default background color (if none is
688 specified or found in the image) is white.</p>
690 <div style="margin: auto;">
691 <h4><a id="bench"></a>-bench <em class="arg">iterations</em></h4>
694 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Measure performance.</td><td style='text-align:right;'></td></tr></table>
696 <p>Repeat the entire command for the given number of <em class="arg"
697 >iterations</em> and report the user-time and elapsed time. For instance,
698 consider the following command and its output. Modify the benchmark with the
699 -duration to run the benchmark for a fixed number of seconds and -concurrent
700 to run the benchmark in parallel (requires the OpenMP feature).</p>
702 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert logo: -resize 1000% -bench 5 logo.png</span><span class='crtout'>Performance[4]: 5i 0.875657ips 6.880u 0:05.710</span></p>
703 <p>In this example, 5 iterations were completed at 0.875657 iterations per
704 second, using 4 threads and 6.88 seconds of the user's allotted time, for
705 a total elapsed time of 5.71 seconds.</p>
707 <div style="margin: auto;">
708 <h4><a id="bias"></a>-bias <em class="arg">value</em>{<em class="arg">%</em>}</h4>
711 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Add bias when convolving an image.</td><td style='text-align:right;'></td></tr></table>
713 <p>This option shifts the output of <a href="command-line-options.html#convolve">‑convolve</a> so that
714 positive and negative results are relative to the specified bias value. </p>
716 <p>This is important for non-HDRI compilations of ImageMagick when dealing
717 with convolutions that contain negative as well as positive values. This is
718 especially the case with convolutions involving high pass filters or edge
719 detection. Without an output bias, the negative values are clipped at
722 <p>When using an ImageMagick with the HDRI compile-time setting, <a href="command-line-options.html#bias">‑bias</a> is not needed, as ImageMagick is able to store/handle any
723 negative results without clipping to the color value range
724 (0..QuantumRange).</p>
726 <p>See the discussion on HDRI implementations of ImageMagick on the page <a
727 href="high-dynamic-range.html" >High Dynamic-Range Images</a>. For more
728 about HDRI go the ImageMagick <a
729 href="http://www.imagemagick.org/Usage/basics/#hdri" >Usage</a> pages or this
731 href="http://en.wikipedia.org/wiki/High_dynamic_range_imaging">Wikipedia</a>
734 <div style="margin: auto;">
735 <h4><a id="black-point-compensation"></a>-black-point-compensation</h4>
738 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Use black point compensation.</td><td style='text-align:right;'></td></tr></table>
740 <div style="margin: auto;">
741 <h4><a id="black-threshold"></a>-black-threshold <em class="arg">value</em>{<em class="arg">%</em>}</h4>
744 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Force to black all pixels below the threshold while leaving all pixels at or above the threshold unchanged.</td><td style='text-align:right;'></td></tr></table>
746 <p> The threshold value can be given as a percentage or as an absolute integer
747 value within [0, <em class="QR">QuantumRange</em>] corresponding to the
748 desired <a href="command-line-options.html#channel">‑channel</a> value. See <a href="command-line-options.html#threshold">‑threshold</a>for more details on thresholds and resulting values. </p>
751 <div style="margin: auto;">
752 <h4><a id="blend"></a>-blend <em class="arg">geometry</em></h4>
755 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>blend an image into another by the given absolute value or percent.</td><td style='text-align:right;'>[<a href="composite.html">composite</a>]</td></tr></table>
757 <p>Blend will average the images together ('plus') according to the
758 percentages given and each pixels transparency. If only a single percentage
759 value is given it sets the weight of the composite or 'source' image, while
760 the background image is weighted by the exact opposite amount. That is a
761 <code>-blend 30%</code> merges 30% of the 'source' image with 70% of the
762 'destination' image. Thus it is equivalent to <code>-blend 30x70%</code>.</p>
765 <div style="margin: auto;">
766 <h4><a id="blue-primary"></a>-blue-primary <em class="arg">x</em>,<em class="arg">y</em></h4>
769 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Set the blue chromaticity primary point.</td><td style='text-align:right;'></td></tr></table>
771 <div style="margin: auto;">
772 <h4><a id="blue-shift"></a>-blue-shift <em class="arg">factor</em></h4>
775 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>simulate a scene at nighttime in the moonlight. Start with a factor of 1.5</td><td style='text-align:right;'></td></tr></table>
777 <div style="margin: auto;">
779 <div style="margin: auto;">
780 <h4><a id="blur"></a>-blur <em class="arg">radius</em><br />-blur <em class="arg">radius</em>x<em class="arg">sigma</em></h4>
783 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Reduce image noise and reduce detail levels.</td><td style='text-align:right;'></td></tr></table>
785 <p>Convolve the image with a Gaussian or normal distribution using the given
786 <em class="arg" >Sigma</em> value. The formula is:</p>
788 <div class="eqn"><img alt="gaussian distribution" width="243px" height="42px" src="../images/gaussian-blur.png"/>
791 <p>The <em class="arg" >Sigma</em> value is the important argument, and
792 determines the actual amount of blurring that will take place. </p>
794 <p>The <em class="arg" >Radius</em> is only used to determine the size of the
795 array which will hold the calculated Gaussian distribution. It should be an
796 integer. If not given, or set to zero, IM will calculate the largest possible
797 radius that will provide meaningful results for the Gaussian distribution.
800 <p>The larger the <em class="arg" >Radius</em> the slower the
801 operation is. However too small a <em class="arg" >Radius</em>, and sever
802 aliasing effects may result. As a guideline, <em class="arg" >Radius</em>
803 should be at least twice the <em class="arg" >Sigma</em> value, though three
804 times will produce a more accurate result. </p>
806 <p>This option differs from <a href="command-line-options.html#gaussian-blur">-gaussian-blur</a> simply
807 by taking advantage of the separability properties of the distribution. Here
808 we apply a single-dimensional Gaussian matrix in the horizontal direction,
809 then repeat the process in the vertical direction.</p>
811 <p>The <a href="command-line-options.html#virtual-pixel">-virtual-pixel</a> setting will determine how
812 pixels which are outside the image proper are blurred into the final result.
816 <div style="margin: auto;">
817 <h4>-blur <em class="arg">Width</em>[x<em class="arg">Height</em>[+<em class="arg">Angle</em>]]</h4>
820 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Variably blur and image according to the overlay mapping.</td><td style='text-align:right;'>[<a href="composite.html">composite</a>]</td></tr></table>
822 <p>Each pixel in the overlaid region is replaced with an Elliptical Weighted
823 Average (EWA) of the source image, scaled according to the grayscale
826 <p>The ellipse is weighted with sigma set to the given <em class="arg"
827 >Width</em> and <em class="arg" >Height</em>. The <em class="arg" >Height</em>
828 defaults to the <em class="arg" >Width</em> for a normal circular Gaussian
829 weighting. The <em class="arg" >Angle</em> will rotate the ellipse from
830 horizontal clock-wise. </p>
832 <p>The <a href="command-line-options.html#virtual-pixel">-virtual-pixel</a> setting will determine how
833 pixels which are outside the image proper are blurred into the final result.
837 <div style="margin: auto;">
838 <h4><a id="border"></a>-border <em class="arg">geometry</em></h4>
841 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Surround the image with a border of color. </td><td style='text-align:right;'></td></tr></table>
843 <p>Set the width and height using the <em class="arg">size</em> portion of the
844 <em class="arg">geometry</em> argument. See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument. Offsets are
847 <p>As of IM 6.7.8-8, the <em class="arg">geometry</em> arguments behave as follows:</p>
849 <table id="borderTable" class="doc">
850 <col width="20%"/> <col width="80%"/>
853 <th style="text-align:center"><em class="arg">size</em></th>
854 <th>General description</th>
859 <td><em class="arg">value</em></td>
860 <td>value is added to both left/right and top/bottom</td>
863 <td><em class="arg">value-x</em>x</td>
864 <td>value-x is added only to left/right and top/bottom are unchanged</td>
867 <td>x<em class="arg">value-y</em></td>
868 <td>value-y is added only to top/bottom and left/right are unchanged</td>
871 <td><em class="arg">value-x</em>x<em class="arg">value-y</em></td>
872 <td>value-x is added to left/right and value-y added to top/bottom</td>
875 <td><em class="arg">value-x</em>x<code>0</code></td>
876 <td>value-x is added only to left/right and top/bottom are unchanged</td>
879 <td><code>0</code>x<em class="arg">value-y</em></td>
880 <td>value-y is added only to top/bottom and left/right are unchanged</td>
887 <td><em class="arg">value</em>%</td>
888 <td>value % of width is added to left/right and value % of height is added to top/bottom</td>
891 <td><em class="arg">value-x</em>x%</td>
892 <td>value-x % of width is added to left/right and to top/bottom</td>
895 <td>x<em class="arg">value-y</em>%</td>
896 <td>value-y % of height is added to top/bottom and to left/right</td>
899 <td><em class="arg">value-x</em>%x<em class="arg">value-y</em>%</td>
900 <td>value-x % of width is added to left/right and value-y % of height is added to top/bottom</td>
903 <td><em class="arg">value-x</em>%x<code>0</code>%</td>
904 <td>value-x % of width is added to left/right and top/bottom are unchanged</td>
907 <td><code>0</code>%xvalue-y</em>%</td>
908 <td>value-y % of height is added to top/bottom and left/right are unchanged</td>
914 <p>Set the border color by preceding with the <a
915 href="command-line-options.html#bordercolor">-bordercolor</a> setting.</p>
917 <p>The <a href="command-line-options.html#border">-border</a> operation is affected by the current <a
918 href="command-line-options.html#compose">-compose</a> setting and assumes that this is using the default
919 '<code>Over</code>' composition method. It generates an image of the appropriate
920 size colors by the current <a href="command-line-options.html#bordercolor">-bordercolor</a> before
921 overlaying the original image in the center of this net image. This means that
922 with the default compose method of '<code>Over</code>' any transparent parts may
923 be replaced by the current <a href="command-line-options.html#bordercolor">-bordercolor</a> setting.</p>
924 <p>See also the <a href="command-line-options.html#frame">-frame</a> option, which has more
927 <div style="margin: auto;">
928 <h4><a id="bordercolor"></a>-bordercolor <em class="arg">color</em></h4>
931 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Set the border color.</td><td style='text-align:right;'></td></tr></table>
933 <p>The color is specified using the format described under the <a href="command-line-options.html#fill">-fill</a> option.</p>
935 <p>The default border color is <code>#DFDFDF</code>, <span style="background-color: #dfdfdf;">this shade of gray</span>.</p>
937 <div style="margin: auto;">
938 <h4><a id="borderwidth"></a>-borderwidth <em class="arg">geometry</em> </h4>
941 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Set the border width.</td><td style='text-align:right;'>[<a href="animate.html">animate</a>, <a href="display.html">display</a>]</td></tr></table>
943 <div style="margin: auto;">
944 <h4><a id="brightness-contrast"></a>-brightness-contrast <em class="arg">brightness</em><br />-brightness-contrast <em class="arg">brightness</em>{x<em class="arg">contrast</em>}{<em class="arg">%</em>}}</h4>
947 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Adjust the brightness and/or contrast of the image.</td><td style='text-align:right;'></td></tr></table>
949 <p>Brightness and Contrast values apply changes to the input image. They are
950 not absolute settings. A brightness or contrast value of zero means no change.
951 The range of values is -100 to +100 on each. Positive values increase the
952 brightness or contrast and negative values decrease the brightness or contrast.
953 To control only contrast, set the brightness=0. To control only brightness,
954 set contrast=0 or just leave it off.</p>
956 <p>You may also use <a href="command-line-options.html#fill">-channel</a> to control which channels to
957 apply the brightness and/or contrast change. The default is to apply the same
958 transformation to all channels.</p>
960 <p>Brightness and Contrast arguments are converted to offset and slope of a
961 linear transform and applied
962 using <a href="command-line-options.html#fill">-function polynomial "slope,offset"</a>.</p>
964 <p>The slope varies from 0 at contrast=-100 to almost vertical at
965 contrast=+100. For brightness=0 and contrast=-100, the result are totally
966 midgray. For brightness=0 and contrast=+100, the result will approach but
967 not quite reach a threshold at midgray; that is the linear transformation
968 is a very steep vertical line at mid gray.</p>
970 <p>Negative slopes, i.e. negating the image, are not possible with this
971 function. All achievable slopes are zero or positive.</p>
973 <p>The offset varies from -0.5 at brightness=-100 to 0 at brightness=0 to +0.5
974 at brightness=+100. Thus, when contrast=0 and brightness=100, the result is
975 totally white. Similarly, when contrast=0 and brightness=-100, the result is
978 <p>As the range of values for the arguments are -100 to +100, adding the '%'
979 symbol is no different than leaving it off.</p>
981 <div style="margin: auto;">
982 <h4><a id="cache"></a>-cache <em class="arg">threshold</em></h4>
985 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>(This option has been replaced by the <a href='command-line-options.html#limit'>-limit</a> option.)</td><td style='text-align:right;'></td></tr></table>
987 <div style="margin: auto;">
988 <h4><a id="caption"></a>-caption <em class="arg">string</em></h4>
991 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Assign a caption to an image.</td><td style='text-align:right;'></td></tr></table>
993 <p>This option sets the caption meta-data of an image read in after this
994 option has been given. To modify a caption of images already in memory use
995 "<code><a href="command-line-options.html#set">-set</a> caption</code>". </p>
997 <p>The caption can contain special format characters listed in the <a
998 href="escape.html">Format and
999 Print Image Properties</a>. These attributes are expanded when the caption
1000 is finally assigned to the individual images. </p>
1002 <p>If the first character of <em class="arg">string</em> is <em
1003 class="arg">@</em>, the image caption is read from a file titled by the
1004 remaining characters in the string. Comments read in from a file are literal;
1005 no embedded formatting characters are recognized.</p>
1007 <p>Caption meta-data is not visible on the image itself. To do that use the
1008 <a href="command-line-options.html#annotate">-annotate</a> or <a href="command-line-options.html#draw">-draw</a> options
1014 -caption "%m:%f %wx%h" bird.miff
1017 <p>produces an image caption of <code>MIFF:bird.miff 512x480</code> (assuming
1018 that the image <code>bird.miff</code> has a width of 512 and a height of
1022 <div style="margin: auto;">
1023 <h4><a id="cdl"></a>-cdl <em class="arg">filename</em></h4>
1026 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>color correct with a color decision list.</td><td style='text-align:right;'></td></tr></table>
1028 <p>Here is an example color correction collection:</p>
1031 <?xml version="1.0" encoding="UTF-8"?>
1032 <ColorCorrectionCollection xmlns="urn:ASC:CDL:v1.2">
1033 <ColorCorrection id="cc06668">
1035 <Slope> 0.9 1.2 0.5 </Slope>
1036 <Offset> 0.4 -0.5 0.6 </Offset>
1037 <Power> 1.0 0.8 1.5 </Power>
1040 <Saturation> 0.85 </Saturation>
1042 </ColorCorrection>
1043 </ColorCorrectionCollection>
1046 <div style="margin: auto;">
1047 <h4><a id="channel"></a>-channel <em class="arg">type</em></h4>
1050 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Specify those image color channels to which subsequent operators are limited.</td><td style='text-align:right;'></td></tr></table>
1052 <p>Choose from: <code>Red</code>, <code>Green</code>, <code>Blue</code>,
1053 <code>Alpha</code>, <code>Cyan</code>, <code>Magenta</code>, <code>Yellow</code>,
1054 <code>Black</code>, <code>Opacity</code>, <code>Index</code>, <code>RGB</code>,
1055 <code>RGBA</code>, <code>CMYK</code>, or <code>CMYKA</code>.</p>
1057 <p>The channels above can also be specified as a comma-separated list or can be
1058 abbreviated as a concatenation of the letters '<code>R</code>', '<code>G</code>',
1059 '<code>B</code>', '<code>A</code>', '<code>O</code>', '<code>C</code>',
1060 '<code>M</code>', '<code>Y</code>', '<code>K</code>'.
1062 For example, to only select the <code>Red</code> and <code>Blue</code> channels
1063 you can either use </p>
1067 <p>or you can use the short hand form</p>
1072 <p>All the channels that are present in an image can be specified using the
1073 special channel type <code>All</code>. Not all operators are 'channel capable',
1074 but generally any operators that are generally 'grey-scale' image operators,
1075 will understand this setting. See individual operator documentation. </p>
1079 <p>On top of the normal channel selection an extra flag can be specified,
1080 '<code>Sync</code>'. This is turned on by default and if set means that
1081 operators that understand this flag should perform: cross-channel
1082 synchronization of the channels. If not specified, then most grey-scale
1083 operators will apply their image processing operations to each individual
1084 channel (as specified by the rest of the <a href="command-line-options.html#channel">-channel</a>
1085 setting) completely independently from each other. </p>
1087 <p>For example for operators such as <a href="command-line-options.html#auto-level">-auto-level</a> and
1088 <a href="command-line-options.html#auto-gamma">-auto-gamma</a> the color channels are modified
1089 together in exactly the same way so that colors will remain in-sync. Without
1090 it being set, then each channel is modified separately and
1091 independently, which may produce color distortion. </p>
1093 <p>The <a href="command-line-options.html#morphology">-morphology</a> '<code>Convolve</code>' method
1094 and the <a href="command-line-options.html#compose">-compose</a> mathematical methods, also understands
1095 the '<code>Sync</code>' flag to modify the behaviour of pixel colors according
1096 to the alpha channel (if present). That is to say it will modify the image
1097 processing with the understanding that fully-transparent colors should not
1098 contribute to the final result. </p>
1100 <p>Basically, by default, operators work with color channels in synchronous, and
1101 treats transparency as special, unless the <a href="command-line-options.html#channel">-channel</a>
1102 setting is modified so as to remove the effect of the '<code>Sync</code>' flag.
1103 How each operator does this depends on that operators current implementation.
1104 Not all operators understands this flag at this time, but that is changing.
1107 <p>To print a complete list of channel types, use <a href="command-line-options.html#list">-list
1112 <p>By default, ImageMagick sets <a href="command-line-options.html#channel">-channel</a> to the value
1113 '<code>RGBK,sync</code>', which specifies that operators act on all color
1114 channels except the transparency channel, and that all the color channels are
1115 to be modified in exactly the same way, with an understanding of transparency
1116 (depending on the operation being applied). The 'plus' form <a
1117 href="command-line-options.html#channel" >+channel</a> will reset the value back to this default. </p>
1119 <p>Options that are affected by the <a href="command-line-options.html#channel" >-channel</a> setting
1120 include the following.
1122 <a href="command-line-options.html#auto-gamma">-auto-gamma</a>,
1123 <a href="command-line-options.html#auto-level">-auto-level</a>,
1124 <a href="command-line-options.html#black-threshold">-black-threshold</a>,
1125 <a href="command-line-options.html#blur">-blur</a>,
1126 <a href="command-line-options.html#clamp">-clamp</a>,
1127 <a href="command-line-options.html#clut">-clut</a>,
1128 <a href="command-line-options.html#combine">-combine</a>,
1129 <a href="command-line-options.html#composite">-composite</a> (Mathematical compose methods only),
1130 <a href="command-line-options.html#convolve">-convolve</a>,
1131 <a href="command-line-options.html#contrast-stretch">-contrast-stretch</a>,
1132 <a href="command-line-options.html#evaluate">-evaluate</a>,
1133 <a href="command-line-options.html#function">-function</a>,
1134 <a href="command-line-options.html#fx">-fx</a>,
1135 <a href="command-line-options.html#gaussian-blur">-gaussian-blur</a>,
1136 <a href="command-line-options.html#hald-clut">-hald-clut</a>,
1137 <a href="command-line-options.html#motion-blur">-motion-blur</a>,
1138 <a href="command-line-options.html#morphology">-morphology</a>,
1139 <a href="command-line-options.html#negate">-negate</a>,
1140 <a href="command-line-options.html#normalize">-normalize</a>,
1141 <a href="command-line-options.html#ordered-dither">-ordered-dither</a>,
1142 <a href="command-line-options.html#radial-blur">-radial-blur</a>,
1143 <a href="command-line-options.html#random-threshold">-random-threshold</a>,
1144 <a href="command-line-options.html#separate">-separate</a>,
1145 <a href="command-line-options.html#threshold">-threshold</a>, and
1146 <a href="command-line-options.html#white-threshold">-white-threshold</a>.
1149 <p>Warning, some operators behave differently when the <a href="command-line-options.html#channel"
1150 >+channel</a> default setting is in effect, verses ANY user defined <a
1151 href="command-line-options.html#channel" >-channel</a> setting (including the equivalent of the
1152 default). These operators have yet to be made to understand the newer 'Sync'
1155 <p>For example <a href="command-line-options.html#threshold">-threshold</a> will by default gray-scale
1156 the image before thresholding, if no <a href="command-line-options.html#channel" >-channel</a> setting
1157 has been defined. This is not 'Sync flag controlled, yet. </p>
1159 <p>Also some operators such as <a href="command-line-options.html#blur">-blur</a>, <a
1160 href="command-line-options.html#gaussian-blur">-gaussian-blur</a>, will modify their handling of the
1161 color channels if the '<code>alpha</code>' channel is also enabled by <a
1162 href="command-line-options.html#channel" >-channel</a>. Generally this done to ensure that
1163 fully-transparent colors are treated as being fully-transparent, and thus any
1164 underlying 'hidden' color has no effect on the final results. Typically
1165 resulting in 'halo' effects. The newer <a href="command-line-options.html#morphology">-morphology</a>
1166 convolution equivalents however does have a understanding of the 'Sync' flag
1167 and will thus handle transparency correctly by default. </p>
1169 <p>As a alpha channel is optional within images, some operators will read the
1170 color channels of an image as a greyscale alpha mask, when the image has no
1171 alpha channel present, and the <a href="command-line-options.html#channel" >-channel</a> setting tells
1172 the operator to apply the operation using alpha channels. The <a
1173 href="command-line-options.html#clut">-clut</a> operator is a good example of this. </p>
1177 <div style="margin: auto;">
1178 <h4><a id="charcoal"></a>-charcoal <em class="arg">factor</em></h4>
1181 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Simulate a charcoal drawing.</td><td style='text-align:right;'></td></tr></table>
1183 <div style="margin: auto;">
1184 <h4><a id="chop"></a>-chop <em class="arg">geometry</em></h4>
1187 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Remove pixels from the interior of an image.</td><td style='text-align:right;'></td></tr></table>
1189 <p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument. The <em class="arg">width</em>
1190 and <em class="arg">height</em> given in the of the <em class="arg">size</em>
1191 portion of the <em class="arg">geometry</em> argument give the number of
1192 columns and rows to remove. The <em class="arg">offset</em> portion of
1193 the <em class="arg">geometry</em> argument is influenced by
1194 a <a href="command-line-options.html#gravity">-gravity</a> setting, if present.</p>
1196 <p>The <a href="command-line-options.html#chop">-chop</a> option removes entire rows and columns,
1197 and moves the remaining corner blocks leftward and upward to close the gaps.</p>
1199 <p>While it can remove internal rows and columns of pixels, it is more
1200 typically used with as <a href="command-line-options.html#gravity">-gravity</a> setting and zero
1201 offsets so as to remove a single edge from an image. Compare this to <a
1202 href="command-line-options.html#shave" >-shave</a> which removes equal numbers of pixels from oppisite
1203 sides of the image. </p>
1205 <p>Using <a href="command-line-options.html#chop">-chop</a> effectively undoes the results of a <a
1206 href="command-line-options.html#splice">-splice</a> that was given the same <em
1207 class="arg">geometry</em> and <a href="command-line-options.html#gravity">-gravity</a> settings. </p>
1209 <div style="margin: auto;">
1210 <h4><a id="clamp"></a>-clamp</h4>
1213 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>set each pixel whose value is below zero to zero and any the pixel whose value is above the quantum range to the quantum range (e.g. 65535) otherwise the pixel value remains unchanged.</td><td style='text-align:right;'></td></tr></table>
1215 <div style="margin: auto;">
1216 <h4><a id="clip"></a>-clip</h4>
1219 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Apply the clipping path if one is present.</td><td style='text-align:right;'></td></tr></table>
1221 <p>If a clipping path is present, it is applied to subsequent operations.</p>
1223 <p>For example, in the command</p>
1225 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert cockatoo.tif -clip -negate negated.tif</span></p>
1226 <p>only the pixels within the clipping path are negated.</p>
1228 <p>The <a href="command-line-options.html#clip">-clip</a> feature requires SVG support. If the SVG
1229 delegate library is not present, the option is ignored.</p>
1231 <p>Use <a href="command-line-options.html#clip">+clip</a> to disable clipping for subsequent operations.</p>
1233 <div style="margin: auto;">
1234 <h4><a id="clip-mask"></a>-clip-mask</h4>
1237 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Clip the image as defined by this mask.</td><td style='text-align:right;'></td></tr></table>
1239 <p>Use the alpha channel of the current image as a mask. Any areas that is
1240 white is not modified by any of the 'image processing operators' that follow,
1241 until the mask is removed. Pixels in the black areas of the clip mask are
1242 modified per the requirements of the operator. </p>
1244 <p>In some ways this is similar to (though not the same) as defining
1245 a rectangular <a href="command-line-options.html#region" >-region</a>, or using the negative of the
1246 mask (third) image in a three image <a href="command-line-options.html#composite" >-composite</a>,
1249 <p>Use <a href="command-line-options.html#clip-mask">+clip-mask</a> to disable clipping for subsequent operations.</p>
1251 <div style="margin: auto;">
1252 <h4><a id="clip-path"></a>-clip-path <em class="arg">id</em></h4>
1255 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Clip along a named path from the 8BIM profile.</td><td style='text-align:right;'></td></tr></table>
1257 <p>This is identical to <a href="command-line-options.html#clip">-clip</a> except choose a specific clip path in the event the image has more than one path available. </p>
1259 <p>Use <a href="command-line-options.html#clip-path">+clip-path</a> to disable clipping for subsequent operations.</p>
1261 <div style="margin: auto;">
1262 <h4><a id="clone"></a>-clone <em class="arg">index(s)</em></h4>
1265 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>make a clone of an image (or images).</td><td style='text-align:right;'></td></tr></table>
1267 <p>Inside parenthesis (where the operator is normally used) it will make a
1268 clone of the images from the last 'pushed' image sequence, and adds them to
1269 the end of the current image sequence. Outside parenthesis
1270 (not recommended) it clones the images from the current image sequence. </p>
1272 <p>Specify the image by its index in the sequence. The first image is index
1273 0. Negative indexes are relative to the end of the sequence; for
1274 example, <code>−1</code>
1275 represents the last image of the sequence. Specify a range of images with a
1276 dash (e.g. <code>0−4</code>). Separate multiple indexes with commas but no
1277 spaces (e.g. <code>0,2,5</code>). A value of '<code>0−−1</code> will
1278 effectively clone all the images. </p>
1280 <p>The <a href="command-line-options.html#clone">+clone</a> will simply make a copy of the last image
1281 in the image sequence, and is thus equivalent to using a argument of
1282 '<code>−1</code>'. </p>
1284 <div style="margin: auto;">
1285 <h4><a id="clut"></a>-clut</h4>
1288 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Replace the channel values in the first image using each
1289 corresponding channel in the second image as a <b>c</b>olor
1290 <b>l</b>ook<b>u</b>p <b>t</b>able.</td><td style='text-align:right;'></td></tr></table>
1292 <p>The second (LUT) image is ordinarily a gradient image containing the
1293 histogram mapping of how each channel should be modified. Typically it is a
1294 either a single row or column image of replacement color values. If larger
1295 than a single row or column, values are taken from a diagonal line from
1296 top-left to bottom-right corners.</p>
1298 <p>The lookup is further controlled by the <a
1299 href="command-line-options.html#interpolate">-interpolate</a> setting, which is especially handy for an
1300 LUT which is not the full length needed by the ImageMagick installed Quality
1301 (Q) level. Good settings for this are the '<code>bilinear</code>' and
1302 '<code>bicubic</code>' interpolation settings, which give smooth color
1303 gradients, and the '<code>integer</code>' setting for a direct, unsmoothed
1304 lookup of color values. </p>
1306 <p>This operator is especially suited to replacing a grayscale image with a
1307 specific color gradient from the CLUT image. </p>
1309 <p>Only the channel values defined by the <a href="command-line-options.html#channel">-channel</a>
1310 setting will have their values replaced. In particular, since the default <a
1311 href="command-line-options.html#channel">-channel</a> setting is <code>RGB</code>, this means that
1312 transparency (alpha/matte channel) is not affected, unless the <a
1313 href="command-line-options.html#channel">-channel</a> setting is modified. When the alpha channel is
1314 set, it is treated by the <a href="command-line-options.html#clut" >-clut</a> operator in the same way
1315 as the other channels, implying that alpha/matte values are replaced using the
1316 alpha/matte values of the original image. </p>
1318 <p>If either the image being modified, or the lookup image, contains no
1319 transparency (i.e. <a href="command-line-options.html#alpha" >-alpha</a> is turned 'off') but the <a
1320 href="command-line-options.html#channel">-channel</a> setting includes alpha replacement, then it is
1321 assumed that image represents a gray-scale gradient which is used for the
1322 replacement alpha values. That is you can use a gray-scale CLUT image to
1323 adjust a existing images alpha channel, or you can color a gray-scale image
1324 using colors form CLUT containing the desired colors, including transparency.
1327 <p>See also <a href="command-line-options.html#hald-clut" >-hald-clut</a> which replaces colors
1328 according to the lookup of the full color RGB value from a 2D representation
1329 of a 3D color cube. </p>
1332 <div style="margin: auto;">
1333 <h4><a id="coalesce"></a>-coalesce</h4>
1336 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Fully define the look of each frame of an GIF animation sequence, to form a 'film strip' animation.</td><td style='text-align:right;'></td></tr></table>
1338 <p>Overlay each image in an image sequence according to
1339 its <a href="command-line-options.html#dispose">-dispose</a> meta-data, to reproduce the look of
1340 an animation at each point in the animation sequence. All images should be
1341 the same size, and are assigned appropriate GIF disposal settings for the
1342 animation to continue working as expected as a GIF animation. Such frames
1343 are more easily viewed and processed than the highly optimized GIF overlay
1346 <p>The animation can be re-optimized after processing using
1347 the <a href="command-line-options.html#layers">-layers</a> method '<code>optimize</code>', although
1348 there is no guarantee that the restored GIF animation optimization is
1349 better than the original. </p>
1352 <div style="margin: auto;">
1353 <h4><a id="colorize"></a>-colorize <em class="arg">value</em></h4>
1356 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Colorize the image by an amount specified by <em class="arg">value</em> using the color specified by the most recent <a href="command-line-options.html#fill" >-fill</a> setting.</td><td style='text-align:right;'></td></tr></table>
1358 <p>Specify the amount of colorization as a percentage. Separate colorization
1359 values can be applied to the red, green, and blue channels of the image with
1360 a comma-delimited list of colorization
1361 values (e.g., <code>-colorize 0,0,50</code>).</p>
1363 <div style="margin: auto;">
1364 <h4><a id="colormap"></a>-colormap <em class="arg">type</em></h4>
1367 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Define the colormap type.</td><td style='text-align:right;'>[<a href="animate.html">animate</a>, <a href="display.html">display</a>]</td></tr></table>
1369 <p>The <em class="arg">type</em> can be <code>shared</code> or <code>private</code>.</p>
1371 <p>This option only applies when the default X server visual
1372 is <code>PseudoColor</code> or <code>GrayScale</code>. Refer
1373 to <a href="command-line-options.html#visual">-visual</a> for more details. By default,
1374 a shared colormap is allocated. The image shares colors with
1375 other X clients. Some image colors could be approximated,
1376 therefore your image may look very different than intended.
1377 If <code>private</code> is chosen, the image colors appear exactly
1378 as they are defined. However, other clients may go <em>technicolor</em>
1379 when the image colormap is installed.</p>
1381 <div style="margin: auto;">
1382 <h4><a id="colors"></a>-colors <em class="arg">value</em></h4>
1385 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Set the preferred number of colors in the image.</td><td style='text-align:right;'></td></tr></table>
1387 <p>The actual number of colors in the image may be less than your request,
1388 but never more. Note that this a color reduction option. Images with fewer
1389 unique colors than specified by <em class="arg">value</em> will have any
1390 duplicate or unused colors removed. The ordering of an existing color
1391 palette may be altered. When converting an image from color to grayscale,
1392 it is more efficient to convert the image to the gray colorspace before
1393 reducing the number of colors. Refer to
1394 the <a href="quantize.html">
1395 color reduction algorithm</a> for more details.</p>
1397 <div style="margin: auto;">
1398 <h4><a id="color-matrix"></a>-color-matrix <em class="arg">matrix</em></h4>
1401 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>apply color correction to the image.</td><td style='text-align:right;'></td></tr></table>
1403 <p>This option permits saturation changes, hue rotation, luminance to alpha,
1404 and various other effects. Although variable-sized transformation matrices
1405 can be used, typically one uses a 5x5 matrix for an RGBA image and a 6x6
1406 for CMYKA (or RGBA with offsets). The matrix is similar to those used by
1407 Adobe Flash except offsets are in column 6 rather than 5 (in support of
1408 CMYKA images) and offsets are normalized (divide Flash offset by 255).</p>
1410 <p>As an example, to add contrast to an image with offsets, try this command:</p>
1413 convert kittens.jpg -color-matrix \
1414 " 1.5 0.0 0.0 0.0, 0.0, -0.157 \
1415 0.0 1.5 0.0 0.0, 0.0, -0.157 \
1416 0.0 0.0 1.5 0.0, 0.0, -0.157 \
1417 0.0 0.0 0.0 1.0, 0.0, 0.0 \
1418 0.0 0.0 0.0 0.0, 1.0, 0.0 \
1419 0.0 0.0 0.0 0.0, 0.0, 1.0" kittens.png
1421 <div style="margin: auto;">
1422 <h4><a id="colorspace"></a>-colorspace <em class="arg">value</em></h4>
1425 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Set the image colorspace.</td><td style='text-align:right;'></td></tr></table>
1434 OHTA Rec601YCbCr Rec709YCbCr RGB
1435 scRGB sRGB Transparent XYZ
1440 <p>To print a complete list of colorspaces, use <a href="command-line-options.html#list">-list colorspace</a>.</p>
1442 <p>For a more accurate color conversion to or from the linear RGB, CMYK, or grayscale colorspaces, use the <a href="command-line-options.html#profile">-profile</a> option. Note, ImageMagick assumes the sRGB colorspace if the image format does not indicate otherwise. For colorspace conversion, the gamma function is first removed to produce linear RGB.</p>
1445 <caption>Conversion of RGB to Other Color Spaces</caption>
1446 <tr><th align="left" valign="middle">CMY</th></tr>
1447 <tr><td align="left" valign="middle">C=<em class="QR">QuantumRange</em>−R</td></tr>
1448 <tr><td align="left" valign="middle">M=<em class="QR">QuantumRange</em>−G</td></tr>
1449 <tr><td align="left" valign="middle">Y=<em class="QR">QuantumRange</em>−B</td></tr>
1450 <tr><th align="left" valign="middle">CMYK — starts with CMY from above</th></tr>
1451 <tr><td align="left" valign="middle">K=min(C,Y,M)</td></tr>
1452 <tr><td align="left" valign="middle">C=<em class="QR">QuantumRange</em>*(C−K)/(<em class="QR">QuantumRange</em>−K)</td></tr>
1453 <tr><td align="left" valign="middle">M=<em class="QR">QuantumRange</em>*(M−K)/(<em class="QR">QuantumRange</em>−K)</td></tr>
1454 <tr><td align="left" valign="middle">Y=<em class="QR">QuantumRange</em>*(Y−K)/(<em class="QR">QuantumRange</em>−K)</td></tr>
1456 <tr><th align="left" valign="middle">Gray</th></tr>
1457 <tr><td align="left" valign="middle">Gray = 0.298839*R+0.586811*G+0.114350*B</td></tr>
1459 <tr><th align="left" valign="middle">HSB — Hue, Saturation, Brightness; like a cone peak downward</th></tr>
1460 <tr><td align="left" valign="middle">H=angle around perimeter (0 to 360 deg); H=0 is red; increasing angles toward green</td></tr>
1461 <tr><td align="left" valign="middle">S=distance from axis outward</td></tr>
1462 <tr><td align="left" valign="middle">B=distance along axis from bottom upward; B=max(R,G,B); <em>intensity-like</em></td></tr>
1464 <tr><th align="left" valign="middle">HSL — Hue, Saturation, Lightness; like a double cone end-to-end with peaks at very top and bottom</th></tr>
1465 <tr><td align="left" valign="middle">H=angle around perimeter (0 to 360 deg); H=0 is red; increasing angles toward green</td></tr>
1466 <tr><td align="left" valign="middle">S=distance from axis outward</td></tr>
1467 <tr><td align="left" valign="middle">L=distance along axis from bottom upward; L=0.5*max(R,G,B) + 0.5*min(R,G,B); <em>intensity-like</em></td></tr>
1469 <tr><th align="left" valign="middle">HWB — Hue, Whiteness, Blackness</th></tr>
1470 <tr><td align="left" valign="middle">Hue (complicated equation)</td></tr>
1471 <tr><td align="left" valign="middle">Whiteness (complicated equation)</td></tr>
1472 <tr><td align="left" valign="middle">Blackness (complicated equation)</td></tr>
1474 <tr><th align="left" valign="middle">LAB</th></tr>
1475 <tr><td align="left" valign="middle">L (complicated equation relating X,Y,Z)</td></tr>
1476 <tr><td align="left" valign="middle">A (complicated equation relating X,Y,Z)</td></tr>
1477 <tr><td align="left" valign="middle">B (complicated equation relating X,Y,Z)</td></tr>
1479 <tr><th align="left" valign="middle">LOG</th></tr>
1480 <tr><td align="left" valign="middle">I1 (complicated equation involving logarithm of R)</td></tr>
1481 <tr><td align="left" valign="middle">I2 (complicated equation involving logarithm of G)</td></tr>
1482 <tr><td align="left" valign="middle">I3 (complicated equation involving logarithm of B)</td></tr>
1484 <tr><th align="left" valign="middle">OHTA — approximates principal components transformation</th></tr>
1485 <tr><td align="left" valign="middle">I1=0.33333*R+0.33334*G+0.33333*B; <em>intensity-like</em></td></tr>
1486 <tr><td align="left" valign="middle">I2=(0.50000*R+0.00000*G−0.50000*B)*(<em class="QR">QuantumRange</em>+1)/2</td></tr>
1487 <tr><td align="left" valign="middle">I3=(−0.25000*R+0.50000*G−0.25000*B)*(<em class="QR">QuantumRange</em>+1)/2</td></tr>
1489 <tr><th align="left" valign="middle">Rec601Luma</th></tr>
1490 <tr><td align="left" valign="middle">Gray = 0.298839*R+0.586811*G+0.114350*B</td></tr>
1492 <tr><th align="left" valign="middle">Rec601YCbCr</th></tr>
1493 <tr><td align="left" valign="middle">Y=0.2988390*R+0.5868110*G+0.1143500*B; <em>intensity-like</em></td></tr>
1494 <tr><td align="left" valign="middle">Cb=(−0.168736*R-0.331264*G+0.500000*B)*(<em class="QR">QuantumRange</em>+1)/2</td></tr>
1495 <tr><td align="left" valign="middle">Cr=(0.500000*R−0.418688*G−0.081312*B)*(<em class="QR">QuantumRange</em>+1)/2</td></tr>
1497 <tr><th align="left" valign="middle">Rec709Luma</th></tr>
1498 <tr><td align="left" valign="middle">Gray=0.212656*R+0.715158*G+0.072186*B</td></tr>
1500 <tr><th align="left" valign="middle">Rec709YCbCr</th></tr>
1501 <tr><td align="left" valign="middle">Y=0.212656*R+0.715158*G+0.072186*B; <em>intensity-like</em></td></tr>
1502 <tr><td align="left" valign="middle">Cb=(−0.114572*R−0.385428*G+0.500000*B)+(<em class="QR">QuantumRange</em>+1)/2</td></tr>
1503 <tr><td align="left" valign="middle">Cr=(0.500000*R−0.454153*G−0.045847*B)+(<em class="QR">QuantumRange</em>+1)/2</td></tr>
1505 <tr><th align="left" valign="middle">sRGB</th></tr>
1506 <tr><td align="left" valign="middle">if R ≤ .0.0031308 then Rs=R/12.92 else Rs=1.055 R ^ (1.0 / 2.4) ? 0.055</td></tr>
1507 <tr><td align="left" valign="middle">if G ≤ .0.0031308 then Gs=B/12.92 else Gs=1.055 R ^ (1.0 / 2.4) ? 0.055</td></tr>
1508 <tr><td align="left" valign="middle">if B ≤ .0.0031308 then Bs=B/12.92 else Bs=1.055 R ^ (1.0 / 2.4) ? 0.055</td></tr>
1510 <tr><th align="left" valign="middle">XYZ</th></tr>
1511 <tr><td align="left" valign="middle">X=0.4124240*R+0.3575790*G+0.1804640*B</td></tr>
1512 <tr><td align="left" valign="middle">Y=0.212656*R+0.715158*G+0.0721856*B</td></tr>
1513 <tr><td align="left" valign="middle">Z=0.0193324*R+0.1191930*G+0.9504440*B</td></tr>
1515 <tr><th align="left" valign="middle">YCC</th></tr>
1516 <tr><td align="left" valign="middle">Y=(0.298839*R+0.586811*G+0.114350*B) (with complicated scaling); <em>intensity-like</em></td></tr>
1517 <tr><td align="left" valign="middle">C1=(−0.298839*R−0.586811*G+0.88600*B) (with complicated scaling)</td></tr>
1518 <tr><td align="left" valign="middle">C2=(0.70100*R−0.586811*G−0.114350*B) (with complicated scaling)</td></tr>
1520 <tr><th align="left" valign="middle">YCbCr</th></tr>
1521 <tr><td align="left" valign="middle">Y=0.2988390*R+0.5868110*G+0.1143500*B; <em>intensity-like</em></td></tr>
1522 <tr><td align="left" valign="middle">Cb=(−0.168736*R−0.331264*G+0.500000*B)*(<em class="QR">QuantumRange</em>+1)/2</td></tr>
1523 <tr><td align="left" valign="middle">Cr=(0.500000*R−0.418688*G−0.081312*B)*(<em class="QR">QuantumRange</em>+1)/2</td></tr>
1525 <tr><th align="left" valign="middle">YIQ</th></tr>
1526 <tr><td align="left" valign="middle">Y=0.298839*R+0.586811*G+0.114350*B; <em>intensity-like</em></td></tr>
1527 <tr><td align="left" valign="middle">I=(0.59600*R−0.27400*G−0.32200*B)*(<em class="QR">QuantumRange</em>+1)/2</td></tr>
1528 <tr><td align="left" valign="middle">Q=(0.21100*R−0.52300*G+0.31200*B)*(<em class="QR">QuantumRange</em>+1)/2</td></tr>
1530 <tr><th align="left" valign="middle">YPbPr</th></tr>
1531 <tr><td align="left" valign="middle">Y=0.2988390*R+0.5868110*G+0.1143500*B; <em>intensity-like</em></td></tr>
1532 <tr><td align="left" valign="middle">Pb=(−0.168736*R−0.331264*G+0.500000*B)*(<em class="QR">QuantumRange</em>+1)/2</td></tr>
1533 <tr><td align="left" valign="middle">Pr=(0.500000*R−0.418688*G−0.081312*B)*(<em class="QR">QuantumRange</em>+1)/2</td></tr>
1535 <tr><th align="left" valign="middle">YUV</th></tr>
1536 <tr><td align="left" valign="middle">Y=0.298839*R+0.586811*G+0.114350*B; <em>intensity-like</em></td></tr>
1537 <tr><td align="left" valign="middle">U=(−0.14740*R−0.28950*G+0.43690*B)*(<em class="QR">QuantumRange</em>+1)/2</td></tr>
1538 <tr><td align="left" valign="middle">V=(0.61500*R−0.51500*G−0.10000*B)*(<em class="QR">QuantumRange</em>+1)/2</td></tr>
1541 <p>Note the scRGB colorspace requires HDRI support otherwise it behaves just like linear RGB.</p>
1543 <div style="margin: auto;">
1544 <h4><a id="combine"></a>-combine</h4>
1547 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Combine one or more images into a single image.</td><td style='text-align:right;'></td></tr></table>
1549 <p>The channels (previously set by <a href="command-line-options.html#channel">-channel</a>) of the
1550 combined image are taken from the grayscale values of each image in the
1551 sequence, in order. For the default -channel setting of <code>RGB</code>, this
1552 means the first image is assigned to the <code>Red</code> channel, the second
1553 to the <code>Green</code> channel, the third to the <code>Blue</code>.</p>
1555 <p>This option can be thought of as the inverse to <a
1556 href="command-line-options.html#separate">-separate</a>, so long as the channel settings are the same.
