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href="../www/command-line-options.html#page">‑page</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#paint">‑paint</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#path">‑path</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#pause_animate_">‑pause[animate]</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#pause_import_">‑pause[import]</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#pen">‑pen</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#ping">‑ping</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#pointsize">‑pointsize</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#polaroid">‑polaroid</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#posterize">‑posterize</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#precision">‑precision</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#preview">‑preview</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#print">‑print</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#process">‑process</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#profile">‑profile</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#quality">‑quality</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#quantize">‑quantize</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#quiet">‑quiet</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#radial-blur">‑radial‑blur</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#raise">‑raise</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#random-threshold">‑random‑threshold</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#red-primary">‑red‑primary</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#regard-warnings">‑regard‑warnings</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#region">‑region</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#remap">‑remap</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#remote">‑remote</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#render">‑render</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#repage">‑repage</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#resample">‑resample</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#resize">‑resize</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#respect-parentheses">‑respect‑parentheses</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#reverse">‑reverse</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#roll">‑roll</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#rotate">‑rotate</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#sample">‑sample</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#sampling-factor">‑sampling‑factor</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#scale">‑scale</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#scene">‑scene</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#screen">‑screen</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#seed">‑seed</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#segment">‑segment</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#selective-blur">‑selective‑blur</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#separate">‑separate</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#sepia-tone">‑sepia‑tone</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#set">‑set</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#shade">‑shade</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#shadow">‑shadow</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#shared-memory">‑shared‑memory</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#sharpen">‑sharpen</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#shave">‑shave</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#shear">‑shear</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#sigmoidal-contrast">‑sigmoidal‑contrast</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#silent">‑silent</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#size">‑size</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#sketch">‑sketch</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#snaps">‑snaps</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#solarize">‑solarize</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#sparse-color">‑sparse‑color</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#splice">‑splice</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#spread">‑spread</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#stegano">‑stegano</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#stereo">‑stereo</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#stretch">‑stretch</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#strip">‑strip</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#stroke">‑stroke</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#strokewidth">‑strokewidth</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#style">‑style</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#subimage-search">‑subimage‑search</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#swap">‑swap</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#swirl">‑swirl</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#synchronize">‑synchronize</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#taint">‑taint</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#text-font">‑text‑font</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#texture">‑texture</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#threshold">‑threshold</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#thumbnail">‑thumbnail</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#tile">‑tile</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#tile-offset">‑tile‑offset</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#tint">‑tint</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#title">‑title</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#transform">‑transform</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#transparent">‑transparent</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#transparent-color">‑transparent‑color</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#transpose">‑transpose</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#transverse">‑transverse</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#treedepth">‑treedepth</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#trim">‑trim</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#type">‑type</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#undercolor">‑undercolor</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#unique-colors">‑unique‑colors</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#units">‑units</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#unsharp">‑unsharp</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#update">‑update</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#verbose">‑verbose</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#version">‑version</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#view">‑view</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#vignette">‑vignette</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#virtual-pixel">‑virtual‑pixel</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#visual">‑visual</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#watermark">‑watermark</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#wave">‑wave</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#weight">‑weight</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#white-point">‑white‑point</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#white-threshold">‑white‑threshold</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#window">‑window</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#window-group">‑window‑group</a> <span class='bull'> • </span> <a href="../www/command-line-options.html#write">‑write</a> ] </p>
177 <p>Below is list of command-line options recognized by the ImageMagick <a
178 href="../www/command-line-tools.html">command-line
179 tools</a>. If you want a description of a particular option, click on the
180 option name in the navigation bar above and you will go right to it. Unless
181 otherwise noted, each option is recognized by the commands <a href="../www/convert.html">convert</a>, <a href="../www/mogrify.html">mogrify</a>.</p>
183 <div style="margin: auto;">
184 <h4><a name="adaptive-blur" id="adaptive-blur"></a>-adaptive-blur <em class="arg">radius</em>[x<em class="arg">sigma</em>]</h4>
187 <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>
188 <p>A Gaussian operator of the given radius and standard deviation (<em class="arg">sigma</em>) is used. If <em class="arg">sigma</em> is not given it defaults to 1.</p>
190 <div style="margin: auto;">
191 <h4><a name="adaptive-resize" id="adaptive-resize"></a>-adaptive-resize <em class="arg">geometry</em></h4>
194 <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>
196 <p>See <a href="../www/command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument. The <a href="#adaptive-resize">-adaptive-resize</a> option defaults to data-dependent triangulation. Use the <a href="#filter">-filter</a> to choose a different resampling algorithm. Offsets, if present in the geometry string, are ignored, and the <a href="#gravity">-gravity</a> option has no effect.</p>
198 <div style="margin: auto;">
199 <h4><a name="adaptive-sharpen" id="adaptive-sharpen"></a>-adaptive-sharpen <em class="arg">radius</em>[x<em class="arg">sigma</em>]</h4>
202 <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>
204 <p>A Gaussian operator of the given radius and standard deviation (<em class="arg">sigma</em>) is used. If <em class="arg">sigma</em> is not given it defaults to 1.</p>
206 <div style="margin: auto;">
207 <h4><a name="adjoin" id="adjoin"></a>-adjoin</h4>
210 <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>
212 <p>This option is enabled by default. An attempt is made to save all
213 images of an image sequence into the given output file.
214 However, some formats, such as JPEG and PNG, do not support more than one
215 image per file, and in that case ImageMagick is forced to write each image as a separate file. As
216 such, if more than one image needs to be written, the filename given is
217 modified by adding a <a href="#scene">-scene</a> number before the
218 suffix, in order to make distinct names for each image. </p>
220 <p>Use <a href="#adjoin">+adjoin</a> to force each image to be written
221 to separate files, whether or not the file format allows multiple images
222 per file (for example, GIF, MIFF, and TIFF). </p>
224 <p>Including a C-style integer format string in the output filename will automagically enable <a href="#adjoin">+adjoin</a> and are used to specify where the <a href="#scene">-scene</a> number is placed in the filenames. These strings, such as '<kbd>%d</kbd>' or '<kbd>%03d</kbd>', are familiar to those who have used the standard <kbd>printf()</kbd>' C-library function. As an example, the command</p>
226 <p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert logo: rose: -morph 15 my%02dmorph.jpg</span></p>
227 <p>will create a sequence of 17 images named my00morph.jpg, my01morph.jpg, my02morph.jpg, ..., my16morph.jpg.
230 <p>In summary, ImageMagick tries to write all images to one file, but will use
231 multiple files if either<br>
232 (1) the output image's file format does not allow multi-image files,<br>
233 (2) the <a href="#adjoin">+adjoin</a> option is given, or<br>
234 (3) a C-style integer format string is present in the output filename. </p>
237 <div style="margin: auto;">
238 <h4><a name="affine" id="affine"></a>-affine <em class="arg">s<sub>x</sub></em>,<em class="arg">r<sub>x</sub></em>,<em class="arg">r<sub>y</sub></em>,<em class="arg">s<sub>y</sub></em>,<em class="arg">t<sub>x</sub></em>,<em class="arg">t<sub>y</sub></em><br/>
239 -affine <em class="arg">s<sub>x</sub></em>,<em class="arg">r<sub>x</sub></em>,<em class="arg">r<sub>y</sub></em>,<em class="arg">s<sub>y</sub></em></h4>
242 <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>
244 <p>This option sets a transformation matrix, encoded as (<em class="arg">s<sub>x</sub></em>, <em class="arg">r<sub>x</sub></em>, <em class="arg">r<sub>y</sub></em>, <em class="arg">s<sub>y</sub></em>, <em class="arg">t<sub>x</sub></em>, <em class="arg">t<sub>y</sub></em>), for use by subsequent <a href="#draw">-draw</a> or <a href="#transform">-transform</a> options.</p>
246 <p>The matrix entries are entered as comma-separated numeric values <i>with no spaces</i>. </p>
248 <p>Internally, the transformation matrix has 3x3 elements, but three of them are omitted from the input because they are constant. The new (transformed) coordinates (<em class="arg">x'</em>, <em class="arg">y'</em>) of a pixel at position (<em class="arg">x</em>, <em class="arg">y</em>) in the original image are calculated using the following matrix equation.</p>
251 <img alt="affine transformation" src="../images/affine.png"/>
255 The size of the resulting image is that of the smallest rectangle that contains the transformed source image. The parameters <em class="arg">t<sub>x</sub></em> and <em class="arg">t<sub>y</sub></em> subsequently shift the image pixels so that those that are moved out of the image area are cut off.</p>
257 <p>The transformation matrix complies with the left-handed pixel coordinate system: positive <em class="arg">x</em> and <em class="arg">y</em> directions are rightward and downward, resp.; positive rotation is clockwise.</p>
259 <p> If the translation coefficients <em class="arg">t<sub>x</sub></em> and <em class="arg">t<sub>y</sub></em> are omotted they default to 0,0. Therefore, four parameters suffice for rotation and scaling without translation.</p>
261 <p>Scaling by the factors <em class="arg">s<sub>x</sub></em> and <em class="arg">s<sub>y</sub></em> in the <em>x</em> and <em>y</em> directions, respectively, is accomplished with the following.</p>
264 -affine <em class="arg">s<sub>x</sub></em>,0,0,<em class="arg">s<sub>y</sub></em>
267 <p>Translation by a displacement (<em class="arg">t<sub>x</sub></em>, <em class="arg">t<sub>y</sub></em>) is accomplished like so:</p>
270 -affine 1,0,0,1,<em class="arg">t<sub>x</sub></em>,<em class="arg">t<sub>y</sub></em>
273 <p>Rotate clockwise about the origin (the upper left-hand corner) by an angle <em>a</em> by letting
274 <em>c</em> = cos(<em>a</em>), <em>s</em> = sin(<em>a</em>), and using the following.</p>
277 -affine <em>c</em>,<em>s</em>,-<em>s</em>,<em>c</em>
280 <p>The cumulative effect of a sequence of <a href="#affine" >-affine</a> transformations can be accomplished by instead by a single <a href="#affine" >-affine</a> operation using the matrix equal to the product of the matrices of the individual transformations.</p>
282 <p>An attempt is made to detect near-singular transformation matrices. If the matrix determinant has a sufficiently small absolute value it is rejected.</p>
284 <div style="margin: auto;">
285 <h4><a name="alpha" id="alpha"></a>-alpha <em class="arg">type</em></h4>
288 <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>
290 <p>Used to set a flag on an image indicating whether or not to use existing alpha
291 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>
297 <th align="left" style="width: 8%">type</th>
298 <th align="left">Description</th>
302 <td valign="top"><kbd>Activate</kbd> or <kbd>On</kbd></td>
304 Enable the image's transparency channel. Note normally <kbd>Set</kbd>
305 should be used instead of this, unless you specifically need to
306 preserve existing (but specifically turned <kbd>Off</kbd>) transparency
310 <td valign="top"><kbd>Deactivate</kbd> or <kbd>Off</kbd></td>
312 Disables the image's transparency channel. Does not delete or change the
313 existing data, just turns off the use of that data.</td></tr>
316 <td valign="top"><kbd>Set</kbd></td>
318 Activates the alpha/matte channel. If it was previously turned off
319 then it also resets the channel to opaque. If the image already had
320 the alpha channel turned on, it will have no effect.</td></tr>
323 <td valign="top"><kbd>Opaque</kbd></td>
325 Enables the alpha/matte channel and forces it to be fully opaque.
329 <td valign="top"><kbd>Transparent</kbd></td>
331 Activates the alpha/matte channel and forces it to be fully
332 transparent. This effectively creates a fully transparent image the
333 same size as the original and with all its original RGB data still
334 intact, but fully transparent. </td></tr>
337 <td valign="top"><kbd>Extract</kbd></td>
339 Copies the alpha channel values into all the color channels and turns
340 '<kbd>Off</kbd>' the the image's transparency, so as to generate
341 a gray-scale mask of the image's shape. The alpha channel data is left
342 intact just deactivated. This is the inverse of '<kbd>Copy</kbd>'.
346 <td valign="top"><kbd>Copy</kbd></td>
348 Turns '<kbd>On</kbd>' the alpha/matte channel, then copies the
349 gray-scale intensity of the image, into the alpha channel, converting
350 a gray-scale mask into a transparent shaped mask ready to be colored
351 appropriately. The color channels are not modified. </td></tr>
354 <td valign="top"><kbd>Shape</kbd></td>
356 As per '<kbd>Copy</kbd>' but also colors the resulting shape mask with
357 the current background color. That is the RGB color channels is
358 replaced, with appropriate alpha shape.
362 <td valign="top"><kbd>Background</kbd></td>
364 Set any fully-transparent pixel to the background color, while leaving
365 it fully-transparent. This can make some image file formats, such as
366 PNG, smaller as the RGB values of transparent pixels are more uniform,
367 and thus can compress better.
372 <p>Note that while the <a href="#matte" >+matte</a> operation is the same as
373 "<kbd><a href="#alpha" >-alpha</a> Off</kbd>", the <a href="#matte"
374 >-matte</a> operation is the same as "<kbd><a href="#alpha" >-alpha</a>
375 Set</kbd>" and not "<kbd><a href="#alpha" >-alpha</a> On</kbd>". </p>
378 <div style="margin: auto;">
379 <h4><a name="annotate" id="annotate"></a>
380 -annotate <em class="arg">degrees</em> <em class="arg">text</em><br />
381 -annotate <em class="arg">Xdegrees</em>x<em class="arg">Ydegrees</em> <em class="arg">text</em><br />
382 -annotate <em class="arg">Xdegrees</em>x<em class="arg">Ydegrees</em> {+-}<em class="arg">t<sub>x</sub></em>{+-}<em class="arg">t<sub>y</sub></em> <em class="arg">text</em></h4>
385 <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>
387 <p>This is a convenience for annotating an image with text. For more precise control over text annotations, use <a href="#draw">-draw</a>.</p>
390 <p>The values <em class="arg">Xdegrees</em> and <em class="arg">Ydegrees</em> control the shears with respect to the , respectively, applied to the text, while <em class="arg">t<sub>x</sub></em> and <em class="arg">t<sub>y</sub></em> are offsets that give the location of the text relative to the upper left corner of the image.</p>
392 <p>Using <a href="#annotate">-annotate</a> <em class="arg">degrees</em> or <a href="#annotate">-annotate</a> <em class="arg">degrees</em>x<em class="arg">degrees</em> produces an unsheared rotation of the text. The direction of the rotation is positive, which means a clockwise rotation if <em class="arg">degrees</em> is positive. (This conforms to the usual mathematical convention once it is realized that the positive <em>y</em>–direction is conventionally considered to be <em>downward</em> for images.)</p>
394 <p>The new (transformed) coordinates (<em class="arg">x'</em>, <em class="arg">y'</em>) of a pixel at position (<em class="arg">x</em>, <em class="arg">y</em>) in the image are calculated using the following matrix equation.</p>
395 <div class="eqn"><img alt="annotate transformation" src="../images/annotate.png"/></div>
397 <p>If <em class="arg">t<sub>x</sub></em> and <em class="arg">t<sub>y</sub></em> are omitted, they default to 0. This makes the bottom-left of the text becomes the upper-left corner of the image, which is probably undesirable. Adding a <a href="#gravity" >-gravity</a> option in this case leads to nice results.</p>
399 <p>Text is any UTF-8 encoded character sequence. If <em class="arg">text</em> is of the form '@mytext.txt', the text is read from the file <kbd>mytext.txt</kbd>. Text in a file is taken literally; no embedded formatting characters are recognized.</p>
401 <div style="margin: auto;">
402 <h4><a name="antialias" id="antialias"></a>-antialias</h4>
405 <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
406 drawing fonts and lines.</td><td style='text-align:right;'></td></tr></table>
408 <p>By default, objects (e.g. text, lines, polygons, etc.) are antialiased when
409 drawn. Use <a href="#antialias">+antialias</a> to disable the addition of
410 antialiasing edge pixels. This will then reduce the number of colors added to
411 an image to just the colors being directly drawn. That is, no mixed colors
412 are added when drawing such objects. </p>
414 <div style="margin: auto;">
415 <h4><a name="append" id="append"></a>-append</h4>
418 <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>
420 <p>This option creates a single longer image image, by joining all the current
421 images in sequence top-to-bottom. Use <a href="#append">+append</a> to
422 stack images left-to-right. </p>
424 <p>If they are not of the same width, narrower images are padded with the
425 current <a href="#background">-background</a> color setting, and their
426 position relative to each other can be controlled by the current <a
427 href="#gravity">-gravity</a> setting. </p>
430 <div style="margin: auto;">
431 <h4><a name="attenuate" id="attenuate"></a>-attenuate <em class="arg">value</em></h4>
434 <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>
437 <div style="margin: auto;">
438 <h4><a name="authenticate" id="authenticate"></a>-authenticate <em class="arg">password</em></h4>
441 <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>
443 <p>Use this option to supply a <em class="arg">password</em> for decrypting a PDF that has been encrypted using Microsoft Crypto API (MSC API). The encrypting using the MSC API is not supported.</p>
445 <p>For a different encryption method, see <a href="#encipher">-encipher</a> and <a href="#decipher">-decipher</a>. </p>
449 <div style="margin: auto;">
450 <h4><a name="auto-gamma" id="auto-gamma"></a>-auto-gamma</h4>
453 <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>
455 <p>This calculates the mean values of an image, then applies a calculated <a
456 href="#gamma" >-gamma</a> adjustment so that is the mean color exists in the
457 image it will get a have a value of 50%. </p>
459 <p>This means that any solid 'gray' image becomes 50% gray. </p>
461 <p>This works well for real-life images with little or no extreme dark and
462 light areas, but tend to fail for images with large amounts of bright sky or
463 dark shadows. It also does not work well for diagrams or cartoon like images.
466 <p>It uses the <a href="#channel" >-channel</a> setting, (including the
467 '<CODE>sync</CODE>' flag for channel syncronization), to determine which color
468 values is used and modified. As the default <a href="#channel"
469 >-channel</a> setting is '<CODE>RGB,sync</CODE>', channels are modified
470 together by the same gamma value, preserving colors. </p>
474 <div style="margin: auto;">
475 <h4><a name="auto-level" id="auto-level"></a>-auto-level</h4>
478 <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>
480 <p>This is a 'perfect' image normalization operator. It finds the exact
481 minimum and maximum color values in the image and then applies a <a
482 href="#level" >-level</a> operator to stretch the values to the full range of
485 <p>The operator is not typically used for real-life images, image scans, or
486 JPEG format images, as a single 'out-rider' pixel can set a bad min/max values
487 for the <a href="#level" >-level</a> operation. On the other hand it is the
488 right operator to use for color stretching gradient images being used to
489 generate Color lookup tables, distortion maps, or other 'mathematically'
492 <p>The operator is very similar to the <a href="#normalize">-normalize</a>, <a
493 href="#contrast-stretch" >-contrast-stretch</a>, and <a href="#linear-stretch"
494 >-linear-stretch</a> operators, but without 'histogram binning' or 'clipping'
495 problems that these operators may have. That is <a href="#auto-level"
496 >-auto-level</a> is the perfect or ideal version these operators. </p>
498 <p>It uses the <a href="#channel" >-channel</a> setting, (including the
499 special '<CODE>sync</CODE>' flag for channel syncronization), to determine
500 which color values are used and modified. As the default <a
501 href="#channel" >+channel</a> setting is '<CODE>RGB,sync</CODE>', the
502 '<CODE>sync</CODE>' ensures that the color channels will are modified
503 together by the same gamma value, preserving colors, and ignoring
507 <div style="margin: auto;">
508 <h4><a name="auto-orient" id="auto-orient"></a>-auto-orient</h4>
511 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Automagically orient (rotate) an image created by a digital camera.</td><td style='text-align:right;'></td></tr></table>
513 <p>This operator reads and resets the EXIF image profile setting 'Orientation'
514 and then performs the appropriate 90 degree rotation on the image to orient
515 the image, for correct viewing. </p>
517 <p>This EXIF profile setting is usually set using a gravity sensor in digital
518 camara, however photos taken directly downward or upward may not have an
519 appropriate value. Also images that have been orientation 'corrected' without
520 reseting this setting, may be 'corrected' again resulting in a incorrect
521 result. If the he EXIF profile was previously stripped, the <a
522 href="#auto-orient" >-auto-orient</a> operator will do nothing. </p>
525 <div style="margin: auto;">
526 <h4><a name="average" id="average"></a>-average</h4>
529 <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>
531 <p>An error results if the images are not identically sized.</p>
534 <div style="margin: auto;">
535 <h4><a name="backdrop" id="backdrop"></a>-backdrop</h4>
538 <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="../www/animate.html">animate</a>, <a href="../www/display.html">display</a>]</td></tr></table>
540 <p>This backdrop covers the entire workstation screen and is useful for hiding other X window activity while viewing the image. The color of the backdrop is specified as the background color. The color is specified using the format described under the <a href="#fill">-fill</a> option.</p>
542 <div style="margin: auto;">
543 <h4><a name="background" id="background"></a>-background <em class="arg">color</em></h4>
546 <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>
548 <p>The color is specified using the format described under the <a href="#fill">-fill</a> option. The default background color (if none is specified or found in the image) is white.</p>
550 <div style="margin: auto;">
551 <h4><a name="bench" id="bench"></a>-bench <em class="arg">iterations</em></h4>
554 <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>
556 <p>Repeat the entire command for the given number of <em class="arg">iterations</em> and report the user-time and elapsed time. For instance, consider the following command and its output. Modify the benchmark with the -duration to run the benchmark for a fixed number of seconds and -concurrent to run the benchmark in parallel (requires the OpenMP feature).</p>
558 <p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert logo: -resize 1000% -bench 5 logo.png</span><span class='crtout'>Performance: 5i 0.875657ips 6.880u 0:05.710</span></p>
559 <p>In this example, 5 iterations were completed at 0.875657 iterations per second, using 6.88 seconds of the user's allotted time, for a total elapsed time of 5.71 seconds.</p>
561 <div style="margin: auto;">
562 <h4><a name="bias" id="bias"></a>-bias <em class="arg">value</em>{<em class="arg">%</em>}</h4>
565 <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>
567 <p>This option shifts the output of <a href="../www/command-line-options.html#convolve">‑convolve</a> so that positive and negative results are relative to the specified bias value. </p>
569 <p>This is important for non-HDRI compilations of ImageMagick when dealing with convolutions that contain negative as well as positive values. This is especially the case with convolutions involving high pass filters or edge detection. Without an output bias, the negative values are clipped at zero.</p>
571 <p>When using an ImageMagick with the HDRI compile-time setting, <a href="../www/command-line-options.html#bias">‑bias</a> is not needed, as ImageMagick is able to store/handle any
572 negative results without clipping to the color value range
573 (0..QuantumRange).</p>
575 <p>See the discussion on HDRI implementations of ImageMagick on the page
576 <a href="/www/high-dynamic-range.html">High Dynamic-Range Images</a>. For more about HDRI go the ImageMagick <a href="http://www.imagemagick.org/Usage/basics/#hdri">Usage</a> pages or this <a href="http://en.wikipedia.org/wiki/High_dynamic_range_imaging">Wikipedia</a> entry.
579 <div style="margin: auto;">
580 <h4><a name="black-point-compensation" id="black-point-compensation"></a>-black-point-compensation</h4>
583 <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>
585 <div style="margin: auto;">
586 <h4><a name="black-threshold" id="black-threshold"></a>-black-threshold <em class="arg">value</em>{<em class="arg">%</em>}</h4>
589 <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>
591 <p> The threshold value can be given as a percentage or as an absolute integer value within [0, <em class="QR">QuantumRange</em>] corresponding to the desired <a href="../www/command-line-options.html#channel">‑channel</a> value. See <a href="../www/command-line-options.html#threshold">‑threshold</a> for more details on thresholds and resulting values.
595 <div style="margin: auto;">
596 <h4><a name="blend" id="blend"></a>-blend <em class="arg">geometry</em></h4>
599 <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="../www/composite.html">composite</a>]</td></tr></table>
601 <p>Blend will average the images together ('plus') according to the
602 percentages given and each pixels transparency. If only a single percentage
603 value is given it sets the weight of the composite or 'source' image, while
604 the background image is weighted by the exact opposite amount. That is a
605 <kbd>-blend 30%</kbd> merges 30% of the 'source' image with 70% of the
606 'destination' image. Thus it is equivalent to <kbd>-blend 30x70%</kbd>.</p>
609 <div style="margin: auto;">
610 <h4><a name="blue-primary" id="blue-primary"></a>-blue-primary <em class="arg">x</em>,<em class="arg">y</em></h4>
613 <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>
615 <div style="margin: auto;">
616 <h4><a name="blue-shift" id="blue-shift"></a>-blue-shift <em class="arg">factor</em></h4>
619 <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>
621 <div style="margin: auto;">
623 <div style="margin: auto;">
624 <h4><a name="blur" id="blur"></a>-blur <em class="arg">radius</em><br />-blur <em class="arg">radius</em>x<em class="arg">sigma</em></h4>
627 <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>
629 <p>Convolve the image with a Gaussian or normal distribution using the given
630 <em class="arg" >Sigma</em> value. The formula is:</p>
632 <div class="eqn"><img alt="gaussian distribution" width="243px" height="42px" src="../images/gaussian-blur.png"/>
635 <p>The <em class="arg" >Sigma</em> value is the important argument, and
636 determines the actual amount of blurring that will take place. </p>
638 <p>The <em class="arg" >Radius</em> is only used to determine the size of the
639 array which will hold the calculated Gaussian distribution. It should be an
640 integer. If not given, or set to zero, IM will calculate the largest possible
641 radius that will provide meaningful results for the Gaussian distribution.
644 <p>The larger the <em class="arg" >Radius</em> the radius the slower the
645 operation is. However too small a <em class="arg" >Radius</em>, and sever
646 aliasing effects may result. As a guideline, <em class="arg" >Radius</em>
647 should be at least twice the <em class="arg" >Sigma</em> value, though three
648 times will produce a more accurite result. </p>
650 <p>This option differs from <a href="#gaussian-blur">-gaussian-blur</a> simply
651 by taking advantage of the separability properties of the distribution. Here
652 we apply a single-dimensional Gaussian matrix in the horizontal direction,
653 then repeat the process in the vertical direction.</p>
655 <p>The <a href="#virtual-pixel">-virtual-pixel</a> setting will determine how
656 pixels which are outside the image proper are blurred into the final result.
660 <div style="margin: auto;">
661 <h4><a name="blur-composite" id="blur"></a>-blur <em class="arg">Width</em>[x<em class="arg">Height</em>[+<em class="arg">Angle</em>]]</h4>
664 <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="../www/composite.html">composite</a>]</td></tr></table>
666 <p>Each pixel in the overlaid region is replaced with an Elliptical Weighted
667 Average (EWA) of the source image, scaled according to the grayscale
670 <p>The ellipse is weighted with sigma set to the given <em class="arg"
671 >Width</em> and <em class="arg" >Height</em>. The <em class="arg" >Height</em>
672 defaults to the <em class="arg" >Width</em> for a normal circular Guassian
673 weighting. The <em class="arg" >Angle</em> will rotate the ellipse from
674 horizontal clock-wise. </p>
676 <p>The <a href="#virtual-pixel">-virtual-pixel</a> setting will determine how
677 pixels which are outside the image proper are blurred into the final result.
681 <div style="margin: auto;">
682 <h4><a name="border" id="border"></a>-border <em class="arg">geometry</em></h4>
685 <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>
687 <p>Set the width and height using the <em class="arg">size</em> portion of the
688 <em class="arg">gravity</em> argument. See <a href="../www/command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument. Offsets are
691 <p>Set the border color by preceding with the <a
692 href="#bordercolor">-bordercolor</a> setting.</p>
694 <p>The <a href="#border">-border</a> operation is affected by the current <a
695 href="#compose">-compose</a> setting and assumes that this is using the default
696 '<kbd>Over</kbd>' composition method. It generates a image of the appropriate
697 size colors by the current <a href="#bordercolor">-bordercolor</a> before
698 overlaying the original image in the center of this net image. This means that
699 with the default compose method of '<kbd>Over</kbd>' any transparent parts may
700 be replaced by the current <a href="#bordercolor">-bordercolor</a> setting.</p>
701 <p>See also the <a href="#frame">-frame</a> option, which has more
704 <div style="margin: auto;">
705 <h4><a name="bordercolor" id="bordercolor"></a>-bordercolor <em class="arg">color</em></h4>
708 <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>
710 <p>The color is specified using the format described under the <a href="#fill">-fill</a> option.</p>
712 <p>The default border color is <kbd>#DFDFDF</kbd>, <span style="background-color: #dfdfdf;">this shade of gray</span>.</p>
714 <div style="margin: auto;">
715 <h4><a name="borderwidth" id="borderwidth"></a>-borderwidth <em class="arg">geometry</em> </h4>
718 <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="../www/animate.html">animate</a>, <a href="../www/display.html">display</a>]</td></tr></table>
720 <div style="margin: auto;">
721 <h4><a name="brightness-contrast" 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>
724 <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>
726 <p>Brightness and Contrast values apply changes to the input image. They are
727 not absolute settings. A brightness or contrast value of zero means no change.
728 The range of values is -100 to +100 on each. Positive values increase the
729 brightness or contrast and negative values decrease the brightness or contrast.
730 To control only contrast, set the brightness=0. To control only brightness,
731 set contrast=0 or just leave it off.</p>
733 <p>You may also use <a href="#fill">-channel</a> to control which channels to
734 apply the brightness and/or contrast change. The default is to apply the same
735 transformation to all channels.</p>
737 <p>Brightness and Contrast arguments are converted to offset and slope of a
738 linear transform and applied
739 using <a href="#fill">-function polynomial "slope,offset"</a>.</p>
741 <p>The slope varies from 0 at contrast=-100 to almost vertical at
742 contrast=+100. For brightness=0 and contrast=-100, the result are totally
743 midgray. For brightness=0 and contrast=+100, the result will approach but
744 not quite reach a threshold at midgray; that is the linear transformation
745 is a very steep vertical line at mid gray.</p>
747 <p>Negative slopes, i.e. negating the image, are not possible with this
748 function. All achievable slopes are zero or positive.</p>
750 <p>The offset varies from -0.5 at brightness=-100 to 0 at brightness=0 to +0.5
751 at brightness=+100. Thus, when contrast=0 and brightness=100, the result is
752 totally white. Similarly, when contrast=0 and brightness=-100, the result is
755 <p>As the range of values for the arguments are -100 to +100, adding the '%'
756 symbol is no different than leaving it off.</p>
758 <div style="margin: auto;">
759 <h4><a name="cache" id="cache"></a>-cache <em class="arg">threshold</em></h4>
762 <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='#limit'>-limit</a> option.)</td><td style='text-align:right;'></td></tr></table>
764 <div style="margin: auto;">
765 <h4><a name="caption" id="caption"></a>-caption <em class="arg">string</em></h4>
768 <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>
770 <p>This option sets the caption meta-data of an image read in after this
771 option has been given. To modify a caption of images already in memory use
772 "<kbd><a href="#set">-set</a> caption</kbd>". </p>
774 <p>The caption can contain special format characters listed in the <a
775 href="../www/escape.html">Format and
776 Print Image Properties</a>. These attributes are expanded when the caption
777 is finally assigned to the individual images. </p>
779 <p>If the first character of <em class="arg">string</em> is <em
780 class="arg">@</em>, the image caption is read from a file titled by the
781 remaining characters in the string. Comments read in from a file are literal;
782 no embedded formatting characters are recognized.</p>
784 <p>Caption meta-data ais not visible on the image itself. To do that use the
785 <a href="#annotate">-annotate</a> or <a href="#draw">-draw</a> options
791 -caption "%m:%f %wx%h" bird.miff
794 <p>produces an image caption of <kbd>MIFF:bird.miff 512x480</kbd> (assuming
795 that the image <kbd>bird.miff</kbd> has a width of 512 and a height of
799 <div style="margin: auto;">
800 <h4><a name="cdl" id="cdl"></a>-cdl <em class="arg">filename</em></h4>
803 <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>
805 <p>Here is an example color correction collection:</p>
808 <?xml version="1.0" encoding="UTF-8"?>
809 <ColorCorrectionCollection xmlns="urn:ASC:CDL:v1.2">
810 <ColorCorrection id="cc06668">
812 <Slope> 0.9 1.2 0.5 </Slope>
813 <Offset> 0.4 -0.5 0.6 </Offset>
814 <Power> 1.0 0.8 1.5 </Power>
817 <Saturation> 0.85 </Saturation>
819 </ColorCorrection>
820 </ColorCorrectionCollection>
823 <div style="margin: auto;">
824 <h4><a name="channel" id="channel"></a>-channel <em class="arg">type</em></h4>
827 <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>
829 <p>Choose from: <kbd>Red</kbd>, <kbd>Green</kbd>, <kbd>Blue</kbd>,
830 <kbd>Alpha</kbd>, <kbd>Cyan</kbd>, <kbd>Magenta</kbd>, <kbd>Yellow</kbd>,
831 <kbd>Black</kbd>, <kbd>Opacity</kbd>, <kbd>Index</kbd>, <kbd>RGB</kbd>,
832 <kbd>RGBA</kbd>, <kbd>CMYK</kbd>, or <kbd>CMYKA</kbd>.</p>
834 <p>The channels above can also be specified as a comma-separated list or can be
835 abbreviated as a concatenation of the letters '<kbd>R</kbd>', '<kbd>G</kbd>',
836 '<kbd>B</kbd>', '<kbd>A</kbd>', '<kbd>O</kbd>', '<kbd>C</kbd>',
837 '<kbd>M</kbd>', '<kbd>Y</kbd>', '<kbd>K</kbd>'.
839 For example, to only select the <kbd>Red</kbd> and <kbd>Blue</kbd> channels
840 you can either use </p>
844 <p>or you can use the short hand form</p>
849 <p>All the channels that is present in an image can be specified using the
850 special channel type <kbd>All</kbd>. Not all operators are 'channel capable',
851 but generally any operators that are generally 'grey-scale' image operators,
852 will understand this setting. See individual operator documentation. </p>
856 <p>On top of the normal channel selection a extra flag can be specified,
857 '<kbd>Sync</kbd>'. This is turned on by default and if set means that
858 operators that understand this flag should perform: cross-channel
859 syncronization of the channels. If not specified, then most grey-scale
860 operators will apply their image processing operations to each individual
861 channel (as specified by the rest of the <a href="#channel">-channel</a>
862 setting) completely independently from each other. </p>
864 <p>For example for operators such as <a href="#auto-level">-auto-level</a> and
865 <a href="#auto-gamma">-auto-gamma</a> the color channels are modified
866 together in exactly the same way so that colors will remain in-sync. Without
867 it being set, then each channel is modified separately and
868 independently, which may produce color distortion. </p>
870 <p>The <a href="#morphology">-morphology</a> '<kdb>Convolve</kdb>' method
871 and the <a href="#compose">-compose</a> mathematical methods, also understands
872 the '<kbd>Sync</kbd>' flag to modify the behaviour of pixel colors according
873 to the alpha channel (if present). That is to say it will modify the image
874 processing with the understanding that fully-transparent colors should not
875 contribute to the final result. </p>
877 Basically, by default, operators work with color channels in syncronous, and
878 treats transparency as special, unless the <a href="#channel">-channel</a>
879 setting is modified so as to remove the effect of the '<kbd>Sync</kbd>' flag.
880 How each operator does this depends on that operators current implementation.
881 Not all operators understands this flag at this time, but that is changing.
884 <p>To print a complete list of channel types, use <a href="#list">-list
889 <p>By default, ImageMagick sets <a href="#channel">-channel</a> to the value
890 '<kbd>RGBK,sync</kbd>', which specifies that operators act on all color
891 channels except the transparency channel, and that all the color channels are
892 to be modified in exactly the same way, with a understanding of transprancy
893 (depending on the operation being applied). The 'plus' form <a
894 href="#channel" >+channel</a> will reset the value back to this default. </p>
896 <p>Options that are affected by the <a href="#channel" >-channel</a> setting
897 include the following.
899 <a href="#auto-gamma">-auto-gamma</a>,
900 <a href="#auto-level">-auto-level</a>,
901 <a href="#black-threshold">-black-threshold</a>,
902 <a href="#blur">-blur</a>,
903 <a href="#clamp">-clamp</a>,
904 <a href="#clut">-clut</a>,
905 <a href="#combine">-combine</a>,
906 <a href="#composite">-composite</a> (Mathematical compose methods only),
907 <a href="#convolve">-convolve</a>,
908 <a href="#contrast-stretch">-contrast-stretch</a>,
909 <a href="#evaluate">-evaluate</a>,
910 <a href="#function">-function</a>,
911 <a href="#fx">-fx</a>,
912 <a href="#gaussian-blur">-gaussian-blur</a>,
913 <a href="#hald-clut">-hald-clut</a>,
914 <a href="#motion-blur">-motion-blur</a>,
915 <a href="#morphology">-morphology</a>,
916 <a href="#negate">-negate</a>,
917 <a href="#normalize">-normalize</a>,
918 <a href="#ordered-dither">-ordered-dither</a>,
919 <a href="#radial-blur">-radial-blur</a>,
920 <a href="#random-threshold">-random-threshold</a>,
921 <a href="#separate">-separate</a>,
922 <a href="#threshold">-threshold</a>, and
923 <a href="#white-threshold">-white-threshold</a>.
926 <p>Warning, some operators behave differently when the <a href="#channel"
927 >+channel</a> default setting is in effect, verses ANY user defined <a
928 href="#channel" >-channel</a> setting (including the equivalent of the
929 default). These operators have yet to be made to understand the newer 'Sync'
932 <p>For example <a href="#threshold">-threshold</a> will by default gray-scale
933 the image before thresholding, if no <a href="#channel" >-channel</a> setting
934 has been defined. This is not 'Sync flag controlled, yet. </p>
936 <p>Also some operators such as <a href="#blur">-blur</a>, <a
937 href="#gaussian-blur">-gaussian-blur</a>, will modify their handling of the
938 color channels if the '<kbd>alpha</kbd>' channel is also enabled by <a
939 href="#channel" >-channel</a>. Generally this done to ensure that
940 fully-transparent colors are treated as being fully-transparent, and thus any
941 underlying 'hidden' color has no effect on the final results. Typically
942 resulting in 'halo' effects. The newer <a href="#morphology">-morphology</a>
943 convolution equivalents however does have a understanding of the 'Sync' flag
944 and will thus handle transparency correctly by default. </p>
946 <p>As a alpha channel is optional within images, some operators will read the
947 color channels of an image as a greyscale alpha mask, when the image has no
948 alpha channel present, and the <a href="#channel" >-channel</a> setting tells
949 the operator to apply the operation using alpha channels. The <a
950 href="#clut">-clut</a> operator is a good example of this. </p>
953 <div style="margin: auto;">
954 <h4><a name="clamp" id="clamp"></a>-clamp</h4>
957 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Restrict image colors from 0 to the quantum depth.</td><td style='text-align:right;'></td></tr></table>
959 <div style="margin: auto;">
960 <h4><a name="charcoal" id="charcoal"></a>-charcoal <em class="arg">factor</em></h4>
963 <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>
965 <div style="margin: auto;">
966 <h4><a name="chop" id="chop"></a>-chop <em class="arg">geometry</em></h4>
969 <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>
971 <p>See <a href="../www/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>
972 and <em class="arg">height</em> given in the of the <em class="arg">size</em>
973 portion of the <em class="arg">geometry</em> argument give the number of
974 columns and rows to remove. The <em class="arg">offset</em> portion of
975 the <em class="arg">geometry</em> argument is influenced by
976 a <a href="#gravity">-gravity</a> setting, if present.</p>
978 <p>The <a href="#chop">-chop</a> option removes entire rows and columns,
979 and moves the remaining corner blocks leftward and upward to close the gaps.</p>
981 <div style="margin: auto;">
982 <h4><a name="clip" id="clip"></a>-clip</h4>
985 <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>
987 <p>If a clipping path is present, it is applied to subsequent operations.</p>
989 <p>For example, in the command</p>
991 <p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert -clip -negate cockatoo.tif negated.tif</span></p>
992 <p>only the pixels within the clipping path are negated.</p>
994 <p>The <a href="#clip">-clip</a> feature requires the XML library. If the XML library is not present, the option is ignored.</p>
996 <div style="margin: auto;">
997 <h4><a name="clip-mask" id="clip-mask"></a>-clip-mask</h4>
1000 <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>
1002 <div style="margin: auto;">
1003 <h4><a name="clip-path" id="clip-path"></a>-clip-path <em class="arg">id</em></h4>
1006 <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 8BImageMagick profile.</td><td style='text-align:right;'></td></tr></table>
1008 <div style="margin: auto;">
1009 <h4><a name="clone" id="clone"></a>-clone <em class="arg">index(s)</em></h4>
1012 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Make a copy of an image (or images).</td><td style='text-align:right;'></td></tr></table>
1014 <p>Specify the image by its index in the sequence. The first image is index
1015 0. Negative indexes are relative to the end of the sequence; for
1017 represents the last image of the sequence. Specify a range of images with a
1018 dash (e.g. 0−4). Separate multiple indexes with commas but no
1019 spaces (e.g. 0,2,5). Use <a
1020 href="#clone">+clone</a> make a copy of the last image in the image
1023 <div style="margin: auto;">
1024 <h4><a name="clut" id="clut"></a>-clut</h4>
1027 <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
1028 corresponding channel in the second image as a <b>c</b>olor
1029 <b>l</b>ook<b>u</b>p <b>t</b>able.</td><td style='text-align:right;'></td></tr></table>
1031 <p>The second (LUT) image is ordinarily a gradient image containing the
1032 histogram mapping of how each channel should be modified. Typically it is a
1033 either a single row or column image of replacement color values. If larger
1034 than a single row or column, values are taken from a diagonal line from
1035 top-left to bottom-right corners.</p>
1037 <p>The lookup is further controlled by the <a
1038 href="#interpolate">-interpolate</a> setting, which is especially handy for an
1039 LUT which is not the full length needed by the ImageMagick installed Quality
1040 (Q) level. Good settings for this are the '<kbd>bilinear</kbd>' and
1041 '<kbd>bicubic</kbd>' interpolation settings, which give smooth color
1042 gradients, and the '<kbd>integer</kbd>' setting for a direct, unsmoothed
1043 lookup of color values. </p>
1045 <p>This operator is especially suited to replacing a grayscale image with a
1046 specific color gradient from the CLUT image. </p>
1048 <p>Only the channel values defined by the <a href="#channel">-channel</a>
1049 setting will have their values replaced. In particular, since the default <a
1050 href="#channel">-channel</a> setting is <kbd>RGB</kbd>, this means that
1051 transparency (alpha/matte channel) is not affected, unless the <a
1052 href="#channel">-channel</a> setting is modified. When the alpha channel is
1053 set, it is treated by the <a href="#clut" >-clut</a> operator in the same way
1054 as the other channels, implying that alpha/matte values are replaced using the
1055 alpha/matte values of the original image. </p>
1057 <p>If either the image being modified, or the lookup image, contains no
1058 transparency (i.e. <a href="#alpha" >-alpha</a> is turned 'off') but the <a
1059 href="#channel">-channel</a> setting includes alpha replacement, then it is
1060 assumed that image represents a gray-scale gradient which is used for the
1061 replacement alpha values. That is you can use a gray-scale CLUT image to
1062 adjust a existing images alpha channel, or you can color a gray-scale image
1063 using colors form CLUT containing the desired colors, including transparency.
1066 <p>See also <a href="#hald-clut" >-hald-clut</a> which replaces colors
1067 according to the lookup of the full color RGB value from a 2D representation
1068 of a 3D color cube. </p>
1071 <div style="margin: auto;">
1072 <h4><a name="coalesce" id="coalesce"></a>-coalesce</h4>
1075 <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>
1077 <p>Overlay each image in an image sequence according to
1078 its <a href="#dispose">-dispose</a> meta-data, to reproduce the look of
1079 an animation at each point in the animation sequence. All images should be
1080 the same size, and are assigned appropriate GIF disposal settings for the
1081 animation to continue working as expected as a GIF animation. Such frames
1082 are more easily viewed and processed than the highly optimized GIF overlay
1085 <p>The animation can be re-optimized after processing using
1086 the <a href="#layers">-layers</a> method '<kbd>optimize</kbd>', although
1087 there is no guarantee that the restored GIF animation optimization is
1088 better than the original. </p>
1091 <div style="margin: auto;">
1092 <h4><a name="colorize" id="colorize"></a>-colorize <em class="arg">value</em></h4>
1095 <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="#fill" >-fill</a> setting.</td><td style='text-align:right;'></td></tr></table>
1097 <p>Specify the amount of colorization as a percentage. Separate colorization
1098 values can be applied to the red, green, and blue channels of the image with
1099 a comma-delimited list of colorization
1100 values (e.g., <kbd>-colorize 0,0,50</kbd>).</p>
1102 <div style="margin: auto;">
1103 <h4><a name="colormap" id="colormap"></a>-colormap <em class="arg">type</em></h4>
1106 <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="../www/animate.html">animate</a>, <a href="../www/display.html">display</a>]</td></tr></table>
1108 <p>The <em class="arg">type</em> can be <kbd>shared</kbd> or <kbd>private</kbd>.</p>
1110 <p>This option only applies when the default X server visual
1111 is <kbd>PseudoColor</kbd> or <kbd>GrayScale</kbd>. Refer
1112 to <a href="#visual">-visual</a> for more details. By default,
1113 a shared colormap is allocated. The image shares colors with
1114 other X clients. Some image colors could be approximated,
1115 therefore your image may look very different than intended.