1557 Thus, in the following example, the final image should be a copy of the
1560 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert original.png -channel RGB -separate sepimage.png</span><span class='crtout'></span><span class="crtprompt"> $ </span><span class='crtin'>convert sepimage-0.png sepimage-1.png sepimage-2.png -channel RGB \ <br/> -combine imagecopy.png</span></p>
1561 <div style="margin: auto;">
1562 <h4><a id="comment"></a>-comment <em class="arg">string</em></h4>
1565 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Embed a comment in an image.</td><td style='text-align:right;'></td></tr></table>
1567 <p>This option sets the comment meta-data of an image read in after this
1568 option has been given. To modify a comment of images already in memory use
1569 "<code><a href="command-line-options.html#set">-set</a> comment</code>". </p>
1571 <p>The comment can contain special format characters listed in the <a
1572 href="escape.html">Format and
1573 Print Image Properties</a>. These attributes are expanded when the comment
1574 is finally assigned to the individual images. </p>
1576 <p>If the first character of <em class="arg">string</em> is <em
1577 class="arg">@</em>, the image comment is read from a file titled by the
1578 remaining characters in the string. Comments read in from a file are literal;
1579 no embedded formatting characters are recognized.</p>
1581 <p>Comment meta-data are not visible on the image itself. To do that use the
1582 <a href="command-line-options.html#annotate">-annotate</a> or <a href="command-line-options.html#draw">-draw</a> options
1588 -comment "%m:%f %wx%h" bird.miff
1591 <p>produces an image comment of <code>MIFF:bird.miff 512x480</code> (assuming
1592 that the image <code>bird.miff</code> has a width of 512 and a height of
1595 <div style="margin: auto;">
1596 <h4><a id="compose"></a>-compose <em class="arg">operator</em></h4>
1599 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Set the type of image composition.</td><td style='text-align:right;'></td></tr></table>
1601 <p>See <a href="compose.html">Alpha Compositing</a> for
1602 a detailed discussion of alpha compositing.</p>
1604 <p>This setting effects image processing operators that merge two (or more)
1605 images together in some way. This includes the operators,
1606 <a href="command-line-options.html#composite">-composite</a>,
1607 <a href="command-line-options.html#layers">-layers</a> composite,
1608 <a href="command-line-options.html#flatten">-flatten</a>,
1609 <a href="command-line-options.html#mosaic">-mosaic</a>,
1610 <a href="command-line-options.html#layers">-layers</a> merge,
1611 <a href="command-line-options.html#border">-border</a>,
1612 <a href="command-line-options.html#frame">-frame</a>,
1613 and <a href="command-line-options.html#extent">-extent</a>. </p>
1615 <p>It is also one of the primary options for the "<code>composite</code>"
1619 <div style="margin: auto;">
1620 <h4><a id="composite"></a>-composite</h4>
1623 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Perform alpha composition on two images and an optional mask</td><td style='text-align:right;'></td></tr></table>
1625 <p>Take the first image 'destination' and overlay the second 'source' image
1626 according to the current <a href="command-line-options.html#compose">-compose</a> setting. The location
1627 of the 'source' or 'overlay' image is controlled according to <a
1628 href="command-line-options.html#geometry" >-geometry</a>, and <a href="command-line-options.html#geometry" >-geometry</a>
1631 <p>If a third image is given this is treated as a gray-scale 'mask' image
1632 relative to the first 'destination' image. This mask will limit what parts of
1633 the destination can be modified by the image composition. However for the
1634 '<code>displace</code>' compose method, the mask is used to provide a separate
1635 Y-displacement image instead. </p>
1637 <p>If a <a href="command-line-options.html#compose">-compose</a> method requires extra numerical
1638 arguments or flags these can be provided by setting the <a
1639 href="command-line-options.html#set">-set</a> '<code class="arg">option:compose:args</code>'
1640 appropriately for the compose method. </p>
1642 <p>Some <a href="command-line-options.html#compose">-compose</a> methods can modify the 'destination'
1643 image outside the overlay area. You can disable this by setting the special <a
1644 href="command-line-options.html#set">-set</a> '<code class="arg">option:compose:outside-overlay</code>'
1645 to '<code>false</code>'. </p>
1648 <div style="margin: auto;">
1649 <h4><a id="compress"></a>-compress <em class="arg">type</em></h4>
1652 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Use pixel compression specified by <em class="arg">type</em> when writing the image.</td><td style='text-align:right;'></td></tr></table>
1654 <p>Choices are: <code class="arg">None</code>, <code class="arg">BZip</code>, <code
1655 class="arg">Fax</code>, <code class="arg">Group4</code>, <code
1656 class="arg">JPEG</code>, <code class="arg">JPEG2000</code>, <code
1657 class="arg">Lossless</code>, <code class="arg">LZW</code>, <code
1658 class="arg">RLE</code> or <code class="arg">Zip</code>.</p>
1660 <p>To print a complete list of compression types, use <a href="command-line-options.html#list">-list
1663 <p>Specify <a href="command-line-options.html#compress">+compress</a> to store the binary image in an
1664 uncompressed format. The default is the compression type of the specified
1667 <p>If <code>LZW</code> compression is specified but LZW compression has not been
1668 enabled, the image data is written in an uncompressed LZW format that can be
1669 read by LZW decoders. This may result in larger-than-expected GIF files.</p>
1671 <p><code>Lossless</code> refers to lossless JPEG, which is only available if the
1672 JPEG library has been patched to support it. Use of lossless JPEG is generally
1673 not recommended.</p>
1676 When writing an ICO file, you may request that the images be encoded in
1677 PNG format, by specifying <code>Zip</code> compression.</p>
1680 When writing a JNG file, specify <code>Zip</code> compression to request that
1681 the alpha channel be encoded in PNG "IDAT" format, or <code>JPEG</code>
1682 to request that it be encoded in JPG "JDAA" format.</p>
1684 <p>Use the <a href="command-line-options.html#quality">-quality</a> option to set the compression level
1685 to be used by JPEG, PNG, MIFF, and MPEG encoders.
1686 Use the <a href="command-line-options.html#sampling-factor">-sampling-factor</a> option to set the
1687 sampling factor to be used by JPEG, MPEG, and YUV encoders for down-sampling
1688 the chroma channels.</p>
1690 <div style="margin: auto;">
1691 <h4><a id="contrast"></a>-contrast</h4>
1694 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Enhance or reduce the image contrast.</td><td style='text-align:right;'></td></tr></table>
1696 <p>This option enhances the intensity differences between the lighter and
1697 darker elements of the image. Use <a href="command-line-options.html#contrast">-contrast</a> to enhance
1698 the image or <a href="command-line-options.html#contrast">+contrast</a> to reduce the image
1701 <p>For a more pronounced effect you can repeat the option:</p>
1703 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert rose: -contrast -contrast rose_c2.png</span></p>
1704 <div style="margin: auto;">
1705 <h4><a id="contrast-stretch"></a>-contrast-stretch <em class="arg">black-point</em><br />-contrast-stretch <em class="arg">black-point</em>{x<em class="arg">white-point</em>}{<em class="arg">%</em>}}</h4>
1708 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Increase the contrast in an image by <em>stretching</em> the range of intensity values.</td><td style='text-align:right;'></td></tr></table>
1710 <p>While performing the stretch, black-out at most <em
1711 class="arg" >black-point</em> pixels and white-out at most <em
1712 class="arg" >white-point</em> pixels. Or, if percent is used, black-out at most
1713 <em class="arg" >black-point %</em> pixels and white-out at most <em
1714 class="arg" >white-point %</em> pixels.</p>
1716 <p>Prior to ImageMagick 6.4.7-0, <a href="command-line-options.html#contrast-stretch"
1717 >-contrast-stretch</a> will black-out at most <em class="arg"
1718 >black-point</em> pixels and white-out at most <em class="arg" >total pixels
1719 minus white-point</em> pixels. Or, if percent is used, black-out at most <em
1720 class="arg">black-point %</em> pixels and white-out at most <em class="arg"
1721 >100% minus white-point %</em> pixels.</p>
1723 <p>Note that <code>-contrast-stretch 0</code> will modify the image such that
1724 the image's min and max values are stretched to 0 and <em class="QR"
1725 >QuantumRange</em>, respectively, without any loss of data due to burn-out or
1726 clipping at either end. This is not the same as <a href="command-line-options.html#normalize"
1727 >-normalize</a>, which is equivalent to <code>-contrast-stretch 0.15x0.05%</code> (or
1728 prior to ImageMagick 6.4.7-0, <code>-contrast-stretch 2%x99%</code>).</p>
1730 <p>Internally operator works by creating a histogram bin, and then uses that
1731 bin to modify the image. As such some colors may be merged together when they
1732 originally fell into the same 'bin'. </p>
1734 <p>All the channels are normalized in concert by the came amount so as to
1735 preserve color integrity, when the default <a href="command-line-options.html#channel" >+channel</a>
1736 setting is in use. Specifying any other <a href="command-line-options.html#channel" >-channel</a>
1737 setting will normalize the RGB channels independently.</p>
1739 <p>See also <a href="command-line-options.html#auto-level" >-auto-level</a> for a 'perfect'
1740 normalization of mathematical images. </p>
1742 <p>This operator is under review for re-development. </p>
1745 <div style="margin: auto;">
1746 <h4><a id="convolve"></a>-convolve <em class="arg">kernel</em></h4>
1749 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Convolve an image with a user-supplied convolution kernel.</td><td style='text-align:right;'></td></tr></table>
1751 <p>The <em class="arg">kernel</em> is a matrix specified as
1752 a comma-separated list of integers (with no spaces), ordered left-to right,
1753 starting with the top row. Presently, only odd-dimensioned kernels are
1754 supported, and therefore the number of entries in the specified <em
1755 class="arg">kernel</em> must be 3<sup>2</sup>=9, 5<sup>2</sup>=25,
1756 7<sup>2</sup>=49, etc. </p>
1758 <p>Note that the <a href="command-line-options.html#convolve">‑convolve</a> operator supports the <a href="command-line-options.html#bias">‑bias</a> setting. This option shifts the convolution so that
1759 positive and negative results are relative to a user-specified bias value.
1760 This is important for non-HDRI compilations of ImageMagick when dealing with
1761 convolutions that contain negative as well as positive values. This is
1762 especially the case with convolutions involving high pass filters or edge
1763 detection. Without an output bias, the negative values is clipped at zero.
1766 <p>When using an ImageMagick with the HDRI compile-time setting, <a href="command-line-options.html#bias">‑bias</a> is not needed, as ImageMagick is able to store/handle any
1767 negative results without clipping to the color value range (0..QuantumRange).
1768 See the discussion on HDRI implementations of ImageMagick on the page <a
1769 href="high-dynamic-range.html">High
1770 Dynamic-Range Images</a>. For more about HDRI go the ImageMagick <a
1771 href="http://www.imagemagick.org/Usage/basics/#hdri">Usage</a> pages or this
1772 <a href="http://en.wikipedia.org/wiki/High_dynamic_range_imaging">Wikipedia</a>
1776 <div style="margin: auto;">
1777 <h4><a id="crop"></a>-crop <em class="arg">geometry</em>{<em class="arg">@</em>}{<em class="arg">!</em>}</h4>
1780 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Cut out one or more rectangular regions of the image.</td><td style='text-align:right;'></td></tr></table>
1782 <p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
1784 <p>The <em class="arg">width</em> and <em class="arg">height</em> of the <em
1785 class="arg">geometry</em> argument give the size of the image that remains
1786 after cropping, and <em class="arg">x</em> and <em class="arg">y</em> in the
1787 <em class="arg">offset</em> (if present) gives the location of the top left
1788 corner of the cropped image with respect to the original image. To specify the
1789 amount to be removed, use <a href="command-line-options.html#shave">-shave</a> instead.</p>
1791 <p>If the <em class="arg">x</em> and <em class="arg">y</em> offsets are
1792 present, a single image is generated, consisting of the pixels from the
1793 cropping region. The offsets specify the location of the upper left corner of
1794 the cropping region measured downward and rightward with respect to the upper
1795 left corner of the image. If the <a href="command-line-options.html#gravity">-gravity</a> option is
1796 present with <code>NorthEast</code>, <code>East</code>, or <code>SouthEast</code>
1797 gravity, it gives the distance leftward from the right edge of the image to
1798 the right edge of the cropping region. Similarly, if the <a
1799 href="command-line-options.html#gravity">-gravity</a> option is present with <code>SouthWest</code>,
1800 <code>South</code>, or <code>SouthEast</code> gravity, the distance is measured
1801 upward between the bottom edges.</p>
1803 <p>If the <em class="arg">x</em> and <em class="arg">y</em> offsets are
1804 omitted, a set of tiles of the specified geometry, covering the entire input
1805 image, is generated. The rightmost tiles and the bottom tiles are smaller if
1806 the specified geometry extends beyond the dimensions of the input image.</p>
1808 <p>You can add the <em class="arg">@</em> to the geometry argument to equally divide the image into the number of tiles generated.</p>
1810 <p>By adding a exclamation character flag to the geometry argument, the
1811 cropped images virtual canvas page size and offset is set as if the
1812 geometry argument was a viewport or window. This means the canvas page size
1813 is set to exactly the same size you specified, the image offset set
1814 relative top left corner of the region cropped. </p>
1816 <p>If the cropped image 'missed' the actual image on its virtual canvas, a
1817 special single pixel transparent 'missed' image is returned, and a 'crop
1818 missed' warning given. </p>
1820 <p>It might be necessary to <a href="command-line-options.html#repage" >+repage</a> the image prior to
1821 cropping the image to ensure the crop coordinate frame is relocated to the
1822 upper-left corner of the visible image.
1824 Similarly you may want to use <a href="command-line-options.html#repage" >+repage</a> after cropping to
1825 remove the page offset that will be left behind. This is especially true when
1826 you are going to write to an image format such as PNG that supports an image
1829 <div style="margin: auto;">
1830 <h4><a id="cycle"></a>-cycle <em class="arg">amount</em></h4>
1833 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>displace image colormap by amount.</td><td style='text-align:right;'></td></tr></table>
1835 <p><em class="arg">Amount</em> defines the number of positions each
1836 colormap entry is shifted.</p>
1839 <div style="margin: auto;">
1840 <h4><a id="debug"></a>-debug <em class="arg">events</em></h4>
1843 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>enable debug printout.</td><td style='text-align:right;'></td></tr></table>
1845 <p>The <code>events</code> parameter specifies which events are to be logged. It
1846 can be either <code>None</code>, <code>All</code>, <code>Trace</code>, or
1847 a comma-separated list consisting of one or more of the following domains:
1848 <code>Accelerate</code>, <code>Annotate</code>, <code>Blob</code>, <code>Cache</code>,
1849 <code>Coder</code>, <code>Configure</code>, <code>Deprecate</code>,
1850 <code>Exception</code>, <code>Locale</code>, <code>Render</code>,
1851 <code>Resource</code>, <code>Security</code>, <code>TemporaryFile</code>,
1852 <code>Transform</code>, <code>X11</code>, or <code>User</code>. </p>
1855 <p>For example, to log cache and blob events, use.</p>
1857 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert -debug "Cache,Blob" rose: rose.png</span></p>
1858 <p>The <code>User</code> domain is normally empty, but developers can log user
1859 events in their private copy of ImageMagick.</p>
1861 <p>To print the complete list of debug methods, use <a href="command-line-options.html#list">-list
1864 <p>Use the <a href="command-line-options.html#log">-log</a> option to specify the format for debugging
1867 <p>Use <a href="command-line-options.html#debug">+debug</a> to turn off all logging.</p>
1869 <p>Debugging may also be set using the <code>MAGICK_DEBUG</code> <a href="resources.html#environment"
1870 >environment variable</a>. The allowed values for the <code>MAGICK_DEBUG</code>
1871 environment variable are the same as for the <a href="command-line-options.html#debug">-debug</a>
1875 <div style="margin: auto;">
1876 <h4><a id="decipher"></a>-decipher <em class="arg">filename</em></h4>
1879 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Decipher and restore pixels that were previously transformed by
1880 <a href="command-line-options.html#encipher">-encipher</a>.</td><td style='text-align:right;'></td></tr></table>
1882 <p>Get the passphrase from the file specified by <em
1883 class="arg">filename</em>.</p>
1885 <p>For more information, see the webpage, <a
1886 href="http://www.imagemagick.org/www/cipher.html">ImageMagick: Encipher or
1887 Decipher an Image</a>.</p>
1890 <div style="margin: auto;">
1891 <h4><a id="deconstruct"></a>-deconstruct</h4>
1894 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>find areas that has changed between images </td><td style='text-align:right;'></td></tr></table>
1896 <p>Given a sequence of images all the same size, such as produced by <a
1897 href="command-line-options.html#coalesce">-coalesce</a>, replace the second and later images, with
1898 a smaller image of just the area that changed relative to the previous image.
1901 <p>The resulting sequence of images can be used to optimize an animation
1902 sequence, though will not work correctly for GIF animations when parts of the
1903 animation can go from opaque to transparent. </p>
1905 <p>This option is actually equivalent to the <a href="command-line-options.html#layers">-layers</a>
1906 method '<code>compare-any</code>'. </p>
1909 <div style="margin: auto;">
1910 <h4><a id="define"></a>-define <em class="arg">key</em>{<em class="arg">=value</em>}<em class="arg">...</em></h4>
1913 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>add specific global settings generally used to control
1914 coders and image processing operations.</td><td style='text-align:right;'></td></tr></table>
1916 <p>This option creates one or more definitions for coders and decoders to use
1917 while reading and writing image data. Definitions are generally used to
1918 control image file format coder modules, and image processing operations,
1919 beyond what is provided by normal means. Defined settings are listed in <a
1920 href="command-line-options.html#verbose" >-verbose</a> information ("<code>info:</code>" output format)
1921 as "Artifacts". </p>
1923 <p>If <em class="arg">value</em> is missing for a definition, an empty-valued
1924 definition of a flag is created with that name. This used to control on/off
1925 options. Use <a href="command-line-options.html#define">+define key</a> to remove definitions
1926 previously created. Use <a href="command-line-options.html#define">+define "*"</a> to remove all
1927 existing definitions.</p>
1929 <p>The same 'artifact' settings can also be defined using the <a
1930 href="command-line-options.html#set" >-set "option:<em class="arg">key</em>" "<em class="arg"
1931 >value</em>"</a> option, which also allows the use of <a href="escape.html" >Format and Print Image
1932 Properties</a> in the defined value. </p>
1934 <p>The <em>option</em> and <em>key</em> are case-independent (they are
1935 converted to lowercase for use within the decoders) while the <em>value</em>
1936 is case-dependent.</p>
1938 <p>Such settings are global in scope, and affect all images and operations. </p>
1940 <p>The following definitions are just some of the artifacts that are
1945 <dt>compose:args=<em class="arg">arguments</em></dt>
1946 <dd>Sets certain compose argument values when using convert ... -compose ...
1947 -composite. See <a href="http://www.imagemagick.org/www/compose.html"
1948 >Image Composition</a></dd>
1950 <dt>distort:scale=<em class="arg">value</em></dt>
1951 <dd>Sets the output scaling factor for use with <a href="command-line-options.html#distort"
1954 <dt>distort:viewport=WxH+X+Y</dt>
1955 <dd>Sets the viewport for use with <a href="command-line-options.html#distort">-distort</a></dd>
1957 <dt>dcm:display-range=reset</dt>
1958 <dd>Set the display range to the minimum and maximum pixel values for the
1959 DCM image format.</dd>
1961 <dt>dot:layout-engine=<em class="arg">value</em></dt>
1962 <dd>Set the specify the layout engine for the DOT image format (e.g.
1963 <code>neato</code>).</dd>
1965 <dt>jpeg:colors=<em class="arg">value</em></dt>
1966 <dd>Set the desired number of colors and let the JPEG encoder do the
1969 <dt>jpeg:block-smoothing=<em class="arg">on|off</em></dt>
1971 <dt>jpeg:dct-method=<em class="arg">value</em></dt>
1972 <dd>Choose from <code>default</code>, <code>fastest</code>, <code>float</code>,
1973 <code>ifast</code>, and <code>islow</code>.</dd>
1975 <dt>jpeg:extent=<em class="arg">value</em></dt>
1976 <dd>Restrict the maximum JPEG file size, for example <code>-define
1977 jpeg:extent=400kb</code>. The JPEG encoder will search for the highest
1978 compression quality level that results in an output file that does not
1979 exceed the value. The <code>-quality</code> option is ignored if it
1980 is also present.</dd>
1982 <dt>jpeg:fancy-upsampling=<em class="arg">on|off</em></dt>
1984 <dt>jpeg:optimize-coding=<em class="arg">on|off</em></dt>
1986 <dt>jpeg:q-table=<em class="arg">table</em></dt>
1988 <dt>jpeg:sampling-factor=<em class="arg">sampling-factor-string</em></dt>
1990 <dt>jpeg:size=<em class="arg">geometry</em></dt>
1991 <dd>Set the size hint of a JPEG image, for
1992 example, <code>-define jpeg:size=128x128</code>.
1993 It is most useful for increasing performance and reducing the memory
1994 requirements when reducing the size of a large JPEG image.</dd>
1996 <dt>jp2:rate=<em class="arg">value</em></dt>
1997 <dd>Specify the compression factor to use while writing JPEG-2000 files. The
1998 compression factor is the reciprocal of the compression ratio. The valid
1999 range is 0.0 to 1.0, with 1.0 indicating lossless compression. If defined,
2000 this value overrides the -quality setting. A quality setting of 75
2001 results in a rate value of 0.06641.</dd>
2003 <dt>mng:need-cacheoff</dt>
2004 <dd>turn playback caching off for streaming MNG.</dd>
2006 <dt>png:bit-depth=<em class="arg">value</em></dt>
2007 <dt>png:color-type=<em class="arg">value</em></dt>
2008 <dd>desired bit-depth and color-type for PNG output. You can force the PNG
2009 encoder to use a different bit-depth and color-type than it would have
2010 normally selected, but only if this does not cause any loss of image
2011 quality. Any attempt to reduce image quality is treated as an error and no
2012 PNG file is written. E.g., if you have a 1-bit black-and-white image, you
2013 can use these "defines" to cause it to be written as an 8-bit grayscale,
2014 indexed, or even a 64-bit RGBA. But if you have a 16-million color image,
2015 you cannot force it to be written as a grayscale or indexed PNG. If you
2016 wish to do this, you must use the appropriate <a href="command-line-options.html#depth">-depth</a>,
2017 <a href="command-line-options.html#colors">-colors</a>, or <a href="command-line-options.html#type">-type</a> directives to
2018 reduce the image quality prior to using the PNG encoder. Note that in
2019 indexed PNG files, "bit-depth" refers to the number of bits per index,
2020 which can be 1, 2, 4, or 8. In such files, the color samples always have
2023 <dt>png:compression-filter=<em class="arg">value</em></dt>
2024 <dd> valid values are 0 through 7. 0-4 are the corresponding PNG filters,
2025 5 means adaptive filtering except for images with a colormap, 6 means
2026 adaptive filtering for all images, 7 means MNG "loco" compression.</dd>
2028 <dt>png:compression-level=<em class="arg">value</em></dt>
2029 <dd> valid values are 0 through 9, with 0 providing the least but fastest
2030 compression and 9 usually providing the best and always the slowest.</dd>
2032 <dt>png:compression-strategy=<em class="arg">value</em></dt>
2033 <dd> valid values are 0 through 4, meaning default, filtered, huffman_only,
2034 rle, and fixed ZLIB compression strategy. If you are using an old zlib
2035 that does not support Z_RLE (before 1.2.0) or Z_FIXED (before 1.2.2.2),
2036 values 3 and 4, respectively, will use the zlib default strategy
2039 <dt>png:format=<em class="arg">value</em></dt>
2040 <dd> valid values are <em class="arg">png8</em>, <em class="arg">png24</em>,
2041 <em class="arg">png32</em>, <em class="arg">png48</em>,
2042 <em class="arg">png64</em>, and <em class="arg">png00</em>.
2043 This property can be useful for specifying
2044 the specific PNG format to be used, when the usual method of prepending the
2045 format name to the output filename is inconvenient, such as when writing
2046 a PNG-encoded ICO file.
2047 Value = <em class="arg">png8</em> reduces the number of colors to 256,
2048 only one of which may be fully transparent, if necessary. The other
2049 values do not force any reduction of quality; it is an error to request
2050 a format that cannot represent the image data without loss (except that
2051 it is allowed to reduce the bit-depth from 16 to 8 for all formats).
2052 Value = <em class="arg">png24</em> and <em class="arg">png48</em>
2053 allow transparency, only if a single color is fully transparent and that
2054 color does not also appear in an opaque pixel; such transparency is
2055 written in a PNG <code>tRNS</code> chunk.
2056 Value = <em class="arg">png00</em> causes the image to inherit its
2057 color-type and bit-depth from the input image, if the input was also
2060 <dt>png:exclude-chunk=<em class="arg">value</em></dt>
2061 <dt>png:include-chunk=<em class="arg">value</em></dt>
2062 <dd>ancillary chunks to be excluded from or included in PNG output.
2064 <p>The <em class="arg">value</em> can be the name of a PNG chunk-type such
2065 as <em class="arg">bKGD</em>, a comma-separated list of chunk-types,
2066 or the word <em class="arg">all</em> or
2067 the word <em class="arg">none</em>. There must be no spaces in the
2068 list. Although PNG chunk-names are case-dependent, you can use
2069 all lowercase names if you prefer.</p>
2071 <p>The "include-chunk" and "exclude-chunk" lists only affect the behavior
2072 of the PNG encoder and have no effect on the PNG decoder.</p>
2074 <p>As a special case, if the <code>sRGB</code> chunk is excluded and
2075 the <code>gAMA</code> chunk is included, the <code>gAMA</code> chunk will
2076 only be written if gamma is not 1/2.2, since most decoders assume
2077 sRGB and gamma=1/2.2 when no colorspace information is included in
2078 the PNG file. Because the list is processed from left to right, you
2079 can achieve this with a single define:</p>
2082 -define png:include-chunk=none,gAMA
2085 <p>As a special case, if the <code>sRGB</code> chunk is not excluded and
2086 the PNG encoder recognizes that the image contains the sRGB ICC profile,
2087 the PNG encoder will write the <code>sRGB</code> chunk instead of the entire
2088 3144-byte ICC profile. To force the PNG encoder to write the sRGB
2089 profile as an <code>iCCP</code> chunk in the output PNG instead of the
2090 <code>sRGB</code> chunk, exclude the <code>sRGB</code> chunk.</p>
2092 <p>The critical PNG chunks <code>IHDR</code>, <code>PLTE</code>,
2093 <code>IDAT</code>, and <code>IEND</code> cannot be excluded. Any such
2094 entries appearing in the list will be ignored.</p>
2096 <p>If the ancillary PNG <code>tRNS</code> chunk is excluded and the
2097 image has transparency, the PNG colortype is forced to be 4 or 6
2098 (GRAY_ALPHA or RGBA). If the image is not transparent, then the
2099 <code>tRNS</code> chunk isn't written anyhow, and there is no effect
2100 on the PNG colortype of the output image.</p>
2102 <p>The <a href="command-line-options.html#strip">-strip</a> option does the equivalent of the
2103 following for PNG output:</p>
2106 -define png:include-chunk=none,trns,gama
2109 <p>The default behavior is to include all known PNG ancillary chunks
2110 plus ImageMagick's private <code>vpAg</code> ("virtual page") chunk,
2111 and to exclude all PNG chunks that are unknown to ImageMagick,
2112 regardless of their PNG "copy-safe" status as described in the
2113 PNG specification.</p>
2115 <p>Any chunk names that are not known to ImageMagick are ignored
2116 if they appear in either the "include-chunk" or "exclude-chunk" list.
2117 The ancillary chunks currently known to ImageMagick are
2118 <code>bKGD</code>, <code>cHRM</code>, <code>gAMA</code>, <code>iCCP</code>,
2119 <code>oFFs</code>, <code>pHYs</code>, <code>sRGB</code>, <code>tEXt</code>,
2120 <code>tRNS</code>, <code>vpAg</code>, and <code>zTXt</code>.</p>
2122 <p>You can also put <code>date</code> in the list to include or exclude
2123 the "Date:create" and "Date:modify" text chunks that ImageMagick normally
2124 inserts in the output PNG.</p>
2128 <dt>png:preserve-colormap</dt>
2129 <dd>Use the existing image->colormap. Normally the PNG encoder will
2130 try to optimize the palette, eliminating unused entries and putting
2131 the transparent colors first. If this flag is set, that behavior
2134 <dt>png:preserve-iCCP</dt>
2135 <dd>By default, the PNG decoder and encoder examine any ICC profile
2136 that is present, either from an <code>iCCP</code> chunk in the PNG
2137 input or supplied via an option, and if the profile is recognized
2138 to be the sRGB profile, converts it to the <code>sRGB</code> chunk.
2139 You can use <code>-define png:preserve-iCCP</code> to prevent
2140 this from happening; in such cases the <code>iCCP</code> chunk
2141 will be read or written and no <code>sRGB</code> chunk will be
2142 written. There are some ICC profiles that claim to be sRGB but
2143 have various errors that cause them to be rejected by libpng16; such
2144 profiles are recognized anyhow and converted to the <code>sRGB</code>
2145 chunk, but are rejected if the <code>-define png:preserve-iCCP</code>
2146 is present. Note that not all "sRGB" ICC profiles are recognized
2147 yet; we will add them to the list as we encounter them.</dd>
2149 <dt>ps:imagemask</dt>
2150 <dd>If the ps:imagemask flag is defined, the PS3 and EPS3 coders will create
2151 Postscript files that render bilevel images with the Postscript imagemask
2152 operator instead of the image operator.</dd>
2154 <dt>quantum:format=<em class="arg">type</em></dt>
2155 <dd>Set the type to <code>floating-point</code> to specify a floating-point
2156 format for raw files (e.g. GRAY:) or for MIFF and TIFF images in HDRI mode
2157 to preserve negative values. If <a href="command-line-options.html#depth">-depth</a> 16 is
2158 included, the result is a single precision floating point format.