1116 If <kbd>private</kbd> is chosen, the image colors appear exactly
1117 as they are defined. However, other clients may go <em>technicolor</em>
1118 when the image colormap is installed.</p>
1120 <div style="margin: auto;">
1121 <h4><a name="colors" id="colors"></a>-colors <em class="arg">value</em></h4>
1124 <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>
1126 <p>The actual number of colors in the image may be less than your request,
1127 but never more. Note that this a color reduction option. Images with fewer
1128 unique colors than specified by <em class="arg">value</em> will have any
1129 duplicate or unused colors removed. The ordering of an existing color
1130 palette may be altered. When converting an image from color to grayscale,
1131 it is more efficient to convert the image to the gray colorspace before
1132 reducing the number of colors. Refer to
1133 the <a href="../www/quantize.html">
1134 color reduction algorithm</a> for more details.</p>
1136 <div style="margin: auto;">
1137 <h4><a name="color-matrix" id="color-matrix"></a>-color-matrix <em class="arg">matrix</em></h4>
1140 <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>
1142 <p>This option permits saturation changes, hue rotation, luminance to alpha,
1143 and various other effects. Although variable-sized transformation matrices
1144 can be used, typically one uses a 5x5 matrix for an RGBA image and a 6x6
1145 for CMYKA (or RGBA with offsets). The matrix is similar to those used by
1146 Adobe Flash except offsets are in column 6 rather than 5 (in support of
1147 CMYKA images) and offsets are normalized (divide Flash offset by 255).</p>
1149 <p>As an example, to add contrast to an image with offsets, try this command:</p>
1152 convert kittens.jpg -color-matrix \
1153 " 1.5 0.0 0.0 0.0, 0.0, -0.157 \
1154 0.0 1.5 0.0 0.0, 0.0, -0.157 \
1155 0.0 0.0 1.5 0.0, 0.0, -0.157 \
1156 0.0 0.0 0.0 1.0, 0.0, 0.0 \
1157 0.0 0.0 0.0 0.0, 1.0, 0.0 \
1158 0.0 0.0 0.0 0.0, 0.0, 1.0" kittens.png
1160 <div style="margin: auto;">
1161 <h4><a name="colorspace" id="colorspace"></a>-colorspace <em class="arg">value</em></h4>
1164 <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>
1193 <p>To print a complete list of colorspaces, use <a href="#list">-list colorspace</a>.</p>
1195 <p>For a more accurate color conversion to or from the RGB, CMYK, or grayscale colorspaces, use the <a href="#profile">-profile</a> option.</p>
1198 <caption>Conversion Of RGB To Other Color Spaces</caption>
1199 <tr><th align="left" valign="middle">CMY</th></tr>
1200 <tr><td align="left" valign="middle">C=<em class="QR">QuantumRange</em>−R</td></tr>
1201 <tr><td align="left" valign="middle">M=<em class="QR">QuantumRange</em>−G</td></tr>
1202 <tr><td align="left" valign="middle">Y=<em class="QR">QuantumRange</em>−B</td></tr>
1203 <tr><th align="left" valign="middle">CMYK — starts with CMY from above</th></tr>
1204 <tr><td align="left" valign="middle">K=min(C,Y,M)</td></tr>
1205 <tr><td align="left" valign="middle">C=<em class="QR">QuantumRange</em>*(C−K)/(<em class="QR">QuantumRange</em>−K)</td></tr>
1206 <tr><td align="left" valign="middle">M=<em class="QR">QuantumRange</em>*(M−K)/(<em class="QR">QuantumRange</em>−K)</td></tr>
1207 <tr><td align="left" valign="middle">Y=<em class="QR">QuantumRange</em>*(Y−K)/(<em class="QR">QuantumRange</em>−K)</td></tr>
1209 <tr><th align="left" valign="middle">Gray</th></tr>
1210 <tr><td align="left" valign="middle">Gray = 0.29900*R+0.58700*G+0.11400*B</td></tr>
1212 <tr><th align="left" valign="middle">HSB — Hue, Saturation, Brightness; like a cone peak downward</th></tr>
1213 <tr><td align="left" valign="middle">H=angle around perimeter (0 to 360 deg); H=0 is red; increasing angles toward green</td></tr>
1214 <tr><td align="left" valign="middle">S=distance from axis outward</td></tr>
1215 <tr><td align="left" valign="middle">B=distance along axis from bottom upward; B=max(R,G,B); <em>intensity-like</em></td></tr>
1217 <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>
1218 <tr><td align="left" valign="middle">H=angle around perimeter (0 to 360 deg); H=0 is red; increasing angles toward green</td></tr>
1219 <tr><td align="left" valign="middle">S=distance from axis outward</td></tr>
1220 <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>
1222 <tr><th align="left" valign="middle">HWB — Hue, Whiteness, Blackness</th></tr>
1223 <tr><td align="left" valign="middle">Hue (complicated equation)</td></tr>
1224 <tr><td align="left" valign="middle">Whiteness (complicated equation)</td></tr>
1225 <tr><td align="left" valign="middle">Blackness (complicated equation)</td></tr>
1227 <tr><th align="left" valign="middle">LAB</th></tr>
1228 <tr><td align="left" valign="middle">L (complicated equation relating X,Y,Z)</td></tr>
1229 <tr><td align="left" valign="middle">A (complicated equation relating X,Y,Z)</td></tr>
1230 <tr><td align="left" valign="middle">B (complicated equation relating X,Y,Z)</td></tr>
1232 <tr><th align="left" valign="middle">LOG</th></tr>
1233 <tr><td align="left" valign="middle">I1 (complicated equation involving logarithm of R)</td></tr>
1234 <tr><td align="left" valign="middle">I2 (complicated equation involving logarithm of G)</td></tr>
1235 <tr><td align="left" valign="middle">I3 (complicated equation involving logarithm of B)</td></tr>
1237 <tr><th align="left" valign="middle">OHTA — approximates principal components transformation</th></tr>
1238 <tr><td align="left" valign="middle">I1=0.33333*R+0.33334*G+0.33333*B; <em>intensity-like</em></td></tr>
1239 <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>
1240 <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>
1242 <tr><th align="left" valign="middle">Rec601Luma</th></tr>
1243 <tr><td align="left" valign="middle">Gray = 0.29900*R+0.58700*G+0.11400*B</td></tr>
1245 <tr><th align="left" valign="middle">Rec601YCbCr</th></tr>
1246 <tr><td align="left" valign="middle">Y=0.299000*R+0.587000*G+0.114000*B; <em>intensity-like</em></td></tr>
1247 <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>
1248 <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>
1250 <tr><th align="left" valign="middle">Rec709Luma</th></tr>
1251 <tr><td align="left" valign="middle">Gray=0.21260*R+0.71520*G+0.07220*B</td></tr>
1253 <tr><th align="left" valign="middle">Rec709YCbCr</th></tr>
1254 <tr><td align="left" valign="middle">Y=0.212600*R+0.715200*G+0.072200*B; <em>intensity-like</em></td></tr>
1255 <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>
1256 <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>
1258 <tr><th align="left" valign="middle">sRGB</th></tr>
1259 <tr><td align="left" valign="middle">if Rs ≤ .03928 then Rs=R/12.92 else Rs=((R+.055)/1.055)^2.4</td></tr>
1260 <tr><td align="left" valign="middle">if Gs ≤ .03928 then Gs=B/12.92 else Gs=((G+.055)/1.055)^2.4</td></tr>
1261 <tr><td align="left" valign="middle">if Bs ≤ .03928 then Bs=B/12.92 else Bs=((B+.055)/1.055)^2.4</td></tr>
1263 <tr><th align="left" valign="middle">XYZ</th></tr>
1264 <tr><td align="left" valign="middle">X=0.4124240*R+0.3575790*G+0.1804640*B</td></tr>
1265 <tr><td align="left" valign="middle">Y=0.2126560*R+0.7151580*G+0.0721856*B</td></tr>
1266 <tr><td align="left" valign="middle">Z=0.0193324*R+0.1191930*G+0.9504440*B</td></tr>
1268 <tr><th align="left" valign="middle">YCC</th></tr>
1269 <tr><td align="left" valign="middle">Y=(0.29900*R+0.58700*G+0.11400*B) (with complicated scaling); <em>intensity-like</em></td></tr>
1270 <tr><td align="left" valign="middle">C1=(−0.29900*R−0.58700*G+0.88600*B) (with complicated scaling)</td></tr>
1271 <tr><td align="left" valign="middle">C2=(0.70100*R−0.58700*G−0.11400*B) (with complicated scaling)</td></tr>
1273 <tr><th align="left" valign="middle">YCbCr</th></tr>
1274 <tr><td align="left" valign="middle">Y=0.299000*R+0.587000*G+0.114000*B; <em>intensity-like</em></td></tr>
1275 <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>
1276 <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>
1278 <tr><th align="left" valign="middle">YIQ</th></tr>
1279 <tr><td align="left" valign="middle">Y=0.29900*R+0.58700*G+0.11400*B; <em>intensity-like</em></td></tr>
1280 <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>
1281 <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>
1283 <tr><th align="left" valign="middle">YPbPr</th></tr>
1284 <tr><td align="left" valign="middle">Y=0.299000*R+0.587000*G+0.114000*B; <em>intensity-like</em></td></tr>
1285 <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>
1286 <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>
1288 <tr><th align="left" valign="middle">YUV</th></tr>
1289 <tr><td align="left" valign="middle">Y=0.29900*R+0.58700*G+0.11400*B; <em>intensity-like</em></td></tr>
1290 <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>
1291 <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>
1294 <div style="margin: auto;">
1295 <h4><a name="combine" id="combine"></a>-combine</h4>
1298 <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>
1300 <p>The channels (previously set by <a href="#channel">-channel</a>) of the combined image are taken from the grayscale values of each image in the sequence, in order. For the default -channel setting of <kbd>RGB</kbd>, this means the first image is assigned to the <kbd>Red</kbd> channel, the second to the <kbd>Green</kbd> channel, the third to the <kbd>Blue</kbd>.</p>
1302 <p>This option can be thought of as the inverse to <a href="#separate">-separate</a>, so long as the channel settings are the same. Thus, in the following example, the final image should be a copy of the original.
1305 <p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert original.png -channel RGB -separate sepimage.png</span><span class='crtout'></span><span class="crtprompt"> $magick> </span><span class='crtin'>convert sepimage-0.png sepimage-1.png sepimage-2.png -channel RGB \ <br/> -combine imagecopy.png</span></p>
1306 <div style="margin: auto;">
1307 <h4><a name="comment" id="comment"></a>-comment <em class="arg">string</em></h4>
1310 <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>
1312 <p>This option sets the comment meta-data of an image read in after this
1313 option has been given. To modify a comment of images already in memory use
1314 "<kbd><a href="#set">-set</a> comment</kbd>". </p>
1316 <p>The comment can contain special format characters listed in the <a
1317 href="../www/escape.html">Format and
1318 Print Image Properties</a>. These attributes are expanded when the comment
1319 is finally assigned to the individual images. </p>
1321 <p>If the first character of <em class="arg">string</em> is <em
1322 class="arg">@</em>, the image comment is read from a file titled by the
1323 remaining characters in the string. Comments read in from a file are literal;
1324 no embedded formatting characters are recognized.</p>
1326 <p>Comment meta-data are not visible on the image itself. To do that use the
1327 <a href="#annotate">-annotate</a> or <a href="#draw">-draw</a> options
1333 -comment "%m:%f %wx%h" bird.miff
1336 <p>produces an image comment of <kbd>MIFF:bird.miff 512x480</kbd> (assuming
1337 that the image <kbd>bird.miff</kbd> has a width of 512 and a height of
1340 <div style="margin: auto;">
1341 <h4><a name="compose" id="compose"></a>-compose <em class="arg">operator</em></h4>
1344 <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>
1346 <p>See <a href="../www/compose.html">Alpha Compositing</a> for
1347 a detailed discussion of alpha compositing.</p>
1349 <p>This setting effects image processing operators that merge two (or more)
1350 images together in some way. This includes the operators,
1351 <a href="#composite">-composite</a>,
1352 <a href="#layers">-layers</a> composite,
1353 <a href="#flatten">-flatten</a>,
1354 <a href="#mosaic">-mosaic</a>,
1355 <a href="#layers">-layers</a> merge,
1356 <a href="#border">-border</a>,
1357 <a href="#frame">-frame</a>,
1358 and <a href="#extent">-extent</a>. </p>
1360 <p>It is also one of the primary options for the "<kbd>composite</kbd>"
1364 <div style="margin: auto;">
1365 <h4><a name="composite" id="composite"></a>-composite</h4>
1368 <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>
1370 <p>Take the first image 'destination' and overlay the second 'source' image
1371 according to the current <a href="#compose">-compose</a> setting. The location
1372 of the 'source' or 'overlay' image is controlled according to <a
1373 href="#geometry" >-geometry</a>, and <a href="#geometry" >-geometry</a>
1376 <p>If a third image is given this is treated as a gray-scale 'mask' image
1377 relative to the first 'destination' image. This mask will limit what parts of
1378 the destination can be modified by the image composition. However for the
1379 '<kbd>displace</kbd>' compose method, the mask is used to provide a separate
1380 Y-displacement image instead. </p>
1382 <p>If a <a href="#compose">-compose</a> method requires extra numerical
1383 arguments or flags these can be provided by setting the <a
1384 href="#set">-set</a> '<kbd class="arg">option:compose:args</kbd>'
1385 appropriately for the compose method. </p>
1387 <p>Some <a href="#compose">-compose</a> methods can modify the 'destination'
1388 image outside the overlay area. You can disable this by setting the special <a
1389 href="#set">-set</a> '<kbd class="arg">option:compose:outside-overlay</kbd>'
1390 to '<kbd>false</kbd>'. </p>
1393 <div style="margin: auto;">
1394 <h4><a name="compress" id="compress"></a>-compress <em class="arg">type</em></h4>
1397 <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>
1399 <p>Choices are: <kbd class="arg">None</kbd>, <kbd class="arg">BZip</kbd>, <kbd class="arg">Fax</kbd>, <kbd class="arg">Group4</kbd>, <kbd class="arg">JPEG</kbd>, <kbd class="arg">JPEG2000</kbd>, <kbd class="arg">Lossless</kbd>, <kbd class="arg">LZW</kbd>, <kbd class="arg">RLE</kbd> or <kbd class="arg">Zip</kbd>.</p>
1401 <p>To print a complete list of compression types, use <a href="#list">-list compress</a>.</p>
1403 <p>Specify <a href="#compress">+compress</a> to store the binary image in an uncompressed format. The default is the compression type of the specified image file.</p>
1405 <p>If <kbd>LZW</kbd> compression is specified but LZW compression has not been enabled, the image data is written in an uncompressed LZW format that can be read by LZW decoders. This may result in larger-than-expected GIF files.</p>
1407 <p><kbd>Lossless</kbd> refers to lossless JPEG, which is only available if the JPEG library has been patched to support it. Use of lossless JPEG is generally not recommended.</p>
1409 <p>Use the <a href="#quality">-quality</a> option to set the compression level to be used by JPEG, PNG, MIFF, and MPEG encoders. Use the <a href="#sampling-factor">-sampling-factor</a> option to set the sampling factor to be used by JPEG, MPEG, and YUV encoders for down-sampling the chroma channels.</p>
1411 <div style="margin: auto;">
1412 <h4><a name="contrast" id="contrast"></a>-contrast</h4>
1415 <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>
1417 <p>This option enhances the intensity differences between the lighter and darker elements of the image. Use <a href="#contrast">-contrast</a> to enhance the image or <a href="#contrast">+contrast</a> to reduce the image contrast.</p>
1419 <p>For a more pronounced effect you can repeat the option:</p>
1421 <p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert rose: -contrast -contrast rose_c2.png</span></p>
1422 <div style="margin: auto;">
1423 <h4><a name="contrast-stretch" 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>
1426 <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>
1428 <p>While performing the stretch, black-out at most <em
1429 class="arg" >black-point</em> pixels and white-out at most <em
1430 class="arg" >white-point</em> pixels. Or, if percent is used, black-out at most
1431 <em class="arg" >black-point %</em> pixels and white-out at most <em
1432 class="arg" >white-point %</em> pixels.</p>
1434 <p>Prior to ImageMagick 6.4.7-0, <a href="#contrast-stretch"
1435 >-contrast-stretch</a> will black-out at most <em class="arg"
1436 >black-point</em> pixels and white-out at most <em class="arg" >total pixels
1437 minus white-point</em> pixels. Or, if percent is used, black-out at most <em
1438 class="arg">black-point %</em> pixels and white-out at most <em class="arg"
1439 >100% minus white-point %</em> pixels.</p>
1441 <p>Note that <kbd>-contrast-stretch 0</kbd> will modify the image such that
1442 the image's min and max values are stretched to 0 and <em class="QR"
1443 >QuantumRange</em>, respectively, without any loss of data due to burn-out or
1444 clipping at either end. This is not the same as <a href="#normalize"
1445 >-normalize</a>, which is equivalent to <kbd>-contrast-stretch 0.15x0.05%</kbd> (or
1446 prior to ImageMagick 6.4.7-0, <kbd>-contrast-stretch 2%x99%</kbd>).</p>
1448 <p>Internally operator works by creating a histogram bin, and then uses that
1449 bin to modify the image. As such some colors may be merged together when they
1450 originally fell into the same 'bin'. </p>
1452 <p>All the channels are normalized in concert by the came amount so as to
1453 preserve color integrity, when the default <a href="#channel" >+channel</a>
1454 setting is in use. Specifying any other <a href="#channel" >-channel</a>
1455 setting will normalize the RGB channels independently.</p>
1457 <p>See also <a href="#auto-level" >-auto-level</a> for a 'perfect'
1458 normalization of mathematical images. </p>
1460 <p>This operator is under review for re-development. </p>
1463 <div style="margin: auto;">
1464 <h4><a name="convolve" id="convolve"></a>-convolve <em class="arg">kernel</em></h4>
1467 <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>
1469 <p>The <em class="arg">kernel</em> is a matrix specified as
1470 a comma-separated list of integers (with no spaces), ordered left-to right,
1471 starting with the top row. Presently, only odd-dimensioned kernels are
1472 supported, and therefore the number of entries in the specified <em
1473 class="arg">kernel</em> must be 3<sup>2</sup>=9, 5<sup>2</sup>=25,
1474 7<sup>2</sup>=49, etc. </p>
1476 <p>Note that the <a href="../www/command-line-options.html#convolve">‑convolve</a> operator supports the <a href="../www/command-line-options.html#bias">‑bias</a> setting. This option shifts the convolution so that
1477 positive and negative results are relative to a user-specified bias value.
1478 This is important for non-HDRI compilations of ImageMagick when dealing with
1479 convolutions that contain negative as well as positive values. This is
1480 especially the case with convolutions involving high pass filters or edge
1481 detection. Without an output bias, the negative values is clipped at zero.
1484 <p>When using an ImageMagick with the HDRI compile-time setting, <a href="../www/command-line-options.html#bias">‑bias</a> is not needed, as ImageMagick is able to store/handle any
1485 negative results without clipping to the color value range (0..QuantumRange).
1486 See the discussion on HDRI implementations of ImageMagick on the page <a
1487 href="/www/high-dynamic-range.html">High
1488 Dynamic-Range Images</a>. For more about HDRI go the ImageMagick <a
1489 href="http://www.imagemagick.org/Usage/basics/#hdri">Usage</a> pages or this
1490 <a href="http://en.wikipedia.org/wiki/High_dynamic_range_imaging">Wikipedia</a>
1494 <div style="margin: auto;">
1495 <h4><a name="crop" id="crop"></a>-crop <em class="arg">geometry</em></h4>
1498 <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>
1500 <p>See <a href="../www/command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
1502 <p>The <em class="arg">width</em> and <em class="arg">height</em> of the <em class="arg">geometry</em> argument give the size of the image that remains after cropping, and <em class="arg">x</em> and <em class="arg">y</em> in the <em class="arg">offset</em> (if present) gives the location of the top left corner of the cropped image with respect to the original image. To specify the amount to be removed, use <a href="#shave">-shave</a> instead.</p>
1504 <p>If the <em class="arg">x</em> and <em class="arg">y</em> offsets are present, a single image is generated, consisting of the pixels from the cropping region. The offsets specify the location of the upper left corner of the cropping region measured downward and rightward with respect to the upper left corner of the image. If the <a href="#gravity">-gravity</a> option is present with <kbd>NorthEast</kbd>, <kbd>East</kbd>, or <kbd>SouthEast</kbd> gravity, it gives the distance leftward from the right edge of the image to the right edge of the cropping region. Similarly, if the <a href="#gravity">-gravity</a> option is present with <kbd>SouthWest</kbd>, <kbd>South</kbd>, or <kbd>SouthEast</kbd> gravity, the distance is measured upward between the bottom edges.</p>
1506 <p>If the <em class="arg">x</em> and <em class="arg">y</em> offsets are omitted, a set of tiles of the specified geometry, covering the entire input image, is generated. The rightmost tiles and the bottom tiles are smaller if the specified geometry extends beyond the dimensions of the input image.</p>
1508 <p>By adding a exclamation character flag to the geometry argument, the
1509 cropped images virtual canvas page size and offset is set as if the
1510 geometry argument was a viewport or window. This means the canvas page size
1511 is set to exactly the same size you specified, the image offset set
1512 relative top left corner of the region cropped. </p>
1514 <p>If the cropped image 'missed' the actual image on its virtual canvas, a
1515 special single pixel transparent 'missed' image is returned, and a 'crop
1516 missed' warning given. </p>
1518 <p>It might be necessary to <a href="#repage" >+repage</a> the image prior to cropping the image to ensure the crop coordinate frame is relocated to the upper-left corner of the visible image.</p>
1520 <div style="margin: auto;">
1521 <h4><a name="cycle" id="cycle"></a>-cycle <em class="arg">amount</em></h4>
1524 <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>
1526 <p><em class="arg">Amount</em> defines the number of positions each
1527 colormap entry is shifted.</p>
1530 <div style="margin: auto;">
1531 <h4><a name="debug" id="debug"></a>-debug <em class="arg">events</em></h4>
1534 <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>
1536 <p>The <kbd>events</kbd> parameter specifies which events are to be logged. It can be either <kbd>None</kbd>, <kbd>All</kbd>, <kbd>Trace</kbd>, or a comma-separated list consisting of one or more of the following domains: <kbd>Annotate</kbd>, <kbd>Blob</kbd>, <kbd>Cache</kbd>, <kbd>Coder</kbd>, <kbd>Configure</kbd>, <kbd>Deprecate</kbd>, <kbd>Exception</kbd>, <kbd>Locale</kbd>, <kbd>Render</kbd>, <kbd>Resource</kbd>, <kbd>Security</kbd>, <kbd>TemporaryFile</kbd>, <kbd>Transform</kbd>, <kbd>X11</kbd>, or <kbd>User</kbd>. </p>
1539 <p>For example, to log cache and blob events, use.</p>
1541 <p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert -debug "Cache,Blob" rose: rose.png</span></p>
1542 <p>The <kbd>User</kbd> domain is normally empty, but developers can log user events in their private copy of ImageMagick.</p>
1544 <p>To print the complete list of debug methods, use <a href="#list">-list debug</a>.</p>
1546 <p>Use the <a href="#log">-log</a> option to specify the format for debugging output.</p>
1548 <p>Use <a href="#debug">+debug</a> to turn off all logging.</p>
1550 <p>Debugging may also be set using the <kbd>MAGICK_DEBUG</kbd> <a href="../www/resources.html#environment">environment variable</a>. The allowed values for the <kbd>MAGICK_DEBUG</kbd> environment variable are the same as for the <a href="#debug">-debug</a> option.</p>
1553 <div style="margin: auto;">
1554 <h4><a name="decipher" id="decipher"></a>-decipher <em class="arg">filename</em></h4>
1557 <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 <a href="#encipher">-encipher</a>.</td><td style='text-align:right;'></td></tr></table>
1559 <p>Get the passphrase from the file specified by <em class="arg">filename</em>.</p>
1561 <p>For more information, see the webpage, <a href="http://www.imagemagick.org/www/cipher.html">ImageMagick: Encipher or Decipher an Image</a>.</p>
1564 <div style="margin: auto;">
1565 <h4><a name="deconstruct" id="deconstruct"></a>-deconstruct</h4>
1568 <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>
1570 <p>Given a sequence of images all the same size, such as produced by <a href="#coalesce">-coalesce</a>, replace the second and later images, with a smaller image of just the area that changed relative to the previous image. </p>
1572 <p>The resulting sequence of images can be used to optimize an animation sequence, though will not work correctly for GIF animations when parts of the animation can go from opaque to transparent. </p>
1574 <p>This option is actually equivalent to the <a href="#layers">-layers</a> method '<kbd>compare-any</kbd>'. </p>
1577 <div style="margin: auto;">
1578 <h4><a name="define" id="define"></a>-define <em class="arg">key</em>{<em class="arg">=value</em>}<em class="arg">...</em></h4>
1581 <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
1582 coders and image processing operations.</td><td style='text-align:right;'></td></tr></table>
1584 <p>This option creates one or more definitions for coders and decoders to use
1585 while reading and writing image data. Definitions are generally used to
1586 control image file format coder modules, and image processing operations,
1587 beyond what is provided by normal means. Defined settings are listed in <a
1588 href="#verbose" >-verbose</a> information ("<kbd>info:</kbd>" output format)
1589 as "Artifacts". </p>
1591 <p>If <em class="arg">value</em> is missing for a definition, an empty-valued
1592 definition of a flag is created with that name. This used to control on/off
1593 options. Use <a href="#define">+define key</a> to remove definitions
1594 previously created. Use <a href="#define">+define "*"</a> to remove all
1595 existing definitions.</p>
1597 <p>The same 'artifact' settings can also be defined using the <a
1598 href="#set" >-set "option:<em class="arg">key</em>" "<em class="arg"
1599 >value</em>"</a> option, which also allows the use of <a href="../www/escape.html" >Format and Print Image
1600 Properties</a> in the defined value. </p>
1602 <p>The <em>option</em> and <em>key</em> are case-independent (they are
1603 converted to lowercase for use within the decoders) while the <em>value</em>
1604 is case-dependent.</p>
1606 <p>Such settings are global in scope, and effect all images and operations. </p>
1608 <p>The following definitions are just some of the artifacts that are
1613 <dt>dcm:display-range=reset</dt>
1614 <dd>Set the display range to the minimum and maximum pixel values for the
1615 DCM image format.</dd><br />
1617 <dt>dot:layout-engine=<em class="arg">value</em></dt>
1618 <dd>Set the specify the layout engine for the DOT image format (e.g.