2159 If <a href="command-line-options.html#depth">-depth</a> 32 is included, the result is
2160 double precision floating point format.</dd>
2162 <dt>quantum:polarity=<em class="arg">photometric-interpretation</em></dt>
2163 <dd>Set the photometric-interpretation of an image (typically for TIFF image
2164 file format) to either <code>min-is-black</code> (default) or
2165 <code>min-is-white</code>.</dd>
2167 <dt>sample:offset=<em class="arg">geometry</em></dt>
2168 <dd>Location of the sampling point within the sub-region being sampled,
2169 expressed as percentages (see <a href="command-line-options.html#sample" >-sample</a>).</dd>
2171 <dt>showkernel=1</em></dt>
2172 <dd>Outputs (to 'standard error') all the information about a generated <a
2173 href="command-line-options.html#morphology" >-morphology</a> kernel.</dd>
2175 <dt>tiff:rows-per-strip=<em class="arg">value</em></dt>
2176 <dd>Sets the number of rows per strip</dd>
2178 <dt>tiff:tile-geometry=<em class="arg">WxH</em></dt>
2179 <dd>Sets the tile size for pyramid tiffs. Requires the suffix PTIF: before the
2185 <p>For example, to create a postscript file that will render only the black
2186 pixels of a bilevel image, use:</p>
2188 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert bilevel.tif -define ps:imagemask eps3:stencil.ps</span></p>
2189 <p>Set attributes of the image registry by prefixing the value with
2190 <code>registry:</code>. For example, to set a temporary path to put work files,
2194 -define registry:temporary-path=/data/tmp
2197 <p>If you want to keep the temporary files ImageMagick creates private, overwrite them with zeros or random data before they are removed. On the first pass, the file is zeroed. For subsequent passes, random data is written. For example, to specify two passes:</p>
2200 -define registry:shred-passes=2
2203 <div style="margin: auto;">
2204 <h4><a id="delay"></a>-delay <em class="arg">ticks</em> <br />-delay <em class="arg">ticks</em>x<em class="arg">ticks-per-second</em> {<em class="arg"><</em>} {<em class="arg">></em>}</h4>
2207 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>display the next image after pausing.</td><td style='text-align:right;'></td></tr></table>
2209 <p>This option is useful for regulating the animation of image sequences
2210 <em>ticks/ticks-per-second</em> seconds must expire before the display of the
2211 next image. The default is no delay between each showing of the image
2212 sequence. The default ticks-per-second is 100.</p>
2214 <p>Use <code>></code> to change the image delay <em>only</em> if its current
2215 value exceeds the given delay. <code><</code> changes the image delay
2216 <em>only</em> if current value is less than the given delay. For example, if
2217 you specify <code>30></code> and the image delay is 20, the image delay does
2218 not change. However, if the image delay is 40 or 50, the delay it is changed
2219 to 30. Enclose the given delay in quotation marks to prevent the
2220 <code><</code> or <code>></code> from being interpreted by your shell as
2221 a file redirection.</p>
2224 <div style="margin: auto;">
2225 <h4><a id="delete"></a>-delete <em class="arg">indexes</em></h4>
2228 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>delete the images specified by index, from the image sequence.</td><td style='text-align:right;'></td></tr></table>
2230 <p>Specify the image by its index in the sequence. The first image is index
2231 0. Negative indexes are relative to the end of the sequence, for example, -1
2232 represents the last image of the sequence. Specify a range of images with
2233 a dash (e.g. 0-4). Separate indexes with a comma (e.g. 0,2). Use
2234 <code>+delete</code> to delete the last image in the current image sequence.</p>
2237 <div style="margin: auto;">
2238 <h4><a id="density"></a>-density <em class="arg">width</em><br />-density <em class="arg">width</em>x<em class="arg">height</em></h4>
2241 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Set the horizontal and vertical resolution of an image for
2242 rendering to devices.</td><td style='text-align:right;'></td></tr></table>
2244 <p>This option specifies the image resolution to store while encoding a raster
2245 image or the canvas resolution while rendering (reading) vector formats such
2246 as Postscript, PDF, WMF, and SVG into a raster image. Image resolution
2247 provides the unit of measure to apply when rendering to an output device or
2248 raster image. The default unit of measure is in dots per inch (DPI). The <a
2249 href="command-line-options.html#units">-units</a> option may be used to select dots per centimeter
2252 <p>The default resolution is 72 dots per inch, which is equivalent to one
2253 point per pixel (Macintosh and Postscript standard). Computer screens are
2254 normally 72 or 96 dots per inch, while printers typically support 150, 300,
2255 600, or 1200 dots per inch. To determine the resolution of your display, use
2256 a ruler to measure the width of your screen in inches, and divide by the
2257 number of horizontal pixels (1024 on a 1024x768 display).</p>
2259 <p>If the file format supports it, this option may be used to update the
2260 stored image resolution. Note that Photoshop stores and obtains image
2261 resolution from a proprietary embedded profile. If this profile is not
2262 stripped from the image, then Photoshop will continue to treat the image using
2263 its former resolution, ignoring the image resolution specified in the standard
2266 <p>The <a href="command-line-options.html#density">-density</a> option sets an <em>attribute</em> and
2267 does not alter the underlying raster image. It may be used to adjust the
2268 rendered size for desktop publishing purposes by adjusting the scale applied
2269 to the pixels. To resize the image so that it is the same size at a different
2270 resolution, use the <a href="command-line-options.html#resample">-resample</a> option.</p>
2272 <div style="margin: auto;">
2273 <h4><a id="depth"></a>-depth <em class="arg">value</em></h4>
2276 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>depth of the image.</td><td style='text-align:right;'></td></tr></table>
2278 <p>This the number of bits in a color sample within a pixel. Use this option
2279 to specify the depth of raw images whose depth is unknown such as GRAY, RGB,
2280 or CMYK, or to change the depth of any image after it has been read.</p>
2282 <div style="margin: auto;">
2283 <h4><a id="descend"></a>-descend</h4>
2286 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>obtain image by descending window hierarchy.</td><td style='text-align:right;'></td></tr></table>
2288 <div style="margin: auto;">
2289 <h4><a id="deskew"></a>-deskew <em class="arg">threshold</em></h4>
2292 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>straighten an image. A threshold of 40% works for most images.</td><td style='text-align:right;'></td></tr></table>
2294 <p>Use <a href="command-line-options.html#set">-set</a> <code>option:deskew:auto-crop
2295 <em>width</em></code> to auto crop the image. The set argument is the pixel
2296 width of the image background (e.g 40).</p>
2298 <div style="margin: auto;">
2299 <h4><a id="despeckle"></a>-despeckle</h4>
2302 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>reduce the speckles within an image.</td><td style='text-align:right;'></td></tr></table>
2304 <div style="margin: auto;">
2305 <h4><a id="direction"></a>-direction <em class="arg">type</em></h4>
2308 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>render text right-to-left or left-to-right.</td><td style='text-align:right;'></td></tr></table>
2310 <div style="margin: auto;">
2311 <h4><a id="displace"></a>-displace <em class="arg">horizontal-scale</em><br />-displace <em class="arg">horizontal-scale</em>x<em class="arg">vertical-scale</em></h4>
2314 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>shift image pixels as defined by a displacement map.</td><td style='text-align:right;'>[<a href="composite.html">composite</a>]</td></tr></table>
2316 <p>With this option, the 'overlay' image, and optionally the 'mask' image,
2317 is used as a displacement map, which is used to displace the lookup of
2318 what part of the 'background' image is seen at each point of the overlaid
2319 area. Much like the displacement map is a 'lens' that redirects light shining
2320 through it so as to present a distorted view the original 'background' image
2323 <p>Any perfect grey areas of the displacement map produce a zero
2324 displacement of the image. Black areas produce the given maximum negative
2325 displacement of the lookup point, while white produce a maximum positive
2326 displacement of the lookup. </p>
2328 <p>Note that it is the lookup of the 'background' that is displaced, not a
2329 displacement of the image itself. As such an area of the displacement map
2330 containing 'white' will have the lookup point 'shifted' by a positive amount,
2331 and thus generating a copy of the destination image to the right/downward from
2332 the correct position. That is the image will look like it may have been
2333 'shifted' in a negative left/upward direction. Understanding this is a very
2334 important in understanding how displacement maps work. </p>
2336 <p>The given arguments define the maximum amount of displacement in pixels
2337 that a particular map can produce. If the displacement scale is large enough
2338 it is also possible to lookup parts of the 'background' image that lie well
2339 outside the bounds of the displacement map itself. That is you could very
2340 easily copy a section of the original image from outside the overlay area
2341 into the overlay area. </p>
2343 <p>The '%' flag makes the displacement scale relative to the size of the
2344 overlay image (100% = half width/height of image). Using '!' switches
2345 percentage arguments to refer to the destination image size instead.
2346 these flags were added as of IM v6.5.3-5.</p>
2348 <p>Normally a single grayscale displacement map is provided, which with the
2349 given scaling values will determine a single direction (vector) in which
2350 displacements can occur (positively or negatively). However, if you also
2351 specify a third image which is normally used as a <em class="arg">mask</em>,
2352 the <em class="arg">composite image</em> is used for horizontal X
2353 displacement, while the <em class="arg">mask image</em> is used for vertical Y
2354 displacement. This allows you to define completely different displacement
2355 values for the X and Y directions, and allowing you to lookup any point within
2356 the <em class="arg">scale</em> bounds. In other words each pixel can lookup
2357 any other nearby pixel, producing complex 2 dimensional displacements, rather
2358 than a simple 1 dimensional vector displacements. </p>
2360 <p>Alternatively rather than supplying two separate images, as of IM v6.4.4-0,
2361 you can use the 'red' channel of the overlay image to specify the horizontal
2362 or X displacement, and the 'green' channel for the vertical or Y displacement.
2365 <p>As of IM v6.5.3-5 any alpha channel in the overlay image is used as a
2366 mask the transparency of the destination image. However areas outside the
2367 overlaid areas will not be effected. </p>
2370 <div style="margin: auto;">
2371 <h4><a id="display"></a>-display <em class="arg">host:display[.screen]</em></h4>
2374 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Specifies the X server to contact.</td><td style='text-align:right;'>[<a href="animate.html">animate</a>, <a href="display.html">display</a>]</td></tr></table>
2376 <p>This option is used with convert for obtaining image or font from this
2377 X server. See <em class="arg">X(1)</em>.</p>
2379 <div style="margin: auto;">
2380 <h4><a id="dispose"></a>-dispose <em class="arg">method</em></h4>
2383 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>define the GIF disposal image setting for images that are being created or read in. </td><td style='text-align:right;'></td></tr></table>
2385 <p>The layer disposal method defines the way each the displayed image is to be
2386 modified after the current 'frame' of an animation has finished being
2387 displayed (after its 'delay' period), but before the next frame on an
2388 animation is to be overlaid onto the display. </p>
2390 <p>Here are the valid methods:</p>
2393 Undefined 0 No disposal specified (equivalent to '<code>none</code>').
2394 None 1 Do not dispose, just overlay next frame image.
2395 Background 2 Clear the frame area with the background color.
2396 Previous 3 Clear to the image prior to this frames overlay.
2399 <p>You can also use the numbers given above, which is what the GIF format
2400 uses internally to represent the above settings. </p>
2402 <p>To print a complete list of dispose methods, use <a href="command-line-options.html#list">-list dispose</a>.</p>
2404 <p>Use <a href="command-line-options.html#dispose" >+dispose</a>, turn off the setting and prevent
2405 resetting the layer disposal methods of images being read in. </p>
2407 <p>Use <a href="command-line-options.html#set">-set</a> '<code>dispose</code>' method to set the image
2408 disposal method for images already in memory.</p>
2410 <div style="margin: auto;">
2411 <h4><a id="dissimilarity-threshold"></a>-dissimilarity-threshold <em class="arg">value</em></h4>
2414 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>maximum RMSE for subimage match (default 0.2).</td><td style='text-align:right;'>[<a href="compare.html">compare</a>]</td></tr></table>
2417 <div style="margin: auto;">
2418 <h4><a id="dissolve"></a>-dissolve <em class="arg">src_percent</em>[x<em class="arg">dst_percent</em>]</h4>
2421 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>dissolve an image into another by the given percent.</td><td style='text-align:right;'>[<a href="composite.html">composite</a>]</td></tr></table>
2423 <p>The opacity of the composite image is multiplied by the given percent, then
2424 it is composited 'over' the main image. If <em class="arg">src_percent</em>
2425 is greater than 100, start dissolving the main image so it becomes
2426 transparent at a value of '<code class="arg">200</code>'. If both percentages
2427 are given, each image are dissolved to the percentages given. </p>
2429 <p>Note that dissolve percentages do not add, two opaque images dissolved
2430 '50,50', produce a 75% transparency. For a 50% + 50% blending of the two
2431 images, you would need to use dissolve values of '50,100'. </p>
2433 <div style="margin: auto;">
2434 <h4><a id="distort"></a>-distort <em class="arg">method arguments</em></h4>
2437 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>distort an image, using the given <em class="arg">method</em> and its required <em class="arg">arguments</em>.</td><td style='text-align:right;'></td></tr></table>
2439 <p>The <em class="arg">arguments</em> is a single string containing a list
2440 of floating point numbers separated by commas or spaces. The number of
2441 and meaning of the floating point values depends on the distortion <em
2442 class="arg">method</em> being used. </p>
2444 <p>Choose from these distortion types:</p>
2448 <th align="left" style="width: 8%">Method</th>
2449 <th align="left">Description</th>
2453 <td valign="top"><code>ScaleRotateTranslate</code>
2454 <br/>or <code>SRT</code></td>
2456 Distort image by first scaling and rotating about a given 'center',
2457 before translating that 'center' to the new location, in that order. It
2458 is an alternative method of specifying a '<code>Affine</code>' type of
2459 distortion, but without shearing effects. It also provides a good way
2460 of rotating and displacing a smaller image for tiling onto a larger
2461 background (IE 2-dimensional animations). <br/>
2463 The number of arguments determine the specific meaning of each
2464 argument for the scales, rotation, and translation operations. <br/>
2466 <table style="margin-left:auto; margin-right:auto;">
2467 <tr><td># </td><td>arguments meaning</td></tr>
2468 <tr><td>1:</td><td><em>Angle_of_Rotation</em></td></tr>
2469 <tr><td>2:</td><td><em>Scale Angle</em></td></tr>
2470 <tr><td>3:</td><td><em>X,Y Angle</em></td></tr>
2471 <tr><td>4:</td><td><em>X,Y Scale Angle</em></td></tr>
2473 <td><em>X,Y ScaleX,ScaleY Angle</em></td></tr>
2475 <td><em>X,Y Scale Angle NewX,NewY</em></td></tr>
2477 <td><em>X,Y ScaleX,ScaleY Angle
2478 NewX,NewY</em></td></tr>
2481 This is actually an alternative way of specifying a 2 dimensional linear
2482 '<code>Affine</code>' or '<code>AffineProjection</code>' distortion. </td> </tr>
2485 <td valign="top"><code>Affine</code></td>
2487 Distort the image linearly by moving a list of at least 3 or more sets
2488 of control points (as defined below). Ideally 3 sets or 12 floating
2489 point values are given allowing the image to be linearly scaled,
2490 rotated, sheared, and translated, according to those three points. See
2491 also the related '<code>AffineProjection</code>' and '<code>SRT</code>'
2494 More than 3 sets given control point pairs (12 numbers) is least
2495 squares fitted to best match a linear affine distortion. If only 2
2496 control point pairs (8 numbers) are given a two point image translation
2497 rotation and scaling is performed, without any possible shearing,
2498 flipping or changes in aspect ratio to the resulting image. If only one
2499 control point pair is provides the image is only translated, (which may
2500 be a floating point non-integer translation). <br/>
2502 This distortion does not include any form of perspective distortion.
2508 <td valign="top"><code>AffineProjection</code></td>
2510 Linearly distort an image using the given Affine Matrix of 6
2511 pre-calculated coefficients forming a set of Affine Equations to map
2512 the source image to the destination image.
2514 <div style="text-align: center"><em>
2515 s<sub>x</sub>, r<sub>x</sub>,
2516 r<sub>y</sub>, s<sub>y</sub>,
2517 t<sub>x</sub>, t<sub>y</sub>
2520 See <a href="command-line-options.html#affine" >-affine</a> setting for more detail, and
2521 meanings of these coefficients. <br/>
2523 The distortions '<code>Affine</code>' and '<code>SRT</code>' provide
2524 alternative methods of defining this distortion, with ImageMagick doing
2525 the calculations needed to generate the required coefficients. You can
2526 see the internally generated coefficients, by using a <a
2527 href="command-line-options.html#verbose" >-verbose</a> setting with those other variants. </td>
2532 <td valign="top"><code>BilinearForward</code><br/>
2533 <code>BilinearReverse</code></td>
2535 Bilinear Distortion, given a minimum of 4 sets of coordinate pairs, or
2536 16 values (see below). Not that lines may not appear straight after
2537 distortion, though the distance between coordinates will remain
2540 The '<code>BilinearForward</code>' is used to map rectangles to any
2541 quadrilateral, while the '<code>BilinearReverse</code>' form maps any
2542 quadrilateral to a rectangle, while preserving the straight line edges
2545 Note that '<code>BilinearForward</code>' can generate invalid pixels
2546 which will be colored using the <a href="command-line-options.html#mattecolor" >-mattecolor</a>
2547 color setting. Also if the quadrilateral becomes 'flipped' the image
2548 may disappear. <br/>
2550 There are future plans to produce a true Bilinear distortion that will
2551 attempt to map any quadrilateral to any other quadrilateral, while
2552 preserving edges (and edge distance ratios).
2558 <td valign="top"><code>Perspective</code></td>
2560 Perspective distort the images, using a list of 4 or more sets of
2561 control points (as defined below). More that 4 sets (16 numbers) of
2562 control points provide least squares fitting for more accurate
2563 distortions (for the purposes of image registration and panorama
2564 effects). Less than 4 sets will fall back to a '<code>Affine</code>'
2565 linear distortion. <br/>
2567 Perspective Distorted images ensures that straight lines remain
2568 straight, but the scale of the distorted image will vary. The horizon
2569 is anti-aliased, and the 'sky' color may be set using the
2570 <a href="command-line-options.html#mattecolor" >-mattecolor</a> setting. </td>
2574 <td valign="top"><code>PerspectiveProjection</code> </td>
2576 Do a '<code>Perspective</code>' distortion biased on a set of 8
2577 pre-calculated coefficients. You can get these coefficients by looking
2578 at the <a href="command-line-options.html#verbose" >-verbose</a> output of a
2579 '<code>Perspective</code>' distortion, or by calculating them yourself.
2580 If the last two perspective scaling coefficients are zero, the
2581 remaining 6 represents a transposed 'Affine Matrix'. </td>
2586 <td valign="top"><code>Arc</code></td>
2588 Arc the image (variation of polar mapping) over the angle given around
2590 <table width="90%" style = "margin-left: auto; margin-right: auto;">
2591 <tr valign="top"><td>Argument</td>
2592 <td>Meaning</td></tr>
2593 <tr valign="top"><td><em>arc_angle</em></td>
2594 <td>The angle over which to arc the image side-to-side</td></tr>
2595 <tr valign="top"><td><em>rotate_angle</em></td>
2596 <td>Angle to rotate resulting image from vertical center</td></tr>
2597 <tr valign="top"><td><em>top_radius</em></td>
2598 <td>Set top edge of source image at this radius</td></tr>
2599 <tr valign="top"><td><em>bottom_radius</em> </td>
2600 <td>Set bottom edge to this radius (radial scaling)</td></tr>
2603 The resulting image is always resized to best fit the resulting image,
2604 (as if using <a href="command-line-options.html#distort" >+distort</a>) while attempting to
2605 preserve scale and aspect ratio of the original image as much as
2606 possible with the arguments given by the user. All four arguments will
2607 be needed to change the overall aspect ratio of an 'Arc'ed image. <br/>
2609 This a variation of a polar distortion designed to try to preserve the
2610 aspect ratio of the image rather than direct Cartesian to Polar
2615 <td valign="top"><code>Polar</code></td>
2617 Like '<code>Arc</code>' but do a complete Cartesian to Polar mapping of
2618 the image. that is the height of the input image is mapped to the
2619 radius limits, while the width is wrapped around between the
2622 Arguments: <em>Rmax,Rmin CenterX,CenterY, start,end_angle</em> <br/>
2624 All arguments are optional. With <em>Rmin</em> defaulting to zero, the
2625 center to the center of the image, and the angles going from -180 (top)
2626 to +180 (top). If <em>Rmax</em> is given the special value of
2627 '<code>0</code>', the the distance from the center to the nearest edge
2628 is used for the radius of the output image, which will ensure the whole
2629 image is visible (though scaled smaller). However a special value of
2630 '<code>-1</code>' will use the distance from the center to the furthest
2631 corner, This may 'clip' the corners from the input rectangular image,
2632 but will generate the exact reverse of a '<code>DePolar</code>' with
2633 the same arguments. <br/>
2635 If the plus form of distort (<a href="command-line-options.html#distort" >+distort</a>) is used
2636 output image center will default to <code>0,0</code> of the virtual
2637 canvas, and the image size adjusted to ensure the whole input image is
2638 made visible in the output image on the virtual canvas. </td>
2643 <td valign="top"><code>DePolar</code></td>
2645 Uses the same arguments and meanings as a '<code>Polar</code>' distortion
2646 but generates the reverse Polar to Cartesian distortion. <br/>
2648 The special <em>Rmax</em> setting of '<code>0</code>' may however clip
2649 the corners of the input image. However using the special
2650 <em>Rmax</em> setting of '<code>-1</code>' (maximum center to corner
2651 distance) will ensure the whole distorted image is preserved in the
2652 generated result, so that the same argument to '<code>Polar</code>' will
2653 reverse the distortion re-producing the original.
2655 Note that as this distortion requires the area resampling of a circular
2656 arc, which can not be handled by the builtin EWA resampling function.
2657 As such the normal EWA filters are turned off. It is recommended some
2658 form of 'super-sampling' image processing technique be used to produce
2659 a high quality result. </td>
2664 <td valign="top"><code>Barrel</code></td>
2666 Given the four coefficients (A,B,C,D) as defined by <a
2667 href="http://wiki.panotools.org/Lens_correction_model" >Helmut
2668 Dersch</a>, perform a barrel or pin-cushion distortion appropriate to
2669 correct radial lens distortions. That is in photographs, make straight
2670 lines straight again. <br/>
2672 Arguments: <em>A B C</em> [ <em>D</em> [
2673 <em>X</em> , <em>Y</em> ] ] <br/>
2674 or <em>A<sub>x</sub> B<sub>x</sub> C<sub>x</sub> D<sub>x</sub>
2675 A<sub>y</sub> B<sub>y</sub> C<sub>y</sub> D<sub>y</sub></em>
2676 [ <em>X</em> , <em>Y</em> ] <br/>
2677 So that it forms the function <br/>
2678 Rsrc = r * ( <em>A</em>*r<sup>3</sup> + <em>B</em>*r<sup>2</sup> +
2679 <em>C</em>*r + <em>D</em> )<br/>
2681 Where <em>X</em>,<em>Y</em> is the optional center of the distortion
2682 (defaulting to the center of the image). <br/>
2683 The second form is typically used to distort images, rather than
2684 correct lens distortions. <br/>
2690 <td valign="top"><code>BarrelInverse</code></td>
2692 This is very similar to '<code>Barrel</code>' with the same set of
2693 arguments, and argument handling. However it uses the inverse
2694 of the radial polynomial,
2695 so that it forms the function <br/>
2696 Rsrc = r / ( <em>A</em>*r<sup>3</sup> + <em>B</em>*r<sup>2</sup> +
2697 <em>C</em>*r + <em>D</em> )<br/>
2698 Note that this is not the reverse of the '<code>Barrel</code>'
2699 distortion, just a different barrel-like radial distortion method.
2705 <td valign="top"><code>Shepards</code></td>
2707 Distort the given list control points (any number) using an Inverse
2708 Squared Distance Interpolation Method (<a
2709 href="http://en.wikipedia.org/wiki/Shepard%27s_method" >Shepards
2710 Method</a>). The control points in effect do 'localized' displacement
2711 of the image around the given control point (preserving the look and
2712 the rotation of the area near the control points. For best results
2713 extra control points should be added to 'lock' the positions of the
2714 corners, edges and other unchanging parts of the image, to prevent
2715 their movement. <br/>
2717 The distortion has been likened to 'taffy pulling' using nails, or
2718 pins' stuck in a block of 'jelly' which is then moved to the new
2719 position, distorting the surface of the jelly. <br/>
2721 Internally it is equivalent to generating a displacement map (see <a
2722 href="command-line-options.html#displace" >-displace</a>) for source image color look-up using
2723 the <a href="command-line-options.html#sparse-color" >-sparse-color</a> method of the same name.
2730 <p>To print a complete list of distortion methods, use <a href="command-line-options.html#list">-list
2733 <p>Many of the above distortion methods such as '<code>Affine</code>',
2734 '<code>Perspective</code>', and '<code>Shepards</code>' use a list control points
2735 defining how these points in the given image should be distorted in the
2736 destination image. Each set of four floating point values represent a source
2737 image coordinate, followed immediately by the destination image coordinate.
2738 This produces a list of values such as...</p>
2739 <div style="text-align: center"><em>
2740 U<sub>1</sub>,V<sub>1</sub> X<sub>1</sub>,Y<sub>1</sub>
2741 U<sub>2</sub>,V<sub>2</sub> X<sub>2</sub>,Y<sub>2</sub>
2742 U<sub>3</sub>,V<sub>3</sub> X<sub>3</sub>,Y<sub>3</sub>
2744 U<sub>n</sub>,V<sub>n</sub> X<sub>n</sub>,Y<sub>n</sub>
2746 <p>where <em>U,V</em> on the source image is mapped to <em>X,Y</em> on the
2747 destination image. </p>
2749 <p>For example, to warp an image using '<code>perspective</code>' distortion,
2750 needs a list of at least 4 sets of coordinates, or 16 numbers. Here is the
2751 perspective distortion of the built-in "rose:" image. Note how spaces were
2752 used to group the 4 sets of coordinate pairs, to make it easier to read and
2755 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>
2756 convert rose: -virtual-pixel black \<br/>
2757 -distort Perspective '0,0,0,0 0,45,0,45 69,0,60,10 69,45,60,35' \<br/>
2758 rose_3d_rotated.gif</span></p>
2759 <p>If more that the required number of coordinate pairs are given for
2760 a distortion, the distortion method is 'least squares' fitted to produce the
2761 best result for all the coordinate pairs given. If less than the ideal number
2762 of points are given, the distort will generally fall back to a simpler form of
2763 distortion that can handles the smaller number of coordinates (usually a linear
2764 '<code>Affine</code>' distortion). </p>
2766 <p>By using more coordinates you can make use of image registration tool to
2767 find matching coordinate pairs in overlapping images, so as to improve the
2768 'fit' of the distortion. Of course a bad coordinate pair can also make the
2769 'fit' worse. Caution is always advised. </p>
2771 <p>Colors are acquired from the source image according to a cylindrical
2772 resampling <a href="command-line-options.html#filter" >-filter</a>, using a special technique known as
2773 EWA resampling. This produces very high quality results, especially when
2774 images become smaller (minified) in the output, which is very common when
2775 using '<code>perspective</code>' distortion. For example here we view
2776 a infinitely tiled 'plane' all the way to the horizon. </p>
2778 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>
2779 convert -size 90x90 pattern:checkerboard -normalize -virtual-pixel tile \<br/>
2780 -distort perspective '0,0,5,45 89,0,45,46 0,89,0,89 89,89,89,89' \<br/>
2781 checks_tiled.jpg</span></p>
2782 <p>Note that a infinitely tiled perspective images involving the horizon can
2783 be very slow, because of the number of pixels that are compressed to generate
2784 each individual pixel close to the 'horizon'. You can turn off EWA
2785 resampling, by specifing the special <a href="command-line-options.html#filter" >-filter</a> setting of
2786 '<code>point</code>' (recommended if you plan to use super-sampling instead).
2789 <p>If an image generates <i>invalid pixels</i>, such as the 'sky' in the last
2790 example, <a href="command-line-options.html#distort" >-distort</a> will use the current <a
2791 href="command-line-options.html#mattecolor" >-mattecolor</a> setting for these pixels. If you do not
2792 what these pixels to be visible, set the color to match the rest of the
2795 <p>The output image size will by default be the same as the input image. This
2796 means that if the part of the distorted image falls outside the viewed area of
2797 the 'distorted space', those parts is clipped and lost. However if you use
2798 the plus form of the operator (<a href="command-line-options.html#distort" >+distort</a>) the operator
2799 will attempt (if possible) to show the whole of the distorted image, while
2800 retaining a correct 'virtual canvas' offset, for image layering. This offset
2801 may need to be removed using <a href="command-line-options.html#repage" >+repage</a>, to remove if it
2804 <p>Setting <a href="command-line-options.html#verbose" >-verbose</a> setting, will cause <a
2805 href="command-line-options.html#distort" >-distort</a> to attempt to output the internal coefficients,
2806 and the <a href="command-line-options.html#fx" >-fx</a> equivalent to the distortion, for expert study,
2807 and debugging purposes. This many not be available for all distorts. </p>
2809 <p>You can alternatively specify a special "<code><a href="command-line-options.html#define"
2810 >-define</a> distort:viewport={geometry_string}</code>" setting which will
2811 specify the size and the offset of the generated 'viewport' image of the
2812 distorted image space.</p>
2814 <p>Setting a "<code><a href="command-line-options.html#define" >-define</a>
2815 distort:scale={scale_factor}</code>" will scale the output image (viewport or
2816 otherwise) by that factor without changing the viewed contents of the
2817 distorted image. This can be used either for 'super-sampling' the image for
2818 a higher quality result, or for panning and zooming around the image (with
2819 appropriate viewport changes, or post-distort cropping and resizing). </p>
2821 <p>Setting "<code><a href="command-line-options.html#define" >-define</a> resample:verbose=1</code>"
2822 will output the cylindrical filter lookup table created by the EWA (Elliptical
2823 Weighted Average) resampling algorithm. Note this table uses a squared radius
2824 lookup value. This is typically only used for debugging EWA resampling. </p>
2827 <div style="margin: auto;">
2828 <h4><a id="distribute-cache"></a>-distribute-cache <em class="arg">port</em></h4>
2831 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>launch a distributed pixel cache server. </td><td style='text-align:right;'></td></tr></table>
2833 <div style="margin: auto;">
2834 <h4><a id="dither"></a>-dither <em class="arg">method</em></h4>
2837 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Apply a Riemersma or Floyd-Steinberg error diffusion dither to
2838 images when general color reduction is applied via an option, or automagically
2839 when saving to specific formats. This enabled by default. </td><td style='text-align:right;'></td></tr></table>
2841 <p>Dithering places two or more colors in neighboring pixels so that to the
2842 eye a closer approximation of the images original color is reproduced. This
2843 reduces the number of colors needed to reproduce the image but at the cost of
2844 a lower level pattern of colors. Error diffusion dithers can use any set of
2845 colors (generated or user defined) to an image. </p>
2847 <p>Dithering is turned on by default, to turn it off use the plus form of the
2848 setting, <a href="command-line-options.html#dither">+dither</a>. This will also also render PostScript
2849 without text or graphic aliasing. Disabling dithering often (but not always)
2850 leads to faster process, a smaller number of colors, but more cartoon like
2851 image coloring. Generally resulting in 'color banding' effects in areas with
2852 color gradients. </p>
2854 <p>The color reduction operators <a href="command-line-options.html#colors">-colors</a>, <a
2855 href="command-line-options.html#monochrome">-monochrome</a>, <a href="command-line-options.html#remap ">-remap</a>, and <a
2856 href="command-line-options.html#posterize">-posterize</a>, apply dithering to images using the reduced
2857 color set they created. These operators are also used as part of automatic
2858 color reduction when saving images to formats with limited color support, such
2859 as <code>GIF:</code>, <code>XBM:</code>, and others, so dithering may also be used
2860 in these cases. </p>
2862 <p>Alternatively you can use <a href="command-line-options.html#random-threshold">-random-threshold</a>
2863 to generate purely random dither. Or use <a
2864 href="command-line-options.html#ordered-dither">-ordered-dither</a> to apply threshold mapped dither
2865 patterns, using uniform color maps, rather than specific color maps. </p>
2868 <div style="margin: auto;">
2869 <h4><a id="draw"></a>-draw <em class="arg">string</em></h4>
2872 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Annotate an image with one or more graphic primitives.</td><td style='text-align:right;'></td></tr></table>
2874 <p>Use this option to annotate or decorate an image with one or more graphic
2875 primitives. The primitives include shapes, text, transformations, and pixel
2878 <p>The shape primitives:</p>
2883 rectangle x0,y0 x1,y1
2884 roundRectangle x0,y0 x1,y1 wc,hc
2885 arc x0,y0 x1,y1 a0,a1
2886 ellipse x0,y0 rx,ry a0,a1
2888 polyline x0,y0 ... xn,yn
2889 polygon x0,y0 ... xn,yn
2890 bezier x0,y0 ... xn,yn
2891 path path specification
2892 image operator x0,y0 w,h filename
2895 <p>The text primitive:</p>
2900 <p>The text gravity primitive:</p>
2903 gravity NorthWest, North, NorthEast, West, Center,
2904 East, SouthWest, South, or SouthEast
2907 <p>The text gravity primitive only affects the placement of text and does not
2908 interact with the other primitives. It is equivalent to using the <a
2909 href="command-line-options.html#gravity">-gravity</a> command-line option, except that it is limited in
2910 scope to the <a href="command-line-options.html#draw">-draw</a> option in which it appears.</p>
2912 <p>The transformation primitives:</p>
2922 <p>The pixel operation primitives:</p>
2929 <p>The shape primitives are drawn in the color specified by the preceding <a
2930 href="command-line-options.html#fill">-fill</a> setting. For unfilled shapes, use <a
2931 href="command-line-options.html#fill">-fill none</a>. You can optionally control the stroke (the
2932 "outline" of a shape) with the <a href="command-line-options.html#stroke">-stroke</a> and <a
2933 href="command-line-options.html#strokewidth">-strokewidth</a> settings.</p>
2935 <p>A <code>point</code> primitive is specified by a single <em>point</em> in the
2936 pixel plane, that is, by an ordered pair of integer coordinates,
2937 <em>x</em>,<em>y</em>. (As it involves only a single pixel, a <code>point</code>
2938 primitive is not affected by <a href="command-line-options.html#stroke">-stroke</a> or <a
2939 href="command-line-options.html#strokewidth">-strokewidth</a>.)</p>
2941 <p>A <code>line</code> primitive requires a start point and end point.</p>
2943 <p>A <code>rectangle</code> primitive is specified by the pair of points at the
2944 upper left and lower right corners.</p>
2946 <p>A <code>roundRectangle</code> primitive takes the same corner points as
2947 a <code>rectangle</code> followed by the width and height of the rounded corners
2950 <p>The <code>circle</code> primitive makes a disk (filled) or circle (unfilled).
2951 Give the center and any point on the perimeter (boundary).</p>
2953 <p>The <code>arc</code> primitive is used to inscribe an elliptical segment in
2954 to a given rectangle. An <code>arc</code> requires the two corners used for
2955 <code>rectangle</code> (see above) followed by the start and end angles of the
2956 arc of the segment segment (e.g. 130,30 200,100 45,90). The start and end
2957 points produced are then joined with a line segment and the resulting segment
2958 of an ellipse is filled.</p>
2960 <p>Use <code>ellipse</code> to draw a partial (or whole) ellipse. Give the
2961 center point, the horizontal and vertical "radii" (the <em>semi-axes</em> of
2962 the ellipse) and start and end angles in degrees (e.g. 100,100 100,150
2965 <p>The <code>polyline</code> and <code>polygon</code> primitives require three or
2966 more points to define their perimeters. A <code>polyline</code> is simply
2967 a <code>polygon</code> in which the final point is not stroked to the start
2968 point. When unfilled, this is a <em>polygonal line</em>. If the <a
2969 href="command-line-options.html#stroke">-stroke</a> setting is <code>none</code> (the default), then
2970 a <code>polyline</code> is identical to a <code>polygon</code>. </p>
2972 <p>A <em>coordinate</em> is a pair of integers separated by a space or
2973 optional comma. </p>
2975 <p>As an example, to define a circle centered at 100,100 that extends to
2979 -draw 'circle 100,100 150,150'
2982 <p>The <code>Bezier</code> primitive creates a spline curve and requires three
2983 or points to define its shape. The first and last points are the
2984 <em>knots</em> and these points are attained by the curve, while any
2985 intermediate coordinates are <em>control points</em>. If two control points
2986 are specified, the line between each end knot and its sequentially respective
2987 control point determines the tangent direction of the curve at that end. If
2988 one control point is specified, the lines from the end knots to the one
2989 control point determines the tangent directions of the curve at each end. If
2990 more than two control points are specified, then the additional control points
2991 act in combination to determine the intermediate shape of the curve. In order
2992 to draw complex curves, it is highly recommended either to use the
2993 <code>path</code> primitive or to draw multiple four-point bezier segments with
2994 the start and end knots of each successive segment repeated. For example:</p>
2997 -draw 'bezier 20,50 45,100 45,0 70,50'
3000 -draw 'bezier 70,50 95,100 95,0 120,50'
3004 <p>A <code>path</code> represents an outline of an object, defined in terms of
3005 moveto (set a new current point), lineto (draw a straight line), curveto (draw
3006 a Bezier curve), arc (elliptical or circular arc) and closepath (close the
3007 current shape by drawing a line to the last moveto) elements. Compound paths
3008 (i.e., a path with subpaths, each consisting of a single moveto followed by
3009 one or more line or curve operations) are possible to allow effects such as
3010 <em>donut holes</em> in objects. (See <a
3011 href="http://www.w3.org/TR/SVG/paths.html">Paths</a>.)</p>
3013 <p>Use <code>image</code> to composite an image with another image. Follow the
3014 image keyword with the composite operator, image location, image size, and
3018 -draw 'image SrcOver 100,100 225,225 image.jpg'
3021 <p>You can use 0,0 for the image size, which means to use the actual
3022 dimensions found in the image header. Otherwise, it is scaled to the given
3023 dimensions. See <a href="compose.html">Alpha Compositing</a> for
3024 a detailed discussion of alpha composition methods that are available. </p>
3026 The "special augmented compose operators" such as "dissolve" that require
3027 arguments cannot be used at present with the <code>-draw image</code> option.
3030 <p>Use <code>text</code> to annotate an image with text. Follow the text
3031 coordinates with a string. If the string has embedded spaces, enclose it in
3032 single or double quotes.</p>
3034 <p>For example, the following annotates the image with <code>Works like
3035 magick!</code> for an image titled <code>bird.miff</code>. </p>
3038 -draw "text 100,100 'Works like magick!' "
3041 <p>See the <a href="command-line-options.html#annotate">-annotate</a> option for another convenient way
3042 to annotate an image with text.</p>
3044 <p>The <code>rotate</code> primitive rotates subsequent shape primitives and
3045 text primitives about the origin of the main image. If the <a
3046 href="command-line-options.html#region">-region</a> option precedes the <a href="command-line-options.html#draw">-draw</a>
3047 option, the origin for transformations is the upper left corner of the
3050 <p>The <code>translate</code> primitive translates subsequent shape and text
3053 <p>The <code>scale</code> primitive scales them.</p>
3055 <p>The <code>skewX</code> and <code>skewY</code> primitives skew them with respect
3056 to the origin of the main image or the region.</p>
3058 <p>The transformations modify the current affine matrix, which is initialized
3059 from the initial affine matrix defined by the <a href="command-line-options.html#affine">-affine</a>
3060 option. Transformations are cumulative within the <a href="command-line-options.html#draw">-draw</a>
3061 option. The initial affine matrix is not affected; that matrix is only changed
3062 by the appearance of another <a href="command-line-options.html#affine">-affine</a> option. If another
3063 <a href="command-line-options.html#draw">-draw</a> option appears, the current affine matrix is
3064 reinitialized from the initial affine matrix.</p>
3066 <p>Use the <code>color</code> primitive to change the color of a pixel to the
3067 fill color (see <a href="command-line-options.html#fill">-fill</a>). Follow the pixel coordinate with
3078 <p>Consider the target pixel as that specified by your coordinate. The
3079 <code>point</code> method recolors the target pixel. The <code>replace</code>
3080 method recolors any pixel that matches the color of the target pixel.
3081 <code>Floodfill</code> recolors any pixel that matches the color of the target
3082 pixel and is a neighbor, whereas <code>filltoborder</code> recolors any neighbor
3083 pixel that is not the border color. Finally, <code>reset</code> recolors all
3086 <p>Use <code>matte</code> to the change the pixel matte value to transparent.
3087 Follow the pixel coordinate with a method (see the <code>color</code> primitive
3088 for a description of methods). The <code>point</code> method changes the matte
3089 value of the target pixel. The <code>replace</code> method changes the matte
3090 value of any pixel that matches the color of the target pixel.
3091 <code>Floodfill</code> changes the matte value of any pixel that matches the
3092 color of the target pixel and is a neighbor, whereas <code>filltoborder</code>
3093 changes the matte value of any neighbor pixel that is not the border color (<a
3094 href="command-line-options.html#bordercolor">-bordercolor</a>). Finally <code>reset</code> changes the
3095 matte value of all pixels.</p>
3097 <p>You can set the primitive color, font, and font bounding box color with <a
3098 href="command-line-options.html#fill">-fill</a>, <a href="command-line-options.html#font">-font</a>, and <a href="command-line-options.html#box">-box</a>
3099 respectively. Options are processed in command line order so be sure to use
3100 these options <em>before</em> the <a href="command-line-options.html#draw">-draw</a> option.</p>
3102 <p>Strings that begin with a number must be quoted (e.g. use '1.png' rather
3105 <p>Drawing primitives conform to the <a href="magick-vector-graphics.html" >Magick
3106 Vector Graphics</a> format.</p>
3109 <div style="margin: auto;">
3110 <h4><a id="duplicate"></a>-duplicate <em class="arg">count,indexes</em></h4>
3113 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>duplicate an image one or more times.</td><td style='text-align:right;'></td></tr></table>
3115 <p>Specify the count and the image to duplicate by its index in the sequence.
3116 The first image is index 0. Negative indexes are relative to the end of the
3117 sequence, for example, -1 represents the last image of the sequence. Specify
3118 a range of images with a dash (e.g. 0-4). Separate indexes with a comma (e.g.
3119 0,2). Use <code>+duplicate</code> to duplicate the last image in the current
3122 <div style="margin: auto;">
3123 <h4><a id="edge"></a>-edge <em class="arg">radius</em></h4>
3126 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>detect edges within an image.</td><td style='text-align:right;'></td></tr></table>
3128 <div style="margin: auto;">
3129 <h4><a id="emboss"></a>-emboss <em class="arg">radius</em></h4>
3132 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>emboss an image.</td><td style='text-align:right;'></td></tr></table>
3134 <div style="margin: auto;">
3135 <h4><a id="encipher"></a>-encipher <em class="arg">filename</em></h4>
3138 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Encipher pixels for later deciphering by <a href="command-line-options.html#decipher">-decipher</a>.</td><td style='text-align:right;'></td></tr></table>
3140 <p>Get the passphrase from the file specified by <em class="arg"
3143 <p>For more information, see the webpage, <a
3144 href="http://www.imagemagick.org/www/cipher.html">ImageMagick: Encipher or
3145 Decipher an Image</a>.</p>
3149 <div style="margin: auto;">
3150 <h4><a id="encoding"></a>-encoding <em class="arg">type</em></h4>
3153 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>specify the text encoding.</td><td style='text-align:right;'></td></tr></table>
3155 <p>Choose from <code>AdobeCustom</code>, <code>AdobeExpert</code>,
3156 <code>AdobeStandard</code>, <code>AppleRoman</code>, <code>BIG5</code>,
3157 <code>GB2312</code>, <code>Latin 2</code>, <code>None</code>, <code>SJIScode</code>,
3158 <code>Symbol</code>, <code>Unicode</code>, <code>Wansung</code>.</p>
3160 <div style="margin: auto;">
3161 <h4><a id="endian"></a>-endian <em class="arg">type</em></h4>
3164 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Specify endianness (<code>MSB</code> or <code>LSB</code>) of the image.</td><td style='text-align:right;'></td></tr></table>
3166 <p>To print a complete list of endian types, use the <a href="command-line-options.html#list">-list endian</a> option.</p>
3168 <p>Use <a href="command-line-options.html#endian">+endian</a> to revert to unspecified endianness.</p>
3171 <div style="margin: auto;">
3172 <h4><a id="enhance"></a>-enhance</h4>
3175 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Apply a digital filter to enhance a noisy image.</td><td style='text-align:right;'></td></tr></table>
3178 <div style="margin: auto;">
3179 <h4><a id="equalize"></a>-equalize</h4>
3182 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>perform histogram equalization on the image channel-by-channel.</td><td style='text-align:right;'></td></tr></table>
3184 <p>To perform histogram equalization on all channels in concert, transform the
3185 image into some other color space, such as HSL, OHTA, YIQ or YUV, then
3186 equalize the appropriate intensity-like channel, then convert back to RGB.</p>
3188 <p>For example using HSL, we have: ... <code>-colorspace HSL -channel lightness
3189 -equalize -colorspace RGB</code> ...</p>
3191 <p>For YIQ, YUV and OHTA use the red channel. For example, OHTA is a principal
3192 components transformation that puts most of the information in the first
3193 channel. Here we have ... <code>-colorspace OHTA -channel red -equalize
3194 -colorspace RGB</code> ...</p>
3196 <div style="margin: auto;">
3197 <h4><a id="evaluate"></a>-evaluate <em class="arg">operator value</em></h4>
3200 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Alter channel pixels by evaluating an arithmetic, relational, or logical expression.</td><td style='text-align:right;'></td></tr></table>
3202 <p>(See the <a href="command-line-options.html#function" >-function</a> operator for some
3203 multi-parameter functions. See the <a href="command-line-options.html#fx" >-fx</a> operator if more
3204 elaborate calculations are needed.)</p>
3206 <p>The behaviors of each <em class="arg">operator</em> are summarized in the
3207 following list. For brevity, the numerical value of a "pixel" referred to
3208 below is the value of the corresponding channel of that pixel, while
3209 a "normalized pixel" is that number divided by the maximum
3210 (installation-dependent) value <em class="QR">QuantumRange</em>. (If
3211 normalized pixels are used, they are restored, following the other
3212 calculations, to the full range by multiplying by <em
3213 class="QR">QuantumRange</em>.)</p>
3220 <th><em class="arg">operator</em></th>
3221 <th>Summary (see further below for details)</th>
3226 <tr><td>Abs </td> <td>Add <em class="arg">value</em> to pixels and return absolute value. </td></tr>
3227 <tr><td>Add </td> <td>Add <em class="arg">value</em> to pixels. </td></tr>
3228 <tr><td>AddModulus </td> <td>Add <em class="arg">value</em> to pixels modulo <em class="QR">QuantumRange</em>.</td></tr>
3229 <tr><td>And </td> <td>Binary AND of pixels with <em class="arg">value</em>.</td></tr>
3230 <tr><td>Cos, Cosine </td> <td>Apply cosine to pixels with frequency <em class="arg">value</em> with 50% bias added.</td></tr>
3231 <tr><td>Divide </td> <td>Divide pixels by <em class="arg">value</em>.</td></tr>
3232 <tr><td>Exp </td> <td>base-e exponential function</td></tr>
3233 <tr><td>Exponential </td> <td>base-e exponential function</td></tr>
3234 <tr><td>LeftShift </td> <td>Shift the pixel values left by <em class="arg">value</em> bits (i.e., multiply pixels by 2<sup><em class="arg">value</em></sup>).</td></tr>
3235 <tr><td>Log </td> <td>Apply scaled logarithm to normalized pixels.</td></tr>
3236 <tr><td>Max </td> <td>Clip pixels at lower bound <em class="arg">value</em>.</td></tr>
3237 <tr><td>Mean </td> <td>Add the <em class="arg">value</em> and divide by 2.</td></tr>
3238 <tr><td>Median </td> <td>Choose the median value from an image sequence.</td></tr>
3239 <tr><td>Min </td> <td>Clip pixels at upper bound <em class="arg">value</em>.</td></tr>
3240 <tr><td>Multiply </td> <td>Multiply pixels by <em class="arg">value</em>.</td></tr>
3241 <tr><td>Or </td> <td>Binary OR of pixels with <em class="arg">value</em>.</td></tr>
3242 <tr><td>Pow </td> <td>Raise normalized pixels to the power <em class="arg">value</em>.</td></tr>
3243 <tr><td>RightShift </td> <td>Shift the pixel values right by <em class="arg">value</em> bits (i.e., divide pixels by 2<sup><em class="arg">value</em></sup>).</td></tr>
3244 <tr><td>Set </td> <td>Set pixel equal to <em class="arg">value</em>.</td></tr>
3245 <tr><td>Sin, Sine </td> <td>Apply sine to pixels with frequency <em class="arg">value</em> with 50% bias added.</td></tr>
3246 <tr><td>Subtract </td> <td>Subtract <em class="arg">value</em> from pixels.</td></tr>
3247 <tr><td>Xor </td> <td>Binary XOR of pixels with <em class="arg">value.</em></td></tr>
3249 <tr><td> </td></tr>
3251 <tr><td>Gaussian-noise</td></tr>
3252 <tr><td>Impulse-noise</td></tr>
3253 <tr><td>Laplacian-noise</td></tr>
3254 <tr><td>Multiplicative-noise</td> <td>(These are equivalent to the corresponding <a href="command-line-options.html#noise" >-noise</a> operators.)</td></tr>
3255 <tr><td>PoissonNoise</td></tr>
3256 <tr><td>Uniform-noise</td></tr>
3258 <tr><td> </td></tr>
3260 <tr><td>Threshold </td> <td>Threshold pixels larger than <em class="arg">value</em>.</td></tr>
3261 <tr><td>ThresholdBlack </td> <td>Threshold pixels to zero values equal to or below <em class="arg">value</em>.</td></tr>
3262 <tr><td>ThresholdWhite </td> <td>Threshold pixels to maximum values above <em class="arg">value</em>. </td></tr>
3266 <p>The specified functions are applied only to each previously set <a
3267 href="command-line-options.html#channel" >-channel</a> in the image. If necessary, the results of the
3268 calculations are truncated (clipped) to fit in the interval [0, <em
3269 class="QR">QuantumRange</em>]. The transparency channel of the image is
3270 represented as a 'alpha' values (0 = fully transparent), so, for example, a
3271 <code>Divide</code> by 2 of the alpha channel will make the image
3272 semi-transparent. Append the percent symbol '<code>%</code>' to specify a value
3273 as a percentage of the <em class="QR">QuantumRange</em>.</p>
3275 <p>To print a complete list of <a href="command-line-options.html#evaluate">-evaluate</a> operators, use
3276 <a href="command-line-options.html#list">-list evaluate</a>.</p>
3278 <p>The results of the <code>Add</code>, <code>Subtract</code> and
3279 <code>Multiply</code> methods can also be achieved using either the <a
3280 href="command-line-options.html#level" >-level</a> or the <a href="command-line-options.html#level" >+level</a> operator, with
3281 appropriate argument, to linearly modify the overall range of color values.
3282 Please note, however, that <a href="command-line-options.html#level" >-level</a> treats transparency as
3283 'matte' values (0 = opaque), while <a href="command-line-options.html#level" >-evaluate</a> works with
3286 <p><code>AddModulus</code> has been added as of ImageMagick 6.4.8-4 and provides
3287 addition modulo the <em class="QR">QuantumRange</em>. It is therefore
3288 equivalent to <code>Add</code> unless the resulting pixel value is outside the
3289 interval [0, <em class="QR">QuantumRange</em>]. </p>
3291 <p><code>Exp or Exponential</code> has been added as of ImageMagick 6.6.5-1 and
3292 works on normalized pixel values. The <em class="arg">value</em> used with
3293 <code>Exp</code> should be negative so as to produce a decaying exponential
3294 function. Non-negative values will always produce results larger unity and
3295 thus outside the interval [0, <em class="QR">QuantumRange</em>]. The
3296 formula is expressed below. </p>
3298 <div style="text-align:center;">
3299 exp(<em class="arg">value</em> × <b><em>u</em></b>)
3302 <p> If the input image is squared, for example, using <a href="command-line-options.html#-function"
3303 >-function polynomial "2 0 0"</a>, then a decaying Gaussian function will be
3306 <p><code>Log</code> has been added as of ImageMagick 6.4.2-1 and works on
3307 normalized pixel values. This a <em>scaled</em> log function. The <em
3308 class="arg">value</em> used with <code>Log</code> provides a <em>scaling
3309 factor</em> that adjusts the curvature in the graph of the log function. The
3310 formula applied to a normalized value <b><em>u</em></b> is below. </p>
3312 <div style="text-align:center;">
3313 log(<em class="arg">value</em> × <b><em>u</em></b> + 1) / log(<em class="arg">value</em> + 1)
3316 <p><code>Pow</code> has been added as of ImageMagick 6.4.1-9, and works on
3317 normalized pixel values. Note that <code>Pow</code> is related to the <a
3318 href="command-line-options.html#gamma" >-gamma</a> operator. For example, <b>-gamma 2</b> is equivalent
3319 to <b>-evaluate pow 0.5</b>, i.e., a 'square root' function. The value used
3320 with <a href="command-line-options.html#gamma" >-gamma</a> is simply the reciprocal of the value used
3321 with <code>Pow</code>.</p>
3323 <p><code>Cosine</code> and <code>Sine</code> was added as of IM v6.4.8-8 and
3324 converts the image values into a value according to a (co)sine wave function.
3325 The synonyms <code>Cos</code> and <code>Sin</code> may also be used. The output
3326 is biased 50% and normalized by 50% so as to fit in the respective color value
3327 range. The <em class="arg">value</em> scaling of the <em>period</em> of the
3328 function (its frequency), and thus determines the number of 'waves' that will
3329 be generated over the input color range. For example, if the <em
3330 class="arg">value</em> is 1, the effective period is simply the <em
3331 class="QR">QuantumRange</em>; but if the <em class="arg">value</em> is 2,
3332 then the effective period is the <em>half</em> the <em
3333 class="QR">QuantumRange</em>.</p>
3335 <div style="text-align:center;">
3336 0.5 + 0.5 × cos(2 π <b><em>u</em></b> × <em class="arg">value</em>).
3339 <p>See also the <a href="command-line-options.html#function" >-function</a> operator, which is a
3340 multi-value version of evaluate. </p>
3342 <div style="margin: auto;">
3343 <h4><a id="evaluate-sequence"></a>-evaluate-sequence <em class="arg">operator</em></h4>
3346 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Alter channel pixels by evaluating an arithmetic, relational, or
3347 logical expression over a sequence of images.</td><td style='text-align:right;'></td></tr></table>
3349 <p>To print a complete list of <a
3350 href="command-line-options.html#evaluate-sequence">-evaluate-sequence</a> operators, use <a
3351 href="command-line-options.html#list">-list evaluate</a>.</p>
3353 <div style="margin: auto;">
3354 <h4><a id="extent"></a>-extent <em class="arg">geometry</em></h4>
3357 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Set the image size and offset.</td><td style='text-align:right;'></td></tr></table>
3359 <p>If the image is enlarged, unfilled areas are set to the background color.
3360 To position the image, use offsets in the <em class="arg">geometry</em>
3361 specification or precede with a <a href="command-line-options.html#gravity">-gravity</a> setting. To
3362 specify how to compose the image with the background, use <a href="command-line-options.html#compose"
3365 <p>This command reduces or expands a JPEG image to fit on an 800x600
3366 display. If the aspect ratio of the input image isn't exactly 4:3, then the
3367 image is centered on an 800x600 black canvas: </p>
3369 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert input.jpg -resize 800x600 -background black -compose Copy \ <br /> -gravity center -extent 800x600 -quality 92 output.jpg</span></p>
3372 <p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
3374 <div style="margin: auto;">
3375 <h4><a id="extract"></a>-extract <em class="arg">geometry</em></h4>
3378 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Extract the specified area from image.</td><td style='text-align:right;'></td></tr></table>
3380 <p>This option is most useful for extracting a subregion of a very large raw
3381 image. Note that these two commands are equivalent:</p>
3383 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert -size 16000x16000 -depth 8 -extract 640x480+1280+960 \ <br/> image.rgb image.png</span><span class='crtout'></span><span class="crtprompt"> $ </span><span class='crtin'>convert -size 16000x16000 -depth 8 'image.rgb[640x480+1280+960]' \ <br/> image.rgb image.png</span></p><p>If you omit the offsets, as in</p>
3385 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert -size 16000x16000 -depth 8 -extract 640x480 \ <br/> image.rgb image.png</span></p>
3386 <p>the image is <em>resized</em> to the specified dimensions instead,
3389 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert -size 16000x16000 -depth 8 -resize 640x480 image.rgb image.png</span></p>
3390 <p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
3392 <div style="margin: auto;">
3393 <h4><a id="family"></a>-family <em class="arg">fontFamily</em></h4>
3396 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Set a font family for text.</td><td style='text-align:right;'></td></tr></table>
3398 <p>This setting suggests a font family that ImageMagick should try to use for
3399 rendering text. If the family can be found it is used; if not, a default font
3400 (e.g., "Arial") or a family known to be similar is substituted (e.g.,
3401 "Courier" might be used if "System" is requested but not found). </p>
3403 <p>For other settings that affect fonts, see the options <a
3404 href="command-line-options.html#font">-font</a>, <a href="command-line-options.html#stretch">-stretch</a>, <a
3405 href="command-line-options.html#style">-style</a>, and <a href="command-line-options.html#weight">-weight</a>. </p>
3407 <div style="margin: auto;">
3408 <h4><a id="features"></a>-features <em class="arg">distance</em></h4>
3411 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>display (cooccurrence matrix) texture measure features for each channel in the image in each of four directions (horizontal, vertical, left and right diagonals) for the specified distance.</td><td style='text-align:right;'>[<a href="identify.html">identify</a>]</td></tr></table>
3414 Angular Second Moment
3417 Sum of Squares Variance
3418 Inverse Difference Moment
3425 Information Measure of Correlation 1
3426 Information Measure of Correlation 2
3427 Maximum Correlation Coefficient
3431 <div style="margin: auto;">
3432 <h4><a id="fft"></a>-fft</h4>
3435 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>implements the forward discrete Fourier transform (DFT).</td><td style='text-align:right;'></td></tr></table>
3437 <p>This option is new as of ImageMagick 6.5.4-3 (and now working for Windows
3438 users in ImageMagick 6.6.0-9). It transforms an image from the normal
3439 (spatial) domain to the frequency domain. In the frequency domain, an image is
3440 represented as a superposition of complex sinusoidal waves of varying
3441 amplitudes. The image x and y coordinates are the possible frequencies along
3442 the x and y directions, respectively, and the pixel intensity values are
3443 complex numbers that correspond to the sinusoidal wave amplitudes. See for
3444 example, <a href="http://en.wikipedia.org/wiki/Fourier_transform">Fourier
3445 Transform</a>, <a href="http://en.wikipedia.org/wiki/DFT">Discrete Fourier
3446 Transform</a> and <a href="http://en.wikipedia.org/wiki/FFT">Fast Fourier
3449 <p>A single image name is provided as output for this option. However, the
3450 output result will have two components. It is either a two-frame image or two
3451 separate images, depending upon whether the image format specified supports
3452 multi-frame images. The reason that we get a dual output result is because the
3453 frequency domain represents an image using complex numbers, which cannot be
3454 visualized directly. Therefore, the complex values are automagically separated
3455 into a two-component image representation. The first component is the
3456 magnitude of the complex number and the second is the phase of the complex
3457 number. See for example, <a
3458 href="http://en.wikipedia.org/wiki/Complex_numbers">Complex Numbers</a>.</p>
3460 <p>The magnitude and phase component images must be specified using image
3461 formats that do not limit the color or compress the image. Thus, MIFF, TIF,
3462 PFM, EXR and PNG are the recommended image formats to use. All of these
3463 formats, except PNG support multi-frame images. So for example,</p>
3465 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert image.png -fft fft_image.miff</span></p>
3466 <p>generates a magnitude image as <code>fft_image.miff[0]</code> and a phase
3467 image as <code>fft_image.miff[1]</code>. Similarly,</p>
3469 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert image.png -fft fft_image.png</span></p>
3470 <p>generates a magnitude image as <code>fft_image-0.png</code> and a phase image
3471 as <code>fft_image-1.png</code>. If you prefer this representation, then you can
3472 force any of the other formats to produce two output images by including <a
3473 href="command-line-options.html#adjoin">+adjoin</a> following -fft in the command line.</p>
3475 <p>The input image can be any size, but if not square and even-dimensioned, it
3476 is padded automagically to the larger of the width or height of the input
3477 image and to an even number of pixels. The padding will occur at the bottom
3478 and/or right sides of the input image. The resulting output magnitude and
3479 phase images is square at this size. The kind of padding relies on the <a
3480 href="command-line-options.html#virtual-pixel">-virtual-pixel</a> setting.</p>
3482 <p>Both output components will have dynamic ranges that fit within
3483 [0, <em class="QR">QuantumRange</em>], so that HDRI need not be enabled.
3484 Phase values nominally range from 0 to 2*π, but is scaled to span the full
3485 dynamic range. (The first few releases had non-HDRI scaled but HDRI not
3486 scaled). The magnitude image is not scaled and thus generally will contain
3487 very small values. As such, the image normally will appear totally black. In
3488 order to view any detail, the magnitude image typically is enhanced with a log
3489 function into what is usually called the spectrum. A log function is used to
3490 enhance the darker values more in comparison to the lighter values. This can
3491 be done, for example, as follows:</p>
3493 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert fft_image.miff[0] -contrast-stretch 0 \ <br />
3494 -evaluate log 1000 fft_image_spectrum.png</span></p>
3495 <p>where either <a href="command-line-options.html#contrast-stretch">-contrast-stretch</a> 0 or <a
3496 href="command-line-options.html#auto-level">-auto-level</a> is used to scale the image to full dynamic
3497 range, first. The argument to the <a href="command-line-options.html#evaluate">-evaluate</a> log
3498 typically is specified between 100 and 10,000, depending upon the amount of
3499 detail that one wants to bring out in the spectrum. Larger values produce more
3500 visible detail. Too much detail, however, may hide the important features.</p>
3502 <p>The <a href="http://www.fftw.org/">FFTW</a> delegate library is required to
3503 use <a href="command-line-options.html#fft">-fft</a>.</p>
3505 <p>Use <a href="command-line-options.html#fft">+fft</a> to produce two output images that are the real
3506 and imaginary components of the complex valued Fourier transform.</p>
3508 <p>However, as the real and imaginary components can contain negative values,
3509 this requires that IM be configured with HDRI enabled. In this case, you must
3510 use either MIFF, TIF, PFM or MPC formats for the real and imaginary component
3511 results, since they are formats that preserve both negative and fractional
3512 values without clipping them or truncating the fractional part. With either
3513 MIFF or TIF, one should add -define quantum:format=32, to allow those image
3514 types to work properly in HDRI mode without clipping.</p>
3516 <p>The real and imaginary component images resulting from <a
3517 href="command-line-options.html#fft">+fft</a> are also square, even dimensioned images due to the same
3518 padding that was discussed above for the magnitude and phase component
3521 <p>See the discussion on HDRI implementations of ImageMagick on the page <a
3522 href="high-dynamic-range.html" >High Dynamic-Range Images</a>. For more
3523 about HDRI go the ImageMagick <a
3524 href="http://www.imagemagick.org/Usage/basics/#hdri" >Usage</a> pages, <a
3525 href="http://www.fmwconcepts.com/imagemagick/fourier_transforms/fourier.html"
3526 >Fred's Fourier Processing With ImageMagick page</a> or this <a
3527 href="http://en.wikipedia.org/wiki/High_dynamic_range_imaging" >Wikipedia</a>
3531 <div style="margin: auto;">
3532 <h4><a id="fill"></a>-fill <em class="arg">color</em></h4>
3535 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>color to use when filling a graphic primitive.</td><td style='text-align:right;'></td></tr></table>
3537 <p>This option accepts a color name, a hex color, or a numerical RGB, RGBA,
3538 HSL, HSLA, CMYK, or CMYKA specification. See <a href="color.html" >Color Names</a> for
3539 a description of how to properly specify the color argument.</p>
3541 <p>Enclose the color specification in quotation marks to prevent the "#" or
3542 the parentheses from being interpreted by your shell.</p>
3553 -fill "rgb(255,255,255)"
3556 <p>See <a href="command-line-options.html#draw">-draw</a> for further details.</p>
3558 <p>To print a complete list of color names, use the <a href="command-line-options.html#list">-list color</a> option.</p>
3560 <div style="margin: auto;">
3561 <h4><a id="filter"></a>-filter <em class="arg">type</em></h4>
3564 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Use this <em class="arg">type</em> of filter when resizing or
3565 distorting an image.</td><td style='text-align:right;'></td></tr></table>
3567 <p>Use this option to affect the resizing operation of an image during
3568 operations such as <a href="command-line-options.html#resize">-resize</a> and <a href="command-line-options.html#distort"
3569 >-distort</a>. For example you can use a simple resize filter such as:</p>
3574 Triangle Quadratic Mitchell
3577 <p>The <code>Bessel</code> and <code>Sinc</code> filter is also provided (as well
3578 as a faster <code>SincFast</code> equivalent form). However these filters are
3579 generally useless on their own as they are infinite filters that are being
3580 clipped to the filters support size. Their direct use is not recommended
3581 except via expert settings (see below). </p>
3583 <p>Instead these special filter functions are typically windowed by a windowing
3584 function that the <a href="command-line-options.html#filter" >-filter</a> setting defines. That is
3585 using these functions will define a 'Windowed' filter, appropriate to the
3586 operator involved. Windowed filters include: </p>
3589 Lanczos Hamming Parzen
3590 Blackman Kaiser Welsh
3591 Hanning Bartlett Bohman
3594 <p>Also one special self-windowing filter is also provided
3595 <code>Lagrange</code>, which will automagically re-adjust its function depending
3596 on the current 'support' or 'lobes' expert settings (see below).</p>
3598 <p>If you do not select a filter with this option, the filter defaults to
3599 <code>Mitchell</code> for a colormapped image, an image with a matte channel, or
3600 if the image is enlarged. Otherwise the filter default to
3601 <code>Lanczos</code>.</p>
3603 <p>To print a complete list of resize filters, use the <a href="command-line-options.html#list">-list
3604 filter</a> option.</p>
3606 <p>You can modify how the filter behaves as it scales your image through the
3607 use of these expert settings (see also <a href="command-line-options.html#define" >-define</a> and <a
3608 href="command-line-options.html#set" >-set</a>):-</p>
3611 <dt>-define filter:blur=<em>factor</em></dt>
3612 <dd>Scale the X axis of the filter (and its window). Use > 1.0 for
3613 blurry or < 1.0 for sharp. This should only be used with Gaussian and
3614 Gaussian-like filters simple filters, or you may not get the expected
3617 <dt>-define filter:support=<em>radius</em></dt>
3618 <dd>Set the filter support radius. Defines how large the filter should be and
3619 thus directly defines how slow the filtered resampling process is. All
3620 filters have a default 'prefered' support size. Some filters like
3621 <code>Lagrange</code> and windowed filters adjust themselves depending on
3622 this value. With simple filters this value either does nothing (but slow
3623 the resampling), or will clip the filter function in a detrimental way.
3626 <dt>-define filter:lobes=<em>count</em></dt>
3627 <dd>Set the number of lobes to use for the Sinc/Bessel filter. This an
3628 alternative way of specifying the 'support' range of the filter, that is
3629 designed to be more suited to windowed filters, especially when used for
3630 image distorts.</dd>
3632 <dt>-define filter:sigma=<em>value</em></dt>
3633 <dd>The 'sigma' value used to define the <code>Gaussian</code> filter. Default
3634 sigma value is '<code>0.5</code>'. It only effects <code>Gaussian</code> but
3635 does not shrink (but may enlarge) the filter's 'support'. It can be used
3636 to generate very small blurs but without the filter 'missing' pixels due
3637 to using a small support setting. A larger value of '<code>0.707</code>'
3638 (a value of '1/sqrt(2)') is another common setting. </dd>
3640 <dt>-define filter:b=<em>b-spline_factor</em></dt>
3641 <dt>-define filter:c=<em>keys_alpha_factor</em></dt>
3642 <dd>Redefine the values used for cubic filters such as <code>Cubic</code>,
3643 <code>Catrom</code>, <code>Mitchel</code>, and <code>Hermite</code>, as well as
3644 the <code>Parzen</code> cubic windowing function. If only one of the values
3645 are defined, the other is set so as to generate a 'Cubic-Keys' filter.
3646 The values meaning was defined by a research paper by
3647 Mitchell-Netravali.</dd>
3649 <dt>-define filter:kaiser-beta=<em>value</em></dt>
3650 <dd>The 'alpha' value used to as part of the Kaiser Windowing function.
3651 Default value is '6.5'. It only effects Kaiser windowing function, and
3652 does not effect any other attributes.</dd>
3654 <dd>Before IM v6.7.6-10, this option was known as "filter:alpha", (an
3655 inheritance from the very old "zoom" program). It was changed to bring the
3656 function in line with more modern academic research usage, and better
3657 assign it be more definitive. </dd>
3659 <dt>-define filter:kaiser-alpha=<em>value</em></dt>
3660 <dd>This value when multiplied by 'PI' is equivelent to "kaiser-beta", and
3661 will override that setting. It only effects Kaiser windowing function,
3662 and does not effect any other attributes. </dd>
3664 <dt>-define filter:filter=<em>filter_function</em></dt>
3665 <dd>Use this function directly as the weighting filter. This will allow
3666 you to directly use a windowing function such as <code>Blackman</code>,
3667 as a resampling filter, rather than as its normal usage as a windowing
3670 <dd>If defined, no windowing function also defined, the window function is set
3671 to <code>Box</code>). Directly specifying <code>Sinc</code> or <code>Jinc</code>
3672 as a filter will also do this. </dd>
3674 <dt>-define filter:window=<em>filter_function</em></dt>
3675 <dd>The IIR (infinite impulse response) filters <code>Sinc</code> and
3676 <code>Jinc</code> are windowed (brought down to zero over the defined
3677 support range) with the given filter. This allows you to specify a filter
3678 function to be used as a windowing function for these IIR filters. </dd>
3680 <dd>Many of the defined filters are actually windowing functions for these IIR
3681 filters. A typical choices is <code>Box</code>, (which effectively turns
3682 off the windowing function). </dd>
3684 <dt>-define filter:win-support=<em>radius</em></dt>
3685 <dd>Scale windowing function to this size instead. This causes the windowing
3686 (or self-windowing Lagrange filter) to act is if the support window is
3687 larger than what is actually supplied to the calling operator. The filter
3688 however is still clipped to the real support size given. If unset this
3689 will equal the normal filter support size. </dd>
3691 <dt>-define filter:verbose=<em>1</em></dt>
3692 <dd>This causes IM to print information on the final internal filter
3693 selection to standard output. This includes a commented header on the
3694 filter settings being used, and data allowing the filter weights to be
3695 easily graphed. </dd>
3697 <dd>Note however that some filters are internally defined in terms of other
3698 filters. The <code>Lanczos</code> filter for example is defined in terms of
3699 a <code>SincFast</code> windowed <code>SincFast</code> filter, while
3700 <code>Mitchell</code> is defined as a general <code>Cubic</code> family filter
3701 with specific 'B' and 'C' settings. </dd>
3705 <p>For example, to get a 8 lobe jinc windowed sinc filter (Genseng filter?):</p>
3707 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert image.png \<br/>
3709 -set filter:window=jinc \<br/>
3710 -set filter:lobes=8 \<br/>
3711 -resize 150% image.jpg</span></p>
3712 <p>Or a raw un-windowed Sinc filter with 4 lobes:</p>
3714 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert image.png \<br/>
3715 -set filter:filter=sinc \<br/>
3716 -set filter:lobes=4 \<br/>
3717 -resize 150% image.jpg</span></p>
3718 <p>To extract the data for a raw windowing function, combine it with
3719 a '<code>Box</code>' filter. For example the '<code>Welch</code> parabolic
3720 windowing function. </p>
3722 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert null: -define filter:filter=Box \<br/>
3723 -define filter:window=Welch \<br/>
3724 -define filter:support=1.0 \<br/>
3725 -define filter:verbose=1 \<br/>
3726 -resize 2 null: > window_welch.dat<br/>
3729 plot "window_welch.dat" with lines</span></p>
3730 <p>Note that the use of expert options is provided for image processing experts
3731 who have studied and understand how resize filters work. Without this
3732 knowledge, and an understanding of the definition of the actual filters
3733 involved, using expert settings are more likely to be detrimental to your image
3737 <div style="margin: auto;">
3738 <h4><a id="flatten"></a>-flatten</h4>
3741 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>This is a simple alias for the <a href="command-line-options.html#layers" >-layers</a> method "flatten".</td><td style='text-align:right;'></td></tr></table>
3744 <div style="margin: auto;">
3745 <h4><a id="flip"></a>-flip</h4>
3748 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>create a <em>mirror image</em>.</td><td style='text-align:right;'></td></tr></table>
3750 <p>reflect the scanlines in the vertical direction. The image will be mirrored
3754 <div style="margin: auto;">
3755 <h4><a id="floodfill"></a>-floodfill {<em class="arg">+-</em>}<em class="arg">x</em>{<em class="arg">+-</em>}<em class="arg">y</em> <em class="arg">color</em></h4>
3758 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>floodfill the image with color at the specified offset.</td><td style='text-align:right;'></td></tr></table>
3760 <p>Flood fill starts from the given 'seed point' which is not gravity effected.
3761 Any color that matches within <a href="command-line-options.html#fuzz" >-fuzz</a> color distance of the
3762 given <em class="arg">color</em> argument, connected to that 'seed point'
3763 will be replaced with the current <a href="command-line-options.html#fill" >-fill</a> color. </p>
3765 <p>Note that if the pixel at the 'seed point' does not itself match the given
3766 <em class="arg">color</em> (according to <a href="command-line-options.html#fuzz" >-fuzz</a>), then no
3767 action will be taken. </p>
3769 <p>This operator works more like the <a href="command-line-options.html#opaque" >-opaque</A> option, than
3770 a more general flood fill that reads the matching color directly at the 'seed
3771 point'. For this form of flood fill, look at <a href="command-line-options.html#draw" >-draw</a> and
3772 its 'color floodfill' drawing method. </p>
3775 <div style="margin: auto;">
3776 <h4><a id="flop"></a>-flop</h4>
3779 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>create a <em>mirror image</em>.</td><td style='text-align:right;'></td></tr></table>
3781 <p>Reflect the scanlines in the horizontal direction, just like the image in
3782 a vertical mirror. </p>
3785 <div style="margin: auto;">
3786 <h4><a id="font"></a>-font <em class="arg">name</em></h4>
3789 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>set the font to use when annotating images with text, or creating labels.</td><td style='text-align:right;'></td></tr></table>
3791 <p>To print a complete list of fonts, use the <a href="command-line-options.html#list">-list font</a>
3792 option (for versions prior to 6.3.6, use 'type' instead of 'font').</p>
3794 <p>In addition to the fonts specified by the above pre-defined list, you can
3795 also specify a font from a specific source. For example <code>Arial.ttf</code>
3796 is a TrueType font file, <code>ps:helvetica</code> is PostScript font, and
3797 <code>x:fixed</code> is X11 font.</p>
3799 <p>For other settings that affect fonts, see the options <a
3800 href="command-line-options.html#family">-family</a>, <a href="command-line-options.html#stretch">-stretch</a>, <a
3801 href="command-line-options.html#style">-style</a>, and <a href="command-line-options.html#weight">-weight</a>. </p>
3804 <div style="margin: auto;">
3805 <h4><a id="foreground"></a>-foreground <em class="arg">color</em></h4>
3808 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Define the foreground color for menus.</td><td style='text-align:right;'>[<a href="display.html">display</a>]</td></tr></table>
3810 <p>The color is specified using the format described under the <a
3811 href="command-line-options.html#fill">-fill</a> option.</p>
3813 <p>The default foreground color is black.</p>
3815 <div style="margin: auto;">
3816 <h4><a id="format"></a>-format <em class="arg">type</em></h4>
3819 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>the image format type.</td><td style='text-align:right;'></td></tr></table>
3821 <p>When used with the <code>mogrify</code> utility, this option converts any
3822 image to the image <a href="formats.html">format</a> you specify.
3823 For a list of image format types supported by ImageMagick, use <a
3824 href="command-line-options.html#list">-list format</a>.</p>
3826 <p>By default the file is written to its original name. However, if the
3827 filename extension matches a supported format, the extension is replaced with
3828 the image format type specified with <a href="command-line-options.html#format">-format</a>. For
3829 example, if you specify <em class="arg">tiff</em> as the format type and the
3830 input image filename is <em class="arg">image.gif</em>, the output image
3831 filename becomes <em class="arg">image.tiff</em>.</p>
3833 <div style="margin: auto;">
3834 <h4><a id="format_identify_"></a>-format <em class="arg">string</em></h4>
3837 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>output formatted image characteristics.</td><td style='text-align:right;'>[<a href="identify.html">identify</a>]</td></tr></table>
3839 <p>See <a href="escape.html">Format and Print Image
3840 Properties</a> for an explanation on how to specify the argument to this
3843 <div style="margin: auto;">
3844 <h4><a id="frame"></a>-frame <em class="arg">geometry</em></h4>
3847 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Surround the image with a border or beveled frame.</td><td style='text-align:right;'></td></tr></table>
3849 <p>The color of the border is specified with the <a href="command-line-options.html#mattecolor"
3850 >-mattecolor</a> command line option. </p>
3852 <p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument. The <em class="arg">size</em> portion of the <em
3853 class="arg">geometry</em> argument indicates the amount of extra width and
3854 height that is added to the dimensions of the image. If no offsets are given
3855 in the <em class="arg">geometry</em> argument, then the border added is
3856 a solid color. Offsets <em>x</em> and <em>y</em>, if present, specify that
3857 the width and height of the border is partitioned to form an outer bevel of
3858 thickness <em>x</em> pixels and an inner bevel of thickness
3859 <em>y</em> pixels. Negative offsets make no sense as frame arguments.
3862 <p>The <a href="command-line-options.html#frame">-frame</a> option is affected by the current <a
3863 href="command-line-options.html#compose">-compose</a> setting and assumes that this is using the default
3864 '<code>Over</code>' composition method. It generates an image of the appropriate
3865 size with the current <a href="command-line-options.html#bordercolor">-bordercolor</a> setting, and then
3866 draws the frame of four distinct colors close to the current <a
3867 href="command-line-options.html#mattecolor">-mattecolor</a>. The original image is then overlaid onto
3868 center of this image. This means that with the default compose method of
3869 '<code>Over</code>' any transparent parts may be replaced by the current <a
3870 href="command-line-options.html#bordercolor">-bordercolor</a> setting.</p>
3872 <p>The image composition is not
3873 affected by the <a href="command-line-options.html#gravity">-gravity</a> option.</p>
3876 <div style="margin: auto;">
3877 <h4><a id="frame_import_"></a>-frame</h4>
3880 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>include the X window frame in the imported image.</td><td style='text-align:right;'>[<a href="import.html">import</a>]</td></tr></table>
3882 <div style="margin: auto;">
3883 <h4><a id="function"></a>-function <em class="arg">function</em> <em class="arg">parameters</em></h4>
3886 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Apply a function to channel values.</td><td style='text-align:right;'></td></tr></table>
3888 <p>This operator performs calculations based on the given arguments to modify
3889 each of the color values for each previously set <a
3890 href="command-line-options.html#channel">-channel</a> in the image. See <a
3891 href="command-line-options.html#evaluate">-evaluate</a> for details concerning how the results of the
3892 calculations are handled.</p>
3894 <p>This is can be considered a multi-argument version of the <a
3895 href="command-line-options.html#evaluate">-evaluate</a> operator. (Added in
3896 ImageMagick 6.4.8−8.)</p>
3898 <p>Here, <em class="arg">parameters</em> is a comma-separated list of
3899 numerical values. The number of values varies depending on which <em
3900 class="arg">function</em> is selected. Choose the <em
3901 class="arg">function</em> from:</p>
3910 <p>To print a complete list of <a href="command-line-options.html#function">-function</a> operators,
3911 use <a href="command-line-options.html#list">-list function</a>. Descriptions follow.</p>
3914 <dt><code>Polynomial</code></dt>
3917 <p>The <code>Polynomial</code> function takes an arbitrary number of parameters,
3918 these being the coefficients of a polynomial, in decreasing order of degree.
3919 That is, entering</p>
3921 <div style="text-align: center">
3922 -function Polynomial <em>a</em><sub><em>n</em></sub>,<em>a</em><sub><em>n</em>-1</sub>,...<em>a</em><sub>1</sub>,<em>a</em><sub>0</sub>
3925 <p>will invoke a polynomial function given by</p>
3927 <div style="text-align: center">
3928 <em>a</em><sub><em>n</em></sub> <b><em>u</em></b><sup><em>n</em></sup> +
3929 <em>a</em><sub><em>n</em>-1</sub> <b><em>u</em></b><sup><em>n</em>-1</sup> +
3930 ··· <em>a</em><sub>1</sub> <b><em>u</em></b> + <em>a</em><sub>0</sub>,
3933 <p>where <b><em>u</em></b> is pixel's original normalized channel value.</p>
3935 <p>The <code>Polynomial</code> function can be used in place of <code>Set</code>
3936 (the <em>constant</em> polynomial) and <code>Add</code>, <code>Divide</code>,
3937 <code>Multiply</code>, and <code>Subtract</code> (some <em>linear</em>
3938 polynomials) of the <a href="command-line-options.html#evaluate">-evaluate</a> operator. The <a
3939 href="command-line-options.html#level">-level</a> operator also affects channels linearly. Some
3940 correspondences follow.</p>
3947 <td>-evaluate Set <em class="arg">value</em> </td>
3948 <td>-function Polynomial <em class="arg">value</em></td>
3949 <td>(Constant functions; set <em class="arg">value</em>×100% gray when channels are RGB.)</td>
3952 <td>-evaluate Add <em class="arg">value</em> </td>
3953 <td>-function Polynomial 1,<em class="arg">value</em></td>
3956 <td>-evaluate Subtract <em class="arg">value</em> </td>
3957 <td>-function Polynomial 1,−<em class="arg">value</em></td>
3960 <td>-evaluate Multiply <em class="arg">value</em> </td>
3961 <td>-function Polynomial <em class="arg">value</em>,0</td>
3964 <td>+level black% x white%</td>
3965 <td>-function Polynomial A,B</td>
3966 <td>(Reduce contrast. Here, A=(white-black)/100 and B=black/100.)</td>
3970 <p>The <code>Polynomial</code> function gives great versatility, since
3971 polynomials can be used to fit any continuous curve to any degree of accuracy
3976 <dt><code>Sinusoid</code></dt>
3978 <p>The <code>Sinusoid</code> function can be used to vary the channel values
3979 sinusoidally by setting frequency, phase shift, amplitude, and a bias. These
3980 values are given as one to four parameters, as follows,</p>
3982 <div style="text-align: center">
3983 -function <code>Sinusoid</code> <em class="arg">freq</em>,[<em class="arg">phase</em>,[<em class="arg">amp</em>,[<em class="arg">bias</em>]]]
3986 <p>where <em>phase</em> is in degrees. (The domain [0,1] of the function
3987 corresponds to 0 through <em class="arg">freq</em>×360 degrees.)