1619 <kbd>neato</kbd>).</dd><br />
1621 <dt>jpeg:extent=<em class="arg">value</em></dt>
1622 <dd>Restrict the maximum JPEG file size, for example <kbd>-define
1623 jpeg:extent=400kb</kbd>.</dd><br />
1625 <dt>jpeg:size=<em class="arg">geometry</em></dt>
1626 <dd>Set the size hint of a JPEG image, for example, -define jpeg:size=128x128.
1627 It is most useful for increasing performance and reducing the memory
1628 requirements when reducing the size of a large JPEG image.</dd><br />
1630 <dt>jp2:rate=<em class="arg">value</em></dt>
1631 <dd>Specify the compression factor to use while writing JPEG-2000 files. The
1632 compression factor is the reciprocal of the compression ratio. The valid
1633 range is 0.0 to 1.0, with 1.0 indicating lossless compression. If defined,
1634 this value overrides the -quality setting. A quality setting of 75
1635 results in a rate value of 0.06641.</dd><br />
1637 <dt>mng:need-cacheoff</dt>
1638 <dd>turn playback caching off for streaming MNG.</dd><br />
1640 <dt>png:bit-depth=<em class="arg">value</em></dt>
1641 <dt>png:color-type=<em class="arg">value</em></dt>
1642 <dd>desired bit-depth and color-type for PNG output. You can force the PNG
1643 encoder to use a different bit-depth and color-type than it would have
1644 normally selected, but only if this does not cause any loss of image
1645 quality. Any attempt to reduce image quality is treated as an error and no
1646 PNG file is written. E.g., if you have a 1-bit black-and-white image, you
1647 can use these "defines" to cause it to be written as an 8-bit grayscale,
1648 indexed, or even a 64-bit RGBA. But if you have a 16-million color image,
1649 you cannot force it to be written as a grayscale or indexed PNG. If you
1650 wish to do this, you must use the appropriate <a href="#depth">-depth</a>,
1651 <a href="#colors">-colors</a>, or <a href="#type">-type</a> directives to
1652 reduce the image quality prior to using the PNG encoder. Note that in
1653 indexed PNG files, "bit-depth" refers to the number of bits per index,
1654 which can be 1, 2, 4, or 8. In such files, the color samples always have
1655 8-bit depth.</dd><br />
1657 <dt>ps:imagemask</dt>
1658 <dd>If the ps:imagemask flag is defined, the PS3 and EPS3 coders will create
1659 Postscript files that render bilevel images with the Postscript imagemask
1660 operator instead of the image operator.</dd><br />
1662 <dt>quantum:format=<em class="arg">type</em></dt>
1663 <dd>Set the type to <kbd>floating-point</kbd> to specify a floating-point
1664 format for raw files (e.g. GRAY:) or for MIFF and TIFF images in HDRI mode
1665 to preserve negative values. If <a href="#depth">-depth</a> 16 is
1666 included, the result is a single precision floating point format.
1667 If <a href="#depth">-depth</a> 32 is included, the result is
1668 double precision floating point format.</dd>
1672 <p>For example, to create a postscript file that will render only the black
1673 pixels of a bilevel image, use:</p>
1675 <p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert bilevel.tif -define ps:imagemask eps3:stencil.ps</span></p>
1676 <p>Set attributes of the image registry by prefixing the value with
1677 <kbd>registry:</kbd>. For example, to set a temporary path to put work files,
1681 -define registry:temporary-path=/data/tmp
1686 <div style="margin: auto;">
1687 <h4><a name="delay" 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>
1690 <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>
1692 <p>This option is useful for regulating the animation of image sequences <em>ticks/ticks-per-second</em> seconds must expire before the display of the next image. The default is no delay between each showing of the image sequence. The default ticks-per-second is 100.</p>
1694 <p>Use <kbd>></kbd> to change the image delay <em>only</em> if its current value exceeds the given delay. <kbd><</kbd> changes the image delay <em>only</em> if current value is less than the given delay. For example, if you specify <kbd>30></kbd> and the image delay is 20, the image delay does not change. However, if the image delay is 40 or 50, the delay it is changed to 30. Enclose the given delay in quotation marks to prevent the <kbd><</kbd> or <kbd>></kbd> from being interpreted by your shell as a file redirection.</p>
1697 <div style="margin: auto;">
1698 <h4><a name="delete" id="delete"></a>-delete <em class="arg">index</em></h4>
1701 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>delete the image, specified by its index, from the image sequence.</td><td style='text-align:right;'></td></tr></table>
1703 <p>Specify the image by its index in the sequence. The first image is index 0. Negative indexes are relative to the end of the sequence, for example, -1 represents the last image of the sequence. Specify a range of images with a dash (e.g. 0-4). Separate indexes with a comma (e.g. 0,2). Use <kbd>+delete</kbd> to delete the last image in the current image sequence.</p>
1706 <div style="margin: auto;">
1707 <h4><a name="density" id="density"></a>-density <em class="arg">width</em><br />-density <em class="arg">width</em>x<em class="arg">height</em></h4>
1710 <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 rendering to devices.</td><td style='text-align:right;'></td></tr></table>
1712 <p>This option specifies the image resolution to store while encoding a raster image or the canvas resolution while rendering (reading) vector formats such as Postscript, PDF, WMF, and SVG into a raster image. Image resolution provides the unit of measure to apply when rendering to an output device or raster image. The default unit of measure is in dots per inch (DPI). The <a href="#units">-units</a> option may be used to select dots per centimeter instead.</p>
1714 <p>The default resolution is 72 dots per inch, which is equivalent to one point per pixel (Macintosh and Postscript standard). Computer screens are normally 72 or 96 dots per inch, while printers typically support 150, 300, 600, or 1200 dots per inch. To determine the resolution of your display, use a ruler to measure the width of your screen in inches, and divide by the number of horizontal pixels (1024 on a 1024x768 display).</p>
1716 <p>If the file format supports it, this option may be used to update the stored image resolution. Note that Photoshop stores and obtains image resolution from a proprietary embedded profile. If this profile is not stripped from the image, then Photoshop will continue to treat the image using its former resolution, ignoring the image resolution specified in the standard file header.</p>
1718 <p>The <a href="#density">-density</a> option sets an <em>attribute</em> and does not alter the underlying raster image. It may be used to adjust the rendered size for desktop publishing purposes by adjusting the scale applied to the pixels. To resize the image so that it is the same size at a different resolution, use the <a href="#resample">-resample</a> option.</p>
1720 <div style="margin: auto;">
1721 <h4><a name="depth" id="depth"></a>-depth <em class="arg">value</em></h4>
1724 <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>
1726 <p>This the number of bits in a color sample within a pixel. Use this option to specify the depth of raw images whose depth is unknown such as GRAY, RGB, or CMYK, or to change the depth of any image after it has been read.</p>
1728 <div style="margin: auto;">
1729 <h4><a name="descend" id="descend"></a>-descend</h4>
1732 <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>
1734 <div style="margin: auto;">
1735 <h4><a name="deskew" id="deskew"></a>-deskew <em class="arg">threshold</em></h4>
1738 <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>
1740 <p>Use <a href="#set">-set</a> <kbd>option:deskew:auto-crop <em>width</em></kbd> to auto crop the image. The set argument is the pixel width of the image background (e.g 40).</p>
1742 <div style="margin: auto;">
1743 <h4><a name="despeckle" id="despeckle"></a>-despeckle</h4>
1746 <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>
1748 <div style="margin: auto;">
1749 <h4><a name="direction" id="direction"></a>-direction <em class="arg">type</em></h4>
1752 <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>
1754 <div style="margin: auto;">
1755 <h4><a name="displace" 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>
1758 <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="../www/composite.html">composite</a>]</td></tr></table>
1760 <p>With this option, the 'overlay' image, and optionally the 'mask' image,
1761 is used as a displacement map, which is used to displace the lookup of
1762 what part of the 'background' image is seen at each point of the overlaid
1763 area. Much like the displacement map is a 'lens' that redirects light shining
1764 through it so as to present a distorted view the original 'background' image
1767 <p>Any perfect grey areas of the displacement map produce a zero
1768 displacement of the image. Black areas produce the given maximum negative
1769 displacement of the lookup point, while white produce a maximum positive
1770 displacement of the lookup. </p>
1772 <p>Note that it is the lookup of the 'background' that is displaced, not a
1773 displacement of the image itself. As such an area of the displacement map
1774 containing 'white' will have the lookup point 'shifted' by a positive amount,
1775 and thus generating a copy of the destination image to the right/downward from
1776 the correct position. That is the image will look like it may have been
1777 'shifted' in a negative left/upward direction. Understanding this is a very
1778 important in understanding how displacement maps work. </p>
1780 <p>The given arguments define the maximum amount of displacement in pixels
1781 that a particular map can produce. If the displacement scale is large enough
1782 it is also possible to lookup parts of the 'background' image that lie well
1783 outside the bounds of the displacement map itself. That is you could very
1784 easily copy a section of the original image from outside the overlay area
1785 into the overlay area. </p>
1787 <p>The '%' flag makes the displacement scale relative to the size of the
1788 overlay image (100% = half width/height of image). Using '!' switches
1789 percentage arguments to refer to the destination image size instead.
1790 these flags were added as of IM v6.5.3-5.</p>
1792 <p>Normally a single grayscale displacement map is provided, which with the
1793 given scaling values will determine a single direction (vector) in which
1794 displacements can occur (positively or negatively). However, if you also
1795 specify a third image which is normally used as a <em class="arg">mask</em>,
1796 the <em class="arg">composite image</em> is used for horizontal X
1797 displacement, while the <em class="arg">mask image</em> is used for vertical Y
1798 displacement. This allows you to define completely different displacement
1799 values for the X and Y directions, and allowing you to lookup any point within
1800 the <em class="arg">scale</em> bounds. In other words each pixel can lookup
1801 any other nearby pixel, producing complex 2 dimensional displacements, rather
1802 than a simple 1 dimensional vector displacements. </p>
1804 <p>Alteratively rather than suppling two separate images, as of IM v6.4.4-0,
1805 you can use the 'red' channel of the overlay image to specify the horizontal
1806 or X displacement, and the 'green' channel for the vertical or Y displacement.
1809 <p>As of IM v6.5.3-5 any alpha channel in the overlay image is used as a
1810 mask the transparency of the destination image. However areas outside the
1811 overlaid areas will not be effected. </p>
1814 <div style="margin: auto;">
1815 <h4><a name="display" id="display"></a>-display <em class="arg">host:display[.screen]</em></h4>
1818 <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="../www/animate.html">animate</a>, <a href="../www/display.html">display</a>]</td></tr></table>
1820 <p>This option is used with convert for obtaining image or font from this X server. See <em class="arg">X(1)</em>.</p>
1822 <div style="margin: auto;">
1823 <h4><a name="dispose" id="dispose"></a>-dispose <em class="arg">method</em></h4>
1826 <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>
1828 <p>The layer disposal method defines the way each the displayed image is to be
1829 modified after the current 'frame' of an animation has finished being
1830 displayed (after its 'delay' period), but before the next frame on an
1831 animation is to be overlaid onto the display. </p>
1833 <p>Here are the valid methods:</p>
1836 Undefined 0 No disposal specified (equivalent to '<kbd>none</kbd>').
1837 None 1 Do not dispose, just overlay next frame image.
1838 Background 2 Clear the frame area with the background color.
1839 Previous 3 Clear to the image prior to this frames overlay.
1842 <p>You can also use the numbers given above, which is what the GIF format
1843 uses internally to represent the above settings. </p>
1845 <p>To print a complete list of dispose methods, use <a href="#list">-list dispose</a>.</p>
1847 <p>Use <a href="#dispose" >+dispose</a>, turn off the setting and prevent
1848 resetting the layer disposal methods of images being read in. </p>
1850 <p>Use <a href="#set">-set</a> '<kbd>dispose</kbd>' method to set the image
1851 disposal method for images already in memory.</p>
1853 <div style="margin: auto;">
1854 <h4><a name="dissimilarity-threshold" id="dissimilarity-threshold"></a>-dissimilarity-threshold <em class="arg">value</em></h4>
1857 <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="../www/compare.html">compare</a>]</td></tr></table>
1860 <div style="margin: auto;">
1861 <h4><a name="dissolve" id="dissolve"></a>-dissolve <em class="arg">src_percent</em>[x<em class="arg">dst_percent</em>]</h4>
1864 <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="../www/composite.html">composite</a>]</td></tr></table>
1866 <p>The opacity of the composite image is multiplied by the given percent, then
1867 it is composited 'over' the main image. If <em class="arg">src_percent</em>
1868 is greater than 100, start dissolving the main image so it becomes
1869 transparent at a value of '<kbd class="arg">200</kbd>'. If both percentages
1870 are given, each image are dissolved to the percentages given. </p>
1872 <p>Note that dissolve percentages do not add, two opaque images dissolved
1873 '50,50', produce a 75% transparency. For a 50% + 50% blending of the two
1874 images, you would need to use dissolve values of '50,100'. </p>
1876 <div style="margin: auto;">
1877 <h4><a name="distort" id="distort"></a>-distort <em class="arg">method arguments</em></h4>
1880 <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>
1882 <p>The <em class="arg">arguments</em> is a single string containing a list
1883 of floating point numbers separated by commas or spaces. The number of
1884 and meaning of the floating point values depends on the distortion <em
1885 class="arg">method</em> being used. </p>
1887 <p>Choose from these distortion types:</p>
1891 <th align="left" style="width: 8%">Method</th>
1892 <th align="left">Description</th>
1896 <td valign="top"><kbd>ScaleRotateTranslate</kbd>
1897 <br/>or <kbd>SRT</kbd></td>
1899 Distort image by first scaling and rotating about a given 'center',
1900 before translating that 'center' to the new location, in that order. It
1901 is an alternative method of specifying a '<kbd>Affine</kbd>' type of
1902 distortion, but without shearing effects. It also provides a good way
1903 of rotating and displacing a smaller image for tiling onto a larger
1904 background (IE 2-dimensional animations). <br/>
1906 The number of arguments determine the specific meaning of each
1907 argument for the scales, rotation, and translation operations. <br/>
1909 <table style="margin-left:auto; margin-right:auto;">
1910 <tr><td># </td><td>arguments meaning</td></tr>
1911 <tr><td>1:</td><td><em>Angle_of_Rotation</em></td></tr>
1912 <tr><td>2:</td><td><em>Scale Angle</em></td></tr>
1913 <tr><td>3:</td><td><em>ScaleX,ScaleY Angle</em></td></tr>
1914 <tr><td>4:</td><td><em>X,Y Scale Angle</em></td></tr>
1916 <td><em>X,Y ScaleX,ScaleY Angle</em></td></tr>
1918 <td><em>X,Y Scale Angle NewX,NewY</em></td></tr>
1920 <td><em>X,Y ScaleX,ScaleY Angle
1921 NewX,NewY</em></td></tr>
1924 This is actually an alternative way of specifying a 2 dimensional linear
1925 '<kbd>Affine</kbd>' or '<kbd>AffineProjection</kbd>' distortion. </td> </tr>
1928 <td valign="top"><kbd>Affine</kbd></td>
1930 Distort the image linearly by moving a list of at least 3 or more sets
1931 of control points (as defined below). Ideally 3 sets or 12 floating
1932 point values are given allowing the image to be linearly scaled,
1933 rotated, sheared, and translated, according to those three points. See
1934 also the related '<kbd>AffineProjection</kbd>' and '<kbd>SRT</kbd>'
1937 More than 3 sets given control point pairs (12 numbers) is least
1938 squares fitted to best match a lineary affine distortion. If only 2
1939 control point pairs (8 numbers) are given a two point image translation
1940 rotation and scaling is performed, without any possible shearing,
1941 flipping or changes in aspect ratio to the resulting image. If only one
1942 control point pair is provides the image is only translated, (which may
1943 be a floating point non-integer translation). <br/>
1945 This distortion does not include any form of perspective distortion.
1951 <td valign="top"><kbd>AffineProjection</kbd></td>
1953 Linearly distort an image using the given Affine Matrix of 6
1954 pre-calculated coefficients forming a set of Affine Equations to map
1955 the source image to the destination image.
1957 <div style="text-align: center"><em>
1958 s<sub>x</sub>, r<sub>x</sub>,
1959 r<sub>y</sub>, s<sub>y</sub>,
1960 t<sub>x</sub>, t<sub>y</sub>
1963 See <a href="#affine" >-affine</a> setting for more detail, and
1964 meanings of these coefficients. <br/>
1966 The distortions '<kbd>Affine</kbd>' and '<kbd>SRT</kbd>' provide
1967 alternative methods of defining this distortion, with ImageMagick doing
1968 the calculations needed to generate the required coefficients. You can
1969 see the internally generated coefficients, by using a <a
1970 href="#verbose" >-verbose</a> setting with those other varients. </td>
1975 <td valign="top"><kbd>BilinearForward</kbd><br/>
1976 <kbd>BilinearReverse</kbd></td>
1978 Bilinear Distortion, given a minimum of 4 sets of coordinate pairs, or
1979 16 values (see below). Not that lines may not appear straight after
1980 distortion, though the distance between coordinates will remain
1983 The '<kbd>BilinearForward</kbd>' is used to map rectangles to any
1984 quadrilateral, while the '<kbd>BilinearReverse</kbd>' form maps any
1985 quadrilateral to a rectangle, while preserving the straigth line edges
1988 Note that '<kbd>BilinearForward</kbd>' can generate invalid pixels
1989 which will be colored using the <a href="#mattecolor" >-mattecolor</a>
1990 color setting. Also if the quadraterial becomes 'flipped' the image
1991 may dissappear. <br/>
1993 There are future plans to produce a true Bilinear distortion that will
1994 attempt to map any quadrilateral to any other quadrilateral, while
1995 preserving edges (and edge distance ratios).
2001 <td valign="top"><kbd>Perspective</kbd></td>
2003 Perspective distort the images, using a list of 4 or more sets of
2004 control points (as defined below). More that 4 sets (16 numbers) of
2005 control points provide least squares fitting for more accurate
2006 distortions (for the purposes of image registration and panarama
2007 effects). Less than 4 sets will fall back to a '<kbd>Affine</kbd>'
2008 linear distortion. <br/>
2010 Perspective Distorted images ensures that straight lines remain
2011 straight, but the scale of the distorted image will vary. The horizon
2012 is anti-aliased, and the 'sky' color may be set using the
2013 <a href="#mattecolor" >-mattecolor</a> setting. </td>
2017 <td valign="top"><kbd>PerspectiveProjection</kbd> </td>
2019 Do a '<kbd>Perspective</kbd>' distortion biased on a set of 8
2020 pre-calculated coefficients. You can get these coefficients by looking
2021 at the <a href="#verbose" >-verbose</a> output of a
2022 '<kbd>Prespective</kbd>' distortion, or by calculating them yourself.
2023 If the last two perspective scaling coefficients are zero, the
2024 remaining 6 represents a transposed 'Affine Matrix'. </td>
2029 <td valign="top"><kbd>Arc</kbd></td>
2031 Arc the image (variation of polar mapping) over the angle given around
2033 <table width="90%" style = "margin-left: auto; margin-right: auto;">
2034 <tr valign="top"><td>Argument</td>
2035 <td>Meaning</td></tr>
2036 <tr valign="top"><td><em>arc_angle</em></td>
2037 <td>The angle over which to arc the image side-to-side</td></tr>
2038 <tr valign="top"><td><em>rotate_angle</em></td>
2039 <td>Angle to rotate resulting image from vertical center</td></tr>
2040 <tr valign="top"><td><em>top_radius</em></td>
2041 <td>Set top edge of source image at this radius</td></tr>
2042 <tr valign="top"><td><em>bottom_radius</em> </td>
2043 <td>Set bottom edge to this radius (radial scaling)</td></tr>
2046 The resulting image is always resized to best fit the resulting image,
2047 (as if using <a href="#distort" >+distort</a>) while attempting to
2048 preserve scale and aspect ratio of the original image as much as
2049 possible with the arguments given by the user. All four arguments will
2050 be needed to change the overall aspect ratio of an 'Arc'ed image. <br/>
2052 This a variation of a polar distortion designed to try to preserve the
2053 aspect ratio of the image rather than direct Cartesian to Polar
2058 <td valign="top"><kbd>Polar</kbd></td>
2060 Like '<kbd>Arc</kbd>' but do a complete Cartesian to Polar mapping of
2061 the image. that is the height of the input image is mapped to the
2062 radius limits, while the width is wrapped around between the
2065 Arguments: <em>Rmax,Rmin CenterX,CenterY, start,end_angle</em> <br/>
2067 All arguments are optional. With <em>Rmin</em> defaulting to zero, the
2068 center to the center of the image, and the angles going from -180 (top)
2069 to +180 (top). If <em>Rmax</em> is given the special value of
2070 '<code>0</code>', the the distance from the center to the nearest edge
2071 is used for the radius of the output image, which will ensure the whole
2072 image is visible (though scaled smaller). However a special value of
2073 '<code>-1</code>' will use the distance from the center to the furthest
2074 corner, This may 'clip' the corners from the input rectangular image,
2075 but will generate the exact reverse of a '<kbd>DePolar</kbd>' with
2076 the same arguments. <br/>
2078 If the plus form of distort (<a href="#distort" >+distort</a>) is used
2079 output image center will default to <code>0,0</code> of the virtual
2080 canvas, and the image size adjusted to ensure the whole input image is
2081 made visible in the output image on the virtual canvas. </td>
2086 <td valign="top"><kbd>DePolar</kbd></td>
2088 Uses the same arguments and meanings as a '<kbd>Polar</kbd>' distortion
2089 but generates the reverse Polar to Cartesian distortion. <br/>
2091 The special <em>Rmax</em> setting of '<code>0</code>' may however clip
2092 the corners of the input image. However using the special
2093 <em>Rmax</em> setting of '<code>-1</code>' (maximum center to corner
2094 distance) will ensure the whole distorted image is preserved in the
2095 generated result, so that the same argument to '<kbd>Polar</kbd>' will
2096 reverse the distortion re-producing the original.
2098 Note that as this distortion requires the area resampling of a circular
2099 arc, which can not be handled by the builtin EWA resampling function.
2100 As such the normal EWA filters are turned off. It is recommended some
2101 form of 'super-sampling' image processing technique be used to produce
2102 a high quality result. </td>
2107 <td valign="top"><kbd>Barrel</kbd></td>
2109 Given the four coefficients (A,B,C,D) as defined by <a
2110 href="http://www.all-in-one.ee/~dersch/barrel/barrel.html" >Helmut
2111 Dersch</a>, perform a barrell or pin-cushion distortion appropriate to
2112 correct radial lens distortions. That is in photographs, make straight
2113 lines straight again. <br/>
2115 Arguments: <em>A B C</em> [ <em>D</em> [
2116 <em>X</em> , <em>Y</em> ] ] <br/>
2117 or <em>A<sub>x</sub> B<sub>x</sub> C<sub>x</sub> D<sub>x</sub>
2118 A<sub>y</sub> B<sub>y</sub> C<sub>y</sub> D<sub>y</sub></em>
2119 [ <em>X</em> , <em>Y</em> ] <br/>
2120 So that it forms the function <br/>
2121 Rsrc = r * ( <em>A</em>*r<sup>3</sup> + <em>B</em>*r<sup>2</sup> +
2122 <em>C</em>*r + <em>D</em> )<br/>
2124 Where <em>X</em>,<em>Y</em> is the optional center of the distortion
2125 (defaulting to the center of the image). <br/>
2126 The second form is typically used to distort images, rather than
2127 correct lens distortions. <br/>
2133 <td valign="top"><kbd>BarrelInverse</kbd></td>
2135 This is very simular to '<kbd>Barrel</kbd>' with the same set of
2136 arguments, and argument handling. However it uses the inverse
2137 of the radial polynomial,
2138 so that it forms the function <br/>
2139 Rsrc = r / ( <em>A</em>*r<sup>3</sup> + <em>B</em>*r<sup>2</sup> +
2140 <em>C</em>*r + <em>D</em> )<br/>
2141 Note that this is not the reverse of the '<kbd>Barrel</kbd>'
2142 distortion, just a different barrel-like radial distortion method.
2148 <td valign="top"><kbd>Shepards</kbd></td>
2150 Distort the given list control points (any number) using an Inverse
2151 Squared Distance Interpolation Method (<a
2152 href="http://en.wikipedia.org/wiki/Shepard%27s_method" >Shepards
2153 Method</a>). The control points in effect do 'localized' displacement
2154 of the image around the given control point (preserving the look and
2155 the rotation of the area near the control points. For best results
2156 extra control points should be added to 'lock' the positions of the
2157 corners, edges and other unchanging parts of the image, to prevent
2158 their movement. <br/>
2160 The distortion has been likened to 'taffy pulling' using nails, or
2161 pins' stuck in a block of 'jelly' which is then moved to the new
2162 position, distorting te surface of the jelly. <br/>
2164 Internally it is equivelent to generating a displacement map (see <a
2165 href="#displace" >-displace</a>) for source image color look-up using
2166 the <a href="#sparse-color" >-sparse-color</a> method of the same name.
2173 <p>To print a complete list of distortion methods, use <a href="#list">-list
2176 <p>Many of the above distortion methods such as '<kbd>Affine</kbd>',
2177 '<kbd>Perspective</kbd>', and '<kbd>Shepards</kbd>' use a list control points
2178 defining how these points in the given image should be distorted in the
2179 destination image. Each set of four floating point values represent a source
2180 image coordinate, followed immediately by the destination image coordinate.
2181 This produces a list of values such as...</p>
2182 <div style="text-align: center"><em>
2183 U<sub>1</sub>,V<sub>1</sub> X<sub>1</sub>,Y<sub>1</sub>
2184 U<sub>2</sub>,V<sub>2</sub> X<sub>2</sub>,Y<sub>2</sub>
2185 U<sub>3</sub>,V<sub>3</sub> X<sub>3</sub>,Y<sub>3</sub>
2187 U<sub>n</sub>,V<sub>n</sub> X<sub>n</sub>,Y<sub>n</sub>
2189 <p>where <em>U,V</em> on the source image is mapped to <em>X,Y</em> on the
2190 destination image. </p>
2192 <p>For example, to warp an image using '<kbd>perspective</kbd>' distortion,
2193 needs a list of at least 4 sets of coordinates, or 16 numbers. Here is the
2194 perspective distortion of the built-in "rose:" image. Note how spaces were
2195 used to group the 4 sets of coordinate pairs, to make it easier to read and
2198 <p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>
2199 convert rose: -virtual-pixel black \<br/>
2200 -distort Perspective '0,0,0,0 0,45,0,45 69,0,60,10 69,45,60,35' \<br/>
2201 rose_3d_rotated.gif</span></p>
2202 <p>If more that the required number of coordinate pairs are given for
2203 a distortion, the distortion method is 'least squares' fitted to produce the
2204 best result for all the coordinate pairs given. If less than the ideal number
2205 of points are given, the distort will generally fall back to a simpler form of
2206 distortion that can handles the smaller number of coordinates (usally a linear
2207 '<kbd>Affine</kbd>' distortion). </p>
2209 <p>By using more coordinates you can make use of image registration tool to
2210 find matching coordinate pairs in overlapping images, so as to improve the
2211 'fit' of the distortion. Of course a bad coordinate pair can also make the
2212 'fit' worse. Caution is always advised. </p>
2214 <p>Colors are acquired from the source image according to the <a
2215 href="#interpolate" >-interpolate</a> color lookup setting, when the image is
2216 magnified. However if the viewed image is minified (image becomes smaller),
2217 a special area resampling function (added ImageMagick v6.3.5-9), is used to
2218 produce a higher quality image. For example you can use
2219 a '<kbd>perspective</kbd>' distortion to view a infinitely tiled 'plane' all
2220 the way to the horizon. </p>
2222 <p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>
2223 convert -size 90x90 pattern:checkerboard -normalize -virtual-pixel tile \<br/>
2224 -distort perspective '0,0,5,45 89,0,45,46 0,89,0,89 89,89,89,89' \<br/>
2225 checks_tiled.jpg</span></p>
2226 <p>Note that a infinitely tiled perspective images involving the horizon can
2227 be very slow to generate due to the use of the high quality 'area resampling'
2228 function (added ImageMagick v6.3.5-9). You can turn off 'area resampling'
2229 using a <a href="#filter" >-filter</a> setting of '<kbd>point</kbd>'
2230 (recommended if you plan to use super-sampling instead). </p>
2232 <p>If an image generates <i>invalid pixels</i>, such as the 'sky' in the last
2233 '<kbd>perspective</kbd>' distortion example, <a href="#distort" >-distort</a>
2234 will use the current <a href="#mattecolor" >-mattecolor</a> setting for these
2235 pixels. If you do not what these pixels to be visible, set the color to match
2236 the rest of the ground. </p>
2238 <p>The output image size will by default be the same as the input image. This
2239 means that if the part of the distorted image falls outside the viewed area of
2240 the 'distorted space', those parts is clipped and lost. However if you use
2241 the plus form of the operator (<a href="#distort" >+distort</a>) the operator
2242 will attempt (if possible) to show the whole of the distorted image, while
2243 retaining a correct 'virtual canvas' offset, for image layering. This offset
2244 may need to be removed using <a href="#repage" >+repage</a>, to remove if it
2247 <p>You can alternatively specify a special "<kbd><a href="#set" >-set</a>
2248 option:distort:viewport {geometry_string}</kbd>" setting which will specify
2249 the size and the offset of the generated 'viewport' image of the distorted
2252 <p>Adding a "<kbd><a href="#set" >-set</a> option:distort:scale
2253 {scale_factor}</kbd>" will scale the output image (viewport or otherwise) by
2254 that factor without changing the viewed contents of the distorted image. This
2255 can be used either for 'super-sampling' the image for a higher quality result,
2256 or for panning and zooming around the image (with appropriate viewport
2257 changes, or post-distort cropping and resizing). </p>
2259 <p>Setting <a href="#verbose" >-verbose</a> setting, will cause <a
2260 href="#distort" >-distort</a> to attempt to output the internal coefficients,
2261 and the <a href="#fx" >-fx</a> equivalent to the distortion, for expert study,
2262 and debugging purposes. This many not be available for all distorts. </p>
2264 <p>Affine rotations and shears (such as '<kbd>SRT</kbd>' distortion), tend to
2265 produce a cleaner result that the equivalent <a href="#rotate" >-rotate</a>
2266 and/or <a href="#shear" >-shear</a> operation, with more control of due to the
2267 above settings. It is algorithmically slower however, though that may not be
2268 the case in ImageMagick's implementation. </p>
2271 <div style="margin: auto;">
2272 <h4><a name="dither" id="dither"></a>-dither <em class="arg">method</em></h4>
2275 <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 images when general color reduction is applied via an option, or automagically when saving to specific formats. This enabled by default. </td><td style='text-align:right;'></td></tr></table>
2277 <p>Dithering places two or more colors in neighboring pixels so that to the eye a closer approximation of the images original color is reproduced. This reduces the number of colors needed to reproduce the image but at the cost of a lower level pattern of colors. Error diffusion dithers can use any set of colors (generated or user defined) to an image. </p>
2279 <p>Dithering is turned on by default, to turn it off use the plus form of the
2280 setting, <a href="#dither">+dither</a>. This will also also render PostScript
2281 without text or graphic aliasing. Disabling dithering often (but not always)
2282 leads to faster process, a smaller number of colors, but more cartoon like
2283 image coloring. Generally resulting in 'color banding' effects in areas with
2284 color gradients. </p>
2286 <p>The color reduction operators <a href="#colors">-colors</a>, <a
2287 href="#monochrome">-monochrome</a>, <a href="#remap ">-remap</a>, and <a href="#posterize">-posterize</a>, apply dithering to images using the reduced color set they created. These operators are also used as part of automatic color reduction when saving images to formats with limited color support, such as <kbd>GIF:</kbd>, <kbd>XBM:</kbd>, and others, so dithering may also be used in these cases. </p>
2289 <p>Alternatively you can use <a href="#random-threshold">-random-threshold</a> to generate purely random dither. Or use <a href="#ordered-dither">-ordered-dither</a> to apply threshold mapped dither patterns, using uniform color maps, rather than specific color maps. </p>
2292 <div style="margin: auto;">
2293 <h4><a name="draw" id="draw"></a>-draw <em class="arg">string</em></h4>
2296 <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>
2298 <p>Use this option to annotate or decorate an image with one or more graphic primitives. The primitives include shapes, text, transformations, and pixel operations.</p>
2300 <p>The shape primitives:</p>
2305 rectangle x0,y0 x1,y1
2306 roundRectangle x0,y0 x1,y1 wc,hc
2307 arc x0,y0 x1,y1 a0,a1
2308 ellipse x0,y0 rx,ry a0,a1
2310 polyline x0,y0 ... xn,yn
2311 polygon x0,y0 ... xn,yn
2312 bezier x0,y0 ... xn,yn
2313 path path specification
2314 image operator x0,y0 w,h filename
2317 <p>The text primitive:</p>
2322 <p>The text gravity primitive:</p>
2325 gravity NorthWest, North, NorthEast, West, Center,
2326 East, SouthWest, South, or SouthEast
2329 <p>The text gravity primitive only affects the placement of text and does not interact with the other primitives. It is equivalent to using the <a href="#gravity">-gravity</a> command-line option, except that it is limited in scope to the <a href="#draw">-draw</a> option in which it appears.</p>
2331 <p>The transformation primitives:</p>
2341 <p>The pixel operation primitives:</p>
2348 <p>The shape primitives are drawn in the color specified by the preceding <a href="#fill">-fill</a> setting. For unfilled shapes, use <a href="#fill">-fill none</a>. You can optionally control the stroke (the "outline" of a shape) with the <a href="#stroke">-stroke</a> and <a href="#strokewidth">-strokewidth</a> settings.</p>
2350 <p>A <kbd>point</kbd> primitive is specified by a single <em>point</em> in the pixel plane, that is, by an ordered pair of integer coordinates, <em>x</em>,<em>y</em>. (As it involves only a single pixel, a <kbd>point</kbd> primitive is not affected by <a href="#stroke">-stroke</a> or <a href="#strokewidth">-strokewidth</a>.)</p>
2352 <p>A <kbd>line</kbd> primitive requires a start point and end point.</p>
2354 <p>A <kbd>rectangle</kbd> primitive is specified by the pair of points at the upper left and lower right corners.</p>
2356 <p>A <kbd>roundRectangle</kbd> primitive takes the same corner points as a <kbd>rectangle</kbd> followed by the width and height of the rounded corners to be removed.</p>
2358 <p>The <kbd>circle</kbd> primitive makes a disk (filled) or circle (unfilled). Give the center and any point on the perimeter (boundary).</p>
2360 <p>The <kbd>arc</kbd> primitive is used to inscribe an elliptical segment in to a given rectangle. An <kbd>arc</kbd> requires the two corners used for <kbd>rectangle</kbd> (see above) followed by the start and end angles of the arc of the segment segment (e.g. 130,30 200,100 45,90). The start and end points produced are then joined with a line segment and the resulting segment of an ellipse is filled.</p>
2362 <p>Use <kbd>ellipse</kbd> to draw a partial (or whole) ellipse. Give the center point, the horizontal and vertical "radii" (the <em>semi-axes</em> of the ellipse) and start and end angles in degrees (e.g. 100,100 100,150 0,360).</p>
2364 <p>The <kbd>polyline</kbd> and <kbd>polygon</kbd> primitives require three or more points to define their perimeters. A <kbd>polyline</kbd> is simply a <kbd>polygon</kbd> in which the final point is not stroked to the start point. When unfilled, this is a <em>polygonal line</em>. If the <a href="#stroke">-stroke</a> setting is <kbd>none</kbd> (the default), then a <kbd>polyline</kbd> is identical to a <kbd>polygon</kbd>.
2367 <p>A <em>coordinate</em> is a pair of integers separated by a space or optional comma. </p>
2369 <p>As an example, to define a circle centered at 100,100 that extends to 150,150 use:</p>
2372 -draw 'circle 100,100 150,150'
2375 <p>The <kbd>Bezier</kbd> primitive creates a spline curve and requires three or points to define its shape. The first and last points are the <em>knots</em> and these points are attained by the curve, while any intermediate coordinates are <em>control points</em>. If two control points are specified, the line between each end knot and its sequentially respective control point determines the tangent direction of the curve at that end. If one control point is specified, the lines from the end knots to the one control point determines the tangent directions of the curve at each end. If more than two control points are specified, then the additional control points act in combination to determine the intermediate shape of the curve. In order to
2376 draw complex curves, it is highly recommended either to use the <kbd>path</kbd> primitive or to draw multiple four-point bezier segments with the start and end knots of each successive segment repeated. For example:</p>
2379 -draw 'bezier 20,50 45,100 45,0 70,50'
2382 -draw 'bezier 70,50 95,100 95,0 120,50'
2386 <p>A <kbd>path</kbd> represents an outline of an object, defined in terms of moveto (set a new current point), lineto (draw a straight line), curveto (draw a Bezier curve), arc (elliptical or circular arc) and closepath (close the current shape by drawing a line to the last moveto) elements. Compound paths (i.e., a path with subpaths, each consisting of a single moveto followed by one or more line or curve operations) are possible to allow effects such as <em>donut holes</em> in objects. (See <a href="http://www.w3.org/TR/SVG/paths.html">Paths</a>.)</p>
2388 <p>Use <kbd>image</kbd> to composite an image with another image. Follow the image keyword with the composite operator, image location, image size, and filename:</p>
2391 -draw 'image SrcOver 100,100 225,225 image.jpg'
2394 <p>You can use 0,0 for the image size, which means to use the actual
2395 dimensions found in the image header. Otherwise, it is scaled to the given
2396 dimensions. See <a href="../www/compose.html">Alpha Compositing</a> for
2397 a detailed discussion of alpha composition methods that are available. </p>
2399 <p>Use <kbd>text</kbd> to annotate an image with text. Follow the text coordinates with a string. If the string has embedded spaces, enclose it in single or double quotes.</p>
2401 <p>For example, the following annotates the image with <kbd>Works like magick!</kbd> for an image titled <kbd>bird.miff</kbd>. </p>
2404 -draw 'text 100,100 "Works like magick!"'
2407 <p>See the <a href="#annotate">-annotate</a> option for another convenient way to annotate an image with text.</p>
2409 <p>The <kbd>rotate</kbd> primitive rotates subsequent shape primitives and text primitives about the origin of the main image. If the <a href="#region">-region</a> option precedes the <a href="#draw">-draw</a> option, the origin for transformations is the upper left corner of the region.</p>
2411 <p>The <kbd>translate</kbd> primitive translates subsequent shape and text primitives.</p>
2413 <p>The <kbd>scale</kbd> primitive scales them.</p>
2415 <p>The <kbd>skewX</kbd> and <kbd>skewY</kbd> primitives skew them with respect to the origin of the main image or the region.</p>
2417 <p>The transformations modify the current affine matrix, which is initialized from the initial affine matrix defined by the <a href="#affine">-affine</a> option. Transformations are cumulative within the <a href="#draw">-draw</a> option. The initial affine matrix is not affected; that matrix is only changed by the appearance of another <a href="#affine">-affine</a> option. If another <a href="#draw">-draw</a> option appears, the current affine matrix is reinitialized from the initial affine
2420 <p>Use the <kbd>color</kbd> primitive to change the color of a pixel to the fill color (see <a href="#fill">-fill</a>). Follow the pixel coordinate with a method:</p>
2430 <p>Consider the target pixel as that specified by your coordinate. The <kbd>point</kbd> method recolors the target pixel. The <kbd>replace</kbd> method recolors any pixel that matches the color of the target pixel. <kbd>Floodfill</kbd> recolors any pixel that matches the color of the target pixel and is a neighbor, whereas <kbd>filltoborder</kbd> recolors any neighbor pixel that is not the border color. Finally, <kbd>reset</kbd> recolors all pixels.</p>
2432 <p>Use <kbd>matte</kbd> to the change the pixel matte value to transparent. Follow the pixel coordinate with a method (see the <kbd>color</kbd> primitive for a description of methods). The <kbd>point</kbd> method changes the matte value of the target pixel. The <kbd>replace</kbd> method changes the matte value of any pixel that matches the color of the target pixel. <kbd>Floodfill</kbd> changes the matte value of any pixel that matches the color of the target pixel and is a neighbor, whereas <kbd>filltoborder</kbd> changes the matte value of any neighbor pixel that is not the border color (<a href="#bordercolor">-bordercolor</a>). Finally <kbd>reset</kbd> changes the matte value of all pixels.</p>
2434 <p>You can set the primitive color, font, and font bounding box color with <a href="#fill">-fill</a>, <a href="#font">-font</a>, and <a href="#box">-box</a> respectively. Options are processed in command line order so be sure to use these options <em>before</em> the <a href="#draw">-draw</a> option.</p>
2436 <p>Strings that begin with a number must be quoted (e.g. use '1.png' rather than 1.png).</p>
2438 <p>Drawing primitives conform to the <a href="../www/magick-vector-graphics.html">Magick Vector Graphics</a> format.</p>
2441 <div style="margin: auto;">
2442 <h4><a name="edge" id="edge"></a>-edge <em class="arg">radius</em></h4>
2445 <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>
2447 <div style="margin: auto;">
2448 <h4><a name="emboss" id="emboss"></a>-emboss <em class="arg">radius</em></h4>
2451 <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>
2453 <div style="margin: auto;">
2454 <h4><a name="encipher" id="encipher"></a>-encipher <em class="arg">filename</em></h4>
2457 <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="#decipher">-decipher</a>.</td><td style='text-align:right;'></td></tr></table>
2459 <p>Get the passphrase from the file specified by <em class="arg">filename</em>.</p>
2461 <p>For more information, see the webpage, <a href="http://www.imagemagick.org/www/cipher.html">ImageMagick: Encipher or Decipher an Image</a>.</p>
2465 <div style="margin: auto;">
2466 <h4><a name="encoding" id="encoding"></a>-encoding <em class="arg">type</em></h4>
2469 <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>
2471 <p>Choose from <kbd>AdobeCustom</kbd>, <kbd>AdobeExpert</kbd>, <kbd>AdobeStandard</kbd>, <kbd>AppleRoman</kbd>, <kbd>BIG5</kbd>, <kbd>GB2312</kbd>, <kbd>Latin 2</kbd>, <kbd>None</kbd>, <kbd>SJIScode</kbd>, <kbd>Symbol</kbd>, <kbd>Unicode</kbd>, <kbd>Wansung</kbd>.</p>
2473 <div style="margin: auto;">
2474 <h4><a name="endian" id="endian"></a>-endian <em class="arg">type</em></h4>
2477 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Specify endianness (<kbd>MSB</kbd> or <kbd>LSB</kbd>) of the image.</td><td style='text-align:right;'></td></tr></table>
2479 <p>To print a complete list of endian types, use the <a href="#list">-list endian</a> option.</p>
2481 <p>Use <a href="#endian">+endian</a> to revert to unspecified endianness.</p>
2484 <div style="margin: auto;">
2485 <h4><a name="enhance" id="enhance"></a>-enhance</h4>
2488 <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>
2491 <div style="margin: auto;">
2492 <h4><a name="equalize" id="equalize"></a>-equalize</h4>
2495 <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>
2497 <p>To perform histogram equalization on all channels in concert, transform the image into some other color space, such as HSL, OHTA, YIQ or YUV, then equalize the appropriate intensity-like channel, then convert back to RGB.</p>
2499 <p>For example using HSL, we have: ... <kbd>-colorspace HSL -channel lightness -equalize -colorspace RGB</kbd> ...</p>
2501 <p>For YIQ, YUV and OHTA use the red channel. For example, OHTA is a principal components transformation that puts most of the information in the first channel. Here we have ... <kbd>-colorspace OHTA -channel red -equalize -colorspace RGB</kbd> ...</p>
2503 <div style="margin: auto;">
2504 <h4><a name="evaluate" id="evaluate"></a>-evaluate <em class="arg">operator value</em></h4>
2507 <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>
2509 <p>(See the <a href="#function" >-function</a> operator for some multi-parameter functions. See the <a href="#fx" >-fx</a> operator if more elaborate calculations are needed.)</p>
2511 <p>The behaviors of each <em class="arg">operator</em> are summarized in the following list. For brevity, the numerical value of a "pixel" referred to below is the value of the corresponding channel of that pixel, while a "normalized pixel" is that number divided by the maximum (installation-dependent) value <em class="QR">QuantumRange</em>. (If normalized pixels are used, they are restored, following the other calculations, to the full range by multiplying by <em class="QR">QuantumRange</em>.)</p>
2518 <th><em class="arg">operator</em></th>
2519 <th>Summary (see further below for details)</th>
2524 <tr><td>Abs </td> <td>Add <em class="arg">value</em> to pixels and return absolute value. </td></tr>
2525 <tr><td>Add </td> <td>Add <em class="arg">value</em> to pixels. </td></tr>
2526 <tr><td>AddModulus </td> <td>Add <em class="arg">value</em> to pixels modulo <em class="QR">QuantumRange</em>.</td></tr>
2527 <tr><td>And </td> <td>Binary AND of pixels with <em class="arg">value</em>.</td></tr>
2528 <tr><td>Cos, Cosine </td> <td>Apply cosine to pixels with frequency <em class="arg">value</em> with 50% bias added.</td></tr>
2529 <tr><td>Divide </td> <td>Divide pixels by <em class="arg">value</em>.</td></tr>
2530 <tr><td>Exp </td> <td>base-e exponential function</td></tr>
2531 <tr><td>Exponential </td> <td>base-e exponential function</td></tr>
2532 <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>
2533 <tr><td>Log </td> <td>Apply scaled logarithm to normalized pixels.</td></tr>
2534 <tr><td>Max </td> <td>Clip pixels at lower bound <em class="arg">value</em>.</td></tr>
2535 <tr><td>Mean </td> <td>Add the <em class="arg">value</em> and divide by 2.</td></tr>
2536 <tr><td>Median </td> <td>Choose the median value from an image sequence.</td></tr>
2537 <tr><td>Min </td> <td>Clip pixels at upper bound <em class="arg">value</em>.</td></tr>
2538 <tr><td>Multiply </td> <td>Multiply pixels by <em class="arg">value</em>.</td></tr>
2539 <tr><td>Or </td> <td>Binary OR of pixels with <em class="arg">value</em>.</td></tr>
2540 <tr><td>Pow </td> <td>Raise normalized pixels to the power <em class="arg">value</em>.</td></tr>
2541 <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>
2542 <tr><td>Set </td> <td>Set pixel equal to <em class="arg">value</em>.</td></tr>
2543 <tr><td>Sin, Sine </td> <td>Apply sine to pixels with frequency <em class="arg">value</em> with 50% bias added.</td></tr>
2544 <tr><td>Subtract </td> <td>Subtract <em class="arg">value</em> from pixels.</td></tr>
2545 <tr><td>Xor </td> <td>Binary XOR of pixels with <em class="arg">value.</em></td></tr>
2547 <tr><td> </td></tr>
2549 <tr><td>Gaussian-noise</td></tr>
2550 <tr><td>Impulse-noise</td></tr>
2551 <tr><td>Laplacian-noise</td></tr>
2552 <tr><td>Multiplicative-noise</td> <td>(These are equivalent to the corresponding <a href="#noise" >-noise</a> operators.)</td></tr>
2553 <tr><td>PoissonNoise</td></tr>
2554 <tr><td>Uniform-noise</td></tr>
2556 <tr><td> </td></tr>
2558 <tr><td>Threshold </td> <td>Threshold pixels larger than <em class="arg">value</em>.</td></tr>
2559 <tr><td>ThresholdBlack </td> <td>Threshold pixels to zero values equal to or below <em class="arg">value</em>.</td></tr>
2560 <tr><td>ThresholdWhite </td> <td>Threshold pixels to maximum values above <em class="arg">value</em>. </td></tr>
2564 <p>The specified functions are applied only to each previously set <a
2565 href="#channel" >-channel</a> in the image. If necessary, the results of the
2566 calculations are truncated (clipped) to fit in the interval [0, <em
2567 class="QR">QuantumRange</em>]. The transparency channel of the image is
2568 represented as a 'alpha' values (0 = fully transparent), so, for example, a
2569 <kbd>Divide</kbd> by 2 of the alpha channel will make the image
2570 semi-transparent. Append the percent symbol '<kbd>%</kbd>' to specify a value
2571 as a percentage of the <em class="QR">QuantumRange</em>.</p>
2573 <p>To print a complete list of <a href="#evaluate">-evaluate</a> operators, use
2574 <a href="#list">-list evaluate</a>.</p>
2576 <p>The results of the <kbd>Add</kbd>, <kbd>Subtract</kbd> and
2577 <kbd>Multiply</kbd> methods can also be achieved using either the <a
2578 href="#level" >-level</a> or the <a href="#level" >+level</a> operator, with
2579 appropriate argument, to linearly modify the overall range of color values.