3988 The result is that if a pixel's normalized channel value is originally
3989 <b><em>u</em></b>, its resulting normalized value is given by </p>
3991 <div style="text-align: center">
3992 <em class="arg">amp</em> * sin(2*π* (<em class="arg">freq</em> * <b><em>u</em></b> + <em class="arg">phase</em> / 360)) + <em class="arg">bias</em>
3995 <p> For example, the following generates a curve that starts and ends at 0.9
3996 (when <b><em>u</em></b>=0 and 1, resp.), oscillating three times between
3997 .7−.2=.5 and .7+.2=.9. </p>
4000 -function Sinusoid 3,-90,.2,.7
4003 <p>The default values of <em class="arg">amp</em> and <em
4004 class="arg">bias</em> are both .5. The default for <em class="arg">phase</em>
4007 <p>The <code>Sinusoid</code> function generalizes <code>Sin</code> and
4008 <code>Cos</code> of the <a href="command-line-options.html#evaluate">-evaluate</a> operator by allowing
4009 varying amplitude, phase and bias. The correspondence is as follows.</p>
4013 <td>-evaluate Sin <em class="arg">freq</em> </td>
4014 <td>-function Sinusoid <em class="arg">freq</em>,0 </td>
4017 <td>-evaluate Cos <em class="arg">freq</em> </td>
4018 <td>-function Sinusoid <em class="arg">freq</em>,90 </td>
4023 <dt><code>ArcSin</code></dt>
4025 <p>The <code>ArcSin</code> function generates the inverse curve of a Sinusoid,
4026 and can be used to generate cylindrical distortion and displacement maps.
4027 The curve can be adjusted relative to both the input values and output range
4030 <p style="text-align: center">
4031 -function <code>ArcSin</code> <em class="arg">width</em>,[<em class="arg">center</em>,[<em class="arg">range</em>,[<em class="arg">bias</em>]]]
4034 <p>with all values given in terms of normalized color values (0.0 for black,
4035 1.0 for white). Defaulting to values covering the full range from 0.0 to 1.0
4036 for bout input (<em class="arg">width</em>), and output (<em
4037 class="arg">width</em>) values. '<code>1.0,0.5,1.0,0.5</code>' </p>
4039 <p style="text-align: center">
4040 <em class="arg">range</em>/π * asin( 2/<em class="arg">width</em> * ( <b><em>u</em></b> - <em class="arg">center</em> ) ) + <em class="arg">bias</em>
4045 <dt><code>ArcTan</code></dt>
4047 <p>The <code>ArcTan</code> function generates a curve that smooth crosses from
4048 limit values at infinities, though a center using the given slope value.
4049 All these values can be adjusted via the arguments.</p>
4051 <p style="text-align: center">
4052 -function <code>ArcTan</code> <em class="arg">slope</em>,[<em class="arg">center</em>,[<em class="arg">range</em>,[<em class="arg">bias</em>]]]
4055 <p>Defaulting to '<code>1.0,0.5,1.0,0.5</code>'.
4058 <p style="text-align: center">
4059 <em class="arg">range</em>/π * atan( <em class="arg">slope</em>*π * ( <b><em>u</em></b> - <em class="arg">center</em> ) ) + <em class="arg">bias</em>
4067 <div style="margin: auto;">
4068 <h4><a id="fuzz"></a>-fuzz <em class="arg">distance</em>{<em class="arg">%</em>}</h4>
4071 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Colors within this <em class="arg">distance</em> are considered equal.</td><td style='text-align:right;'></td></tr></table>
4073 <p>A number of algorithms search for a target color. By default the color must
4074 be exact. Use this option to match colors that are close to the target color
4075 in RGB space. For example, if you want to automagically trim the edges of an
4076 image with <a href="command-line-options.html#trim">-trim</a> but the image was scanned and the target
4077 background color may differ by a small amount. This option can account for
4078 these differences.</p>
4080 <p>The <em class="arg">distance</em> can be in absolute intensity units or, by
4081 appending <code>%</code> as a percentage of the maximum possible intensity (255,
4082 65535, or 4294967295).</p>
4085 <div style="margin: auto;">
4086 <h4><a id="fx"></a>-fx <em class="arg">expression</em></h4>
4089 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>apply a mathematical expression to an image or image channels.</td><td style='text-align:right;'></td></tr></table>
4091 <p>If the first character of <em class="arg">expression</em> is <code>@</code>,
4092 the expression is read from a file titled by the remaining characters in the
4095 <p>See <a href="fx.html">FX,
4096 The Special Effects Image Operator</a> for a detailed discussion of this
4100 <div style="margin: auto;">
4101 <h4><a id="gamma"></a>-gamma <em class="arg">value</em></h4>
4104 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>level of gamma correction.</td><td style='text-align:right;'></td></tr></table>
4106 <p>The same color image displayed on two different workstations may look
4107 different due to differences in the display monitor. Use gamma correction to
4108 adjust for this color difference. Reasonable values extend from
4109 <code>0.8</code> to <code>2.3</code>. Gamma less than 1.0 darkens the image and
4110 gamma greater than 1.0 lightens it. Large adjustments to image gamma may
4111 result in the loss of some image information if the pixel quantum size is only
4112 eight bits (quantum range 0 to 255).</p>
4114 <p>Gamma adjusts the image's channel values pixel-by-pixel according to
4115 a power law, namely, pow(pixel,1/gamma) or pixel^(1/gamma), where pixel is the
4116 normalized or 0 to 1 color value. For example, using a value of gamma=2 is the
4117 same as taking the square root of the image.</p>
4119 <p>You can apply separate gamma values to the red, green, and blue channels of
4120 the image with a gamma value list delimited with commas (e.g.,
4121 <code>1.7,2.3,1.2</code>).</p>
4123 <p>Use <a href="command-line-options.html#gamma">+gamma <em class="arg">value</em></a> to set the
4124 image gamma level without actually adjusting the image pixels. This option
4125 is useful if the image is of a known gamma but not set as an image attribute
4126 (e.g. PNG images). Write the "file gamma" which is the reciprocal of the
4127 display gamma; e.g., if your image is sRGB and you want to write a PNG gAMA
4129 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert input.png +gamma .45455 output.png</span></p>(0.45455 is 1/2.2)</p>
4131 <p>Note that gamma adjustments are also available via the <a href="command-line-options.html#level">-level</a> operator.</p>
4133 <div style="margin: auto;">
4134 <h4><a id="gaussian-blur"></a>-gaussian-blur <em class="arg">radius</em><br />-gaussian-blur <em class="arg">radius</em>x<em class="arg">sigma</em>+<em class="arg">bias</em></h4>
4137 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Blur the image with a Gaussian operator.</td><td style='text-align:right;'></td></tr></table>
4139 <p>Convolve the image with a Gaussian or normal distribution using the given
4140 <em class="arg" >Sigma</em> value. The formula is:</p>
4142 <div class="eqn"><img alt="gaussian distribution" width="243px" height="42px" src="../images/gaussian-blur.png"/>
4145 <p>The <em class="arg" >Sigma</em> value is the important argument, and
4146 determines the actual amount of blurring that will take place. </p>
4148 <p>The <em class="arg" >Radius</em> is only used to determine the size of the
4149 array which will hold the calculated Gaussian distribution. It should be an
4150 integer. If not given, or set to zero, IM will calculate the largest possible
4151 radius that will provide meaningful results for the Gaussian distribution.
4154 <p>The larger the <em class="arg" >Radius</em> the radius the slower the
4155 operation is. However too small a <em class="arg" >Radius</em>, and sever
4156 aliasing effects may result. As a guideline, <em class="arg" >Radius</em>
4157 should be at least twice the <em class="arg" >Sigma</em> value, though three
4158 times will produce a more accurate result. </p>
4160 <p>This differs from the faster <a href="command-line-options.html#blur">-blur</a> operator in that a
4161 full 2-dimensional convolution is used to generate the weighted average of the
4162 neighboring pixels. </p>
4164 <p>The <a href="command-line-options.html#virtual-pixel">-virtual-pixel</a> setting will determine how
4165 pixels which are outside the image proper are blurred into the final result.
4169 <div style="margin: auto;">
4170 <h4><a id="geometry"></a>-geometry <em class="arg">geometry</em></h4>
4173 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Set the preferred size and location of the image.</td><td style='text-align:right;'></td></tr></table>
4175 <p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
4177 <div style="margin: auto;">
4178 <h4><a id="gravity"></a>-gravity <em class="arg">type</em></h4>
4181 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Sets the current gravity suggestion for various other settings and options.</td><td style='text-align:right;'></td></tr></table>
4183 <p>Choices include: <code>NorthWest</code>, <code>North</code>,
4184 <code>NorthEast</code>, <code>West</code>, <code>Center</code>, <code>East</code>,
4185 <code>SouthWest</code>, <code>South</code>, <code>SouthEast</code>. Use <a
4186 href="command-line-options.html#list">-list gravity</a> to get a complete list of <a
4187 href="command-line-options.html#gravity">-gravity</a> settings available in your ImageMagick
4190 <p>The direction you choose specifies where to position text or subimages. For
4191 example, a gravity of <code>Center</code> forces the text to be centered within
4192 the image. By default, the image gravity is <code>NorthWest</code>. See <a
4193 href="command-line-options.html#draw">-draw</a> for more details about graphic primitives. Only the
4194 text primitive of <a href="command-line-options.html#draw">-draw</a> is affected by the <a
4195 href="command-line-options.html#gravity">-gravity</a> option.</p>
4197 <p>The <a href="command-line-options.html#gravity">-gravity</a> option is also used in concert with the
4198 <a href="command-line-options.html#geometry">-geometry</a> setting and other settings or options that
4199 take <em class="arg">geometry</em> as an argument, such as the <a
4200 href="command-line-options.html#crop">-crop</a> option. </p>
4202 <p>If a <a href="command-line-options.html#gravity">-gravity</a> setting occurs before another option
4203 or setting having a <em class="arg">geometry</em> argument that specifies an
4204 offset, the offset is usually applied to the point within the image suggested
4205 by the <a href="command-line-options.html#gravity">-gravity</a> argument. Thus, in the following
4206 command, for example, suppose the file <code>image.png</code> has dimensions
4207 200x100. The offset specified by the argument to <a href="command-line-options.html#region">-region</a>
4208 is (−40,+20). The argument to <a href="command-line-options.html#gravity">-gravity</a> is
4209 <code>Center</code>, which suggests the midpoint of the image, at the point
4210 (100,50). The offset (−40,20) is applied to that point, giving
4211 (100−40,50+20)=(60,70), so the specified 10x10 region is located at
4212 that point. (In addition, the <a href="command-line-options.html#gravity">-gravity</a> affects the
4213 region itself, which is <em>centered</em> at the pixel
4214 coordinate (60,70). (See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.)</p>
4216 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert image.png -gravity Center -region 10x10-40+20 \ <br/> -negate output.png</span></p>
4217 <p>When used as an option to <a href="composite.html">composite</a>, <a
4218 href="command-line-options.html#gravity">-gravity</a> gives the direction that the image gravitates
4219 within the composite.</p>
4221 <p>When used as an option to <a href="montage.html">montage</a>, <a
4222 href="command-line-options.html#gravity">-gravity</a> gives the direction that an image gravitates
4223 within a tile. The default gravity is <code>Center</code> for this purpose.</p>
4226 <div style="margin: auto;">
4227 <h4><a id="grayscale"></a>-grayscale <em class="arg">method</em></h4>
4230 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>convert image to grayscale.</td><td style='text-align:right;'></td></tr></table>
4232 </p>This will use one of the <a href="command-line-options.html#intensity" >-intensity</a> methods to
4233 convert the given image into a linear-grayscale image. </p>
4235 <p>For example, to convert an image to (linear) Rec709Luminance grayscale, type:</p>
4237 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert in.png -grayscale Rec709Luminance out.png</span></p>
4238 <p>which is equivalent to:</p>
4240 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert in.png -colorspace gray out.png</span></p>
4241 <p>Similarly, to convert an image to (non-linear) Rec709Luma grayscale, type:</p>
4243 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert in.png -grayscale Rec709Luma out.png</span></p>
4244 <p>which is equivalent to:</p>
4246 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert in.png -set colorspace RGB -colorspace gray out.png</span></p>
4247 <p>Note that a 'colorspace' intensity method will produce the same result
4248 regardless of the current colorpsace of the image. But a 'mathematical'
4249 intensity method will depend on the current colorspace the image is currently
4252 <p>While this operation uses an <a href="command-line-options.html#intensity" >-intensity</a> method,
4253 it does not use or set the <a href="command-line-options.html#intensity" >-intensity</a> setting, so
4254 will not effect other operations that may use that setting.</p>
4257 <div style="margin: auto;">
4258 <h4><a id="green-primary"></a>-green-primary <em class="arg">x,y</em></h4>
4261 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>green chromaticity primary point.</td><td style='text-align:right;'></td></tr></table>
4264 <div style="margin: auto;">
4265 <h4><a id="hald-clut"></a>-hald-clut</h4>
4268 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>apply a Hald color lookup table to the image.</td><td style='text-align:right;'></td></tr></table>
4270 <p>A Hald color lookup table is a 3-dimensional color cube mapped to 2
4271 dimensions. Create it with the <code>HALD:</code> prefix (e.g. HALD:8). You
4272 can apply any color transformation to the Hald image and then use this option
4273 to apply the transform to the image. </p>
4275 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert image.png hald.png -hald-clut transform.png</span></p>
4276 <p>This option provides a convenient method for you to use Gimp or Photoshop
4277 to make color corrections to the Hald CLUT image and subsequently apply them
4278 to multiple images using an ImageMagick script. </p>
4280 <p>Note that the representation is only of the normal RGB color space and that
4281 the whole color value triplet is used for the interpolated lookup of the
4282 represented Hald color cube image. Because of this the operation is not <a
4283 href="command-line-options.html#channel" >-channel</a> setting effected, nor can it adjust or modify an
4284 images transparency or alpha/matte channel.</p>
4286 <p>See also <a href="command-line-options.html#clut" >-clut</a> which provides color value replacement
4287 of the individual color channels, usually involving a simpler gray-scale
4288 image. E.g: gray-scale to color replacement, or modification by a histogram
4292 <div style="margin: auto;">
4293 <h4><a id="help"></a>-help</h4>
4296 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>print usage instructions.</td><td style='text-align:right;'></td></tr></table>
4298 <div style="margin: auto;">
4299 <h4><a id="highlight-color"></a>-highlight-color <em class="arg">color</em></h4>
4302 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>when comparing images, emphasize pixel differences with this color.</td><td style='text-align:right;'></td></tr></table>
4304 <div style="margin: auto;">
4305 <h4><a id="iconGeometry"></a>-iconGeometry <em class="arg">geometry</em></h4>
4308 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>specify the icon geometry.</td><td style='text-align:right;'></td></tr></table>
4310 <p>Offsets, if present in the geometry specification, are handled in the same
4311 manner as the <a href="command-line-options.html#geometry">-geometry</a> option, using X11 style to
4312 handle negative offsets.</p>
4314 <p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
4316 <div style="margin: auto;">
4317 <h4><a id="iconic"></a>-iconic</h4>
4320 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>start in icon mode in X Windows</td><td style='text-align:right;'>[<a href="animate.html">animate</a>, <a href="display.html">display</a>]</td></tr></table>
4322 <div style="margin: auto;">
4323 <h4><a id="identify"></a>-identify</h4>
4326 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>identify the format and characteristics of the image.</td><td style='text-align:right;'></td></tr></table>
4328 <p>This information is printed: image scene number; image name; image size;
4329 the image class (<em class="arg">DirectClass</em> or <em
4330 class="arg">PseudoClass</em>); the total number of unique colors; and the
4331 number of seconds to read and transform the image. Refer to <a href="miff.html">MIFF</a> for
4332 a description of the image class.</p>
4334 <p>If <a href="command-line-options.html#colors">-colors</a> is also specified, the total unique colors
4335 in the image and color reduction error values are printed. Refer to <a
4336 href="quantize.html">color
4337 reduction algorithm</a> for a description of these values.</p>
4339 <p>If <a href="command-line-options.html#verbose">-verbose</a> precedes this option, copious
4340 amounts of image properties are displayed including image statistics, profiles,
4341 image histogram, and others.</p>
4343 <div style="margin: auto;">
4344 <h4><a id="ift"></a>-ift</h4>
4347 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>implements the inverse discrete Fourier transform (DFT).</td><td style='text-align:right;'></td></tr></table>
4349 <p>This option is new as of ImageMagick 6.5.4-3 (and now working for Windows
4350 users in ImageMagick 6.6.0-9). It transforms a pair of magnitude and phase
4351 images from the frequency domain to a single image in the normal or spatial
4352 domain. See for example, <a
4353 href="http://en.wikipedia.org/wiki/Fourier_transform">Fourier Transform</a>,
4354 <a href="http://en.wikipedia.org/wiki/DFT">Discrete Fourier Transform</a> and
4355 <a href="http://en.wikipedia.org/wiki/FFT">Fast Fourier Transform</a>.</p>
4357 <p>For example, depending upon the image format used to store the result of
4358 the <a href="command-line-options.html#fft">-fft</a>, one would use either</p>
4360 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert fft_image.miff -ift fft_image_ift.png</span></p>
4363 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert fft_image-0.png fft_image-1.png -ift fft_image_ift.png</span></p>
4365 <p>The resulting image may need to be cropped due to padding introduced when
4366 the original image, prior to the <a href="command-line-options.html#fft">-fft</a> or <a
4367 href="command-line-options.html#fft">+fft</a>, was not square or even dimensioned. Any padding is at
4368 the right and/or bottom sides of the image.</p>
4370 <p>The <a href="http://www.fftw.org/">FFTW</a> delegate library is required to
4371 use <a href="command-line-options.html#ift">-ift</a>.</p>
4373 <p>Use <a href="command-line-options.html#ift">+ift</a> (with HDRI enabled) to transform a pair of real
4374 and imaginary images from the frequency domain to a single image in the normal
4375 (spatial) domain.</p>
4377 <div style="margin: auto;">
4378 <h4><a id="immutable"></a>-immutable</h4>
4381 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>make image immutable.</td><td style='text-align:right;'></td></tr></table>
4383 <div style="margin: auto;">
4384 <h4><a id="implode"></a>-implode <em class="arg">factor</em></h4>
4387 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>implode image pixels about the center.</td><td style='text-align:right;'></td></tr></table>
4389 <div style="margin: auto;">
4390 <h4><a id="insert"></a>-insert <em class="arg">index</em></h4>
4393 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>insert the last image into the image sequence.</td><td style='text-align:right;'></td></tr></table>
4395 <p>This option takes last image in the current image sequence and inserts it
4396 at the given index. If a negative index is used, the insert position is
4397 calculated before the last image is removed from the sequence. As such
4398 <code>-insert -1</code> will result in no change to the image sequence.</p>
4400 <p>The <code>+insert</code> option is equivalent to <code>-insert -1</code>. In
4401 other words, insert the last image, at the end of the current image sequence.
4402 Consequently this has no effect on the image sequence order.</p>
4404 <div style="margin: auto;">
4405 <h4><a id="intensity"></a>-intensity <em class="arg">method</em></h4>
4408 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>method to generate intensity value from pixel.</td><td style='text-align:right;'></td></tr></table>
4410 <p>ImageMagick provides a number of methods used in situations where an
4411 operatory needs to determine a single grayscale value for some purpose, from
4412 an image with red, green, and blue pixel components. Typically the linear
4413 <code>Rec709Luminance</code> formula is used, which is the same formula used when
4414 converting images to <code>-colorspace gray</code>. </p>
4416 <p>The following formulas are currently provided, and will first convert
4417 the pixel values to linear-RGB or non-linear sRGB colorspace before
4418 being applied to calulate the final greyscale value. </p>
4421 Rec601Luma 0.298839R' + 0.586811G'+ 0.114350B'
4422 Rec601Luminance 0.298839R + 0.586811G + 0.114350B
4423 Rec709Luma 0.212656R' + 0.715158G' + 0.072186B'
4424 Rec709Luminance 0.212656R + 0.715158G + 0.072186B
4425 Brightness max(R', G', B')
4426 Lightness (min(R', G', B') + max(R', G', B')) / 2.0
4428 <p>Note that the above R,G,B values is the image's linear-RGB values, while
4429 R',G',B' are sRGB non-linear values. </p>
4431 <p>These intensity methods are mathematical in nature and will use the
4432 current value in the images respective R,G,B channel regardless of
4433 what that is, or what colorspace the image is currently using.</p>
4436 Average (R + G + B) / 3.0
4437 MS (R^2 + G^2 + B^2) / 3.0
4438 RMS sqrt( (R^2 + G^2 + B^2) / 3.0 )
4441 <p>These methods are often used for other purposes, such as generating a
4442 grayscale difference image between two color images (using <a href="command-line-options.html#compose"
4443 >-compose</a> '<code>Difference</code>' composition. </p>
4445 <p> For example The 'MS' (Mean Squared) setting is good for minimizing color
4446 error comparisions. While... The method 'RMS' (Root Mean Squared) for
4447 example is appropriate for calculating color vector distance, from a color
4448 difference image. This is equivelent to the color only component of the <a
4449 href="command-line-options.html#fuzz" >-fuzz</a> factor color compare setting. </p>
4451 <p>See also <a href="command-line-options.html#grayscale" >-grayscale</a> which applies one of the above
4452 grayscaling formula directly to an image without setting the <a
4453 href="command-line-options.html#intensity" >-intensity</a> setting.</p>
4455 <p>The <a href="command-line-options.html#colorspace" >-colorspace gray</a> image conversion also uses
4456 the current intensity setting, but will always convert the image to the
4457 appropriate sRGB or linear-RGB colorspace before appling the above
4460 <p>To print a complete list of posible pixel intensity setting methods, use <a href="command-line-options.html#list">-list intensity</a>.</p>
4462 <p>Operators affected by the <a href="command-line-options.html#intensity" >-intensity</a> setting include:</p>
4468 -clut (when mapping greyscale CLUT image to alpha channel if set by -channels)
4469 -colors for gray colorspace
4470 -compose {LightenIntensity, DarkenIntensity, CopyOpacity, CopyBlack}
4472 -distort {ErodeIntensity, DilateIntensity}
4482 <div style="margin: auto;">
4483 <h4><a id="intent"></a>-intent <em class="arg">type</em></h4>
4486 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>use this type of rendering intent when managing the image color.</td><td style='text-align:right;'></td></tr></table>
4488 <p>Use this option to affect the color management operation of an image (see
4489 <a href="command-line-options.html#profile">-profile</a>). Choose from these intents: <code>Absolute,
4490 Perceptual, Relative, Saturation</code>.</p>
4492 <p>The default intent is Perceptual for the sRGB colorspace and undefined for the RGB and gray colorspaces.</p>
4494 <p>To print a complete list of rendering intents, use <a href="command-line-options.html#list">-list intent</a>.</p>
4496 <div style="margin: auto;">
4497 <h4><a id="interlace"></a>-interlace <em class="arg">type</em></h4>
4500 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>the type of interlacing scheme.</td><td style='text-align:right;'></td></tr></table>
4514 <p>This option is used to specify the type of interlacing scheme for raw image
4515 formats such as <code>RGB</code> or <code>YUV</code>.</p>
4517 <p><code>None</code> means do not interlace (RGBRGBRGBRGBRGBRGB...),</p>
4519 <p><code>Line</code> uses scanline interlacing (RRR...GGG...BBB...RRR...GGG...BBB...), and.</p>
4521 <p><code>Plane</code> uses plane interlacing (RRRRRR...GGGGGG...BBBBBB...).</p>
4523 <p><code>Partition</code> is like plane except the different planes are saved to
4524 individual files (e.g. image.R, image.G, and image.B).</p>
4526 <p>Use <code>Line</code> or <code>Plane</code> to create an <code>interlaced
4527 PNG</code> or <code>GIF</code> or <code>progressive JPEG</code> image.</p>
4529 <p>To print a complete list of interlacing schemes, use <a href="command-line-options.html#list">-list
4532 <div style="margin: auto;">
4533 <h4><a id="interpolate"></a>-interpolate <em class="arg">type</em></h4>
4536 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Set the pixel color interpolation method to use when looking up a color based on a floating point or real value.</td><td style='text-align:right;'></td></tr></table>
4538 <p>When looking up the color of a pixel using a non-integer floating point
4539 value, you typically fall in between the pixel colors defined by the source
4540 image. This setting determines how the color is determined from the colors of
4541 the pixels surrounding that point. That is how to determine the color of a
4542 point that falls between two, or even four different colored pixels. </p>
4545 integer The color of the top-left pixel (floor function)
4546 nearest-neighbor The nearest pixel to the lookup point (rounded function)
4547 average The average color of the surrounding four pixels
4548 bilinear A double linear interpolation of pixels (the default)
4549 mesh Divide area into two flat triangular interpolations
4550 bicubic Fitted bicubic-spines of surrounding 16 pixels
4551 spline Direct spline curves (colors are blurred)
4552 filter Use resize <a href="command-line-options.html#filter">-filter</a> settings
4555 <p>This most important for distortion operators such as <a href="command-line-options.html#distort"
4556 >-distort</a>, <a href="command-line-options.html#implode" >-implode</a>, <a href="command-line-options.html#transform"
4557 >-transform</a> and <a href="command-line-options.html#fx" >-fx</a>. </p>
4559 <p>To print a complete list of interpolation methods, use <a href="command-line-options.html#list">-list interpolate</a>.</p>
4561 <p>See also <a href="command-line-options.html#virtual-pixel" >-virtual-pixel</a>, for control of the
4562 lookup for positions outside the boundaries of the image. </p>
4565 <div style="margin: auto;">
4566 <h4><a id="interline-spacing"></a>-interline-spacing <em class="arg">value</em></h4>
4569 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>the space between two text lines.</td><td style='text-align:right;'></td></tr></table>
4571 <div style="margin: auto;">
4572 <h4><a id="interword-spacing"></a>-interword-spacing <em class="arg">value</em></h4>
4575 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>the space between two words.</td><td style='text-align:right;'></td></tr></table>
4577 <div style="margin: auto;">
4578 <h4><a id="kerning"></a>-kerning <em class="arg">value</em></h4>
4581 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>the space between two letters.</td><td style='text-align:right;'></td></tr></table>
4583 <div style="margin: auto;">
4584 <h4><a id="label"></a>-label <em class="arg">name</em></h4>
4587 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>assign a label to an image.</td><td style='text-align:right;'></td></tr></table>
4589 <p>Use this option to assign a specific label to the image, as it is read in
4590 or created. You can use the <a href="command-line-options.html#set" >-set</a> operation to re-assign
4591 a the labels of images already read in. Image formats such as TIFF, PNG,
4592 MIFF, supports saving the label information with the image.</p>
4594 <p>When saving an image to a <em class="arg">PostScript</em> file, any label
4595 assigned to an image is used as a header string to print above the postscript
4598 <p>You can include the image filename, type, width, height, or other image
4599 attribute by embedding special format character. See <a href="escape.html">Format and Print Image
4600 Properties</a> for details of the percent escape codes.</p>
4605 -label "%m:%f %wx%h" bird.miff
4608 <p>assigns an image label of <code>MIFF:bird.miff 512x480</code> to the
4609 "<code>bird.miff</code>" image and whose width is 512 and height is 480, as it
4610 is read in. If a <a href="command-line-options.html#label">+label</a> option was used instead, any
4611 existing label present in the image would be used. You can remove all labels
4612 from an image by assigning the empty string. </p>
4614 <p>A label is not drawn on the image, but is embedded in the image datastream
4615 via <em>Label</em> tag or similar mechanism. If you want the label to be
4616 visible on the image itself, use the <a href="command-line-options.html#draw">-draw</a> option, or
4617 during the final processing in the creation of an image montage.</p>
4619 <p>If the first character of <em class="arg">string</em> is <em
4620 class="arg">@</em>, the image label is read from a file titled by the
4621 remaining characters in the string. Labels in a file are literal, no embedded
4622 formatting characters are recognized.</p>
4625 <div style="margin: auto;">
4626 <h4><a id="lat"></a>-lat <em class="arg">width</em><br />-lat <em class="arg">width</em>x<em class="arg">height</em>{<em class="arg">+-</em>}<em class="arg">offset</em>{<em class="arg">%</em>}</h4>
4629 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>perform local adaptive threshold.</td><td style='text-align:right;'></td></tr></table>
4631 <p>Adaptively threshold each pixel based on the value of pixels in a
4632 surrounding window. If the current pixel is lighter than this average plus
4633 the optional <code>offset</code>, then it is made white, otherwise it is made
4634 black. Small variations in pixel values such as found in scanned documents
4635 can be ignored if offset is positive. A negative offset will make it more
4636 sensitive to those small variations. </p>
4638 <p>This is commonly used to threshold images with an uneven background. It is
4639 based on the assumption that average color of the small window is the
4640 the local background color, from which to separate the foreground color. </p>
4643 <div style="margin: auto;">
4644 <h4><a id="layers"></a>-layers <em class="arg">method</em></h4>
4647 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>handle multiple images forming a set of image layers or animation frames.</td><td style='text-align:right;'></td></tr></table>
4649 <p>Perform various image operation methods to a ordered sequence of images
4650 which may represent either a set of overlaid 'image layers', a GIF disposal
4651 animation, or a fully-'coalesced' animation sequence. </p>
4656 <th align="left" style="width: 8%">Method</th>
4657 <th align="left">Description</th>
4661 <td valign="top">compare-any</td>
4662 <td valign="top">Crop the second and later frames to the smallest rectangle
4663 that contains all the differences between the two images. No GIF <a
4664 href="command-line-options.html#dispose" >-dispose</a> methods are taken into account. </td>
4667 <tr><td></td><td>This exactly the same as the <a href="command-line-options.html#deconstruct"
4668 >-deconstruct</a> operator, and does not preserve animations normal
4669 working, especially when animation used layer disposal methods such as
4670 '<code>Previous</code>' or '<code>Background</code>'. </td>
4674 <td valign="top">compare-clear</td>
4675 <td valign="top">As '<code>compare-any</code>' but crop to the bounds of any
4676 opaque pixels which become transparent in the second frame. That is the
4677 smallest image needed to mask or erase pixels for the next frame. </td>
4681 <td valign="top">compare-overlay</td>
4682 <td valign="top">As '<code>compare-any</code>' but crop to pixels that add
4683 extra color to the next image, as a result of overlaying color pixels.
4684 That is the smallest single overlaid image to add or change colors. </td>
4687 <tr><td></td><td>This can be used with the <a href="command-line-options.html#compose" >-compose</a> alpha
4688 composition method '<code>change-mask</code>', to reduce the image to
4689 just the pixels that need to be overlaid. </td>
4693 <td valign="top">coalesce</td>
4694 <td valign="top">Equivalent to a call to the <a href="command-line-options.html#coalesce"
4695 >-coalesce</a> operator. Apply the layer disposal methods set in the
4696 current image sequence to form a fully defined animation sequence, as
4697 it should be displayed. Effectively converting a GIF animation into a
4698 'film strip'-like animation. </td>
4702 <td valign="top">composite</td>
4703 <td valign="top">Alpha Composition of two image lists, separated by a
4704 "<code>null:</code>" image, with the destination image list first, and
4705 the source images last. An image from each list are composited
4706 together until one list is finished. The separator image and source
4707 image lists are removed. </td>
4712 <td>The <a href="command-line-options.html#geometry" >-geometry</a> offset is adjusted according
4713 to <a href="command-line-options.html#gravity" >-gravity</a> in accordance of the virtual
4714 canvas size of the first image in each list. Unlike a normal <a
4715 href="command-line-options.html#composite" >-composite</a> operation, the canvas offset is also
4716 added to the final composite positioning of each image. </td> </tr>
4719 <td>If one of the image lists only contains one image, that image is
4720 applied to all the images in the other image list, regardless of which
4721 list it is. In this case it is the image meta-data of the list which
4727 <td valign="top">dispose</td>
4728 <td valign="top">This like '<code>coalesce</code>' but shows the look of
4729 the animation after the layer disposal method has been applied, before
4730 the next sub-frame image is overlaid. That is the 'dispose' image that
4731 results from the application of the GIF <a href="command-line-options.html#dispose"
4732 >-dispose</a> method. This allows you to check what
4733 is going wrong with a particular animation you may be developing.
4738 <td valign="top">flatten</td>
4739 <td valign="top">Create a canvas the size of the first images virtual
4740 canvas using the current <a href="command-line-options.html#background" >-background</a> color,
4741 and <a href="command-line-options.html#compose" >-compose</a> each image in turn onto that
4742 canvas. Images falling outside that canvas is clipped. Final
4743 image will have a zero virtual canvas offset. </td>
4747 <td>This usually used as one of the final 'image layering' operations
4748 overlaying all the prepared image layers into a final image. </td>
4752 <td>For a single image this method can also be used to fillout a virtual
4753 canvas with real pixels, or to underlay an opaque color to remove
4754 transparency from an image.</td>
4759 <td valign="top">merge</td>
4760 <td valign="top">As 'flatten' method but merging all the given image
4761 layers to create a new layer image just large enough to hold all the
4762 image without clipping or extra space. The new images virtual offset
4763 will preserve the position of the new layer, even if this offset is
4764 negative. The virtual canvas size of the first image is preserved.
4768 <tr><td></td><td>Caution is advised when handling image layers with
4769 negative offsets as few image file formats handle them correctly.
4770 Following this operation method with <a href="command-line-options.html#repage" >+repage</a>
4771 will remove the layer offset, and create an image in which all the
4772 overlaid image positions relative to each other is preserved, though
4773 not necessarily exactly where you specified them.
4777 <tr><td></td><td>See also 'trim-bounds' below which is closely related but
4778 without doing the'flatten' to merge the images together. </td>
4782 <td valign="top">mosaic</td>
4783 <td valign="top">As 'flatten' method but expanding the initial canvas size
4784 of the first image in a positive direction only so as to hold all the
4785 image layers. However as a virtual canvas is 'locked' to the origin,
4786 by its own definition, image layers with a negative offsets will still
4787 become clipped by the top and left edges. See 'merge' or 'trim-bounds'
4788 if this could be a problem. </td>
4792 <tr><td></td><td>This method is commonly used to layout individual image
4793 using various offset but without knowing the final canvas size. The
4794 resulting image will, like 'flatten' not have any virtual offset, so
4795 can be saved to any image file format. </td>
4800 <td valign="top">optimize</td>
4801 <td valign="top">Optimize a coalesced animation, into GIF animation using
4802 a number of general techniques. This currently a short cut to
4803 apply both the '<code>optimize-frame</code>', and
4804 '<code>optimize-transparency</code>' methods but may be expanded to
4805 include other optimization methods as they are developed. </td>
4809 <td valign="top">optimize-frame</td>
4810 <td valign="top">Optimize a coalesced animation, into GIF animation by
4811 reducing the number of pixels per frame as much as possible by
4812 attempting to pick the best layer disposal method to use, while ensuring
4813 the result will continue to animate properly. </td>
4816 <tr><td></td><td> There is no guarantee that the best optimization is found.
4817 But then no reasonably fast GIF optimization algorithm can do this.
4818 However this does seem to do better than most other GIF frame
4819 optimizers seen. </td>
4823 <td valign="top">optimize-plus</td>
4824 <td valign="top">As '<code>optimize-frame</code>' but attempt to improve the
4825 overall optimization by adding extra frames to the animation, without
4826 changing the final look or timing of the animation. The frames are
4827 added to attempt to separate the clearing of pixels from the
4828 overlaying of new additional pixels from one animation frame to the
4829 next. If this does not improve the optimization (for the next frame
4830 only), it will fall back to the results of the previous normal
4831 '<code>optimize-frame</code>' technique. </td>
4834 <tr><td></td><td>There is the possibility that the change in the disposal
4835 style will result in a worsening in the optimization of later frames,
4836 though this is unlikely. In other words there no guarantee that it is
4837 better than the normal '<code>optimize-frame</code>' technique. For some
4838 animations however you can get a vast improvement in the final
4839 animation size. </td>
4843 <td valign="top">optimize-transparency</td>
4844 <td valign="top">Given a GIF animation, replace any pixel in the sub-frame
4845 overlay images with transparency, if it does not change the resulting
4846 animation by more than the current <a href="command-line-options.html#fuzz" >-fuzz</a> factor.
4850 <tr><td></td><td>This should allow a existing frame optimized GIF animation
4851 to compress into a smaller file size due to larger areas of one
4852 (transparent) color rather than a pattern of multiple colors repeating
4853 the current disposed image of the last frame. </td>
4857 <td valign="top">remove-dups</td>
4858 <td valign="top">Remove (and merge time delays) of duplicate consecutive
4859 images, so as to simplify layer overlays of coalesced animations.
4863 <tr><td></td><td>Usually this a result of using a constant time delay
4864 across the whole animation, or after a larger animation was split into
4865 smaller sub-animations. The duplicate frames could also have been
4866 used as part of some frame optimization methods. </td>
4870 <td valign="top">remove-zero</td>
4871 <td valign="top">Remove any image with a zero time delay, unless ALL the
4872 images have a zero time delay (and is not a proper timed animation, a
4873 warning is then issued). </td>
4876 <tr><td></td><td>In a GIF animation, such images are usually frames which
4877 provide partial intermediary updates between the frames that are
4878 actually displayed to users. These frames are usually added for
4879 improved frame optimization in GIF animations. </td>
4883 <td valign="top">trim-bounds</td>
4884 <td valign="top">Find the bounds of all the images in the current
4885 image sequence, then adjust the offsets so all images are contained on
4886 a minimal positive canvas. None of the image data is modified or
4887 merged, only the individual image virtual canvas size and offset.