2580 Please note, however, that <a href="#level" >-level</a> treats transparency as
2581 'matte' values (0 = opaque), while <a href="#level" >-evaluate</a> works with
2584 <p><kbd>AddModulus</kbd> has been added as of ImageMagick 6.4.8-4 and provides addition modulo the <em class="QR">QuantumRange</em>. It is therefore equivalent to <kbd>Add</kbd> unless the resulting pixel value is outside the interval [0, <em class="QR">QuantumRange</em>]. </p>
2586 <p><kbd>Exp or Exponential</kbd> has been added as of ImageMagick 6.6.5-1 and works on normalized pixel values. The <em class="arg">value</em> used with <kbd>Exp</kbd> should be negative so as to produce a decaying exponential function. Non-negative values will always produce results larger unity and thus outside the interval [0, <em class="QR">QuantumRange</em>]. The formula is expressed below. </p>
2588 <div style="text-align:center;">
2589 exp(<em class="arg">value</em> × <b><em>u</em></b>)
2592 <p> If the input image is squared, for example, using <a
2593 href="#-function" >-function polynomial "2 0 0"</a>, then a decaying Gaussian function will be the result.</p>
2595 <p><kbd>Log</kbd> has been added as of ImageMagick 6.4.2-1 and works on normalized pixel values. This a <em>scaled</em> log function. The <em class="arg">value</em> used with <kbd>Log</kbd> provides a <em>scaling factor</em> that adjusts the curvature in the graph of the log function. The formula applied to a normalized value <b><em>u</em></b> is below. </p>
2597 <div style="text-align:center;">
2598 log(<em class="arg">value</em> × <b><em>u</em></b> + 1) / log(<em class="arg">value</em> + 1)
2601 <p><kbd>Pow</kbd> has been added as of ImageMagick 6.4.1-9, and works on
2602 normalized pixel values. Note that <kbd>Pow</kbd> is related to the <a
2603 href="#gamma" >-gamma</a> operator. For example, <b>-gamma 2</b> is equivalent
2604 to <b>-evaluate pow 0.5</b>, i.e., a 'square root' function. The value used
2605 with <a href="#gamma" >-gamma</a> is simply the reciprocal of the value used
2606 with <kbd>Pow</kbd>.</p>
2608 <p><kbd>Cosine</kbd> and <kbd>Sine</kbd> was added as of IM v6.4.8-8 and
2609 converts the image values into a value according to a (co)sine wave function.
2610 The synonyms <kbd>Cos</kbd> and <kbd>Sin</kbd> may also be used. The output
2611 is biased 50% and normalized by 50% so as to fit in the respective color value
2612 range. The <em class="arg">value</em> scaling of the <em>period</em> of the
2613 function (its frequency), and thus determines the number of 'waves' that will
2614 be generated over the input color range. For example, if the <em
2615 class="arg">value</em> is 1, the effective period is simply the <em
2616 class="QR">QuantumRange</em>; but if the <em class="arg">value</em> is 2,
2617 then the effective period is the <em>half</em> the <em
2618 class="QR">QuantumRange</em>.
2620 <div style="text-align:center;">
2621 0.5 + 0.5 × cos(2 π <b><em>u</em></b> × <em class="arg">value</em>).
2624 See also the <a href="#function" >-function</a> operator, which is a
2625 multi-value version of evaluate. </P>
2627 <div style="margin: auto;">
2628 <h4><a name="evaluate-sequence" id="evaluate-sequence"></a>-evaluate-sequence <em class="arg">operator</em></h4>
2631 <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 over a sequence of images.</td><td style='text-align:right;'></td></tr></table>
2633 <div style="margin: auto;">
2634 <h4><a name="extent" id="extent"></a>-extent <em class="arg">geometry</em></h4>
2637 <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>
2639 <p>If the image is enlarged, unfilled areas are set to the background color. To position the image, use offsets in the <em class="arg">geometry</em> specification or precede with a <a href="#gravity">-gravity</a> setting. To specify how to compose the image with the background, use <a href="#compose" >-compose</a>.</p>
2640 <p>This command reduces or expands a JPEG image to fit on an 800x600
2641 display. If the aspect ratio of the input image isn't exactly 4:3, then the
2642 image is centered on an 800x600 black canvas: </p>
2644 <p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert input.jpg -resize 800x600 -background black -compose Copy \ <br /> -gravity center -extent 800x600 -quality 92 output.jpg</span></p>
2647 <p>See <a href="../www/command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
2649 <div style="margin: auto;">
2650 <h4><a name="extract" id="extract"></a>-extract <em class="arg">geometry</em></h4>
2653 <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>
2655 <p>This option is most useful for extracting a subregion of a very large raw image. Note that these two commands are equivalent:</p>
2657 <p class='crt'><span class="crtprompt"> $magick> </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"> $magick> </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>
2659 <p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert -size 16000x16000 -depth 8 -extract 640x480 \ <br/> image.rgb image.png</span></p>
2660 <p>the image is <em>resized</em> to the specified dimensions instead,
2663 <p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert -size 16000x16000 -depth 8 -resize 640x480 image.rgb image.png</span></p>
2664 <p>See <a href="../www/command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
2666 <div style="margin: auto;">
2667 <h4><a name="family" id="family"></a>-family <em class="arg">fontFamily</em></h4>
2670 <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>
2672 <p>This setting suggests a font family that ImageMagick should try to use for rendering text. If the family can be found it is used; if not, a default font (e.g., "Arial") or a family known to be similar is substituted (e.g., "Courier" might be used if "System" is requested but not found).
2675 <p>For other settings that affect fonts, see the options <a href="#font">-font</a>, <a href="#stretch">-stretch</a>, <a href="#style">-style</a>, and <a href="#weight">-weight</a>.
2678 <div style="margin: auto;">
2679 <h4><a name="features" id="features"></a>-features <em class="arg">distance</em></h4>
2682 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>display 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;'></td></tr></table>
2684 <div style="margin: auto;">
2685 <h4><a name="fft" id="fft"></a>-fft</h4>
2688 <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>
2690 <p>This option is new as of ImageMagick 6.5.4-3 (and now working for Windows users in ImageMagick 6.6.0-9). It transforms an image from the normal (spatial) domain to the frequency domain. In the frequency domain, an image is represented as a superposition of complex sinusoidal waves of varying amplitudes. The image x and y coordinates are the possible frequencies along the x and y directions, respectively, and the pixel intensity values are complex numbers that correspond to the sinusoidal wave amplitudes. See for example, <a href="http://en.wikipedia.org/wiki/Fourier_transform" target="_blank">Fourier Transform</a>, <a href="http://en.wikipedia.org/wiki/DFT" target="_blank">Discrete Fourier Transform</a> and <a href="http://en.wikipedia.org/wiki/FFT" target="_blank">Fast Fourier Transform</a>.</p>
2692 <p>A single image name is provided as output for this option. However, the output result will have two components. It is either a two-frame image or two separate images, depending upon whether the image format specified supports multi-frame images. The reason that we get a dual output result is because the frequency domain represents an image using complex numbers, which cannot be visualized directly. Therefore, the complex values are automagically separated into a two-component image representation. The first component is the magnitude of the complex number and the second is the phase of the complex number. See for example, <a href="http://en.wikipedia.org/wiki/Complex_numbers" target="_blank">Complex Numbers</a>.<p>
2694 <p>The magnitude and phase component images must be specified using image formats that do not limit the color or compress the image. Thus, MIFF, TIF, PFM, EXR and PNG are the recommended image formats to use. All of these formats, except PNG support multi-frame images. So for example,</p>
2696 <p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert image.png -fft fft_image.miff</span></p>
2697 <p>generates a magnitude image as <kbd>fft_image.miff[0]</kbd> and a phase image as <kbd>fft_image.miff[1]</kbd>. Similarly,</p>
2699 <p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert image.png -fft fft_image.png</span></p>
2700 <p>generates a magnitude image as <kbd>fft_image-0.png</kbd> and a phase image as <kbd>fft_image-1.png</kbd>. If you prefer this representation, then you can force any of the other formats to produce two output images by including <a href="#adjoin">+adjoin</a> following -fft in the command line.</p>
2702 <p>The input image can be any size, but if not square and even-dimensioned, it is padded automagically to the larger of the width or height of the input image and to an even number of pixels. The padding will occur at the bottom and/or right sides of the input image. The resulting output magnitude and phase images is square at this size. The kind of padding relies on the <a href="#virtual-pixel">-virtual-pixel</a> setting.</p>
2704 <p>Both output components will have dynamic ranges that fit within [0, <em class="QR">QuantumRange</em>], so that HDRI need not be enabled. Phase values nominally range from 0 to 2*π, but for non-HDRI compilations of ImageMagick, the phase image is scaled to span the full dynamic range. The magnitude image is not scaled and thus generally will contain very small values. As such, the image normally will appear totally black. In order to view any detail, the magnitude image typically is enhanced with a log function into what is usually called the spectrum. A log function is used to enhance the darker values more in comparison to the lighter values. This can be done, for example, as follows:</p>
2706 <p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert fft_image.miff[0] -contrast-stretch 0 \ <br />
2707 -evaluate log 1000 fft_image_spectrum.png</span></p>
2708 <p>where the <a href="#contrast-stretch">-contrast-stretch</a> 0 is used to scale the image to full dynamic range, first. The argument to the <a href="#evaluate">-evaluate</a> log typically is specified between 100 and 10,000, depending upon the amount of detail that one wants to bring out in the spectrum. Larger values produce more visible detail. Too much detail, however, may hide the important features.</p>
2710 <p>The <a href="http://www.fftw.org/" target="_blank">FFTW</a> delegate library is required to use <a href="#fft">-fft</a>.
2712 <p>Use <a href="#fft">+fft</a> to produce two output images that are the real and imaginary components of the complex valued Fourier transform.</p>
2714 <p>However, as the real and imaginary components can contain negative values, this requires that IM be configured with HDRI enabled. In this case, you must use either MIFF, TIF or PFM formats for the real and imaginary component results, since they are formats that preserve both negative and fractional values without clipping them or truncating the fractional part.</p>
2716 <p>The real and imaginary component images resulting from <a href="#fft">+fft</a> is also square, even dimensioned images due to the same padding that was discussed above for the magnitude and phase component images.</a>
2718 <p>See the discussion on HDRI implementations of ImageMagick on the page
2719 <a href="/www/high-dynamic-range.html">High Dynamic-Range Images</a>. For more about HDRI go the ImageMagick <a href="http://www.imagemagick.org/Usage/basics/#hdri">Usage</a> pages or this <a href="http://en.wikipedia.org/wiki/High_dynamic_range_imaging">Wikipedia</a> entry.
2723 <div style="margin: auto;">
2724 <h4><a name="fill" id="fill"></a>-fill <em class="arg">color</em></h4>
2727 <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>
2729 <p>This option accepts a color name, a hex color, or a numerical RGB, RGBA, HSL, HSLA, CMYK, or CMYKA specification. See <a href="../www/color.html">Color Names</a> for a description of how to properly specify the color argument.</p>
2731 <p>Enclose the color specification in quotation marks to prevent the "#" or the parentheses from being interpreted by your shell.</p>
2742 -fill "rgb(255,255,255)"
2745 <p>See <a href="#draw">-draw</a> for further details.</p>
2747 <p>To print a complete list of color names, use the <a href="#list">-list color</a> option.</p>
2749 <div style="margin: auto;">
2750 <h4><a name="filter" id="filter"></a>-filter <em class="arg">type</em></h4>
2753 <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
2754 distorting an image.</td><td style='text-align:right;'></td></tr></table>
2756 <p>Use this option to affect the resizing operation of an image during
2757 operations such as <a href="#resize">-resize</a> and <a href="#distort"
2758 >-distort</a>. For example you can use a simple resize filter such as:</p>
2763 Triangle Quadratic Mitchell
2766 <p>The <kbd>Bessel</kbd> and <kbd>Sinc</kbd> filter is also provided (as well
2767 as a faster <kbd>SincFast</kbd> equivalent form). However these filters are
2768 generally useless on their own as they are infinite filters that are being
2769 clipped to the filters support size. Their direct use is not recommended
2770 except via expert settings (see below). </p>
2772 Instead these special filter functions are typically windowed by a windowing
2773 function that the <a href="#filter" >-filter</a> setting defines. That is
2774 using these functions will define a 'Windowed' filter, appropriate to the
2775 operator involved. Windowed filters include: </p>
2778 Lanczos Hamming Parzen
2779 Blackman Kaiser Welsh
2780 Hanning Bartlett Bohman
2783 <p>Also one special self-windowing filter is also provided
2784 <kbd>Lagrange</kbd>, which will automagically re-adjust its function depending
2785 on the current 'support' or 'lobes' expert settings (see below).</p>
2787 <p>If you do not select a filter with this option, the filter defaults to
2788 <kbd>Mitchell</kbd> for a colormapped image, a image with a matte channel, or
2789 if the image is enlarged. Otherwise the filter default to
2790 <kbd>Lanczos</kbd>.</p>
2792 <p>To print a complete list of resize filters, use the <a href="#list">-list
2793 filter</a> option.</p>
2795 <p>You can modify how the filter behaves as it scales your image through the
2796 use of these expert settings (see also <a href="#define" >-define</a> and <a
2797 href="#set" >-set</a>):-</p>
2800 <dt>-define filter:blur=<em>factor</em></dt>
2801 <dd>Scale the X axis of the filter (and its window). Use > 1.0 for
2802 blurry or < 1.0 for sharp. This should only be used with Gaussian and
2803 Gaussian-like filters simple filters, or you may not get the expected
2806 <dt>-define filter:support=<em>radius</em></dt>
2807 <dd>Set the filter support radius. Defines how large the filter should be and
2808 thus directly defines how slow the filtered resampling process is. All
2809 filters have a default 'prefered' support size. Some filters like
2810 <kbd>Lagrange</kbd> and windowed filters adjust themselves depending on
2811 this value. With simple filters this value either does nothing (but slow
2812 the resampling), or will clip the filter function in a detrimental way.
2815 <dt>-define filter:lobes=<em>count</em></dt>
2816 <dd>Set the number of lobes to use for the Sinc/Bessel filter. This an
2817 alternative way of specifying the 'support' range of the filter, that is
2818 designed to be more suited to windowed filters, especially when used for
2819 image distorts.</dd>
2821 <dt>-define filter:b=<em>b-spline_factor</em></dt>
2822 <dt>-define filter:c=<em>keys_alpha_factor</em></dt>
2823 <dd>Redefine the values used for cubic filters such as <kbd>Cubic</kbd>,
2824 <kbd>Catrom</kbd>, <kbd>Mitchel</kbd>, and <kbd>Hermite</kbd>, as well as
2825 the <kbd>Parzen</kbd> Sinc windowing function. If only one of the values
2826 are defined, the other is set so as to generate a 'Keys' type cubic
2827 filter. Values meaning was defined by a research paper by
2830 <dt>-define filter:filter=<em>filter_function</em></dt>
2831 <dd>Use this function directly as the scaling filter. This will allow
2832 you to directly use a windowing filter such as <kbd>Blackman</kbd>,
2833 rather than as its normal usage as a windowing function for 'Sinc' or
2834 'Bessel' functions. If defined, no windowing function is used, unless the
2835 following expert setting is also defined.</dd>
2837 <dt>-define filter:window=<em>filter_function</em></dt>
2838 <dd>The IIR (infinite impulse response) filters <kbd>Bessel</kbd> and
2839 <kbd>Sinc</kbd> are windowed (brought down to zero over the defined
2840 support range) with the given filter. This allows you to specify a filter
2841 function that is not normally used as a windowing function, such as
2842 <kbd>Box</kbd>, (which effectively turns off the windowing function),
2843 to window a <kbd>Sinc</kbd>, or the function the previous setting defined.
2846 <dt>-define filter:verbose=<em>1</em></dt>
2847 <dd>This causes IM to print information on the final internal filter
2848 selection to standard output. This includes a commented header on the
2849 filter settings being used, and data allowing the filter weights to be
2850 easily graphed. </dd>
2852 <dd>Note however that some filters are internally defined in terms of other
2853 filters. The <kbd>Lanczos</kbd> filter for example is defined in terms of
2854 a <kbd>SincFast</kbd> windowed <kbd>SincFast</kbd> filter, while
2855 <kbd>Mitchell</kbd> is defined as a <kbd>Cubic</kbd> filter with specific
2856 'B' and 'C' settings. </dd>
2860 <p>For example, to get a 8 lobe Bessel windowed Bessel filter:</p>
2862 <p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert image.png -filter bessel \ <br/>
2863 -set filter:window=bessel -set filter:lobes=8 \ <br/>
2864 -resize 150% image.jpg</span></p>
2865 <p>Or a raw un-windowed Sinc filter with 4 lobes:</p>
2867 <p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert image.png -set filter:filter=sinc -set filter:lobes=4 \ <br/>
2868 -resize 150% image.jpg</span></p>
2869 <p>Note that the use of expert options (except for 'blur' with simple resize
2870 filters, and 'verbose' for viewing the internal filter selection), are
2871 provided for image processing experts who have studied and understood how
2872 resize filters work. Without this knowledge, and an understanding of the
2873 definition of the actual filters involved, using expert settings are more
2874 likely to be detrimental to your image resizing.</p>
2877 <div style="margin: auto;">
2878 <h4><a name="flatten" id="flatten"></a>-flatten</h4>
2881 <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="#layers" >-layers</a> method "flatten".</td><td style='text-align:right;'></td></tr></table>
2884 <div style="margin: auto;">
2885 <h4><a name="flip" id="flip"></a>-flip</h4>
2888 <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>
2890 <p>reflect the scanlines in the vertical direction.</p>
2892 <div style="margin: auto;">
2893 <h4><a name="floodfill" 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>
2896 <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. Using <a href="#fuzz" >-fuzz</a> to floodfill pixels which only change by a small amount.</td><td style='text-align:right;'></td></tr></table>
2898 <div style="margin: auto;">
2899 <h4><a name="flop" id="flop"></a>-flop</h4>
2902 <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>
2904 <p>reflect the scanlines in the horizontal direction.</p>
2907 <div style="margin: auto;">
2908 <h4><a name="font" id="font"></a>-font <em class="arg">name</em></h4>
2911 <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>
2913 <p>To print a complete list of fonts, use the <a href="#list">-list font</a> option (for versions prior to 6.3.6, use 'type' instead of 'font').</p>
2915 <p>In addition to the fonts specified by the above pre-defined list, you can
2916 also specify a font from a specific source. For example <kbd>Arial.ttf</kbd>
2917 is a TrueType font file, <kbd>ps:helvetica</kbd> is PostScript font, and
2918 <kbd>x:fixed</kbd> is X11 font.</p>
2920 <p>For other settings that affect fonts, see the options <a href="#family">-family</a>, <a href="#stretch">-stretch</a>, <a href="#style">-style</a>, and <a href="#weight">-weight</a>. </p>
2923 <div style="margin: auto;">
2924 <h4><a name="foreground" id="foreground"></a>-foreground <em class="arg">color</em></h4>
2927 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Define the foreground color.</td><td style='text-align:right;'></td></tr></table>
2929 <p>The color is specified using the format described under the <a href="#fill">-fill</a> option.</p>
2931 <p>The default foreground color is black.</p>
2933 <div style="margin: auto;">
2934 <h4><a name="format" id="format"></a>-format <em class="arg">type</em></h4>
2937 <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>
2939 <p>When used with the <kbd>mogrify</kbd> utility, this option converts any image to the image <a href="/www/formats.html">format</a> you specify. For a list of image format types supported by ImageMagick, use <a href="#list">-list format</a>.</p>
2941 <p>By default the file is written to its original name. However, if the filename extension matches a supported format, the extension is replaced with the image format type specified with <a href="#format">-format</a>. For example, if you specify <em class="arg">tiff</em> as the format type and the input image filename is <em class="arg">image.gif</em>, the output image filename becomes <em class="arg">image.tiff</em>.</p>
2943 <div style="margin: auto;">
2944 <h4><a name="format_identify_" id="format_identify_"></a>-format <em class="arg">string</em></h4>
2947 <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="../www/identify.html">identify</a>]</td></tr></table>
2949 <p>See <a href="../www/escape.html">Format and Print Image Properties</a> for an explanation on how to specify the argument to this option.</p>
2951 <div style="margin: auto;">
2952 <h4><a name="frame" id="frame"></a>-frame <em class="arg">geometry</em></h4>
2955 <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>
2957 <p>The color of the border is specified with the <a href="#mattecolor"
2958 >-mattecolor</a> command line option. </p>
2960 <p>See <a href="../www/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
2961 class="arg">geometry</em> argument indicates the amount of extra width and
2962 height that is added to the dimensions of the image. If no offsets are given
2963 in the <em class="arg">geometry</em> argument, then the border added is
2964 a solid color. Offsets <em>x</em> and <em>y</em>, if present, specify that
2965 the width and height of the border is partitioned to form an outer bevel of
2966 thickness <em>x</em> pixels and an inner bevel of thickness
2967 <em>y</em> pixels. Negative offsets make no sense as frame arguments.
2970 <p>The <a href="#frame">-frame</a> option is affected by the current <a
2971 href="#compose">-compose</a> setting and assumes that this is using the default
2972 '<kbd>Over</kbd>' composition method. It generates a image of the appropriate
2973 size with the current <a href="#bordercolor">-bordercolor</a> setting, and then
2974 draws the frame of four distinct colors close to the current <a
2975 href="#mattecolor">-mattecolor</a>. The original image is then overlaid onto
2976 center of this image. This means that with the default compose method of
2977 '<kbd>Over</kbd>' any transparent parts may be replaced by the current <a
2978 href="#bordercolor">-bordercolor</a> setting.</p>
2980 <p>The image composition is not
2981 affected by the <a href="#gravity">-gravity</a> option.</p>
2984 <div style="margin: auto;">
2985 <h4><a name="frame_import_" id="frame_import_"></a>-frame</h4>
2988 <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="../www/import.html">import</a>]</td></tr></table>
2990 <div style="margin: auto;">
2991 <h4><a name="function" id="function"></a>-function <em class="arg">function</em> <em class="arg">parameters</em></h4>
2994 <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>
2996 <p>This operator performs calculations based on the given arguments to modify each of the color values for each previously set <a href="#channel">-channel</a> in the image. See <a href="#evaluate">-evaluate</a> for details concerning how the results of the calculations are handled.</p>
2998 <p>This is can be considered a multi-argument version of the <a href="#evaluate">-evaluate</a> operator. (Added in ImageMagick 6.4.8−8.)</p>
3000 <p>Here, <em class="arg">parameters</em> is a comma-separated list of numerical values. The number of values varies depending on which <em class="arg">function</em> is selected. Choose the <em class="arg">function</em> from:</p>
3009 <p>To print a complete list of <a href="#function">-function</a> operators, use <a href="#list">-list function</a>. Descriptions follow.</p>
3012 <dt><kbd>Polynomial</kbd></dt>
3014 <p>The <kbd>Polynomial</kbd> function takes an arbitrary number of parameters, these being the coefficients of a polynomial, in decreasing order of degree. That is, entering</p>
3016 <div style="text-align: center">
3017 -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>
3020 <p>will invoke a polynomial function given by</p>
3022 <div style="text-align: center">
3023 <em>a</em><sub><em>n</em></sub> <b><em>u</em></b><sup><em>n</em></sup> +
3024 <em>a</em><sub><em>n</em>-1</sub> <b><em>u</em></b><sup><em>n</em>-1</sup> +
3025 ··· <em>a</em><sub>1</sub> <b><em>u</em></b> + <em>a</em><sub>0</sub>,
3028 <p>where <b><em>u</em></b> is pixel's original normalized channel value.</p>
3030 <p>The <kbd>Polynomial</kbd> function can be used in place of <kbd>Set</kbd> (the <em>constant</em> polynomial) and <kbd>Add</kbd>, <kbd>Divide</kbd>, <kbd>Multiply</kbd>, and <kbd>Subtract</kbd> (some <em>linear</em> polynomials) of the <a href="#evaluate">-evaluate</a> operator. The <a href="#level">-level</a> operator also affects channels linearly. Some correspondences follow.</p>
3037 <td>-evaluate Set <em class="arg">value</em> </td>
3038 <td>-function Polynomial <em class="arg">value</em></td>
3039 <td>(Constant functions; set <em class="arg">value</em>×100% gray when channels are RGB.)</td>
3042 <td>-evaluate Add <em class="arg">value</em> </td>
3043 <td>-function Polynomial 1,<em class="arg">value</em></td>
3046 <td>-evaluate Subtract <em class="arg">value</em> </td>
3047 <td>-function Polynomial 1,−<em class="arg">value</em></td>
3050 <td>-evaluate Multiply <em class="arg">value</em> </td>
3051 <td>-function Polynomial <em class="arg">value</em>,0</td>
3054 <td>+level black% x white%</td>
3055 <td>-function Polynomial A,B</td>
3056 <td>(Reduce contrast. Here, A=(white-black)/100 and B=black/100.)</td>
3060 <p>The <kbd>Polynomial</kbd> function gives great versatility, since polynomials can be used to fit any continuous curve to any degree of accuracy desired.</p>
3063 <dt><kbd>Sinusoid</kbd></dt>
3065 <p>The <kbd>Sinusoid</kbd> function can be used to vary the channel values sinusoidally by setting frequency, phase shift, amplitude, and a bias. These values are given as one to four parameters, as follows,</p>
3067 <div style="text-align: center">
3068 -function <kbd>Sinusoid</kbd> <em class="arg">freq</em>,[<em class="arg">phase</em>,[<em class="arg">amp</em>,[<em class="arg">bias</em>]]]
3071 <p>where <em>phase</em> is in degrees. (The domain [0,1] of the function corresponds to 0 through <em class="arg">freq</em>×360 degrees.) The result is that if a pixel's normalized channel value is originally <b><em>u</em></b>, its resulting normalized value is given by </p>
3073 <div style="text-align: center">
3074 <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>
3077 <p> For example, the following generates a curve that starts and ends at 0.9 (when <b><em>u</em></b>=0 and 1, resp.), oscillating three times between .7−.2=.5 and .7+.2=.9. </p>
3080 -function Sinusoid 3,-90,.2,.7
3083 <p>The default values of <em class="arg">amp</em> and <em class="arg">bias</em> are both .5. The default for <em class="arg">phase</em> is 0.</p>
3085 <p>The <kbd>Sinusoid</kbd> function generalizes <kbd>Sin</kbd> and <kbd>Cos</kbd> of the <a href="#evaluate">-evaluate</a> operator by allowing varying amplitude, phase and bias. The correspondence is as follows.</p>
3089 <td>-evaluate Sin <em class="arg">freq</em> </td>
3090 <td>-function Sinusoid <em class="arg">freq</em>,0 </td>
3093 <td>-evaluate Cos <em class="arg">freq</em> </td>
3094 <td>-function Sinusoid <em class="arg">freq</em>,90 </td>
3099 <dt><kbd>ArcSin</kbd></dt>
3101 <p>The <kbd>ArcSin</kbd> function generates the inverse curve of a Sinusoid,
3102 and can be used to generate cylindrical distortion and displacement maps.
3103 The curve can be adjusted relative to both the input values and output range
3106 <div style="text-align: center">
3107 -function <kbd>ArcSin</kbd> <em class="arg">width</em>,[<em class="arg">center</em>,[<em class="arg">range</em>,[<em class="arg">bias</em>]]]
3110 <p>with all values given in terms of noramlize color values (0.0 for black,
3111 1.0 for white). Defaulting to values covering the full range from 0.0 to 1.0
3112 for bout input (<em class="arg">width</em>), and output (<em
3113 class="arg">width</em>) values. '<code>1.0,0.5,1.0,0.5</code>' </p>
3115 <div style="text-align: center">
3116 <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>
3121 <dt><kbd>ArcTan</kbd></dt>
3123 <p>The <kbd>ArcTan</kbd> function generates a curve that smooth crosses from
3124 limit values at infinities, though a center using the given slope value.
3125 All these values can be adjusted via the arguments.
3127 <div style="text-align: center">
3128 -function <kbd>ArcTan</kbd> <em class="arg">slope</em>,[<em class="arg">center</em>,[<em class="arg">range</em>,[<em class="arg">bias</em>]]]
3131 <p>Defaulting to '<code>1.0,0.5,1.0,0.5</code>'.
3134 <div style="text-align: center">
3135 <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>
3143 <div style="margin: auto;">
3144 <h4><a name="fuzz" id="fuzz"></a>-fuzz <em class="arg">distance</em>{<em class="arg">%</em>}</h4>
3147 <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>
3149 <p>A number of algorithms search for a target color. By default the color must be exact. Use this option to match colors that are close to the target color in RGB space. For example, if you want to automagically trim the edges of an image with <a href="#trim">-trim</a> but the image was scanned and the target background color may differ by a small amount. This option can account for these differences.</p>
3151 <p>The <em class="arg">distance</em> can be in absolute intensity units or, by appending <kbd>%</kbd> as a percentage of the maximum possible intensity (255, 65535, or 4294967295).</p>
3154 <div style="margin: auto;">
3155 <h4><a name="fx" id="fx"></a>-fx <em class="arg">expression</em></h4>
3158 <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>
3160 <p>If the first character of <em class="arg">expression</em> is <kbd>@</kbd>, the expression is read from a file titled by the remaining characters in the string.</p>
3162 <p>See <a href="../www/fx.html">FX, The Special Effects Image Operator</a> for a detailed discussion of this option.</p>
3165 <div style="margin: auto;">
3166 <h4><a name="gamma" id="gamma"></a>-gamma <em class="arg">value</em></h4>
3169 <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>
3171 <p>The same color image displayed on two different workstations may look different due to differences in the display monitor. Use gamma correction to adjust for this color difference. Reasonable values extend from <kbd>0.8</kbd> to <kbd>2.3</kbd>. Gamma less than 1.0 darkens the image and gamma greater than 1.0 lightens it. Large adjustments to image gamma may result in the loss of some image information if the pixel quantum size is only eight bits (quantum range 0 to 255).</p>
3173 <p>Gamma adjusts the image's channel values pixel-by-pixel according to a power law, namely, pow(pixel,1/gamma) or pixel^(1/gamma), where pixel is the normalized or 0 to 1 color value. For example, using a value of gamma=2 is the same as taking the square root of the image.</p>
3175 <p>You can apply separate gamma values to the red, green, and blue channels of the image with a gamma value list delimited with commas (e.g., <kbd>1.7,2.3,1.2</kbd>).</p>
3177 <p>Use <a href="#gamma">+gamma <em class="arg">value</em></a> to set the image gamma level without actually adjusting the image pixels. This option is useful if the image is of a known gamma but not set as an image attribute (e.g. PNG images).</p>
3179 <p>Note that gamma adjustments are also available via the <a href="#level">-level</a> operator.</p>
3181 <div style="margin: auto;">
3182 <h4><a name="gaussian-blur" 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></h4>
3185 <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>
3187 <p>Convolve the image with a Gaussian or normal distribution using the given
3188 <em class="arg" >Sigma</em> value. The formula is:</p>
3190 <div class="eqn"><img alt="gaussian distribution" width="243px" height="42px" src="../images/gaussian-blur.png"/>
3193 <p>The <em class="arg" >Sigma</em> value is the important argument, and
3194 determines the actual amount of blurring that will take place. </p>
3196 <p>The <em class="arg" >Radius</em> is only used to determine the size of the
3197 array which will hold the calculated Gaussian distribution. It should be an
3198 integer. If not given, or set to zero, IM will calculate the largest possible
3199 radius that will provide meaningful results for the Gaussian distribution.
3202 <p>The larger the <em class="arg" >Radius</em> the radius the slower the
3203 operation is. However too small a <em class="arg" >Radius</em>, and sever
3204 aliasing effects may result. As a guideline, <em class="arg" >Radius</em>
3205 should be at least twice the <em class="arg" >Sigma</em> value, though three
3206 times will produce a more accurite result. </p>
3208 <p>This differs from the faster <a href="#blur">-blur</a> operator in that a
3209 full 2-dimensional convolution is used to generate the weighted average of the
3210 neighboring pixels. </p>
3212 <p>The <a href="#virtual-pixel">-virtual-pixel</a> setting will determine how
3213 pixels which are outside the image proper are blurred into the final result.
3217 <div style="margin: auto;">
3218 <h4><a name="geometry" id="geometry"></a>-geometry <em class="arg">geometry</em></h4>
3221 <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>
3223 <p>See <a href="../www/command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
3225 <div style="margin: auto;">
3226 <h4><a name="gravity" id="gravity"></a>-gravity <em class="arg">type</em></h4>
3229 <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>
3231 <p>Choices include: <kbd>NorthWest</kbd>, <kbd>North</kbd>, <kbd>NorthEast</kbd>,
3232 <kbd>West</kbd>, <kbd>Center</kbd>, <kbd>East</kbd>, <kbd>SouthWest</kbd>,
3233 <kbd>South</kbd>, <kbd>SouthEast</kbd>. Use <a href="#list">-list gravity</a> to get a complete
3234 list of <a href="#gravity">-gravity</a> settings available in your ImageMagick
3237 <p>The direction you choose specifies where to position text or subimages. For example, a gravity of <kbd>Center</kbd> forces the text to be centered within the image. By default, the image gravity is <kbd>NorthWest</kbd>. See <a href="#draw">-draw</a> for more details about graphic primitives. Only the text primitive of <a href="#draw">-draw</a> affected by the <a href="#gravity">-gravity</a> option.</p>
3239 <p>The <a href="#gravity">-gravity</a> option is also used in concert with the <a href="#geometry">-geometry</a> setting and other settings or options that take <em class="arg">geometry</em> as an argument, such as the <a href="#crop">-crop</a> option. </p>
3241 <p>If a <a href="#gravity">-gravity</a> setting occurs before another option or setting having a <em class="arg">geometry</em> argument that specifies an offset, the offset is usually applied to the point within the image suggested by the <a href="#gravity">-gravity</a> argument. Thus, in the following command, for example, suppose the file <kbd>image.png</kbd> has dimensions 200x100. The offset specified by the argument to <a href="#region">-region</a> is (−40,+20). The argument to <a href="#gravity">-gravity</a> is <kbd>Center</kbd>, which suggests the midpoint of the image, at the point (100,50). The offset (−40,20) is applied to that point, giving (100−40,50+20)=(60,70), so the specified 10x10 region is located at that point. (In addition, the <a href="#gravity">-gravity</a> affects the region itself, which is <em>centered</em> at the pixel coordinate (60,70). (See <a href="../www/command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.)</p>
3243 <p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert image.png -gravity Center -region 10x10-40+20 \ <br/> -negate output.png</span></p>
3244 <p>When used as an option to <a href="../www/composite.html">composite</a>, <a href="#gravity">-gravity</a> gives the direction that the image gravitates within the composite.</p>
3246 <p>When used as an option to <a href="../www/montage.html">montage</a>, <a href="#gravity">-gravity</a> gives the direction that an image gravitates within a tile. The default gravity is <kbd>Center</kbd> for this purpose.</p>
3249 <div style="margin: auto;">
3250 <h4><a name="green-primary" id="green-primary"></a>-green-primary <em class="arg">x,y</em></h4>
3253 <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>
3256 <div style="margin: auto;">
3257 <h4><a name="hald-clut" id="hald-clut"></a>-hald-clut</h4>
3260 <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>
3262 <p>A Hald color lookup table is a 3-dimensional color cube mapped to 2
3263 dimensions. Create it with the <kbd>HALD:</kbd> prefix (e.g. HALD:8). You
3264 can apply any color transformation to the Hald image and then use this option
3265 to apply the transform to the image. </p>
3267 <p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert image.png hald.png -hald-clut transform.png</span></p>
3268 <p>This option provides a convenient method for you to use Gimp or Photoshop
3269 to make color corrections to the Hald CLUT image and subsequently apply them
3270 to multiple images using an ImageMagick script. </p>
3272 <p>Note that the representation is only of the normal RGB color space and that
3273 the whole color value triplet is used for the interpolated lookup of the
3274 represented Hald color cube image. Because of this the operation is not <a
3275 href="#channel" >-channel</a> setting effected, nor can it adjust or modify an
3276 images transparency or alpha/matte channel.</p>
3278 <p>See also <a href="#clut" >-clut</a> which provides color value replacement
3279 of the individual color channels, usally involving a simplier gray-scale
3280 image. E.g: gray-scale to color replacement, or modification by a histogram
3284 <div style="margin: auto;">
3285 <h4><a name="help" id="help"></a>-help</h4>
3288 <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>
3290 <div style="margin: auto;">
3291 <h4><a name="highlight-color" id="highlight-color"></a>-highlight-color <em class="arg">color</em></h4>
3294 <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>
3296 <div style="margin: auto;">
3297 <h4><a name="iconGeometry" id="iconGeometry"></a>-iconGeometry <em class="arg">geometry</em></h4>
3300 <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>
3302 <p>Offsets, if present in the geometry specification, are handled in the same manner as the <a href="#geometry">-geometry</a> option, using X11 style to handle negative offsets.</p>
3304 <p>See <a href="../www/command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
3306 <div style="margin: auto;">
3307 <h4><a name="iconic" id="iconic"></a>-iconic</h4>
3310 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>iconic animation.</td><td style='text-align:right;'></td></tr></table>
3312 <div style="margin: auto;">
3313 <h4><a name="identify" id="identify"></a>-identify</h4>
3316 <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>
3318 <p>This information is printed: image scene number; image name; image size; the image class (<em class="arg">DirectClass</em> or <em class="arg">PseudoClass</em>); the total number of unique colors; and the number of seconds to read and transform the image. Refer to <a href="../www/miff.html">MIFF</a> for a description of the image class.</p>
3320 <p>If <a href="#colors">-colors</a> is also specified, the total unique colors in the image and color reduction error values are printed. Refer to <a href="/www/quantize.html">color reduction algorithm</a> for a description of these values.</p>
3322 <p>If <a href="#verbose">-verbose</a> precedes this option, copious
3323 amounts of image properties are displayed including image statistics, profiles,
3324 image histogram, and others.</p>
3326 <div style="margin: auto;">
3327 <h4><a name="ift" id="ift"></a>-ift</h4>
3330 <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>
3332 <p>This option is new as of ImageMagick 6.5.4-3 (and now working for Windows users in ImageMagick 6.6.0-9). It transforms a pair of magnitude and phase images from the frequency domain to a single image in the normal or spatial domain. See for example, <a href="http://en.wikipedia.org/wiki/Fourier_transform" target="_blank">Fourier Transform</a>, <a href="http://en.wikipedia.org/wiki/DFT" target="_blank">Discrete Fourier Transform</a> and <a href="http://en.wikipedia.org/wiki/FFT" target="_blank">Fast Fourier Transform</a>.</p>
3334 <p>For example, depending upon the image format used to store the result of the <a href="#fft">-fft</a>, one would use either</p>
3336 <p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert fft_image.miff -ift fft_image_ift.png</span></p>
3339 <p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert fft_image-0.png fft_image-1.png -ift fft_image_ift.png</span></p>
3341 <p>The resulting image may need to be cropped due to padding introduced when the original image, prior to the <a href="#fft">-fft</a> or <a href="#fft">+fft</a>, was not square or even dimensioned. Any padding is at the right and/or bottom sides of the image.
3343 <p>The <a href="http://www.fftw.org/" target="_blank">FFTW</a> delegate library is required to use <a href="#ift">-ift</a>.
3345 <p>Use <a href="#ift">+ift</a> (with HDRI enabled) to transform a pair of real and imaginary images from the frequency domain to a single image in the normal (spatial) domain.
3347 <div style="margin: auto;">
3348 <h4><a name="immutable" id="immutable"></a>-immutable</h4>
3351 <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>
3353 <div style="margin: auto;">
3354 <h4><a name="implode" id="implode"></a>-implode <em class="arg">factor</em></h4>
3357 <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>
3359 <div style="margin: auto;">
3360 <h4><a name="insert" id="insert"></a>-insert <em class="arg">index</em></h4>
3363 <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>
3365 <p>This option takes last image in the current image sequence and inserts it at the given index. If a negative index is used, the insert position is calculated before the last image is removed from the sequence. As such <kbd>-insert -1</kbd> will result in no change to the image sequence.</p>
3367 <p>The <kbd>+insert</kbd> option is equivalent to <kbd>-insert -1</kbd>. In other words, insert the last image, at the end of the current image sequence. Consequently this has no effect on the image sequence order.</p>
3369 <div style="margin: auto;">
3370 <h4><a name="intent" id="intent"></a>-intent <em class="arg">type</em></h4>
3373 <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>
3375 <p>Use this option to affect the color management operation of an image (see <a href="#profile">-profile</a>). Choose from these intents: <kbd>Absolute, Perceptual, Relative, Saturation</kbd>.</p>
3377 <p>The default intent is undefined.</p>
3379 <p>To print a complete list of rendering intents, use <a href="#list">-list intent</a>.</p>
3381 <div style="margin: auto;">
3382 <h4><a name="interlace" id="interlace"></a>-interlace <em class="arg">type</em></h4>
3385 <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>
3399 <p>This option is used to specify the type of interlacing scheme for raw image formats such as <kbd>RGB</kbd> or <kbd>YUV</kbd>.</p>
3401 <p><kbd>None</kbd> means do not interlace (RGBRGBRGBRGBRGBRGB...),</p>
3403 <p><kbd>Line</kbd> uses scanline interlacing (RRR...GGG...BBB...RRR...GGG...BBB...), and.</p>
3405 <p><kbd>Plane</kbd> uses plane interlacing (RRRRRR...GGGGGG...BBBBBB...).</p>
3407 <p><kbd>Partition</kbd> is like plane except the different planes are saved to individual files (e.g. image.R,
3408 image.G, and image.B).</p>
3410 <p>Use <kbd>Line</kbd> or <kbd>Plane</kbd> to create an <kbd>interlaced PNG</kbd> or <kbd>GIF</kbd> or <kbd>progressive JPEG</kbd>
3413 <p>To print a complete list of interlacing schemes, use <a href="#list">-list interlace</a>.</p>
3415 <div style="margin: auto;">
3416 <h4><a name="interpolate" id="interpolate"></a>-interpolate <em class="arg">type</em></h4>
3419 <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>
3421 <p>When looking up the color of a pixel using a non-integer floating point
3422 value, you typically fall in between the pixel colors defined by the source
3423 image. This setting determines how the color is determined from the colors of
3424 the pixels surrounding that point. That is how to determine the color of a
3425 point that falls between two, or even four different colored pixels. </p>
3428 integer: The color of the top-left pixel (floor function)
3429 nearest-neighbor: The nearest pixel to the lookup point (rounded function)
3430 average: The average color of the surrounding four pixels
3431 bilinear A double linear interpolation of pixels (the default)
3432 mesh Divide area into two flat triangular interpolations
3433 bicubic Fitted bicubic-spines of surrounding 16 pixels
3434 spline Direct spline curves (colors are blurred)
3435 filter Use resize <a href="#filter">-filter</a> settings
3438 <p>This most important for distortion operators such as <a href="#distort"
3439 >-distort</a>, <a href="#implode" >-implode</a>, <a href="#transform"
3440 >-transform</a> and <a href="#fx" >-fx</a>. </p>
3442 <p>To print a complete list of interpolation methods, use <a href="#list">-list interpolate</a>.</p>
3444 <p>See also <a href="#virtual-pixel" >-virtual-pixel</a>, for control of the
3445 lookup for positions outside the boundaries of the image. </p>
3448 <div style="margin: auto;">
3449 <h4><a name="interline-spacing" id="interline-spacing"></a>-interline-spacing <em class="arg">value</em></h4>
3452 <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>
3454 <div style="margin: auto;">
3455 <h4><a name="interword-spacing" id="interword-spacing"></a>-interword-spacing <em class="arg">value</em></h4>
3458 <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>
3460 <div style="margin: auto;">
3461 <h4><a name="kerning" id="kerning"></a>-kerning <em class="arg">value</em></h4>
3464 <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>
3466 <div style="margin: auto;">
3467 <h4><a name="label" id="label"></a>-label <em class="arg">name</em></h4>
3470 <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>
3472 <p>Use this option to assign a specific label to the image, as it is read in
3473 or created. You can use the <a href="#set" >-set</a> operation to re-assign
3474 a the labels of images already read in. Image formats such as TIFF, PNG,
3475 MIFF, supports saving the label information with the image.</p>
3477 <p>When saving an image to a <em class="arg">PostScript</em> file, any label
3478 assigned to an image is used as a header string to print above the postscript
3481 <p>You can include the image filename, type, width, height, or other image
3482 attribute by embedding special format character. See <a href="../www/escape.html">Format and Print Image
3483 Properties</a> for details of the percent escape codes.</p>
3488 -label "%m:%f %wx%h" bird.miff
3491 <p>assigns an image label of <kbd>MIFF:bird.miff 512x480</kbd> to the
3492 "<kbd>bird.miff</kbd>" image and whose width is 512 and height is 480, as it
3493 is read in. If a <a href="#label">+label</a> option was used instead, any
3494 existing label present in the image would be used. You can remove all labels
3495 from an image by assigning the empty string. </p>
3497 <p>A label is not drawn on the image, but is embedded in the image datastream
3498 via <em>Label</em> tag or similar mechanism. If you want the label to be
3499 visible on the image itself, use the <a href="#draw">-draw</a> option, or
3500 during the final processing in the creation of a image montage.</p>
3502 <p>If the first character of <em class="arg">string</em> is <em
3503 class="arg">@</em>, the image label is read from a file titled by the
3504 remaining characters in the string. Labels in a file are literal, no embedded
3505 formatting characters are recognized.</p>
3508 <div style="margin: auto;">
3509 <h4><a name="lat" 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>
3512 <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>
3514 <p>Adaptively threshold each pixel based on the value of pixels in a
3515 surrounding window. If the current pixel is lighter than this average plus
3516 the optional <kbd>offset</kbd>, then it is made white, otherwise it is made
3517 black. Small variations in pixel values such as found in scanned documents
3518 can be ignored if offset is positive. A negative offset will make it more
3519 sensitive to those small variations. </p>
3521 <p>This is commonly used to threshold images with an uneven background. It is
3522 based on the assumption that average color of the small window is the
3523 the local background color, from which to separate the forground color. </p>
3526 <div style="margin: auto;">
3527 <h4><a name="layers" id="layers"></a>-layers <em class="arg">method</em></h4>
3530 <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>
3532 <p>Perform various image operation methods to a ordered sequence of images
3533 which may represent either a set of overlaid 'image layers', a GIF disposal
3534 animation, or a fully-'coalesced' animation sequence. </p>
3539 <th align="left" style="width: 8%">Method</th>
3540 <th align="left">Description</th>
3544 <td valign="top">compare-any</td>
3545 <td valign="top">Crop the second and later frames to the smallest rectangle
3546 that contains all the differences between the two images. No GIF <a
3547 href="#dispose" >-dispose</a> methods are taken into account. </td>
3550 <tr><td></td><td>This exactly the same as the <a href="#deconstruct"
3551 >-deconstruct</a> operator, and does not preserve animations normal
3552 working, especially when animation used layer disposal methods such as
3553 '<kbd>Previous</kbd>' or '<kbd>Background</kbd>'. </td>
3557 <td valign="top">compare-clear</td>
3558 <td valign="top">As '<kbd>compare-any</kbd>' but crop to the bounds of any
3559 opaque pixels which become transparent in the second frame. That is the
3560 smallest image needed to mask or erase pixels for the next frame. </td>
3564 <td valign="top">compare-overlay</td>
3565 <td valign="top">As '<kbd>compare-any</kbd>' but crop to pixels that add
3566 extra color to the next image, as a result of overlaying color pixels.