4888 All the images is given the same canvas size, and and will have
4889 a positive offset, but will remain in the same position relative to
4890 each other. As a result of the minimal canvas size at least one image
4891 will touch every edge of that canvas. The image data touching those
4892 edges however may be transparent. </td>
4895 <tr><td></td><td>The result is much like if you used 'merge' followed by a
4896 <a href="command-line-options.html#repage" >+repage</a> option, except that all the images
4897 have been kept separate. If 'flatten' is used after using
4898 'trim-bounds' you will get the same result. </td>
4904 <p>To print a complete list of layer types, use <a href="command-line-options.html#list">-list layers</a>.</p>
4906 <p>The operators <a href="command-line-options.html#coalesce" >-coalesce</a>, <a href="command-line-options.html#deconstruct"
4907 >-deconstruct</a>, <a href="command-line-options.html#flatten" >-flatten</a>, and <a href="command-line-options.html#mosaic"
4908 >-mosaic</a> are only aliases for the above methods and may be depreciated in
4909 the future. Also see <a href="command-line-options.html#page" >-page</a>, <a href="command-line-options.html#repage"
4910 >-repage</a> operators, the <a href="command-line-options.html#compose" >-compose</a> setting, and the
4911 GIF <a href="command-line-options.html#dispose" >-dispose</a> and <a href="command-line-options.html#delay" >-delay</a>
4915 <div style="margin: auto;">
4916 <h4><a id="level"></a>-level <em class="arg">black_point</em>{,<em class="arg">white_point</em>}{<em class="arg">%</em>}{,<em class="arg">gamma</em>}</h4>
4919 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>adjust the level of image channels.</td><td style='text-align:right;'></td></tr></table>
4921 <p>Given one, two or three values delimited with commas: black-point,
4922 white-point, gamma (for example: 10,250,1.0 or 2%,98%,0.5). The black and
4923 white points range from 0 to <em class="QR">QuantumRange</em>, or from 0 to
4924 100%; if the white point is omitted it is set to (<em
4925 class="QR">QuantumRange</em> - black_point), so as to center contrast changes.
4926 If a <code>%</code> sign is present anywhere in the string, both black and white
4927 points are percentages of the full color range. Gamma will do a <a
4928 href="command-line-options.html#gamma">-gamma</a> adjustment of the values. If it is omitted, the
4929 default of 1.0 (no gamma correction) is assumed.</p>
4931 <p>In normal usage (<code>-level</code>) the image values are stretched so that
4932 the given '<code>black_point</code>' value in the original image is set to zero
4933 (or black), while the given '<code>white_point</code>' value is set to <em
4934 class="QR">QuantumRange</em> (or white). This provides you with direct
4935 contrast adjustments to the image. The '<code>gamma</code>' of the resulting
4936 image will then be adjusted. </p>
4938 <p>From ImageMagick v6.4.1-9 using the plus form of the operator
4939 (<code>+level</code>) or adding the special '!' flag anywhere in the argument
4940 list, will cause the operator to do the reverse of the level adjustment. That
4941 is a zero, or <em class="QR">QuantumRange</em> value (black, and white, resp.)
4942 in the original image, is adjusted to the given level values, allowing you to
4943 de-contrast, or compress the channel values within the image. The
4944 '<code>gamma</code>' is adjusted before the level adjustment to de-contrast the
4947 <p>Only the channels defined by the current <a href="command-line-options.html#channel">-channel</a>
4948 setting are adjusted (defaults to RGB color channels only), allowing you to
4949 limit the effect of this operator. </p>
4951 <p>Please note that the transparency channel is treated as 'matte'
4952 values (0 is opaque) and not as 'alpha' values (0 is transparent).</p>
4955 <div style="margin: auto;">
4956 <h4><a id="level-colors"></a>-level-colors {<em
4957 class="arg">black_color</em>}{,}{<em class="arg">white_color</em>}</h4>
4960 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>adjust the level of an image using the provided dash separated colors.</td><td style='text-align:right;'></td></tr></table>
4962 <p>This function is exactly like <a href="command-line-options.html#level">-level</a>, except that the
4963 value value for each color channel is determined by the
4964 '<code>black_color</code>' and '<code>white_color</code>' colors given (as
4965 described under the <a href="command-line-options.html#fill">-fill</a> option). </p>
4967 <p>This effectually means the colors provided to <code>-level-colors</code>
4968 is mapped to become 'black' and 'white' respectively, with all the other
4969 colors linearly adjusted (or clipped) to match that change. Each channel is
4970 adjusted separately using the channel values of the colors specified. </p>
4972 <p>On the other hand the plus form of the operator (<code>+level-colors</code>)
4973 will map the image color 'black' and 'white' to the given colors
4974 respectively, resulting in a gradient (de-contrasting) tint of the image to
4975 those colors. This can also be used to convert a plain gray-scale image into a
4976 one using the gradient of colors specified. </p>
4978 <p>By supplying a single color with a comma separator either before or after
4979 that color, will just replace the respective 'black' or 'white' point
4980 respectively. But if no comma separator is provided, the given color is
4981 used for both the black and white color points, making the operator either
4982 threshold the images around that color (- form) or set all colors to that
4983 color (+ form). </p>
4986 <div style="margin: auto;">
4987 <h4><a id="limit"></a>-limit <em class="arg">type value</em></h4>
4990 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Set the pixel cache resource limit.</td><td style='text-align:right;'></td></tr></table>
4992 <p>Choose from: <code>area</code>, <code>disk</code>, <code>file</code>,
4993 <code>map</code>, <code>memory</code>, <code>threads</code>, or <code>time</code>.</p>
4995 <p>The value for <code>file</code> is in number of files. The other limits are
4996 in bytes. Define arguments for the memory, map, area, and disk resource limits
4997 with SI prefixes (.e.g 100MB).<p>
4999 <p>By default the limits are 768 files, 3GB of image area, 1.5GiB memory, 3GiB
5000 memory map, and 18.45EB of disk. These limits are adjusted relative to the
5001 available resources on your computer if this information is available. When
5002 any limit is reached, ImageMagick fails in some fashion but attempts to take
5003 compensating actions, if possible. For example, the following limits
5007 -limit memory 32MiB -limit map 64MiB
5010 <p>Use <a href="command-line-options.html#list">-list resource</a> to list the current limits. For example, our system shows these limits:</p>
5012 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>identify -list resource</span><span class='crtout'></span></p><pre class="text">
5013 File Area Memory Map Disk Thread Time
5014 ------------------------------------------------------------------------------
5015 768 12.404GB 8.6642GiB 23.104GiB 18.446744EB 8 unlimited
5018 <p>Requests for pixel storage to keep intermediate images are satisfied by one
5019 of three resource categories: in-memory pool, memory-mapped files pool, and
5020 disk pool (in that order) depending on the <a href="command-line-options.html#limit">‑limit</a> settings
5021 and whether the system honors a resource request. If the total size of
5022 allocated pixel storage in the given pool reaches the corresponding limit, the
5023 request is passed to the next pool. Additionally, requests that exceed the
5024 <code>area</code> limit automagically are allocated on disk.</p>
5026 <p>To illustrate how ImageMagick utilizes resource limits, consider a typical
5027 image resource request. First, ImageMagick tries to allocate the pixels in
5028 memory. The request might be denied if the resource request exceeds the
5029 <code>memory</code> limit or if the system does not honor the request. If
5030 a memory request is not honored, the pixels are allocated to disk and the file
5031 is memory-mapped. However, if the allocation request exceeds the
5032 <code>map</code> limit, the resource allocation goes to disk. In all cases, if
5033 the resource request exceeds the <code>area</code> limit, the pixels are
5034 automagically cached to disk. If the disk has a hard limit, the program
5037 <p>In most cases you simply do not need to concern yourself with resource
5038 limits. ImageMagick chooses reasonable defaults and most images do not tax
5039 your computer resources. Where limits do come in handy is when you process
5040 images that are large or on shared systems where ImageMagick can consume all
5041 or most of the available memory. In this case, the ImageMagick workflow slows
5042 other processes or, in extreme cases, brings the system to a halt. Under
5043 these circumstances, setting limits give some assurances that the ImageMagick
5044 workflow will not interfere with other concurrent uses of the computer. For
5045 example, assume you have a web interface that processes images uploaded from
5046 the Internet. To assure ImageMagick does not exceed 10MiB of memory you can
5047 simply set the area limit to 10MiB:</p>
5053 <p>Now whenever a large image is processed, the pixels are automagically
5054 cached to disk instead of memory. This of course implies that large images
5055 typically process very slowly, simply because pixel processing in memory can
5056 be an order of magnitude faster than on disk. Because your web site users
5057 might inadvertently upload a huge image to process, you should set a disk
5061 -limit area 10MB -limit disk 500MB
5064 <p>Here ImageMagick stops processing if an image requires more than 500MB of disk storage.</p>
5066 <p>In addition to command-line resource limit option, resources can be set
5067 with <a href="resources.html#environment" >environment variables</a>. Set the
5068 environment variables <code>MAGICK_AREA_LIMIT</code>,
5069 <code>MAGICK_DISK_LIMIT</code>, <code>MAGICK_FILE_LIMIT</code>,
5070 <code>MAGICK_MEMORY_LIMIT</code>, <code>MAGICK_MAP_LIMIT</code>,
5071 <code>MAGICK_THREAD_LIMIT</code>, <code>MAGICK_TIME_LIMIT</code> for limits of
5072 image area, disk space, open files, heap memory, memory map, number of threads
5073 of execution, and maximum elapsed time in seconds respectively.</p>
5075 <p> Inquisitive users can try adding <a href="command-line-options.html#debug">-debug cache</a> to
5076 their commands and then scouring the generated output for references to the
5077 pixel cache, in order to determine how the pixel cache was allocated and how
5078 resources were consumed. Advanced Unix/Linux users can pipe that output
5079 through <code>grep memory|open|destroy|disk</code> for more readable sifting.
5082 <p>For more about ImageMagick's use of resources, see the section <b>Cache
5083 Storage and Resource Requirements</b> on the <a href="architecture.html#cache
5084 ">Architecture</a> page. </p>
5086 <div style="margin: auto;">
5087 <h4><a id="linear-stretch"></a>-linear-stretch <em class="arg">black-point</em><br />-linear-stretch <em class="arg">black-point</em>{x<em class="arg">white-point</em>}{<em class="arg">%</em>}}</h4>
5090 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Linear with saturation stretch.</td><td style='text-align:right;'></td></tr></table>
5092 <p>This is very similar to <a href="command-line-options.html#contrast-stretch" >-contrast-stretch</a>,
5093 and uses a 'histogram bin' to determine the range of color values that needs to
5094 be stretched. However it then stretches those colors using the <a
5095 href="command-line-options.html#level" >-level</a> operator.</p>
5097 <p>As such while the initial determination may have 'binning' round off
5098 effects, the image colors are stretched mathematically, rather than using the
5099 histogram bins. This makes the operator more accurate. </p>
5101 <p>note however that a <a href="command-line-options.html#linear-stretch" >-linear-stretch</a> of
5102 '<code>0</code>' does nothing, while a value of '<code>1</code>' does a near
5103 perfect stretch of the color range. </p>
5105 <p>See also <a href="command-line-options.html#auto-level" >-auto-level</a> for a 'perfect'
5106 normalization of mathematical images. </p>
5108 <p>This operator is under review for re-development. </p>
5111 <div style="margin: auto;">
5112 <h4><a id="linewidth"></a>-linewidth</h4>
5115 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>the line width for subsequent draw operations.</td><td style='text-align:right;'></td></tr></table>
5117 <div style="margin: auto;">
5118 <h4><a id="liquid-rescale"></a>-liquid-rescale <em class="arg">geometry</em></h4>
5121 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>rescale image with seam-carving.</td><td style='text-align:right;'></td></tr></table>
5123 <p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
5125 <div style="margin: auto;">
5126 <h4><a id="list"></a>-list <em class="arg">type</em></h4>
5129 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Print a list of supported arguments for various options or settings. Choose from these list types:</td><td style='text-align:right;'></td></tr></table>
5132 Align Alpha Boolean Channel
5133 Class ClipPath Coder Color
5134 Colorspace Command Compose Compress
5135 Configure DataType Debug Decoration
5136 Delegate Direction Dispose Distort
5137 Dither Endian Evaluate FillRule
5138 Filter Font Format Function
5139 Gravity ImageList Intent Interlace
5140 Interpolate Kernel Layers LineCap
5141 LineJoin List Locale LogEvent
5142 Log Magic Method Metric
5143 Mime Mode Morphology Module
5144 Noise Orientation Policy PolicyDomain
5145 PolicyRights Preview Primitive QuantumFormat
5146 Resource SparseColor Storage Stretch
5147 Style Threshold Type Units
5148 Validate VirtualPixel
5151 <p>These lists vary depending on your version of ImageMagick. Use "<code>-list
5152 list</code>" to get a complete listing of all the "<code>-list</code>" arguments
5155 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>identify -list list</span></p>
5156 <div style="margin: auto;">
5157 <h4><a id="log"></a>-log <em class="arg">string</em></h4>
5160 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Specify format for debug log.</td><td style='text-align:right;'></td></tr></table>
5162 <p>This option specifies the format for the log printed when the <a
5163 href="command-line-options.html#debug">-debug</a> option is active.</p>
5165 <p>You can display the following components by embedding special format
5185 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert -debug coders -log "%u %m:%l %e" in.gif out.png</span></p>
5186 <p>The default behavior is to print all of the components.</p>
5188 <div style="margin: auto;">
5189 <h4><a id="loop"></a>-loop <em class="arg">iterations</em></h4>
5192 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>add Netscape loop extension to your GIF animation.</td><td style='text-align:right;'></td></tr></table>
5194 <p>Set iterations to zero to repeat the animation an infinite number of times,
5195 otherwise the animation repeats itself up to <em class="arg">iterations</em>
5198 <div style="margin: auto;">
5199 <h4><a id="lowlight-color"></a>-lowlight-color <em class="arg">color</em></h4>
5202 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>when comparing images, de-emphasize pixel differences with this color.</td><td style='text-align:right;'></td></tr></table>
5204 <div style="margin: auto;">
5205 <h4><a id="magnify"></a>-magnify</h4>
5208 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>double the size of the image with pixel art scaling.</td><td style='text-align:right;'></td></tr></table>
5211 <div style="margin: auto;">
5212 <h4><a id="map"></a>-map <em class="arg">type</em></h4>
5215 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Display image using this <em class="arg">type</em>.</td><td style='text-align:right;'>[<a href="animate.html">animate</a>, <a href="display.html">display</a>]</td></tr></table>
5217 <p>Choose from these <em class="arg">Standard Colormap</em> types:</p>
5228 <p>The <em class="arg">X server</em> must support the <em class="arg">Standard
5229 Colormap</em> you choose, otherwise an error occurs. Use <code>list</code> as
5230 the type and <code>display</code> searches the list of colormap types in
5231 <code>top-to-bottom</code> order until one is located. See <em
5232 class="arg">xstdcmap(1)</em> for one way of creating Standard Colormaps.</p>
5235 <div style="margin: auto;">
5236 <h4><a id="map_stream_"></a>-map <em class="arg">components</em></h4>
5239 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>pixel map.</td><td style='text-align:right;'>[<a href="stream.html">stream</a>]</td></tr></table>
5241 <p>Here are the valid components of a map:</p>
5244 r red pixel component
5245 g green pixel component
5246 b blue pixel component
5247 a alpha pixel component (0 is transparent)
5248 o opacity pixel component (0 is opaque)
5249 i grayscale intensity pixel component
5250 c cyan pixel component
5251 m magenta pixel component
5252 y yellow pixel component
5253 k black pixel component
5254 p pad component (always 0)
5257 <p>You can specify as many of these components as needed in any order (e.g.
5258 bgr). The components can repeat as well (e.g. rgbr).</p>
5261 <div style="margin: auto;">
5262 <h4><a id="mask"></a>-mask
5263 <em class="arg">filename</em></h4>
5266 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Prevent updates to image pixels specified by the mask.</td><td style='text-align:right;'></td></tr></table>
5268 <p>This the same as using a mask used for composite masking operations, with
5269 grayscale values causing blended updates of the image the mask is attached to.
5272 <p>Use <a href="command-line-options.html#mask">+mask</a> to remove the mask from images.</p>
5274 <p>Also see <a href="command-line-options.html#clip-mask">-clip-mask</a> which work in the same way,
5275 but with strict boolean masking. </p>
5277 <div style="margin: auto;">
5278 <h4><a id="mattecolor"></a>-mattecolor <em class="arg">color</em></h4>
5281 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Specify the color to be used with the <a href="command-line-options.html#frame">-frame</a> option.</td><td style='text-align:right;'></td></tr></table>
5283 <p>The color is specified using the format described under the <a href="command-line-options.html#fill">-fill</a> option.</p>
5285 <p>The default matte color is <code>#BDBDBD</code>, <span
5286 style="background-color: #bdbdbd;">this shade of gray</span>.</p>
5288 <div style="margin: auto;">
5289 <h4><a id="maximum"></a>-maximum</h4>
5292 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>return the maximum intensity of an image sequence.</td><td style='text-align:right;'></td></tr></table>
5294 <p>Select the 'maximum' value from all the surrounding pixels. </p>
5296 <p>This is legacy option from the <a href="command-line-options.html#statistic" >method</A> of the same
5299 <div style="margin: auto;">
5300 <h4><a id="median"></a>-median <em class="arg">geometry</em></h4>
5303 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>apply a median filter to the image.</td><td style='text-align:right;'></td></tr></table>
5305 <p>Select the 'middle' value from all the surrounding pixels. </p>
5307 <p>This is legacy option from the <a href="command-line-options.html#statistic" >method</A> of the same
5310 <div style="margin: auto;">
5311 <h4><a id="metric"></a>-metric <em class="arg">type</em></h4>
5314 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Output to STDERR a measure of the differences between images according to the <em class="arg">type</em> given metric.</td><td style='text-align:right;'></td></tr></table>
5319 AE absolute error count, number of different pixels (-fuzz effected)
5320 FUZZ mean color distance
5321 MAE mean absolute error (normalized), average channel error distance
5322 MEPP mean error per pixel (normalized mean error, normalized peak error)
5323 MSE mean error squared, average of the channel error squared
5324 NCC normalized cross correlation
5325 PAE peak absolute (normalize peak absolute)
5326 PSNR peak signal to noise ratio
5327 RMSE root mean squared (normalized root mean squared)
5330 <p>Control the '<code>AE</code>', or absolute count of pixels that are different,
5331 with the <a href="command-line-options.html#fuzz" >-fuzz</a> factor (ignore pixels which
5332 only changed by a small amount). Use '<code>PAE</code>' to find the
5333 size of the <a href="command-line-options.html#fuzz" >-fuzz</a> factor needed to make all pixels
5334 'similar', while '<code>MAE</code>' determines the factor needed
5335 for about half the pixels to be similar. </p>
5337 <p>The '<code>MEPP</code>' metric returns three different metrics
5338 ('<code>MAE</code>', '<code>MAE</code>' normalized, and '<code>PAE</code>'
5339 normalized) from a single comparison run. </p>
5341 <p>To print a complete list of metrics, use the <a href="command-line-options.html#list">-list
5342 metrics</a> option.</p>
5345 <div style="margin: auto;">
5346 <h4><a id="minimum"></a>-minimum</h4>
5349 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>return the minimum intensity of an image sequence.</td><td style='text-align:right;'></td></tr></table>
5351 <p>Select the 'minimal' value from all the surrounding pixels. </p>
5353 <p>This is legacy option from the <a href="command-line-options.html#statistic" >method</A> of the same
5358 <div style="margin: auto;">
5359 <h4><a id="mode"></a>-mode <em class="arg">geometry</em></h4>
5362 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>make each pixel the 'predominant color' of the neighborhood.</td><td style='text-align:right;'>[<a href="convert.html">convert</a>, <a href="mogrify.html">mogrify</a>]</td></tr></table>
5364 <div style="margin: auto;">
5365 <h4>-mode <em class="arg">value</em></h4>
5368 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Mode of operation.</td><td style='text-align:right;'>[<a href="montage.html">montage</a>]</td></tr></table>
5370 <p>Choose the <em class="arg">value</em> from these styles: <code>Frame,
5371 Unframe, or Concatenate</code></p>
5373 <p>Use the <a href="command-line-options.html#list" >-list</a> option with a '<code>Mode</code>' argument
5374 for a list of <a href="command-line-options.html#mode" >-mode</a> arguments available in your
5375 ImageMagick installation.</p>
5378 <div style="margin: auto;">
5379 <h4><a id="modulate"></a>-modulate <em class="arg">brightness</em>[,<em class="arg">saturation</em>,<em class="arg">hue</em>]</h4>
5382 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Vary the <em class="arg">brightness</em>, <em
5383 class="arg">saturation</em>, and <em class="arg">hue</em> of an image.</td><td style='text-align:right;'></td></tr></table>
5385 <p>The arguments are given as a percentages of variation. A value of 100 means
5386 no change, and any missing values are taken to mean 100.</p>
5388 <p>The <em class="arg">brightness</em> is a multiplier of the overall
5389 brightness of the image, so 0 means pure black, 50 is half as bright, 200 is
5390 twice as bright. To invert its meaning <a href="command-line-options.html#negate">-negate</a> the image
5391 before and after. </p>
5393 <p>The <em class="arg">saturation</em> controls the amount of color in an
5394 image. For example, 0 produce a grayscale image, while a large value such as
5395 200 produce a very colorful, 'cartoonish' color.</p>
5397 <p>The <em class="arg">hue</em> argument causes a "rotation" of the colors
5398 within the image by the amount specified. For example, 50 results in
5399 a counter-clockwise rotation of 90, mapping red shades to purple, and so on.
5400 A value of either 0 or 200 results in a complete 180 degree rotation of the
5401 image. Using a value of 300 is a 360 degree rotation resulting in no change to
5402 the original image. </p>
5404 <p>For example, to increase the color brightness by 20% and decrease the color
5405 saturation by 10% and leave the hue unchanged, use <a
5406 href="command-line-options.html#modulate">-modulate 120,90</a>.</p>
5408 <p>Use <a href="command-line-options.html#set">-set</a> attribute of '<code
5409 class="arg">option:modulate:colorspace</code>' to specify which colorspace to
5410 modulate. Choose from <code>HCL</code>, <code>HCLp</code>, <code>HSB</code>, <code>HSI</code>, <code>HSL</code> (the default), <code>HSV</code>, <code>HWB</code>, or <code>LCH</code> (LCHuv). For example,</p>
5412 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert image.png -set option:modulate:colorspace hsb -modulate 120,90 modulate.png</span></p>
5414 <div style="margin: auto;">
5415 <h4><a id="monitor"></a>-monitor</h4>
5418 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>monitor progress.</td><td style='text-align:right;'></td></tr></table>
5421 <div style="margin: auto;">
5422 <h4><a id="monochrome"></a>-monochrome</h4>
5425 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>transform the image to black and white.</td><td style='text-align:right;'></td></tr></table>
5427 <div style="margin: auto;">
5428 <h4><a id="morph"></a>-morph <em class="arg">frames</em></h4>
5431 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>morphs an image sequence.</td><td style='text-align:right;'></td></tr></table>
5433 <p>Both the image pixels and size are linearly interpolated to give the
5434 appearance of a metamorphosis from one image to the next, over all the images
5435 in the current image list. The added images are the equivalent of a <a
5436 href="command-line-options.html#blend">-blend</a> composition. The <em class="arg">frames</em>
5437 argument determine how many images to interpolate between each image. </p>
5440 <div style="margin: auto;">
5441 <h4><a id="morphology"></a>-morphology</h4>
5442 <h4>-morphology <em class="arg">method</em> <em class="arg">kernel</em></h4>
5445 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>apply a morphology method to the image.</td><td style='text-align:right;'></td></tr></table>
5447 <p>Until I get around to writing an option summary for this, see <a
5448 href="http://www.imagemagick.org/Usage/morphology/" >IM Usage Examples,
5449 Morphology</a>. </p>
5452 <div style="margin: auto;">
5453 <h4><a id="mosaic"></a>-mosaic</h4>
5456 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>an simple alias for the <a href="command-line-options.html#layers" >-layers</a> method "mosaic"</td><td style='text-align:right;'></td></tr></table>
5459 <div style="margin: auto;">
5460 <h4><a id="motion-blur"></a>-motion-blur <em class="arg">radius</em><br />-motion-blur <em class="arg">radius</em>x<em class="arg">sigma</em>+<em class="arg">angle</em>+<em class="arg">bias</em></h4>
5463 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>simulate motion blur.</td><td style='text-align:right;'></td></tr></table>
5465 <p>Blur with the given radius, standard deviation (sigma), and angle. The
5466 angle given is the angle toward which the image is blurred. That is the
5467 direction people would consider the object is coming from. </p>
5469 <p>Note that the blur is not uniform distribution, giving the motion a
5470 definite sense of direction of movement. </p>
5472 <p>The <a href="command-line-options.html#virtual-pixel">-virtual-pixel</a> setting will determine how
5473 pixels which are outside the image proper are blurred into the final result.
5476 <div style="margin: auto;">
5477 <h4><a id="name"></a>-name</h4>
5480 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>name an image.</td><td style='text-align:right;'></td></tr></table>
5481 <div style="margin: auto;">
5482 <h4><a id="negate"></a>-negate</h4>
5485 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>replace each pixel with its complementary color.</td><td style='text-align:right;'></td></tr></table>
5487 <p>The red, green, and blue intensities of an image are negated. White becomes
5488 black, yellow becomes blue, etc. Use <a href="command-line-options.html#negate">+negate</a> to only
5489 negate the grayscale pixels of the image.</p>
5491 <div style="margin: auto;">
5492 <h4><a id="noise"></a>-noise <em class="arg">geometry</em><br/>
5493 +noise <em class="arg">type</em></h4>
5496 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Add or reduce noise in an image.</td><td style='text-align:right;'></td></tr></table>
5498 <p>The principal function of noise peak elimination filter is to smooth the
5499 objects within an image without losing edge information and without creating
5500 undesired structures. The central idea of the algorithm is to replace a pixel
5501 with its next neighbor in value within a pixel window, if this pixel has been
5502 found to be noise. A pixel is defined as noise if and only if this pixel is
5503 a maximum or minimum within the pixel window.</p>
5505 <p>Use <code><a href="command-line-options.html#noise">-noise</a> <em class="arg">radius</em></code> to
5506 specify the width of the neighborhood when reducing noise. This is equivelent
5507 to using a <code><a href="command-line-options.html#statistic" >-statistic</a> NonPeak</code> operation,
5508 which should be used in preference.</p>
5510 <p>Use <a href="command-line-options.html#noise">+noise</a> followed by a noise <em
5511 class="arg">type</em> to add noise to an image. Choose from these noise
5524 <p>The amount of noise added can be controled by the <code><a
5525 href="command-line-options.html#attunuuate" >-attenuate</a></code> setting. If unset the value is
5526 equivelent to 1.0, or a maximum noise addition.</p>
5528 <p>Note that Random will replace the image with noise rather than add noise to the image. Use Uniform, if you wish to add random noise to the image.
5530 <p>To print a complete list of noises, use the <a href="command-line-options.html#list">-list noise</a> option.</p>
5532 <p>Also see the <a href="command-line-options.html#evaluate">-evaluate</a> noise functions that allows
5533 the use of a controlling value to specify the amount of noise that should be
5534 added to an image. </p>
5537 <div style="margin: auto;">
5538 <h4><a id="normalize"></a>-normalize</h4>
5541 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Increase the contrast in an image by <em>stretching</em> the range of intensity values.</td><td style='text-align:right;'></td></tr></table>
5543 <p>The intensity values are stretched to cover the entire range of possible
5544 values. While doing so, black-out at most <em>2%</em> of the pixels and
5545 white-out at most <em>1%</em> of the pixels.</p>
5547 <p>Note that as of ImageMagick 6.4.7-0, <a href="command-line-options.html#normalize" >-normalize</a>
5548 is equivalent to <a href="command-line-options.html#contrast-stretch" >-contrast-stretch 2%x1%</a>.
5549 (Before this version, it was equivalent to <a href="command-line-options.html#contrast-stretch"
5550 >-contrast-stretch 2%x99%</a>).</p>
5552 <p>All the channels are normalized in concert by the came amount so as to
5553 preserve color integrity, when the default <a href="command-line-options.html#channel" >+channel</a>
5554 setting is in use. Specifying any other <a href="command-line-options.html#channel" >-channel</a>
5555 setting will normalize the RGB channels independently.</p>
5557 <p>See <a href="command-line-options.html#contrast-stretch" >-contrast-stretch</a> for more details.
5558 Also see <a href="command-line-options.html#auto-level" >-auto-level</a> for a 'perfect' normalization
5559 that is better suited to mathematically generated images. </p>
5561 <p>This operator is under review for re-development. </p>
5564 <div style="margin: auto;">
5565 <h4><a id="ordered-dither"></a>-ordered-dither <em class="arg">threshold_map</em>{,<em class="arg">level</em>...}</h4>
5568 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>dither the image using a pre-defined ordered dither <em
5569 class="arg">threshold map</em> specified, and a uniform color map with the
5570 given number of <em class="arg">levels</em> per color channel . </td><td style='text-align:right;'></td></tr></table>
5572 <p>You can choose from these standard threshold maps:</p>
5575 threshold 1x1 Threshold 1x1 (non-dither)
5576 checks 2x1 Checkerboard 2x1 (dither)
5577 o2x2 2x2 Ordered 2x2 (dispersed)
5578 o3x3 3x3 Ordered 3x3 (dispersed)
5579 o4x4 4x4 Ordered 4x4 (dispersed)
5580 o8x8 8x8 Ordered 8x8 (dispersed)
5581 h4x4a 4x1 Halftone 4x4 (angled)
5582 h6x6a 6x1 Halftone 6x6 (angled)
5583 h8x8a 8x1 Halftone 8x8 (angled)
5584 h4x4o Halftone 4x4 (orthogonal)
5585 h6x6o Halftone 6x6 (orthogonal)
5586 h8x8o Halftone 8x8 (orthogonal)
5587 h16x16o Halftone 16x16 (orthogonal)
5588 c5x5b c5x5 Circles 5x5 (black)
5589 c5x5w Circles 5x5 (white)
5590 c6x6b c6x6 Circles 6x6 (black)
5591 c6x6w Circles 6x6 (white)
5592 c7x7b c7x7 Circles 7x7 (black)
5593 c7x7w Circles 7x7 (white)
5596 <p> The <code>threshold</code> generated a simple 50% threshold of the image.
5597 This could be used with <em class="arg" >level</em> to do the equivalent of <a
5598 href="command-line-options.html#posterize" >-posterize</a> to reduce an image to basic primary colors.
5601 <p>The <code>checks</code> pattern produces a 3 level checkerboard dither
5602 pattern. That is a grayscale will become a pattern of solid black, solid
5603 white, and mid-tone colors into a checkerboard pattern of black and white.
5606 <p>You can define your own <em class="arg" >threshold map</em> for ordered
5607 dithering and halftoning your images, in either personal or system
5608 <code>thresholds.xml</code> XML file. See <a href="resources.html" >Resources</A>
5609 for more details of configuration files. </p>
5611 <p>To print a complete list of the thresholds that have been defined, use the
5612 <a href="command-line-options.html#list" >-list threshold</a> option.</p>
5614 <p>Note that at this time the same threshold dithering map is used for all
5615 color channels, no attempt is made to offset or rotate the map for different
5616 channels is made, to create an offset printing effect. Also as the maps are
5617 simple threshold levels, the halftone and circle maps will create incomplete
5618 circles along the edges of a colored area. Also all the effects are purely
5619 on/off boolean effects, without anti-aliasing to make the circles smooth
5620 looking. Large dots can be made to look better with a small amount of blurring
5621 after being created. </p>
5624 <div style="margin: auto;">
5625 <h4><a id="opaque"></a>-opaque <em class="arg">color</em></h4>
5628 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>change this color to the fill color within the image.</td><td style='text-align:right;'></td></tr></table>
5630 <p>The <em class="arg">color</em> argument is defined using the format
5631 described under the <a href="command-line-options.html#fill" >-fill</a> option. The <a href="command-line-options.html#fuzz"
5632 >-fuzz</a> setting can be used to match and replace colors similar to the one
5635 <p>Use <a href="command-line-options.html#opaque">+opaque</a> to paint any pixel that does not match
5636 the target color. </p>
5638 <p>The <a href="command-line-options.html#transparent">-transparent</a> operator is exactly the same
5639 as <a href="command-line-options.html#opaque" >-opaque</a> but replaces the matching color with
5640 transparency rather than the current <a href="command-line-options.html#fill">-fill</a> color setting.
5641 To ensure that it can do this it also ensures that the image has an alpha
5642 channel enabled, as per "<code><a href="command-line-options.html#alpha" >-alpha</a> set</code>", for
5643 the new transparent colors, and does not require you to modify the <a
5644 href="command-line-options.html#channel">-channel</a> to enable alpha channel handling. </p>
5647 <div style="margin: auto;">
5648 <h4><a id="orient"></a>-orient <em class="arg">image orientation</em></h4>
5651 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>specify orientation of a digital camera image.</td><td style='text-align:right;'></td></tr></table>
5653 <p>Choose from these orientations:</p>
5667 <p>To print a complete list of orientations, use the <a href="command-line-options.html#list" >-list
5668 orientation</a> option.</p>
5671 <div style="margin: auto;">
5672 <h4><a id="page"></a>-page <em class="arg">geometry</em><br/>
5673 -page <em class="arg">media</em>[<em class="arg">offset</em>][{<em class="arg">^!<></em>}]<br/>
5678 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Set the size and location of an image on the larger virtual canvas.</td><td style='text-align:right;'></td></tr></table>
5680 <p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
5682 <p>For convenience you can specify the page size using <em
5683 class="arg">media</em> (see below). Offsets can then be added as with other
5684 <em class="arg">geometry</em> arguments (e.g. <a
5685 href="command-line-options.html#page">-page</a> <code>Letter+43+43</code>).</p>
5687 <p>Use <em class="arg">media</em> as shorthand to specify the dimensions (<em
5688 class="arg">width</em>x<em class="arg">height</em>) of the <em
5689 class="arg">PostScript</em> page in dots per inch or a TEXT page in pixels.
5690 The choices for a PostScript page are:</p>
5692 <table id="geometryTable" cellpadding="2" cellspacing="0" border="1"
5693 width="50%" style="margin-left: auto; margin-right: auto;">
5696 <th align="center"><em class="arg">media</em></th>
5697 <th align="center"><em class="arg">width</em></th>
5698 <th align="center"><em class="arg">height</em></th>
5702 <tr><td align="left"> 11x17 </td> <td align="right"> 792</td> <td align="right"> 1224</td> </tr>
5703 <tr><td align="left"> Ledger </td> <td align="right"> 1224</td> <td align="right"> 792</td> </tr>
5704 <tr><td align="left"> Legal </td> <td align="right"> 612</td> <td align="right"> 1008</td> </tr>
5705 <tr><td align="left"> Letter </td> <td align="right"> 612</td> <td align="right"> 792</td> </tr>
5706 <tr><td align="left"> LetterSmall</td> <td align="right"> 612</td> <td align="right"> 792</td> </tr>
5707 <tr><td align="left"> ArchE </td> <td align="right"> 2592</td> <td align="right"> 3456</td> </tr>
5708 <tr><td align="left"> ArchD </td> <td align="right"> 1728</td> <td align="right"> 2592</td> </tr>
5709 <tr><td align="left"> ArchC </td> <td align="right"> 1296</td> <td align="right"> 1728</td> </tr>
5710 <tr><td align="left"> ArchB </td> <td align="right"> 864</td> <td align="right"> 1296</td> </tr>
5711 <tr><td align="left"> ArchA </td> <td align="right"> 648</td> <td align="right"> 864</td> </tr>
5712 <tr><td align="left"> A0 </td> <td align="right"> 2380</td> <td align="right"> 3368</td> </tr>
5713 <tr><td align="left"> A1 </td> <td align="right"> 1684</td> <td align="right"> 2380</td> </tr>
5714 <tr><td align="left"> A2 </td> <td align="right"> 1190</td> <td align="right"> 1684</td> </tr>
5715 <tr><td align="left"> A3 </td> <td align="right"> 842</td> <td align="right"> 1190</td> </tr>
5716 <tr><td align="left"> A4 </td> <td align="right"> 595</td> <td align="right"> 842</td> </tr>
5717 <tr><td align="left"> A4Small </td> <td align="right"> 595</td> <td align="right"> 842</td> </tr>
5718 <tr><td align="left"> A5 </td> <td align="right"> 421</td> <td align="right"> 595</td> </tr>
5719 <tr><td align="left"> A6 </td> <td align="right"> 297</td> <td align="right"> 421</td> </tr>
5720 <tr><td align="left"> A7 </td> <td align="right"> 210</td> <td align="right"> 297</td> </tr>
5721 <tr><td align="left"> A8 </td> <td align="right"> 148</td> <td align="right"> 210</td> </tr>
5722 <tr><td align="left"> A9 </td> <td align="right"> 105</td> <td align="right"> 148</td> </tr>
5723 <tr><td align="left"> A10 </td> <td align="right"> 74</td> <td align="right"> 105</td> </tr>
5724 <tr><td align="left"> B0 </td> <td align="right"> 2836</td> <td align="right"> 4008</td> </tr>
5725 <tr><td align="left"> B1 </td> <td align="right"> 2004</td> <td align="right"> 2836</td> </tr>
5726 <tr><td align="left"> B2 </td> <td align="right"> 1418</td> <td align="right"> 2004</td> </tr>
5727 <tr><td align="left"> B3 </td> <td align="right"> 1002</td> <td align="right"> 1418</td> </tr>
5728 <tr><td align="left"> B4 </td> <td align="right"> 709</td> <td align="right"> 1002</td> </tr>
5729 <tr><td align="left"> B5 </td> <td align="right"> 501</td> <td align="right"> 709</td> </tr>
5730 <tr><td align="left"> C0 </td> <td align="right"> 2600</td> <td align="right"> 3677</td> </tr>
5731 <tr><td align="left"> C1 </td> <td align="right"> 1837</td> <td align="right"> 2600</td> </tr>
5732 <tr><td align="left"> C2 </td> <td align="right"> 1298</td> <td align="right"> 1837</td> </tr>
5733 <tr><td align="left"> C3 </td> <td align="right"> 918</td> <td align="right"> 1298</td> </tr>
5734 <tr><td align="left"> C4 </td> <td align="right"> 649</td> <td align="right"> 918</td> </tr>
5735 <tr><td align="left"> C5 </td> <td align="right"> 459</td> <td align="right"> 649</td> </tr>
5736 <tr><td align="left"> C6 </td> <td align="right"> 323</td> <td align="right"> 459</td> </tr>
5737 <tr><td align="left"> Flsa </td> <td align="right"> 612</td> <td align="right"> 936</td> </tr>
5738 <tr><td align="left"> Flse </td> <td align="right"> 612</td> <td align="right"> 936</td> </tr>
5739 <tr><td align="left"> HalfLetter </td> <td align="right"> 396</td> <td align="right"> 612</td> </tr>
5744 <p>This option is also used to place subimages when writing to a multi-image
5745 format that supports offsets, such as GIF89 and MNG. When used for this
5746 purpose the offsets are always measured from the top left corner of the canvas
5747 and are not affected by the <a href="command-line-options.html#gravity">-gravity</a> option. To
5748 position a GIF or MNG image, use <a href="command-line-options.html#page">-page</a><em
5749 class="arg">{+-}x{+-}y</em> (e.g. -page +100+200). When writing to a MNG
5750 file, a <a href="command-line-options.html#page">-page</a> option appearing ahead of the first image in
5751 the sequence with nonzero width and height defines the width and height values
5752 that are written in the <code>MHDR</code> chunk. Otherwise, the MNG width and
5753 height are computed from the bounding box that contains all images in the
5754 sequence. When writing a GIF89 file, only the bounding box method is used to
5755 determine its dimensions.</p>
5757 <p>For a PostScript page, the image is sized as in <a
5758 href="command-line-options.html#geometry">-geometry</a> but positioned relative to the <em>lower
5759 left-hand corner</em> of the page by {+-}<code>x</code><em
5760 class="arg">offset</em>{+-}<code>y</code> <em class="arg">offset</em>. Use <a
5761 href="command-line-options.html#page">-page 612x792</a>, for example, to center the image within the
5762 page. If the image size exceeds the PostScript page, it is reduced to fit the
5763 page. The default gravity for the <a href="command-line-options.html#page">-page</a> option is <em
5764 class="arg">NorthWest</em>, i.e., positive <code>x</code> and <code>y</code> <em
5765 class="arg">offset</em> are measured rightward and downward from the top left
5766 corner of the page, unless the <a href="command-line-options.html#gravity">-gravity</a> option is
5767 present with a value other than <em class="arg">NorthWest</em>.</p>
5769 <p>The default page dimensions for a TEXT image is 612x792.</p>
5771 <p>This option is used in concert with <a href="command-line-options.html#density">-density</a>.</p>
5773 <p>Use <a href="command-line-options.html#page">+page</a> to remove the page settings for an image.</p>
5775 <div style="margin: auto;">
5776 <h4><a id="paint"></a>-paint <em class="arg">radius</em></h4>
5779 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>simulate an oil painting.</td><td style='text-align:right;'></td></tr></table>
5781 <p>Each pixel is replaced by the most frequent color in a circular
5782 neighborhood whose width is specified with <em class="arg">radius</em>.</p>
5784 <div style="margin: auto;">
5785 <h4><a id="path"></a>-path <em class="arg">path</em></h4></div>
5787 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>write images to this path on disk.</td><td style='text-align:right;'></td></tr></table>
5789 <div style="margin: auto;">
5790 <h4><a id="pause_animate_"></a>-pause <em class="arg">seconds</em></h4>
5793 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Pause between animation loops.</td><td style='text-align:right;'>[<a href="animate.html">animate</a>]</td></tr></table>
5795 <p>Pause for the specified number of seconds before repeating the animation.</p>
5797 <div style="margin: auto;">
5798 <h4><a id="pause_import_"></a>-pause <em class="arg">seconds</em></h4>
5801 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Pause between snapshots.</td><td style='text-align:right;'>[<a href="import.html">import</a>]</td></tr></table>
5803 <p>Pause for the specified number of seconds before taking the next snapshot.</p>
5805 <div style="margin: auto;">
5806 <h4><a id="perceptible"></a>-perceptible <em class="arg">epsilon</em></h4>
5809 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>set each pixel whose value is less than |<em>epsilon</em>| to <em>-epsilon</em> or <em>epsilon</em> (whichever is closer) otherwise the pixel value remains unchanged.</td><td style='text-align:right;'></td></tr></table>
5811 <div style="margin: auto;">
5812 <h4><a id="ping"></a>-ping</h4>
5815 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>efficiently determine image characteristics.</td><td style='text-align:right;'></td></tr></table>
5817 <div style="margin: auto;">
5818 <h4><a id="pointsize"></a>-pointsize <em class="arg">value</em></h4>
5821 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>pointsize of the PostScript, OPTION1, or TrueType font.</td><td style='text-align:right;'></td></tr></table>
5823 <div style="margin: auto;">
5824 <h4><a id="polaroid"></a>-polaroid <em class="arg">angle</em></h4>
5827 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>simulate a Polaroid picture.</td><td style='text-align:right;'></td></tr></table>
5829 <p>Use <code>+polaroid</code> to rotate the image at a random angle between -15 and +15 degrees.</p>
5831 <div style="margin: auto;">
5832 <h4><a id="poly"></a>-poly <em class="arg">"wt,exp ..."</em></h4>
5835 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>combines multiple images according to a weighted sum of polynomials; one floating point weight (coefficient) and one floating point polynomial exponent (power) for each image expressed as comma separated pairs.</td><td style='text-align:right;'></td></tr></table>
5837 <p> The weights should typically be fractions between -1 and 1. But the sum of weights should be 1 or at least between 0 and 1 to avoid clamping in non-hdri mode at black and white.
5839 <p>The exponents may be positive, negative or zero. A negative exponent is equivalent to 1 divided by the image raised to the corresponding positive exponent. A zero exponent always produces 1 scaled by quantumrange to white, i.e. wt*white, no matter what the image.</p>
5841 <p>The format is: output = wt1*image1^exp1 + wt2*image2^exp2 ...</p>
5843 <p>Some simple uses are:</p>
5845 <li>A weighted sum of each image provided all weights add to unity and all exponents=1. If the the weights are all equal to 1/(number of images), then this is equivalent to <a href="command-line-options.html#profile">-evaluate-sequence</a> <em class="arg">mean</em>.</li>
5847 <li>The sum of squares of two or more images, provided the weights are equal (and sum to 1 to avoid clamping) and the exponents equal 2.</li>
5850 <p>Note that one may add a constant color to the expression simply by using xc:somecolor for one of the images and specifying the desired weight and exponent equal to 0.</p>
5852 <p>Similarly one may add white to the expression by simply using null: (or xc:white) for one of the images with the appropriate weight and exponent equal to 0.</p>
5855 <div style="margin: auto;">
5856 <h4><a id="posterize"></a>-posterize <em class="arg">levels</em></h4>
5859 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>reduce the image to a limited number of color levels per channel.</td><td style='text-align:right;'></td></tr></table>
5861 <p>Very low values of <em class="arg">levels</em>, e.g., 2, 3, 4, have the most
5864 <div style="margin: auto;">
5865 <h4><a id="precision"></a>-precision <em class="arg">value</em></h4>
5868 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>set the maximum number of significant digits to be printed.</td><td style='text-align:right;'></td></tr></table>
5870 <div style="margin: auto;">
5871 <h4><a id="preview"></a>-preview <em class="arg">type</em></h4>
5874 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>image preview type.</td><td style='text-align:right;'></td></tr></table>
5876 <p>Use this option to affect the preview operation of an image (e.g.
5877 <code>convert file.png -preview Gamma Preview:gamma.png</code>). Choose from
5881 Rotate Shear Roll Hue
5882 Saturation Brightness Gamma Spiff
5883 Dull Grayscale Quantize Despeckle
5884 ReduceNoise Add Noise Sharpen Blur
5885 Threshold EdgeDetect Spread Shade
5886 Raise Segment Solarize Swirl
5887 Implode Wave OilPaint CharcoalDrawing
5891 <p>To print a complete list of previews, use the <a href="command-line-options.html#list">-list preview</a> option.</p>
5893 <p>The default preview is <code>JPEG</code>.</p>
5895 <div style="margin: auto;">
5896 <h4><a id="print"></a>-print <em class="arg">string</em></h4>
5899 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>interpret string and print to console.</td><td style='text-align:right;'></td></tr></table>
5901 <div style="margin: auto;">
5902 <h4><a id="process"></a>-process <em class="arg">command</em></h4>
5905 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>process the image with a custom image filter.</td><td style='text-align:right;'></td></tr></table>
5907 <p>The command arguments has the form <code>"module arg1 arg2 arg3 ...
5908 argN"</code> where <code>module</code> is the name of the module to invoke (e.g.
5909 "Analyze") and arg1 arg2 arg3 ... argN are an arbitrary number of arguments to
5910 pass to the process module.</p>
5912 <div style="margin: auto;">
5913 <h4><a id="profile"></a>-profile <em class="arg">filename</em><br/>
5914 +profile <em class="arg">profile_name</em></h4>
5917 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Manage ICM, IPTC, or generic profiles in an image.</td><td style='text-align:right;'></td></tr></table>
5919 <p>Using <a href="command-line-options.html#profile">-profile</a> <em class="arg">filename</em> adds an
5920 ICM (ICC color management), IPTC (newswire information), or a generic profile
5923 <p>Use <a href="command-line-options.html#profile">+profile <em class="arg">profile_name</em></a> to
5924 remove the indicated profile. ImageMagick uses standard filename globbing, so
5925 wildcard expressions may be used to remove more than one profile. Here we
5926 remove all profiles from the image except for the XMP profile: <code>+profile
5927 "!xmp,*"</code>. </p>
5929 <p>Use <code>identify -verbose</code> to find out which profiles are in the
5930 image file. Use <a href="command-line-options.html#strip">-strip</a> to remove all profiles (and
5933 <p>To extract a profile, the <a href="command-line-options.html#profile">-profile</a> option is not
5934 used. Instead, simply write the file to an image format such as <em
5935 class="arg">APP1, 8BIM, ICM,</em> or <em class="arg">IPTC</em>.</p>
5937 <p>For example, to extract the Exif data (which is stored in JPEG files in the
5938 <em class="arg">APP1</em> profile), use.</p>
5940 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert cockatoo.jpg profile.exif</span></p>
5941 <p>It is important to note that results may depend on whether or not the
5942 original image already has an included profile. Also, keep in mind that <a
5943 href="command-line-options.html#profile">-profile</a> is an "operator" (as opposed to a "setting") and
5944 therefore a conversion is made each time it is encountered, in order, in the
5945 command-line. For instance, in the following example, if the original image is
5946 CMYK with profile, a CMYK-CMYK-RGB conversion results.</p>
5948 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert CMYK.tif -profile "CMYK.icc" -profile "RGB.icc" RGB.tiff</span></p>
5949 <p>Furthermore, since ICC profiles are not necessarily symmetric, extra
5950 conversion steps can yield unwanted results. CMYK profiles are often very
5951 asymmetric since they involve 3−>4 and 4−>3 channel mapping.
5954 <div style="margin: auto;">
5955 <h4><a id="quality"></a>-quality <em class="arg">value</em></h4>
5958 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>JPEG/MIFF/PNG compression level.</td><td style='text-align:right;'></td></tr></table>
5960 <p>For the JPEG and MPEG image formats, quality is 1 (lowest image quality and
5961 highest compression) to 100 (best quality but least effective compression).
5962 The default is to use the estimated quality of your input image if it can
5963 be determined, otherwise 92. When the quality is greater than 90, then the
5964 chroma channels are not downsampled.
5965 Use the <a href="command-line-options.html#sampling-factor">-sampling-factor</a> option to specify the
5966 factors for chroma downsampling.</p>
5968 <p>For the MIFF image format, quality/10 is the zlib compression level, which
5969 is 0 (worst but fastest compression) to 9 (best but slowest). It has no effect
5970 on the image appearance, since the compression is always lossless.</p>
5972 <p>For the JPEG-2000 image format, quality is mapped using a non-linear
5973 equation to the compression ratio required by the Jasper library. This
5974 non-linear equation is intended to loosely approximate the quality provided by
5975 the JPEG v1 format. The default quality value 100, a request for non-lossy
5976 compression. A quality of 75 results in a request for 16:1 compression.</p>
5978 <p>For the MNG and PNG image formats, the quality value sets the zlib
5979 compression level (quality / 10) and filter-type (quality % 10). The default
5980 PNG "quality" is 75, which means compression level 7 with adaptive PNG
5981 filtering, unless the image has a color map, in which case it means
5982 compression level 7 with no PNG filtering.</p>
5984 <p>For compression level 0, the Huffman-only strategy is used, which is
5985 fastest but not necessarily the worst compression.</p>
5987 <p>If filter-type is 4 or less, the specified PNG filter-type is used for
5998 <p>If filter-type is 5, adaptive filtering is used when quality is greater
5999 than 50 and the image does not have a color map, otherwise no filtering is
6002 <p>If filter-type is 6, adaptive filtering
6003 with <em class="arg">minimum-sum-of-absolute-values</em> is used.</p>
6005 <p>Only if the output is MNG, if filter-type is 7, the LOCO color
6006 transformation (intrapixel differencing) and adaptive filtering
6007 with <em class="arg">minimum-sum-of-absolute-values</em> are used.</p>
6009 <p>If the filter-type is 8 the zlib Z_RLE compression strategy is used with
6010 no PNG filtering.</p>
6012 <p>If the filter-type is 9 the zlib Z_RLE compression strategy is used with
6013 adaptive PNG filtering.</p>
6015 <p>The quality setting has no effect on the appearance or signature of PNG
6016 and MNG images, since the compression is always lossless.</p>
6018 <p>Not all combinations of compression level, strategy, and PNG filter type
6019 can be obtained using the -quality option. For more precise control,
6020 you can use the PNG:compression-level=N, PNG:compression-strategy=N, and
6021 PNG:compression-filter=N defines, respectively, instead.
6022 See <a href="command-line-options.html#define">-define</a>. Values from the defines take precedence
6023 over values from the -quality option.</p>
6025 <p>For further information, see
6026 the <a href="http://www.w3.org/pub/WWW/TR">PNG</a> specification.</p>
6028 <div style="margin: auto;">
6029 <h4><a id="quantize"></a>-quantize <em class="arg">colorspace</em></h4>
6032 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>reduce colors using this colorspace.</td><td style='text-align:right;'></td></tr></table>
6034 <p>This setting defines the colorspace used to sort out and reduce the number
6035 of colors needed by an image (for later dithering) by operators such as <a
6036 href="command-line-options.html#colors" >-colors</a>, Note that color reduction also happens
6037 automatically when saving images to color-limited image file formats, such as
6041 <div style="margin: auto;">
6042 <h4><a id="quiet"></a>-quiet</h4>
6045 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>suppress all warning messages. Error messages are still reported.</td><td style='text-align:right;'></td></tr></table>
6047 <div style="margin: auto;">
6048 <h4><a id="radial-blur"></a>-radial-blur <em class="arg">angle</em></h4>
6051 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Blur around the center of the image.</td><td style='text-align:right;'></td></tr></table>
6053 <p>Note that this is actually a rotational blur rather than a radial and as
6054 such actually mis-named. </p>
6056 <p>The <a href="command-line-options.html#virtual-pixel">-virtual-pixel</a> setting will determine how
6057 pixels which are outside the image proper are blurred into the final result.
6061 <div style="margin: auto;">
6062 <h4><a id="raise"></a>-raise <em class="arg">thickness</em></h4>
6065 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Lighten or darken image edges.</td><td style='text-align:right;'></td></tr></table>
6067 <p>This will create a 3-D effect. Use <a href="command-line-options.html#raise">-raise</a> to create
6068 a raised effect, otherwise use <a href="command-line-options.html#raise">+raise</a>. </p>
6070 <p>Unlike the similar <a href="command-line-options.html#frame">-frame</a> option, <a
6071 href="command-line-options.html#raise">-raise</a> does not alter the dimensions of the image.</p>
6073 <div style="margin: auto;">
6074 <h4><a id="random-threshold"></a>-random-threshold <em class="arg">low</em>x<em class="arg">high</em></h4>
6077 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Apply a random threshold to the image.</td><td style='text-align:right;'></td></tr></table>
6079 <div style="margin: auto;">
6080 <h4><a id="red-primary"></a>-red-primary <em class="arg">x,y</em></h4>
6083 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Set the red chromaticity primary point.</td><td style='text-align:right;'></td></tr></table>
6085 <div style="margin: auto;">
6086 <h4><a id="regard-warnings"></a>-regard-warnings</h4>
6089 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Pay attention to warning messages.</td><td style='text-align:right;'></td></tr></table>
6091 <p>This option causes some warnings in some image formats to be treated
6094 <div style="margin: auto;">
6095 <h4><a id="remap"></a>-remap <em class="arg">filename</em></h4>
6098 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Reduce the number of colors in an image to the colors used by this image.</td><td style='text-align:right;'></td></tr></table>
6100 <p>If the <a href="command-line-options.html#dither">-dither</a> setting is enabled (the default) then
6101 the given colors are dithered over the image as necessary, otherwise the closest
6102 color (in RGB colorspace) is selected to replace that pixel in the image. </p>
6104 <p>As a side effect of applying a <a href="command-line-options.html#remap">-remap</a> of colors across all
6105 images in the current image sequence, all the images will have the same color
6106 table. That means that when saved to a file format such as GIF, it will use
6107 that color table as a single common or global color table, for all the images,
6108 without requiring extra local color tables. </p>
6110 <p>Use <a href="command-line-options.html#remap">+remap</a> to reduce all images in the current image
6111 sequence to use a common color map over all the images. This equivalent to
6112 appending all the images together (without extra background colors) and color
6113 reducing those images using <a href="command-line-options.html#colors">-colors</a> with a 256 color
6114 limit, then <a href="command-line-options.html#remap">-remap</a> those colors over the original list of
6115 images. This ensures all the images follow a single color map. </p>
6117 <p>If the number of colors over all the images is less than 256, then <a
6118 href="command-line-options.html#remap">+remap</a> should not perform any color reduction or dithering, as
6119 no color changes are needed. In that case, its only effect is to force the use
6120 of a global color table. This recommended after using either <a
6121 href="command-line-options.html#colors">-colors</a> or <a href="command-line-options.html#ordered-dither">-ordered-dither</a> to
6122 reduce the number of colors in an animated image sequence. </p>
6124 <p>Note, the remap image colormap has at most 8-bits of precision. Deeper color maps are automagically coalesced with other colors to meet this requirement.</p>
6126 <div style="margin: auto;">
6127 <h4><a id="region"></a>-region <em class="arg">geometry</em></h4>
6130 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Set a region in which subsequent operations apply.</td><td style='text-align:right;'></td></tr></table>
6132 <p>The <em class="arg">x</em> and <em class="arg">y</em> offsets are treated
6133 in the same manner as in <a href="command-line-options.html#crop">-crop</a>.</p>
6135 <p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
6137 <div style="margin: auto;">
6138 <h4><a id="remote"></a>-remote</h4>
6141 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>perform a remote operation.</td><td style='text-align:right;'></td></tr></table>
6143 <p>The only command recognized is the name of an image file to load.</p>
6145 <p>If you have more than one <a href="display.html">display</a> application
6146 running simultaneously, use the <a href="command-line-options.html#window"> window</a> option to
6147 specify which application to control.</p>
6149 <div style="margin: auto;">
6150 <h4><a id="render"></a>-render</h4>
6153 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>render vector operations.</td><td style='text-align:right;'></td></tr></table>
6155 <p>Use <a href="command-line-options.html#render">+render</a> to turn off rendering vector operations.
6156 This useful when saving the result to vector formats such as MVG or SVG.</p>
6158 <div style="margin: auto;">
6159 <h4><a id="repage"></a>-repage <em class="arg">geometry</em></h4>
6162 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Adjust the canvas and offset information of the image.</td><td style='text-align:right;'></td></tr></table>
6164 <p>This option is like <a href="command-line-options.html#page">-page</a> but acts as an image operator
6165 rather than a setting. You can separately set the canvas size or the offset
6166 of the image on that canvas by only providing those components. </p>
6168 <p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
6170 <p>If a <code>!</code> flag is given the offset given is added to the existing
6171 offset to move the image relative to its previous position. This useful for
6172 animation sequences. </p>
6174 <p>A given a canvas size of zero such as '<code>0x0</code>' forces it to
6175 recalculate the canvas size so the image (at its current offset) will appear
6176 completely on that canvas (unless it has a negative offset).</p>
6178 <p>Use <a href="command-line-options.html#repage">+repage</a> to completely remove/reset the virtual
6179 canvas meta-data from the images. </p>
6181 <p>The <a href="command-line-options.html#set">-set</a> '<code>page</code>' option can be used to
6182 directly assign virtual canvas meta-data. </p>
6185 <div style="margin: auto;">
6186 <h4><a id="resample"></a>-resample <em class="arg">horizontal</em>x<em class="arg">vertical</em></h4>
6189 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Resample image to specified horizontal and vertical resolution.</td><td style='text-align:right;'></td></tr></table>
6191 <p>Resize the image so that its rendered size remains the same as the original
6192 at the specified target resolution. For example, if a 300 DPI image renders at
6193 3 inches by 2 inches on a 300 DPI device, when the image has been resampled to
6194 72 DPI, it will render at 3 inches by 2 inches on a 72 DPI device. Note that
6195 only a small number of image formats (e.g. JPEG, PNG, and TIFF) are capable of
6196 storing the image resolution. For formats which do not support an image
6197 resolution, the original resolution of the image must be specified via <a
6198 href="command-line-options.html#density">-density</a> on the command line prior to specifying the
6199 resample resolution.</p>
6201 <p>Note that Photoshop stores and obtains image resolution from a proprietary
6202 embedded profile. If this profile exists in the image, then Photoshop will
6203 continue to treat the image using its former resolution, ignoring the image
6204 resolution specified in the standard file header.</p>
6206 <div style="margin: auto;">
6207 <h4><a id="resize"></a>-resize <em class="arg">geometry</em></h4>
6210 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Resize an image.</td><td style='text-align:right;'></td></tr></table>
6212 <p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument. Offsets, if present in the geometry string, are
6213 ignored, and the <a href="command-line-options.html#gravity">-gravity</a> option has no effect.</p>
6215 <p>If the <a href="command-line-options.html#filter">-filter</a> option precedes the <a
6216 href="command-line-options.html#resize">-resize</a> option, the image is resized with the specified
6219 <p>Many image processing algorithms assume your image is in a linear-light
6220 coding. If your image is gamma-corrected, you can remove the nonlinear gamma
6221 correction, apply the transform, then restore it like this:</p>
6223 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert portrait.jpg -gamma .45455 -resize 25% -gamma 2.2 \ <br/> -quality 92 passport.jpg</span></p>
6224 <div style="margin: auto;">
6225 <h4><a id="respect-parentheses"></a>-respect-parentheses</h4>
6228 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>settings remain in effect until parenthesis boundary.</td><td style='text-align:right;'></td></tr></table>
6230 <div style="margin: auto;">
6231 <h4><a id="reverse"></a>-reverse</h4>
6234 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Reverse the order of images in the current image list.</td><td style='text-align:right;'></td></tr></table>
6237 <div style="margin: auto;">
6238 <h4><a id="roll"></a>-roll {<em class="arg">+-</em>}<em class="arg">x</em>{<em class="arg">+-</em>}<em class="arg">y</em></h4>
6241 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>roll an image vertically or horizontally by the amount given.</td><td style='text-align:right;'></td></tr></table>
6243 <p>A negative <em class="arg">x</em> offset rolls the image left-to-right.
6244 A negative <em class="arg">y</em> offset rolls the image top-to-bottom.</p>
6247 <div style="margin: auto;">
6248 <h4><a id="rotate"></a>-rotate <em class="arg">degrees</em>{<em class="arg"><</em>}{<em class="arg">></em>}</h4>
6251 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Apply Paeth image rotation (using shear operations) to the image.</td><td style='text-align:right;'></td></tr></table>
6253 <p>Use <code>></code> to rotate the image only if its width exceeds the
6254 height. <code><</code> rotates the image <em>only</em> if its width is less
6255 than the height. For example, if you specify <code>-rotate "-90>"</code> and
6256 the image size is 480x640, the image is not rotated. However, if the image is
6257 640x480, it is rotated by -90 degrees. If you use <code>></code> or
6258 <code><</code>, enclose it in quotation marks to prevent it from being
6259 misinterpreted as a file redirection.</p>
6261 <p>Empty triangles in the corners, left over from rotating the image, are
6262 filled with the <code>background</code> color. </p>
6264 <p>See also the <a href="command-line-options.html#distort">-distort</a> operator and specifically the
6265 '<code>ScaleRotateTranslate</code>' distort method. </p>
6268 <div style="margin: auto;">
6269 <h4><a id="sample"></a>-sample <em class="arg">geometry</em></h4>
6272 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>minify / magnify the image with pixel subsampling and pixel replication, respectively.</td><td style='text-align:right;'></td></tr></table>
6274 <p>Change the image size simply by directly sampling the pixels original
6275 from the image. When magnifying, pixels are replicated in blocks. When
6276 minifying, pixels are sub-sampled (i.e., some rows and columns are skipped
6279 <p>The results are thus equivalent to using <a href="command-line-options.html#resize">-resize</a> with
6280 a <a href="command-line-options.html#filter">-filter</a> setting of <code>point</code> (nearest
6281 neighbour), though <a href="command-line-options.html#sample">-sample</a> is a lot faster, as it
6282 avoids all the filter processing of the image. As such it completely ignores
6283 the current <a href="command-line-options.html#filter">-filter</a> setting. </p>
6285 <p>The key feature of the <a href="command-line-options.html#sample">-sample</a> is that no new colors
6286 will be added to the resulting image, though some colors may disappear. </p>
6288 <p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument. Offsets, if present in the geometry string, are
6289 ignored, unlike <a href="command-line-options.html#resize">-resize</a>. </p>
6292 <p>The actual sampling point is the middle of the sub-region being sampled.
6293 As such a single pixel sampling of an image will take the middle pixel, (or
6294 top-left-middle if image has even dimensions). However the <a
6295 href="command-line-options.html#define">-define</a> '<code>sample:offset</code>' can be set to modify
6296 this position some other location within each sub-region being sampled, as
6297 a percentage offset.</p>
6299 <p>By default this value is '<code>50</code>' for the midpoint, but could be set
6300 to '<code>0</code>' for top-left, '<code>100</code>' for bottom-right, or with
6301 separate X and Y offsets such as '<code>0x50</code>' for left-middle edge of
6302 sampling sub-region.</p>
6305 <div style="margin: auto;">
6306 <h4><a id="sampling-factor"></a>-sampling-factor <em class="arg">horizontal-factor</em>x<em class="arg">vertical-factor</em></h4>
6309 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>sampling factors used by JPEG or MPEG-2 encoder and YUV decoder/encoder.</td><td style='text-align:right;'></td></tr></table>
6311 <p>This option specifies the sampling factors to be used by the JPEG encoder
6312 for chroma downsampling. If this option is omitted, the JPEG library will use
6313 its own default values. When reading or writing the YUV format and when
6314 writing the M2V (MPEG-2) format, use <a
6315 href="command-line-options.html#sampling-factor">-sampling-factor 2x1</a> or <a
6316 href="command-line-options.html#sampling-factor">-sampling-factor 4:2:2</a> to specify the 4:2:2
6317 downsampling method.</p>
6319 <div style="margin: auto;">
6320 <h4><a id="scale"></a>-scale <em class="arg">geometry</em></h4>
6323 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>minify / magnify the image with pixel block averaging and pixel replication, respectively.</td><td style='text-align:right;'></td></tr></table>
6325 <p>Change the image size simply by replacing pixels by averaging pixels
6326 together when minifying, or replacing pixels when magnifying. </p>
6328 <p>The results are thus equivalent to using <a href="command-line-options.html#resize">-resize</a> with
6329 a <a href="command-line-options.html#filter">-filter</a> setting of <code>box</code>. Though it is a lot
6330 faster, as it avoids all the filter processing of the image. As such it
6331 completely ignores the current <a href="command-line-options.html#filter">-filter</a> setting. </p>
6333 <p>If when shrinking (minifying) images the original image is some integer
6334 multiple of the new image size, the number of pixels averaged together to
6335 produce the new pixel color is the same across the whole image. This is
6336 a special case known as 'binning' and is often used as a method of reducing
6337 noise in image such as those generated by digital cameras, especially in low
6338 light conditions. </p>
6341 <div style="margin: auto;">
6342 <h4><a id="scene"></a>-scene <em class="arg">value</em></h4>
6345 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>set scene number.</td><td style='text-align:right;'></td></tr></table>
6347 <p>This option sets the scene number of an image or the first image in an image sequence.</p>
6349 <div style="margin: auto;">
6350 <h4><a id="screen"></a>-screen</h4>
6353 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>specify the screen to capture.</td><td style='text-align:right;'></td></tr></table>
6355 <p>This option indicates that the GetImage request used to obtain the image
6356 should be done on the root window, rather than directly on the specified
6357 window. In this way, you can obtain pieces of other windows that overlap the
6358 specified window, and more importantly, you can capture menus or other popups
6359 that are independent windows but appear over the specified window.</p>
6361 <div style="margin: auto;">
6362 <h4><a id="seed"></a>-seed</h4>
6365 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>seed a new sequence of pseudo-random numbers</td><td style='text-align:right;'></td></tr></table>
6367 <div style="margin: auto;">
6368 <h4><a id="segment"></a>-segment <em class="arg">cluster-threshold</em>x<em class="arg">smoothing-threshold</em></h4>
6371 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>segment the colors of an image.</td><td style='text-align:right;'></td></tr></table>
6373 <p>Segment an image by analyzing the histograms of the color components and
6374 identifying units that are homogeneous with the fuzzy c-means technique. This
6375 is part of the ImageMagick color quantization routines. </p>
6377 <p>Specify <em class="arg">cluster threshold</em> as the number of pixels in
6378 each cluster that must exceed the cluster threshold to be considered valid.
6379 <em class="arg">Smoothing threshold</em> eliminates noise in the second
6380 derivative of the histogram. As the value is increased, you can expect
6381 a smoother second derivative. The default is 1.5.</p>
6383 <p>If the <a href="command-line-options.html#verbose">-verbose</a> setting is defined, a detailed report
6384 of the color clusters is returned.</p>
6387 <div style="margin: auto;">
6388 <h4><a id="selective-blur"></a>-selective-blur <em class="arg">radius</em><br />-selective-blur <em class="arg">radius</em>x<em class="arg">sigma</em>{<em class="arg">+threshold</em>}</h4>
6391 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Selectively blur pixels within a contrast threshold.</td><td style='text-align:right;'></td></tr></table>
6393 <p>Blurs those pixels that are less than or equal to the threshold in
6394 contrast. The threshold may be expressed as a fraction of <em
6395 class="QR">QuantumRange</em> or as a percentage.</p>
6397 <div style="margin: auto;">
6398 <h4><a id="separate"></a>-separate</h4>
6401 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>separate an image channel into a grayscale image. Specify the channel with <a href="command-line-options.html#channel">-channel</a>.</td><td style='text-align:right;'></td></tr></table>
6403 <div style="margin: auto;">
6404 <h4><a id="sepia-tone"></a>-sepia-tone <em class="arg">threshold</em></h4>
6407 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>simulate a sepia-toned photo.</td><td style='text-align:right;'></td></tr></table>
6409 <p>Specify <em class="arg">threshold</em> as the percent threshold of the intensity (0 - 99.9%).</p>
6411 <p>This option applies a special effect to the image, similar to the effect
6412 achieved in a photo darkroom by sepia toning. Threshold ranges from 0 to <em
6413 class="QR">QuantumRange</em> and is a measure of the extent of the sepia
6414 toning. A threshold of 80% is a good starting point for a reasonable
6419 <div style="margin: auto;">
6420 <h4><a id="set"></a>-set <em class="arg">key value</em></h4>
6421 <h4>+set <em class="arg">key</em></h4>
6424 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>sets image attributes and properties for images in the current
6425 image sequence.</td><td style='text-align:right;'></td></tr></table>
6427 <p>This will assign (or modify) specific settings attached to all the images
6428 in the current image sequence. Using the <a href="command-line-options.html#set">+set</a> form of the
6429 option will either remove, or reset that setting to a default state, as
6432 <p>For example, it will modify specific well known image meta-data
6433 'attributes' such as those normally overridden by: the options <a
6434 href="command-line-options.html#delay" >-delay</a>, <a href="command-line-options.html#dispose" >-dispose</a>, and <a
6435 href="command-line-options.html#page" >-page</a>, <a href="command-line-options.html#colorspace" >-colorspace</a>; generally
6436 assigned before the image is read in, by using a <em class="arg">key</em> of
6439 <p>If the given <em class="arg">key</em> does not match a specific known
6440 'attribute ', such as shown above, the setting is stored as a a free form
6441 'property' string. Such settings are listed in <a href="command-line-options.html#verbose"
6442 >-verbose</a> information ("<code>info:</code>" output format) as "Properties".
6445 <p>This includes string 'properties' that are set by and assigned to images
6446 using the options <a href="command-line-options.html#comment" >-comment</a>, <a href="command-line-options.html#label"
6447 >-label</a>, <a href="command-line-options.html#caption" >-caption</a>. These options actually assign
6448 a global 'artifact' which are automatically assigned (and any <a href="escape.html" >Format Percent
6449 Escapes</a> expanded) to images as they are read in. For example:</p>
6451 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert rose: -set comment 'Rose is a rose is a rose is a rose' rose.png</span><span class='crtout'>identify -format %c rose.png</span><span class="crtprompt"> $ </span><span class='crtin'>Rose is a rose is a rose is a rose</span></p>
6452 <p>The set value can also make use of <a href="escape.html" >Format and Print Image
6453 Properties</a> in the defined value. For example:</p>
6455 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert rose: -set origsize '%wx%h' -resize 50% \</span><span class='crtout'> -format 'Old size = %[origsize] New size = %wx%h' info:</span><span class="crtprompt"> $ </span><span class='crtin'>Old size = 70x46 New size = 35x23</span></p>
6456 <p>Other well known 'properties' that are availible include:
6457 '<code>date:create</code>' and '<code>date:modify</code>' and
6458 '<code>signature</code>'. </p>
6460 <p>The <a href="command-line-options.html#repage">-repage</a> operator will also allow you to modify
6461 the '<code>page</code>' attribute of an image for images already in memory (also
6462 see <a href="command-line-options.html#repage">-page</a>). However it is designed to provide a finer
6463 control of the sub-parts of this 'attribute'. The <a href="command-line-options.html#set">-set page</a>
6464 option will only provide a direct, unmodified assignment of '<code>page</code>'
6467 <p>This option can also associate a colorspace or profile with your image.
6470 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert image.psd -set profile ISOcoated_v2_eci.icc image-icc.psd</span></p>
6471 <p>Some 'properties' must be defined in a specific way to be used. For
6472 example only 'properties' prefixed with "<code>filename:</code>" can be used to
6473 modify the output filename of an image. For example</p>
6475 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert rose: -set filename:mysize '%wx%h' 'rose_%[filename:mysize].png'</span></p>
6476 <p>If the setting value is prefixed with "<code>option:</code>" the setting will
6477 be saved as a global "Artifact" exactly as if it was set using the <a
6478 href="command-line-options.html#define" >-define</a> option. As such settings are global in scope, they
6479 can be used to pass 'attributes' and 'properties' of one specific image,
6480 in a way that allows you to use them in a completely different image, even if
6481 the original image has long since been modified or destroyed. For example: </p>
6483 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert rose: -set option:rosesize '%wx%h' -delete 0 \</span><span class='crtout'> label:'%[rosesize]' label_size_of_rose.gif</span></p>
6484 <p>Note that <a href="escape.html" >Format Percent Escapes</a> will only match
6485 a 'artifact' if the given <em class="arg">key</em> does not match an existing
6486 'attribute' or 'property'. </p>
6488 <p>You can set the attributes of the image registry by prefixing the value
6489 with <code>registry:</code>.</p>
6491 <p>The <a href="command-line-options.html#set">-set profile</a> option can also be used to inject
6492 previously-formatted ancillary chunks into the output PNG file, using
6493 the commandline option as shown below or by setting the profile via a
6494 programming interface:</p>
6496 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert in.png -set profile PNG-chunk-x:<filename> out.png</span></p>
6497 <p>where <em>x</em> is a location flag and
6498 <em class="arg">filename</em> is a file containing the chunk
6499 name in the first 4 bytes, then a colon (":"), followed by the chunk data.
6500 This encoder will compute the chunk length and CRC, so those must not
6501 be included in the file.</p>
6503 <p>"x" can be "b" (before PLTE), "m" (middle, i.e., between PLTE and IDAT),
6504 or "e" (end, i.e., after IDAT). If you want to write multiple chunks
6505 of the same type, then add a short unique string after the "x" to prevent
6506 subsequent profiles from overwriting the preceding ones, e.g.,</p>
6509 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert in.png -set profile PNG-chunk-b01:file01 / <br/>
6510 -profile PNG-chunk-b02:file02 out.png</span></p>
6512 <div style="margin: auto;">
6513 <h4><a id="shade"></a>-shade <em class="arg">azimuth</em>x<em class="arg">elevation</em></h4>
6516 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>shade the image using a distant light source.</td><td style='text-align:right;'></td></tr></table>
6518 <p>Specify <em class="arg">azimuth</em> and <em class="arg">elevation</em> as
6519 the position of the light source. Use <a href="command-line-options.html#shade">+shade</a> to return
6520 the shading results as a grayscale image.</p>
6522 <div style="margin: auto;">
6523 <h4><a id="shadow"></a>-shadow <em class="arg">percent-opacity</em>{x<em class="arg">sigma</em>}{<em class="arg">+-</em>}<em class="arg">x</em>{<em class="arg">+-</em>}<em class="arg">y</em>{<em class="arg">%</em>}</h4>
6526 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>simulate an image shadow.</td><td style='text-align:right;'></td></tr></table>
6528 <div style="margin: auto;">
6530 id="shared-memory"></a>-shared-memory</h4>
6533 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>use shared memory.</td><td style='text-align:right;'></td></tr></table>
6535 <p>This option specifies whether the utility should attempt to use shared
6536 memory for pixmaps. ImageMagick must be compiled with shared memory support,
6537 and the display must support the <em class="arg">MIT-SHM</em> extension.
6538 Otherwise, this option is ignored. The default is <code>True</code>.</p>
6540 <div style="margin: auto;">
6541 <h4><a id="sharpen"></a>-sharpen <em class="arg">radius</em><br />-sharpen <em class="arg">radius</em>x<em class="arg">sigma</em>+<em class="arg">bias</em></h4>
6544 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>sharpen the image.</td><td style='text-align:right;'></td></tr></table>
6546 <p>Use a Gaussian operator of the given radius and standard deviation (sigma).</p>
6548 <div style="margin: auto;">
6549 <h4><a id="shave"></a>-shave <em class="arg">geometry</em></h4>
6552 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Shave pixels from the image edges.</td><td style='text-align:right;'></td></tr></table>
6554 <p>The <em class="arg">size</em> portion of the <em class="arg">geometry</em>
6555 argument specifies the width of the region to be removed from both sides of
6556 the image and the height of the regions to be removed from top and bottom.
6557 Offsets are ignored.</p>
6559 <p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
6561 <div style="margin: auto;">
6562 <h4><a id="shear"></a>-shear <em class="arg">Xdegrees</em>[x<em class="arg">Ydegrees</em>]</h4>
6565 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Shear the image along the x-axis and/or y-axis.</td><td style='text-align:right;'></td></tr></table>
6567 <p>The shear angles may be positive, negative, or zero. When <em
6568 class="arg">Ydegrees</em> is omitted it defaults to 0. When both angles are
6569 given, the horizontal component of the shear is performed before the vertical
6572 <p>Shearing slides one edge of an image along the x-axis or y-axis (i.e.,
6573 horizontally or vertically, respectively),creating a parallelogram. The amount
6574 of each is controlled by the respective shear angle. For horizontal shears,
6575 <em class="arg">Xdegrees</em> is measured clockwise relative to "up" (the
6576 negative y-axis), sliding the top edge to the right when 0°<<em
6577 class="arg">Xdegrees</em><90° and to the left when 90°<<em
6578 class="arg">Xdegrees</em><180°. For vertical shears <em
6579 class="arg">Ydegrees</em> is measured clockwise relative to "right" (the
6580 positive x-axis), sliding the right edge down when 0°<<em
6581 class="arg">Ydegrees</em><90° and up when 90°<<em
6582 class="arg">Ydegrees</em><180°.</p>
6584 <p>Empty triangles left over from shearing the image are filled with the color
6585 defined by the <a href="command-line-options.html#fill">-background</a> option. The color is specified
6586 using the format described under the <a href="command-line-options.html#fill">-fill</a> option.</p>
6588 <p>The horizontal shear is performed before the vertical part. This is
6589 important to note, since horizontal and vertical shears do not
6590 <em>commute</em>, i.e., the order matters in a sequence of shears. For
6591 example, the following two commands are not equivalent.</p>
6593 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert logo: -shear 20x0 -shear 0x60 logo-sheared.png</span><span class='crtout'></span><span class="crtprompt"> $ </span><span class='crtin'>convert logo: -shear 0x60 -shear 20x0 logo-sheared.png</span></p>
6594 <p>The first of the two commands above is equivalent to the following, except
6595 for the amount of empty space created; the command that follows generates
6596 a smaller image, and so is a better choice in terms of time and space.</p>
6598 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert logo: -shear 20x60 logo-sheared.png</span></p>
6599 <div style="margin: auto;">
6600 <h4><a id="sigmoidal-contrast"></a>-sigmoidal-contrast <em class="arg">contrast</em>x<em class="arg">mid-point</em></h4>
6603 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>increase the contrast without saturating highlights or shadows.</td><td style='text-align:right;'></td></tr></table>
6605 <p>Increase the contrast of the image using a sigmoidal transfer function
6606 without saturating highlights or shadows. <em class="arg">Contrast</em>
6607 indicates how much to increase the contrast. For example, near 1 is none, 3 is
6608 typical and 20 is a lot. Note that exactly zero is mathematically invalid.
6611 <p>The <em class="arg">mid-point</em> indicates where the maximum change
6612 'slope' in contrast should fall in the resultant image (0 is white; 50% is
6613 middle-gray; 100% is black). </p>
6615 <p>By default the image contrast is increased, use <em
6616 class="arg">+sigmoidal-contrast</em> to decrease the contrast.</p>
6618 <p>To achieve the equivalent of a sigmoidal brightness change (similar to
6619 a gamma adjustment), you would use <em class="arg">-sigmoidal-contrast
6620 {brightness}x0%</em> to increase brightness and <em
6621 class="arg">+sigmoidal-contrast {brightness}x0%</em> to decrease brightness.
6622 Note the use of '0' fo rthe mid-point of the sigmoidal curve. </p>
6624 <p>Using a very high <em class="arg">contrast</em> will produce a sort of
6625 'smoothed thresholding' of the image. Not as sharp (with high aliasing
6626 effects) of a true threshold, but with tapered gray-levels around the threshold
6627 <em class="arg">mid-point</em>. </p>
6629 <div style="margin: auto;">
6630 <h4><a id="silent"></a>-silent</h4>
6633 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>operate silently.</td><td style='text-align:right;'></td></tr></table>
6635 <div style="margin: auto;">
6636 <h4><a id="similarity-threshold"></a>-similarity-threshold <em class="arg">value</em></h4>
6639 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>minimum RMSE for subimage match (default 0.0).</td><td style='text-align:right;'>[<a href="compare.html">compare</a>]</td></tr></table>
6641 <div style="margin: auto;">
6642 <h4><a id="size"></a>-size <em class="arg">width</em>[x<em class="arg">height</em>][<em class="arg">+offset</em>]</h4>
6645 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>set the width and height of the image.</td><td style='text-align:right;'></td></tr></table>
6647 <p>Use this option to specify the width and height of raw images whose
6648 dimensions are unknown such as <code>GRAY</code>, <code>RGB</code>, or
6649 <code>CMYK</code>. In addition to width and height, use <a
6650 href="command-line-options.html#size">-size</a> with an offset to skip any header information in the
6651 image or tell the number of colors in a <code>MAP</code> image file, (e.g. -size
6654 <p>For Photo CD images, choose from these sizes:</p>
6664 <div style="margin: auto;">
6665 <h4><a id="sketch"></a>-sketch <em class="arg">radius</em><br />-sketch <em class="arg">radius</em>x<em class="arg">sigma</em>+<em class="arg">angle</em></h4>
6668 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>simulate a pencil sketch.</td><td style='text-align:right;'></td></tr></table>
6670 <p>Sketch with the given radius, standard deviation (sigma), and angle. The
6671 angle given is the angle toward which the image is sketched. That is the
6672 direction people would consider the object is coming from. </p>
6674 <div style="margin: auto;">
6675 <h4><a id="smush"></a>-smush <em class="arg">offset</em></h4>
6678 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>smush an image sequence together.</td><td style='text-align:right;'></td></tr></table>
6680 <div style="margin: auto;">
6681 <h4><a id="snaps"></a>-snaps <em class="arg">value</em></h4>
6684 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Set the number of screen snapshots.</td><td style='text-align:right;'>[<a href="import.html">import</a>]</td></tr></table>
6686 <p>Use this option to grab more than one image from the X server screen, to create an animation sequence.</p>
6688 <div style="margin: auto;">
6689 <h4><a id="solarize"></a>-solarize <em class="arg">threshold</em></h4>
6692 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>negate all pixels above the threshold level.</td><td style='text-align:right;'></td></tr></table>
6694 <p>Specify <em class="arg">factor</em> as the percent threshold of the intensity (0 - 99.9%).</p>
6696 <p>This option produces a <em class="arg">solarization</em> effect seen when
6697 exposing a photographic film to light during the development process.</p>
6699 <div style="margin: auto;">
6700 <h4><a id="sparse-color"></a>-sparse-color <em
6701 class="arg">method</em> '<em class="arg">x</em>,<em class="arg">y</em> <em class="arg">color</em> ...'</h4>
6704 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'> color the given image using the specified points of color, and filling the other intervening colors using the given methods. </td><td style='text-align:right;'></td></tr></table>
6710 <th align="left" style="width: 8%">Method</th>
6711 <th align="left">Description</th>
6715 <td valign="top">barycentric</td>
6716 <td valign="top">three point triangle of color given 3 points.
6717 Giving only 2 points will form a linear gradient between those points.
6718 The gradient generated extends beyond the triangle created by those
6723 <td valign="top">bilinear</td>
6724 <td valign="top">Like barycentric but for 4 points. Less than 4 points
6725 fall back to barycentric. </td>
6728 <td valign="top">voronoi</td>
6729 <td valign="top">Simply map each pixel to the to nearest color point
6730 given. The result are polygonal 'cells' of solid color. </td>
6734 <td valign="top">shepards</td>
6735 <td valign="top">Colors points biased on the ratio of inverse distance
6736 squared. Generating spots of color in a sea of the average of
6741 <td valign="top">inverse</td>
6742 <td valign="top">Colors points biased on the ratio of inverse distance.
6743 This generates sharper points of color rather than rounded spots of
6744 '<code>shepards</code>' Generating spots of color in a sea of the
6745 average of colors. </td>
6751 <p>The points are placed according to the images location on the virtual
6752 canvas (<a href="command-line-options.html#page" >-page</a> or <a href="command-line-options.html#repage" >-repage</a>
6753 offset), and do not actually have to exist on the given image, but may be
6754 some point beyond the edge of the image. All points are floating point values.
6757 <p>Only the color channels defined by the <a href="command-line-options.html#channel" >-channel</a> are
6758 modified, which means that by default matte/alpha transparency channel is not
6759 effected. Typically transparency channel is turned off either before or after
6762 Of course if some color points are transparent to generate a transparent
6763 gradient, then the image also requires transparency enabled to store the
6766 <p>All the above methods when given a single point of color will replace all
6767 the colors in the image with the color given, regardless of the point. This is
6768 logical, and provides an alternative technique to recolor an image to some
6772 <div style="margin: auto;">
6773 <h4><a id="splice"></a>-splice <em class="arg">geometry</em></h4>
6776 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Splice the current background color into the image.</td><td style='text-align:right;'></td></tr></table>
6778 <p>This will add rows and columns of the current <a
6779 href="command-line-options.html#background">-background</a> color into the given image according to the
6780 given <a href="command-line-options.html#gravity">-gravity</a> geometry setting. >See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument. Essentially <a href="command-line-options.html#splice">-splice</a> will divide the
6781 image into four quadrants, separating them by the inserted rows and columns.
6784 If a dimension of geometry is zero no rows or columns will be added for that
6785 dimension. Similarly using a zero offset with the appropriate <a
6786 href="command-line-options.html#gravity">-gravity</a> setting will add rows and columns to the edges of
6787 the image, padding the image only along that one edge. Edge padding is what <a
6788 href="command-line-options.html#splice">-splice</a> is most commonly used for. </p>
6790 <p>If the exact same <em class="arg">geometry</em> and <a
6791 href="command-line-options.html#gravity">-gravity</a> is later used with <a href="command-line-options.html#chop">-chop</a> the
6792 added added all splices removed. </p>
6794 <div style="margin: auto;">
6795 <h4><a id="spread"></a>-spread <em class="arg">amount</em></h4>
6798 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>displace image pixels by a random amount.</td><td style='text-align:right;'></td></tr></table>
6800 <p>The argument <em class="arg">amount</em> defines the size of the
6801 neighborhood around each pixel from which to choose a candidate pixel to
6804 <div style="margin: auto;">
6805 <h4><a id="statistic"></a>-statistic <em class="arg">type</em> <em class="arg">geometry</em></h4>
6808 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>replace each pixel with corresponding statistic from the neighborhood.</td><td style='text-align:right;'>[<a href="convert.html">convert</a>, <a href="mogrify.html">mogrify</a>]</td></tr></table>
6810 <p>Choose from these statistic types:</p>
6812 Gradient maximum difference in area
6813 Maximum maximum value per channel in neighborhood
6814 Minimum minimum value per channel in neighborhood
6815 Mean average value per channel in neighborhood
6816 Median median value per channel in neighborhood
6817 Mode mode (most frequent) value per channel in neighborhood
6818 Nonpeak value just before or after the median value per channel in neighborhood
6821 <div style="margin: auto;">
6822 <h4><a id="stegano"></a>-stegano <em class="arg">offset</em></h4>
6825 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>hide watermark within an image.</td><td style='text-align:right;'></td></tr></table>
6827 <p>Use an offset to start the image hiding some number of pixels from the
6828 beginning of the image. Note this offset and the image size. You will need
6829 this information to recover the steganographic image (e.g. display -size
6830 320x256+35 stegano:image.png).</p>
6832 <div style="margin: auto;">
6833 <h4><a id="stereo"></a>-stereo <em class="arg">+x</em>{<em class="arg">+y</em>}</h4>
6836 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>composite two images to create a red / cyan stereo anaglyph.</td><td style='text-align:right;'>[<a href="composite.html">composite</a>]</td></tr></table>
6838 <p>The left side of the stereo pair (second image) is saved as the red channel of the output image. The right side (first image) is saved as the green and blue channels. Red-green stereo glasses are required to properly view the stereo image.</p>
6840 <div style="margin: auto;">
6841 <h4><a id="storage-type"></a>-storage-type <em class="arg">type</em></h4>
6844 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>pixel storage type. Here are the valid types:</td><td style='text-align:right;'></td></tr></table>
6847 char unsigned characters
6852 quantum pixels in the native depth of your ImageMagick distribution
6853 short unsigned shorts
6856 <p>Float and double types are normalized from 0.0 to 1.0 otherwise the pixels
6857 values range from 0 to the maximum value the storage type can support.</p>
6859 <div style="margin: auto;">
6860 <h4><a id="stretch"></a>-stretch <em class="arg">fontStretch</em></h4>
6863 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Set a type of stretch style for fonts.</td><td style='text-align:right;'></td></tr></table>
6865 <p>This setting suggests a type of stretch that ImageMagick should try to
6866 apply to the currently selected font family. Select <em
6867 class="arg">fontStretch</em> from the following.</p>
6882 <p>To print a complete list of stretch types, use <a href="command-line-options.html#list">-list
6885 <p>For other settings that affect fonts, see the options <a
6886 href="command-line-options.html#font">-font</a>, <a href="command-line-options.html#family">-family</a>, <a
6887 href="command-line-options.html#style">-style</a>, and <a href="command-line-options.html#weight">-weight</a>. </p>
6889 <div style="margin: auto;">
6890 <h4><a id="strip"></a>-strip</h4>
6893 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>strip the image of any profiles or comments.</td><td style='text-align:right;'></td></tr></table>
6895 <div style="margin: auto;">
6896 <h4><a id="stroke"></a>-stroke <em class="arg">color</em></h4>
6899 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>color to use when stroking a graphic primitive.</td><td style='text-align:right;'></td></tr></table>
6901 <p>The color is specified using the format described under the <a href="command-line-options.html#fill">-fill</a> option.</p>
6903 <p>See <a href="command-line-options.html#draw">-draw</a> for further details.</p>
6905 <div style="margin: auto;">
6906 <h4><a id="strokewidth"></a>-strokewidth <em class="arg">value</em></h4>
6909 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>set the stroke width.</td><td style='text-align:right;'></td></tr></table>
6911 <p>See <a href="command-line-options.html#draw">-draw</a> for further details.</p>
6913 <div style="margin: auto;">
6914 <h4><a id="style"></a>-style <em class="arg">fontStyle</em></h4>
6917 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Set a font style for text.</td><td style='text-align:right;'></td></tr></table>
6919 <p>This setting suggests a font style that ImageMagick should try to apply to
6920 the currently selected font family. Select <em class="arg">fontStyle</em> from
6930 <p>For other settings that affect fonts, see the options <a
6931 href="command-line-options.html#font">-font</a>, <a href="command-line-options.html#family">-family</a>, <a
6932 href="command-line-options.html#stretch">-stretch</a>, and <a href="command-line-options.html#weight">-weight</a>. </p>
6934 <div style="margin: auto;">
6935 <h4><a id="subimage-search"></a>-subimage-search</h4>
6938 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>search for subimage.</td><td style='text-align:right;'>[<a href="compare.html">compare</a>]</td></tr></table>
6940 <p>This option is required to have compare search for the best match location
6941 of a small image within a larger image. This search will produce two images
6942 (or two frames). The first is the "difference" image and the second will
6943 be the "match score" image.</p>
6945 <p>The "match-score" image is smaller containing a pixel for ever possible
6946 position of the top-left corner of the given sub-image. that is its size will
6947 be the size of the larger_image - sub_image + 1. The brightest location in
6948 this image is the location s the locate on the best match that is also
6949 reported. Note that this may or may not be a perfect match, and the actual
6950 brightness will reflect this. Other bright 'peaks' can be used to locate other
6951 possible matching locations. </p>
6953 <p>Note that the search will try to compare the sub-image at every possible
6954 location in the larger image, as such it can be very slow. The smaller the
6955 sub-image the faster this search is. </p>
6958 <div style="margin: auto;">
6959 <h4><a id="swap"></a>-swap <em class="arg">index,index</em></h4>
6962 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Swap the positions of two images in the image sequence.</td><td style='text-align:right;'></td></tr></table>
6964 <p>For example, <a href="command-line-options.html#swap">-swap 0,2</a> swaps the first and the third
6965 images in the current image sequence. Use <a href="command-line-options.html#swap">+swap</a> to switch
6966 the last two images in the sequence.</p>
6968 <div style="margin: auto;">
6969 <h4><a id="swirl"></a>-swirl <em class="arg">degrees</em></h4>
6972 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>swirl image pixels about the center.</td><td style='text-align:right;'></td></tr></table>
6974 <p><em class="arg">Degrees</em> defines the tightness of the swirl.</p>
6976 <div style="margin: auto;">
6977 <h4><a id="synchronize"></a>-synchronize</h4>
6980 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>synchronize image to storage device.</td><td style='text-align:right;'></td></tr></table>
6982 <p>Set to "true" to ensure all image data is fully flushed and synchronized to disk. There is a performance penalty, but the benefit include ensuring a valid image file in the event of a system crash and early reporting if there is not anout disk space for the image pixel cache.</p>
6984 <div style="margin: auto;">
6985 <h4><a id="taint"></a>-taint</h4>
6988 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Mark the image as modified.</td><td style='text-align:right;'></td></tr></table>
6990 <div style="margin: auto;">
6991 <h4><a id="text-font"></a>-text-font <em class="arg">name</em></h4>
6994 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>font for writing fixed-width text.</td><td style='text-align:right;'></td></tr></table>
6996 <p>Specifies the name of the preferred font to use in fixed (typewriter style)
6997 formatted text. The default is 14 point <em class="arg">Courier</em>.</p>
6999 <p>You can tag a font to specify whether it is a PostScript, TrueType, or
7000 OPTION1 font. For example, <code>Courier.ttf</code> is a TrueType font and
7001 <code>x:fixed</code> is OPTION1.</p>
7003 <div style="margin: auto;">
7004 <h4><a id="texture"></a>-texture <em class="arg">filename</em></h4>
7007 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>name of texture to tile onto the image background.</td><td style='text-align:right;'></td></tr></table>
7009 <div style="margin: auto;">
7010 <h4><a id="threshold"></a>-threshold <em class="arg">value</em>{<em class="arg">%</em>}</h4>
7013 <!-- {<em class="arg">green,blue,opacity</em>}
7014 <p>If the green or blue value is omitted, these channels use the same value as
7015 the first one provided. If all three color values are the same, the result is
7016 a bi-level image. If the opacity threshold is omitted, OpaqueOpacity is used
7017 and any partially transparent pixel becomes fully transparent.</p>
7020 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Apply simultaneous black/white threshold to the image.</td><td style='text-align:right;'></td></tr></table>
7022 <p>Any pixel values (more specifically, those channels set using <a href="command-line-options.html#channel">‑channel</a>) that exceed the specified threshold are reassigned the
7023 maximum channel value, while all other values are assigned the minimum.</p>
7025 <p> The threshold value can be given as a percentage or as an absolute integer
7026 value corresponding to the desired channel value. When given as an integer,
7027 the minimum attainable value is 0 (corresponding to black when all channels
7028 are affected), but the maximum value (corresponding to white) is that of the
7029 <code>quantum depth</code> of the particular build of ImageMagick, and is
7030 therefore dependent on the installation. For that reason, a reasonable
7031 recommendation for most applications is to specify the threshold values as
7034 <p> The following would force pixels with red values above 50% to have 100%
7035 red values, while those at or below 50% red would be set to 0 in the red
7036 channel. The green, blue, and alpha channels (if present) would be unchanged.
7039 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert in.png -channel red -threshold 50% out.png</span></p>
7040 <p>As (possibly) impractical but instructive examples, the following would
7041 generate an all-black and an all-white image with the same dimensions as the
7045 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert in.png -threshold 100% black.png</span><span class='crtout'></span><span class="crtprompt"> $ </span><span class='crtin'>convert in.png -threshold -1 white.png</span></p>
7046 <p>Note that the values of the transparency channel is treated as 'matte'
7047 values (0 is opaque) and not as 'alpha' values (0 is transparent).</p>
7049 <p> See also <a href="command-line-options.html#black-threshold">‑black‑threshold</a> and <a href="command-line-options.html#white-threshold">‑white‑threshold</a>.
7052 <div style="margin: auto;">
7053 <h4><a id="thumbnail"></a>-thumbnail <em class="arg">geometry</em></h4>
7056 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Create a thumbnail of the image.</td><td style='text-align:right;'></td></tr></table>
7058 <p>This is similar to <a href="command-line-options.html#resize">-resize</a>, except it is optimized
7059 for speed and any image profile, other than a color profile, is removed to
7060 reduce the thumbnail size. To strip the color profiles as well, add <a
7061 href="command-line-options.html#strip">-strip</a> just before of after this option.</p>
7063 <p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
7065 <div style="margin: auto;">
7066 <h4><a id="tile"></a>-tile <em class="arg">filename</em></h4>
7069 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Set the tile image used for filling a subsequent graphic primitive.</td><td style='text-align:right;'></td></tr></table>
7071 <div style="margin: auto;">
7072 <h4>-tile <em class="arg">geometry</em></h4>
7075 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Specify the layout of images .</td><td style='text-align:right;'>[<a href="montage.html">montage</a>]</td></tr></table>
7077 <p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
7079 <div style="margin: auto;">
7083 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Specifies that a subsequent composite operation is repeated across and down image.</td><td style='text-align:right;'>[<a href="composite.html">composite</a>]</td></tr></table>
7085 <div style="margin: auto;">
7086 <h4><a id="tile-offset"></a>-tile-offset {<em class="arg">+-</em>}<em class="arg">x</em>{<em class="arg">+-</em>}<em class="arg">y</em></h4>
7089 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Specify the offset for tile images, relative to the background image it is tiled on.</td><td style='text-align:right;'></td></tr></table>
7091 <p>This should be set before the tiling image is set by <a href="command-line-options.html#tile"
7092 >-tile</a> or <a href="command-line-options.html#texture" >-texture</a>, or directly applied for
7093 creating a tiled canvas using <code>TILE:</code> or <code>PATTERN:</code> input
7096 <p>Internally ImageMagick does a <a href="command-line-options.html#roll" >-roll</a> of the tile image
7097 by the arguments given when the tile image is set. </p>
7099 <div style="margin: auto;">
7100 <h4><a id="tint"></a>-tint <em class="arg">value</em></h4>
7103 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Tint the image with the fill color.</td><td style='text-align:right;'></td></tr></table>
7105 <p>Tint the image with the fill color.</p>
7107 <p>Specify the amount of tinting as a percentage. Pure colors like black,
7108 white red, yellow, will not be affected by -tint. Only mid-range colors such
7109 as the various shades of grey.</p>
7111 <div style="margin: auto;">
7112 <h4><a id="title"></a>-title <em class="arg">string</em></h4>
7115 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Assign a title to displayed image.</td><td style='text-align:right;'>[<a href="animate.html">animate</a>, <a href="display.html">display</a>, <a href="montage.html">montage</a>]</td></tr></table>
7117 <p>Use this option to assign a specific title to the image. This assigned to
7118 the image window and is typically displayed in the window title bar.
7119 Optionally you can include the image filename, type, width, height, Exif data,
7120 or other image attribute by embedding special format characters described
7121 under the <a href="command-line-options.html#format">-format</a> option.</p>
7126 -title "%m:%f %wx%h"
7129 <p>produces an image title of <code>MIFF:bird.miff 512x480</code> for an image
7130 titled <code>bird.miff</code> and whose width is 512 and height is 480.</p>
7133 <div style="margin: auto;">
7134 <h4><a id="transform"></a>-transform</h4>
7137 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>transform the image.</td><td style='text-align:right;'></td></tr></table>
7139 <p>This option applies the transformation matrix from a previous <a href="command-line-options.html#affine">-affine</a> option.</p>
7141 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert -affine 2,2,-2,2,0,0 -transform bird.ppm bird.jpg</span></p>
7143 <p>This operator has been now been superseded by the <a
7144 href="command-line-options.html#distort">-distort</a> '<code>AffineProjection</code>' method. </p>
7147 <div style="margin: auto;">
7148 <h4><a id="transparent"></a>-transparent <em class="arg">color</em></h4>
7151 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Make this color transparent within the image.</td><td style='text-align:right;'></td></tr></table>
7153 <p>The <em class="arg">color</em> argument is defined using the format
7154 described under the <a href="command-line-options.html#fill">-fill</a> option. The <a href="command-line-options.html#fuzz"
7155 >-fuzz</a> setting can be used to match and replace colors similar to the one
7158 <p>Use <a href="command-line-options.html#transparent" >+transparent</a> to invert the pixels matched.
7159 that is make all non-matching colors transparent. </p>
7161 <p>The <a href="command-line-options.html#opaque">-opaque</a> operator is exactly the same as <a
7162 href="command-line-options.html#transparent" >-transparent</a> but replaces the matching color with the
7163 current <a href="command-line-options.html#fill">-fill</a> color setting, rather than transparent.
7164 However the <a href="command-line-options.html#transparent" >-transparent</a> operator also ensures
7165 that the image has an alpha channel enabled, as per "<code><a href="command-line-options.html#alpha"
7166 >-alpha</a> set</code>", and does not require you to modify the <a
7167 href="command-line-options.html#channel">-channel</a> to enable alpha channel handling. </p>
7169 <p>Note that this does not define the color as being the 'transparency color'
7170 used for color-mapped image formats, such as GIF. For that use <a
7171 href="command-line-options.html#transparent-color" >-transparent-color</a> </p>
7174 <div style="margin: auto;">
7175 <h4><a id="transparent-color"></a>-transparent-color <em class="arg">color</em></h4>
7178 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Set the transparent color.</td><td style='text-align:right;'></td></tr></table>
7180 <p>Sometimes this is used for saving to image formats such as
7181 GIF and PNG8 which uses this color to represent boolean transparency. This
7182 does not make a color transparent, it only defines what color the transparent
7183 color is in the color palette of the saved image. Use <a
7184 href="command-line-options.html#transparent">-transparent</a> to make an opaque color transparent.</p>
7186 <p>This option allows you to have both an opaque visible color, as well as a
7187 transparent color of the same color value without conflict. That is, you can
7188 use the same color for both the transparent and opaque color areas within an
7189 image. This, in turn, frees to you to select a transparent color that is
7190 appropriate when an image is displayed by an application that does not handle a
7191 transparent color index, while allowing ImageMagick to correctly handle images of this
7194 <p>The default transparent color is <code>#00000000</code>, which is fully transparent black.</p>
7196 <div style="margin: auto;">
7197 <h4><a id="transpose"></a>-transpose</h4>
7200 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Mirror the image along the top-left to bottom-right diagonal.</td><td style='text-align:right;'></td></tr></table>
7202 <p> This option mathematically transposes the pixel array. It is equivalent to the sequence <code>-flip -rotate 90</code>.
7205 <div style="margin: auto;">
7206 <h4><a id="transverse"></a>-transverse</h4>
7209 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Mirror the image along the images bottom-left top-right diagonal. Equivalent to the operations <code>-flop -rotate 90</code>.</td><td style='text-align:right;'></td></tr></table>
7212 <div style="margin: auto;">
7213 <h4><a id="treedepth"></a>-treedepth <em class="arg">value</em></h4>
7216 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>tree depth for the color reduction algorithm.</td><td style='text-align:right;'></td></tr></table>
7218 <p>Normally, this integer value is zero or one. A value of zero or one causes
7219 the use of an optimal tree depth for the color reduction algorithm.</p>
7221 <p>An optimal depth generally allows the best representation of the source
7222 image with the fastest computational speed and the least amount of memory.
7223 However, the default depth is inappropriate for some images. To assure the
7224 best representation, try values between 2 and 8 for this parameter. Refer to
7225 the <a href="quantize.html"
7226 >color reduction algorithm</a> for more details.</p>
7228 <p>The <a href="command-line-options.html#colors">-colors</a> or <a href="command-line-options.html#monochrome">-monochrome</a>
7229 option, or writing to an image format which requires color reduction, is
7230 required for this option to take effect.</p>
7232 <div style="margin: auto;">
7233 <h4><a id="trim"></a>-trim</h4>
7236 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>trim an image.</td><td style='text-align:right;'></td></tr></table>
7238 <p>This option removes any edges that are exactly the same color as the corner
7239 pixels. Use <a href="command-line-options.html#fuzz">-fuzz</a> to make <a href="command-line-options.html#trim">-trim</a> remove
7240 edges that are nearly the same color as the corner pixels.</p>
7242 <p>The page or virtual canvas information of the image is preserved allowing
7243 you to extract the result of the <a href="command-line-options.html#trim">-trim</a> operation from the
7244 image. Use a <a href="command-line-options.html#repage">+repage</a> to remove the virtual canvas page
7245 information if it is unwanted.</p>
7247 <p>If the trimmed image 'disappears' an warning is produced, and a special
7248 single pixel transparent 'missed' image is returned, in the same way as when a
7249 <a href="command-line-options.html#crop">-crop</a> operation 'misses' the image proper. </p>
7252 <div style="margin: auto;">
7253 <h4><a id="type"></a>-type <em class="arg">type</em></h4>
7256 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>the image type.</td><td style='text-align:right;'></td></tr></table>
7257 <p>Choose from: <code>Bilevel</code>,
7258 <code>Grayscale</code>, <code>GrayscaleMatte</code>, <code>Palette</code>,
7259 <code>PaletteMatte</code>, <code>TrueColor</code>, <code>TrueColorMatte</code>,
7260 <code>ColorSeparation</code>, or <code>ColorSeparationMatte</code>.</p>
7262 <p>Normally, when a format supports different subformats such as grayscale and
7263 truecolor, the encoder will try to choose an efficient subformat. The <a
7264 href="command-line-options.html#type">-type</a> option can be used to override this behavior. For
7265 example, to prevent a JPEG from being written in grayscale format even though
7266 only gray pixels are present, use.</p>
7268 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert bird.png -type TrueColor bird.jpg</span></p>
7269 <p>Similarly, use <a href="command-line-options.html#type">-type TrueColorMatte</a> to force the
7270 encoder to write an alpha channel even though the image is opaque, if the
7271 output format supports transparency.</p>
7273 <p>Use <a href="command-line-options.html#type">-type optimize</a> to ensure the image is written in the smallest possible file size.</p>
7275 <div style="margin: auto;">
7276 <h4><a id="undercolor"></a>-undercolor <em class="arg">color</em></h4>
7279 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>set the color of the annotation bounding box.</td><td style='text-align:right;'></td></tr></table>
7281 <p>The color is specified using the format described under the <a href="command-line-options.html#fill">-fill</a> option.</p>
7283 <p>See <a href="command-line-options.html#draw">-draw</a> for further details.</p>
7286 <div style="margin: auto;">
7287 <h4><a id="update"></a>-update <em class="arg">seconds</em></h4>
7290 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>detect when image file is modified and redisplay.</td><td style='text-align:right;'></td></tr></table>
7292 <p>Suppose that while you are displaying an image the file that is currently
7293 displayed is over-written. <code>display</code> will automagically detect that
7294 the input file has been changed and update the displayed image
7298 <div style="margin: auto;">
7299 <h4><a id="unique-colors"></a>-unique-colors</h4>
7302 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>discard all but one of any pixel color.</td><td style='text-align:right;'></td></tr></table>
7305 <div style="margin: auto;">
7306 <h4><a id="units"></a>-units <em class="arg">type</em></h4>
7309 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>the units of image resolution.</td><td style='text-align:right;'></td></tr></table>
7311 <p>Choose from: <code>Undefined</code>, <code>PixelsPerInch</code>, or
7312 <code>PixelsPerCentimeter</code>. This option is normally used in conjunction
7313 with the <a href="command-line-options.html#density">-density</a> option.</p>
7316 <div style="margin: auto;">
7317 <h4><a id="unsharp"></a>-unsharp <em class="arg">radius</em><br />-unsharp <em class="arg">radius</em>x<em class="arg">sigma</em>{<em class="arg">+gain</em>}{<em class="arg">+threshold</em>}</h4>
7320 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>sharpen the image with an unsharp mask operator.</td><td style='text-align:right;'></td></tr></table>
7322 <p>The <a href="command-line-options.html#unsharp">-unsharp</a> option sharpens an image. The image is
7323 convolved with a Gaussian operator of the given radius and standard deviation
7324 (sigma). For reasonable results, radius should be larger than sigma. Use
7325 a radius of 0 to have the method select a suitable radius.</p>
7327 <p>The parameters are:</p>
7330 radius The radius of the Gaussian, in pixels, not counting the center
7332 sigma The standard deviation of the Gaussian, in pixels (default 1.0).
7333 gain The fraction of the difference between the original and the blur
7334 image that is added back into the original (default 1.0).
7335 threshold The threshold, as a fraction of <em class="QR">QuantumRange</em>, needed to apply the
7336 difference amount (default 0.05).
7340 <div style="margin: auto;">
7341 <h4><a id="verbose"></a>-verbose</h4>
7344 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>print detailed information about the image when this option
7345 precedes the <a href="command-line-options.html#identify">-identify</a> option or
7346 <code>info:</code>.</td><td style='text-align:right;'></td></tr></table>
7349 <div style="margin: auto;">
7350 <h4><a id="version"></a>-version</h4>
7353 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>print ImageMagick version string and exit.</td><td style='text-align:right;'></td></tr></table>
7356 <div style="margin: auto;">
7357 <h4><a id="view"></a>-view <em class="arg">string</em></h4>
7360 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>FlashPix viewing parameters.</td><td style='text-align:right;'></td></tr></table>
7363 <div style="margin: auto;">
7364 <h4><a id="vignette"></a>-vignette <em class="arg">radius</em>{x<em class="arg">sigma</em>}{<em class="arg">+-</em>}<em class="arg">x</em>{<em class="arg">+-</em>}<em class="arg">y</em>{<em class="arg">%</em>}</h4>
7367 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>soften the edges of the image in vignette style.</td><td style='text-align:right;'></td></tr></table>
7370 <div style="margin: auto;">
7371 <h4><a id="virtual-pixel"></a>-virtual-pixel <em class="arg">method</em></h4>
7374 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Specify contents of <em>virtual pixels</em>.</td><td style='text-align:right;'></td></tr></table>
7376 <p>This option defines what color source should be used if and when a color
7377 lookup completely 'misses' the source image. The color(s) that appear to
7378 surround the source image. Generally this color is derived from the source
7379 image, but could also be set to a specify background color. </p>
7381 <p>Choose from these methods:</p>
7384 background the area surrounding the image is the background color
7385 black the area surrounding the image is black
7386 checker-tile alternate squares with image and background color
7387 dither non-random 32x32 dithered pattern
7388 edge extend the edge pixel toward infinity
7389 gray the area surrounding the image is gray
7390 horizontal-tile horizontally tile the image, background color above/below
7391 horizontal-tile-edge horizontally tile the image and replicate the side edge pixels
7392 mirror mirror tile the image
7393 random choose a random pixel from the image
7394 tile tile the image (default)
7395 transparent the area surrounding the image is transparent blackness
7396 vertical-tile vertically tile the image, sides are background color
7397 vertical-tile-edge vertically tile the image and replicate the side edge pixels
7398 white the area surrounding the image is white
7401 <p>The default value is "edge".</p>
7403 <p>This most important for distortion operators such as <a href="command-line-options.html#distort"
7404 >-distort</a>, <a href="command-line-options.html#implode" >-implode</a>, and <a href="command-line-options.html#fx" >-fx</a>.
7405 However it also effects operations that may access pixels just outside the
7406 image proper, such as <a href="command-line-options.html#convolve">-convolve</a>, <a
7407 href="command-line-options.html#blur">-blur</a>, and <a href="command-line-options.html#sharpen">-sharpen</a>. </p>
7409 <p>To print a complete list of virtual pixel types, use the <a
7410 href="command-line-options.html#list">-list virtual-pixel</a> option.</p>
7413 <div style="margin: auto;">
7414 <h4><a id="visual"></a>-visual <em class="arg">type</em></h4>
7417 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Animate images using this X visual type.</td><td style='text-align:right;'>[<a href="animate.html">animate</a>, <a href="display.html">display</a>]</td></tr></table>
7419 <p>Choose from these visual classes:</p>
7432 <p>The X server must support the visual you choose, otherwise an error occurs.
7433 If a visual is not specified, the visual class that can display the most
7434 simultaneous colors on the default screen is chosen.</p>
7437 <div style="margin: auto;">
7438 <h4><a id="watermark"></a>-watermark <em
7439 class="arg">brightness</em>x<em class="arg">saturation</em></h4>
7442 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Watermark an image using the given percentages of brightness and
7443 saturation.</td><td style='text-align:right;'>[<a href="composite.html">composite</a>]</td></tr></table>
7445 <p>Take a grayscale image (with alpha mask) and modify the destination image's
7446 brightness according to watermark image's grayscale value and the <em
7447 class="arg">brightness</em> percentage. The destinations color saturation
7448 attribute is just direct modified by the <em class="arg">saturation</em>
7449 percentage, which defaults to 100 percent (no color change). </p>
7452 <div style="margin: auto;">
7453 <h4><a id="wave"></a>-wave <em class="arg">amplitude</em><br />-wave <em class="arg">amplitude</em>x<em class="arg">wavelength</em></h4>
7456 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Shear the columns of an image into a sine wave.</td><td style='text-align:right;'></td></tr></table>
7458 <p>Specify <em class="arg">amplitude</em> and <em class="arg">wavelength</em>
7461 <div style="margin: auto;">
7462 <h4><a id="weight"></a>-weight <em class="arg">fontWeight</em></h4>
7465 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Set a font weight for text.</td><td style='text-align:right;'></td></tr></table>
7467 <p>This setting suggests a font weight that ImageMagick should try to apply to
7468 the currently selected font family. Use a positive integer for <em
7469 class="arg">fontWeight</em> or select from the following.</p>
7476 <th><em class="arg">fontWeight</em></th>
7477 <th>Description</th>
7482 <td>No effect. </td></tr>
7484 <td>Same as <em class="arg">fontWeight</em> = 700.</td></tr>
7485 <tr><td>Bolder </td>
7486 <td>Add 100 to font weight if currently ≤ 800.</td></tr>
7487 <tr><td>Lighter </td>
7488 <td>Subtract 100 to font weight if currently ≤ 100.</td></tr>
7489 <tr><td>Normal </td>
7490 <td>Same as <em class="arg">fontWeight</em> = 400.</td></tr>
7494 <p>To print a complete list of weight types, use <a href="command-line-options.html#list">-list
7497 <p>For other settings that affect fonts, see the options <a
7498 href="command-line-options.html#font">-font</a>, <a href="command-line-options.html#family">-family</a>, <a
7499 href="command-line-options.html#stretch">-stretch</a>, and <a href="command-line-options.html#style">-style</a>. </p>
7501 <div style="margin: auto;">
7502 <h4><a id="white-point"></a>-white-point <em class="arg">x,y</em></h4>
7505 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>chromaticity white point.</td><td style='text-align:right;'></td></tr></table>
7507 <div style="margin: auto;">
7508 <h4><a id="white-threshold"></a>-white-threshold <em class="arg">value</em>{<em class="arg">%</em>}</h4>
7511 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Force to white all pixels above the threshold while leaving all
7512 pixels at or below the threshold unchanged.</td><td style='text-align:right;'></td></tr></table>
7514 <p> The threshold value can be given as a percentage or as an absolute integer
7515 value within [0, <em class="QR">QuantumRange</em>] corresponding to the
7516 desired <a href="command-line-options.html#channel">‑channel</a> value. See <a href="command-line-options.html#threshold">‑threshold</a>for more details on thresholds and resulting values. </p>
7518 <div style="margin: auto;">
7519 <h4><a id="window"></a>-window <em class="arg">id</em></h4>
7522 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Make the image the background of a window.</td><td style='text-align:right;'>[<a href="animate.html">animate</a>, <a href="display.html">display</a>]</td></tr></table>
7524 <p><em class="arg">id</em> can be a window id or name. Specify <code>root</code>
7525 to select X's root window as the target window.</p>
7527 <p>By default the image is tiled onto the background of the target window. If
7528 <code>backdrop</code> or <a href="command-line-options.html#geometry">-resize</a> are specified, the
7529 image is surrounded by the background color. Refer to <code>X RESOURCES</code>
7532 <p>The image will not display on the root window if the image has more unique
7533 colors than the target window colormap allows. Use <a
7534 href="command-line-options.html#colors">-colors</a> to reduce the number of colors.</p>
7536 <div style="margin: auto;">
7537 <h4><a id="window-group"></a>-window-group</h4>
7540 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>specify the window group.</td><td style='text-align:right;'></td></tr></table>
7542 <div style="margin: auto;">
7543 <h4><a id="write"></a>-write <em class="arg">filename</em></h4>
7546 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>write an image sequence.</td><td style='text-align:right;'></td></tr></table>
7547 <p>The image sequence preceding the <a href="command-line-options.html#write">-write</a> <em class="arg">filename</em> option is written out, and processing continues with the same image in its current state if there are additional options. To restore the image to its original state after writing it, use the <a href="command-line-options.html#write">+write</a> <em class="arg">filename</em> option.</p>
7549 <p>Use <a href="command-line-options.html#compress">-compress</a> to specify the type of image compression.</p>
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