3567 That is the smallest single overlaid image to add or change colors. </td>
3570 <tr><td></td><td>This can be used with the <a href="#compose" >-compose</a> alpha
3571 composition method '<kbd>change-mask</kbd>', to reduce the image to
3572 just the pixels that need to be overlaid. </td>
3576 <td valign="top">coalesce</td>
3577 <td valign="top">Equivalent to a call to the <a href="#coalesce"
3578 >-coalesce</a> operator. Apply the layer disposal methods set in the
3579 current image sequence to form a fully defined animation sequence, as
3580 it should be displayed. Effectively converting a GIF animation into a
3581 'film strip'-like animation. </td>
3585 <td valign="top">composite</td>
3586 <td valign="top">Alpha Composition of two image lists, separated by a
3587 "<kbd>null:</kbd>" image, with the destination image list first, and
3588 the source images last. An image from each list are composited
3589 together until one list is finished. The separator image and source
3590 image lists are removed. </td>
3595 <td>The <a href="#geometry" >-geometry</a> offset is adjusted according
3596 to <a href="#gravity" >-gravity</a> in accordance of the virtual
3597 canvas size of the first image in each list. Unlike a normal <a
3598 href="#composite" >-composite</a> operation, the canvas offset is also
3599 added to the final composite positioning of each image. </td> </tr>
3602 <td>If one of the image lists only contains one image, that image is
3603 applied to all the images in the other image list, regardless of which
3604 list it is. In this case it is the image meta-data of the list which
3610 <td valign="top">dispose</td>
3611 <td valign="top">This like '<kbd>coalesce</kbd>' but shows the look of
3612 the animation after the layer disposal method has been applied, before
3613 the next sub-frame image is overlaid. That is the 'dispose' image that
3614 results from the application of the GIF <a href="#dispose"
3615 >-dispose</a> method. This allows you to check what
3616 is going wrong with a particular animation you may be developing.
3621 <td valign="top">flatten</td>
3622 <td valign="top">Create a canvas the size of the first images virtual
3623 canvas using the current <a href="#background" >-background</a> color,
3624 and <a href="#compose" >-compose</a> each image in turn onto that
3625 canvas. Images falling outside that canvas is clipped. Final
3626 image will have a zero virtual canvas offset. </td>
3630 <td>This usally used as one of the final 'image layering' operations
3631 overlaying all the prepared image layers into a final image. </td>
3635 <td>For a single image this method can also be used to fillout a virtual
3636 canvas with real pixels, or to underlay a opaque color to remove
3637 transparency from an image.</td>
3642 <td valign="top">merge</td>
3643 <td valign="top">As 'flatten' method but merging all the given image
3644 layers into a new layer image just large enough to hold all the image
3645 without clipping or extra space. The new images virtual offset will
3646 prevere the position of the new layer, even if this offset is
3647 negative. the virtual canvas size of the first image is preserved.
3651 <tr><td></td><td>Caution is advised when handling image layers with negative offsets
3652 as few image file formats handle them correctly. </td>
3656 <td valign="top">mosaic</td>
3657 <td valign="top">As 'flatten' method but expanding the initial canvas size
3658 of the first image so as to hold all the image layers. However as a
3659 virtual canvas is 'locked' to the origin, by definition, image layers
3660 with a negative offsets will still be clipped by the top and left
3664 <tr><td></td><td>This method is commonly used to layout individual image using various
3665 offset but without knowing the final canvas size. The resulting image
3666 will, like 'flatten' not have any virtual offset, so can be saved to
3667 any image file format. </td>
3672 <td valign="top">optimize</td>
3673 <td valign="top">Optimize a coalesced animation, into GIF animation using
3674 a number of general techniques. This currently a short cut to
3675 apply both the '<kbd>optimize-frame</kbd>', and
3676 '<kbd>optimize-transparency</kbd>' methods but may be expanded to
3677 include other optimization methods as they are developed. </td>
3681 <td valign="top">optimize-frame</td>
3682 <td valign="top">Optimize a coalesced animation, into GIF animation by
3683 reducing the number of pixels per frame as much as possible by
3684 attempting to pick the best layer disposal method to use, while ensuring
3685 the result will continue to animate properly. </td>
3688 <tr><td></td><td> There is no guarantee that the best optimization is found. But
3689 then no reasonably fast GIF optimization algorithm can do this.
3690 However this does seem to do better than most other GIF frame
3691 optimizers seen. </td>
3695 <td valign="top">optimize-plus</td>
3696 <td valign="top">As '<kbd>optimize-frame</kbd>' but attempt to improve the
3697 overall optimization by adding extra frames to the animation, without
3698 changing the final look or timing of the animation. The frames are
3699 added to attempt to separate the clearing of pixels from the
3700 overlaying of new additional pixels from one animation frame to the
3701 next. If this does not improve the optimization (for the next frame
3702 only), it will fall back to the results of the previous normal
3703 '<kbd>optimize-frame</kbd>' technique. </td>
3706 <tr><td></td><td>There is the possibility that the change in the disposal style will
3707 result in a worsening in the optimization of later frames, though this
3708 is unlikely. In other words there no guarantee that it is better than
3709 the normal '<kbd>optimize-frame</kbd>' technique. For some animations
3710 however you can get a vast improvement in the final animation size. </td>
3714 <td valign="top">optimize-transparency</td>
3715 <td valign="top">Given a GIF animation, replace any pixel in the sub-frame
3716 overlay images with transparency, if it does not change the resulting
3717 animation by more than the current <a href="#fuzz" >-fuzz</a> factor.
3721 <tr><td></td><td>This should allow a existing frame optimized GIF animation to compress
3722 into a smaller file size due to larger areas of one (transparent)
3723 color rather than a pattern of multiple colors repeating the current
3724 disposed image of the last frame. </td>
3728 <td valign="top">remove-dups</td>
3729 <td valign="top">Remove (and merge time delays) of duplicate consecutive
3730 images, so as to simplify layer overlays of coalesced animations.
3734 <tr><td></td><td>Usually this a result of using a constant time delay across the
3735 whole animation, or after a larger animation was split into smaller
3736 sub-animations. The duplicate frames could also have been used as
3737 part of some frame optimization methods. </td>
3741 <td valign="top">remove-zero</td>
3742 <td valign="top">Remove any image with a zero time delay, unless ALL the
3743 images have a zero time delay (and is not a proper timed animation, a
3744 warning is then issued). </td>
3747 <tr><td></td><td>In a GIF animation, such images are usually frames which provide
3748 partial intermediary updates between the frames that are actually
3749 displayed to users. These frames are usally added for improved frame
3750 optimization in GIF animations. </td>
3754 <td valign="top">trim-bounds</td>
3755 <td valign="top">Find the bounds of all the images in the current
3756 image sequence, then adjust the offsets so all images are contained on
3757 a minimal positive canvas. None of the image data is modified, only
3758 there virtual canvas size and offset. The all the image is given
3759 the same canvas size, and and will have a positive offset, but will
3760 remain in the same position relative to each other. As a result of the
3761 minimal canvas size at least one image will touch every edge of that
3762 canvas. The image data however may be transparent.
3769 <p>To print a complete list of layer types, use <a href="#list">-list layers</a>.</p>
3771 <p>The operators <a href="#coalesce" >-coalesce</a>, <a href="#deconstruct"
3772 >-deconstruct</a>, <a href="#flatten" >-flatten</a>, and <a href="#mosaic"
3773 >-mosaic</a> are only aliases for the above methods. Also see <a
3774 href="#page" >-page</a>, <a href="#repage" >-repage</a> operators, the <a
3775 href="#compose" >-compose</a> setting, and the GIF <a href="#dispose"
3776 >-dispose</a> and <a href="#delay" >-delay</a> settings. </p>
3779 <div style="margin: auto;">
3780 <h4><a name="level" 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>
3783 <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>
3785 <p>Given one, two or three values delimited with commas: black-point,
3786 white-point, gamma (for example: 10,250,1.0 or 2%,98%,0.5). The black and
3787 white points range from 0 to <em class="QR">QuantumRange</em>, or from 0 to 100%; if the white
3788 point is omitted it is set to (<em class="QR">QuantumRange</em> - black_point), so as to center
3789 contrast changes. If a <kbd>%</kbd> sign is present anywhere in the string,
3790 both black and white points are percentages of the full color range. Gamma
3791 will do a <a href="#gamma">-gamma</a> adjustment of the values. If it is
3792 omitted, the default of 1.0 (no gamma correction) is assumed.</p>
3794 <p>In normal usage (<kbd>-level</kbd>) the image values are stretched so that
3795 the given '<kbd>black_point</kbd>' value in the original image is set to
3796 zero (or black), while the given '<kbd>white_point</kbd>' value is set to
3797 <em class="QR">QuantumRange</em> (or white). This provides you with direct contrast adjustments
3798 to the image. The '<kbd>gamma</kbd>' of the resulting image will then be
3801 <p>From ImageMagick v6.4.1-9 using the plus form of the operator (<kbd>+level</kbd>) or
3802 adding the special '!' flag anywhere in the argument list, will cause the
3803 operator to do the reverse of the level adjustment. That is a zero, or
3804 <em class="QR">QuantumRange</em> value (black, and white, resp.) in the original image, is
3805 adjusted to the given level values, allowing you to de-contrast, or compress
3806 the channel values within the image. The '<kbd>gamma</kbd>' is adjusted before the level adjustment to de-contrast the image is made. </p>
3808 <p>Only the channels defined by the current <a href="#channel">-channel</a>
3809 setting are adjusted (defaults to RGB color channels only), allowing you to
3810 limit the effect of this operator. </p>
3812 <p>Please note that the transparency channel is treated as 'matte'
3813 values (0 is opaque) and not as 'alpha' values (0 is transparent).</p>
3816 <div style="margin: auto;">
3817 <h4><a name="level-colors" id="level-colors"></a>-level-colors {<em
3818 class="arg">black_color</em>}{,}{<em class="arg">white_color</em>}</h4>
3821 <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>
3823 <p>This function is exactly like <a href="#level">-level</a>, except that the
3824 value value for each color channel is determined by the
3825 '<kbd>black_color</kbd>' and '<kbd>white_color</kbd>' colors given (as
3826 described under the <a href="#fill">-fill</a> option). </p>
3828 <p>This effectually means the colors provided to <kbd>-level-colors</kbd>
3829 is mapped to become 'black' and 'white' respectively, with all the other
3830 colors linearly adjusted (or clipped) to match that change. Each channel is
3831 adjusted separately using the channel values of the colors specified. </p>
3833 <p>On the other hand the plus form of the operator (<kbd>+level-colors</kbd>)
3834 will map the image color 'black' and 'white' to the given colors
3835 respectively, resulting in a gradient (de-contrasting) tint of the image to
3836 those colors. This can also be used to convert a plain gray-scale image into a
3837 one using the gradient of colors specified. </p>
3839 <p>By supplying a single color with a comma separator either before or after
3840 that color, will just replace the respective 'black' or 'white' point
3841 respectively. But if no comma separator is provided, the given color is
3842 used for both the black and white color points, making the operator either
3843 threshold the images around that color (- form) or set all colors to that
3844 color (+ form). </p>
3847 <div style="margin: auto;">
3848 <h4><a name="limit" id="limit"></a>-limit <em class="arg">type value</em></h4>
3851 <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>
3853 <p>Choose from: <kbd>area</kbd>, <kbd>disk</kbd>, <kbd>file</kbd>, <kbd>map</kbd>, <kbd>memory</kbd>, <kbd>threads</kbd>, or <kbd>time</kbd>.</p>
3855 <p>The value for <kbd>file</kbd> is in number of files. The other limits are in bytes. By default the limits are 768 files, 2GB of image area, 1.5GiB memory, 8GiB memory map, and 18.45EB of disk. These limits are adjusted relative to the available resources on your computer if this information is available. When any limit is reached, ImageMagick fails in some fashion but attempts to take compensating actions, if possible. For example, the following limits memory:</p>
3858 -limit memory 32MiB -limit map 64MiB
3861 <p>Use <a href="#list">-list resource</a> to list the current limits. For example, our system shows these limits:</p>
3863 <p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>identify -list resource</span><span class='crtout'><pre>File Area Memory Map Disk Thread Time
3864 ------------------------------------------------------------------------------
3865 768 12.404GB 8.6642GiB 23.104GiB 18.446744EB 8 unlimited</pre>
3867 <p>Requests for pixel storage to keep intermediate images are satisfied by one of three resource categories: in-memory pool, memory-mapped files pool, and disk pool (in that order) depending on the <a href="../www/command-line-options.html#limit">‑limit</a> settings and whether the system honors a resource request. If the total size of allocated pixel storage in the given pool reaches the corresponding limit, the request is passed to the next pool. Additionally, requests that exceed the <kbd>area</kbd> limit automagically are allocated on disk.</p>
3869 <p>To illustrate how ImageMagick utilizes resource limits, consider a typical image resource request. First, ImageMagick tries to allocate the pixels in memory. The request might be denied if the resource request exceeds the <kbd>memory</kbd> limit or if the system does not honor the request. If a memory request is not honored, the pixels are allocated to disk and the file is memory-mapped. However, if the allocation request exceeds the <kbd>map</kbd> limit, the resource allocation goes to disk. In all cases, if the resource request exceeds the <kbd>area</kbd> limit, the pixels are automagically cached to disk. If the disk has a hard limit, the program fails.</p>
3871 <p>In most cases you simply do not need to concern yourself with resource limits. ImageMagick chooses reasonable defaults and most images do not tax your computer resources. Where limits do come in handy is when you process images that are large or on shared systems where ImageMagick can consume all or most of the available memory. In this case, the ImageMagick workflow slows other processes or, in extreme cases, brings the system to a halt. Under these circumstances, setting limits give some assurances that the ImageMagick workflow will not interfere with other concurrent uses of the computer. For example, assume you have a web interface that processes images uploaded from the Internet. To assure ImageMagick does not exceed 10mb of memory you can simply set the area limit to 10mb:</p>
3877 <p>Now whenever a large image is processed, the pixels are automagically cached to disk instead of memory. This of course implies that large images typically process very slowly, simply because pixel processing in memory can be an order of magnitude faster than on disk. Because your web site users might inadvertently upload a huge image to process, you should set a disk limit as well:</p>
3880 -limit area 10mb -limit disk 500mb
3883 <p>Here ImageMagick stops processing if an image requires more than 500MB of disk storage.</p>
3885 <p>In addition to command-line resource limit option, resources can be set with <a href="../www/resources.html#environment">environment variables</a>. Set the environment variables <kbd>MAGICK_AREA_LIMIT</kbd>, <kbd>MAGICK_DISK_LIMIT</kbd>, <kbd>MAGICK_FILE_LIMIT</kbd>, <kbd>MAGICK_MEMORY_LIMIT</kbd>, <kbd>MAGICK_MAP_LIMIT</kbd>, <kbd>MAGICK_THREAD_LIMIT</kbd>, <kbd>MAGICK_TIME_LIMIT</kbd> for limits of image area, disk space, open files, heap memory, memory map, number of threads of execution, and maximum elapsed time in seconds respectively.</p>
3887 <p> Inquisitive users can try adding <a href="#debug">-debug cache</a> to their commands and then scouring the generated output for references to the pixel cache, in order to determine how the pixel cache was allocated and how resources were consumed. Advanced Unix/Linux users can pipe that output through <kbd>grep memory|open|destroy|disk</kbd> for more readable sifting.
3890 <p>For more about ImageMagick's use of resources, see the section <b>Cache Storage and Resource Requirements</b> on the <a href="../www/architecture.html#cache">Architecture</a> page.
3893 <div style="margin: auto;">
3894 <h4><a name="linear-stretch" 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>
3897 <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>
3899 <p>This is very similar to <a href="#contrast-stretch" >-contrast-stretch</a>,
3900 and uses a 'histogram bin' to determine the range of color values that needs to
3901 be stretched. However it then stretchs those colors using the <a
3902 href="#level" >-level</a> operator.</p>
3904 <p>As such while the initial determination may have 'binning' round off
3905 effects, the image colors are stretched mathematically, rather than using the
3906 histogram bins. This makes the operator more accurate. </p>
3908 <p>note however that a <a href="#linear-stretch" >-linear-stretch</a> of
3909 '<kbd>0</kbd>' does nothing, while a value of '<kbd>1</kbd>' does a near
3910 perfect stretch of the color range. </p>
3912 <p>See also <a href="#auto-level" >-auto-level</a> for a 'perfect'
3913 normalization of mathematical images. </p>
3915 <p>This operator is under review for re-development. </p>
3918 <div style="margin: auto;">
3919 <h4><a name="linewidth" id="linewidth"></a>-linewidth</h4>
3922 <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>
3924 <div style="margin: auto;">
3925 <h4><a name="liquid-rescale" id="liquid-rescale"></a>-liquid-rescale <em class="arg">geometry</em></h4>
3928 <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>
3930 <p>See <a href="../www/command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
3932 <div style="margin: auto;">
3933 <h4><a name="list" id="list"></a>-list <em class="arg">type</em></h4>
3936 <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>
4007 <p>These lists vary depending on your version of ImageMagick. Use "<kbd>-list
4008 list</kbd>" to get a complete listing of all the "<kbd>-list</kbd>" arguments
4011 <p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>identify -list list</span></p>
4012 <div style="margin: auto;">
4013 <h4><a name="log" id="log"></a>-log <em class="arg">string</em></h4>
4016 <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>
4018 <p>This option specifies the format for the log printed when the <a
4019 href="#debug">-debug</a> option is active.</p>
4021 <p>You can display the following components by embedding special format
4041 <p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert -debug coders -log "%u %m:%l %e" in.gif out.png</span></p>
4042 <p>The default behavior is to print all of the components.</p>
4044 <div style="margin: auto;">
4045 <h4><a name="loop" id="loop"></a>-loop <em class="arg">iterations</em></h4>
4048 <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>
4050 <p>Set iterations to zero to repeat the animation an infinite number of times,
4051 otherwise the animation repeats itself up to <em class="arg">iterations</em>
4054 <div style="margin: auto;">
4055 <h4><a name="lowlight-color" id="lowlight-color"></a>-lowlight-color <em class="arg">color</em></h4>
4058 <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>
4060 <div style="margin: auto;">
4061 <h4><a name="magnify" id="magnify"></a>-magnify <em class="arg">factor</em></h4>
4064 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>magnify the image.</td><td style='text-align:right;'></td></tr></table>
4067 <div style="margin: auto;">
4068 <h4><a name="map" id="map"></a>-map <em class="arg">type</em></h4>
4071 <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="../www/animate.html">animate</a>, <a href="../www/display.html">display</a>]</td></tr></table>
4073 <p>Choose from these <em class="arg">Standard Colormap</em> types:</p>
4084 <p>The <em class="arg">X server</em> must support the <em class="arg">Standard
4085 Colormap</em> you choose, otherwise an error occurs. Use <kbd>list</kbd> as
4086 the type and <kbd>display</kbd> searches the list of colormap types in
4087 <kbd>top-to-bottom</kbd> order until one is located. See <em
4088 class="arg">xstdcmap(1)</em> for one way of creating Standard Colormaps.</p>
4091 <div style="margin: auto;">
4092 <h4><a name="map_stream_" id="map_stream_"></a>-map <em class="arg">components</em></h4>
4095 <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="../www/stream.html">stream</a>]</td></tr></table>
4097 <p>Here are the valid components of a map:</p>
4100 r red pixel component
4101 g green pixel component
4102 b blue pixel component
4103 a alpha pixel component (0 is transparent)
4104 o opacity pixel component (0 is opaque)
4105 i grayscale intensity pixel component
4106 c cyan pixel component
4107 m magenta pixel component
4108 y yellow pixel component
4109 k black pixel component
4110 p pad component (always 0)
4113 <p>You can specify as many of these components as needed in any order (e.g.
4114 bgr). The components can repeat as well (e.g. rgbr).</p>
4117 <div style="margin: auto;">
4118 <h4><a name="mask" id="mask"></a>-mask
4119 <em class="arg">filename</em></h4>
4122 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Composite the image pixels as defined by the mask.</td><td style='text-align:right;'></td></tr></table>
4124 <p>Use <a href="#mask">+mask</a> to remove the image mask.</p>
4126 <div style="margin: auto;">
4127 <h4><a name="mattecolor" id="mattecolor"></a>-mattecolor <em class="arg">color</em></h4>
4130 <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="#frame">-frame</a> option.</td><td style='text-align:right;'></td></tr></table>
4132 <p>The color is specified using the format described under the <a href="#fill">-fill</a> option.</p>
4134 <p>The default matte color is <kbd>#BDBDBD</kbd>, <span
4135 style="background-color: #bdbdbd;">this shade of gray</span>.</p>
4137 <div style="margin: auto;">
4138 <h4><a name="maximum" id="maximum"></a>-maximum</h4>
4141 <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>
4143 <div style="margin: auto;">
4144 <h4><a name="median" id="median"></a>-median <em class="arg">radius</em></h4>
4147 <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>
4149 <div style="margin: auto;">
4150 <h4><a name="metric" id="metric"></a>-metric <em class="arg">type</em></h4>
4153 <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>
4158 AE absolute error count, number of different pixels (-fuzz effected)
4159 MAE mean absolute error (normalized), average channel error distance
4160 MEPP mean error per pixel (normalized mean error, normalized peak error)
4161 MSE mean error squared, average of the channel error squared
4162 NCC normalized cross correlation
4163 PAE peak absolute (normalize peak absolute)
4164 PSNR peak signal to noise ratio
4165 RMSE root mean squared (normalized root mean squared)
4168 <p>Control the '<kbd>AE</kbd>', or absolute count of pixels that are different,
4169 with the <a href="#fuzz" >-fuzz</a> factor (ignore pixels which
4170 only changed by a small amount). Use '<kbd>PAE</kbd>' to find the
4171 size of the <a href="#fuzz" >-fuzz</a> factor needed to make all pixels
4172 'similar', while '<kbd>MAE</kbd>' dtermines the factor needed
4173 for about half the pixels to be similar. </p>
4175 <p>The '<kbd>MEPP</kbd>' metric returns three different metrics
4176 ('<kbd>MAE</kbd>', '<kbd>MAE</kbd>' normalized, and '<kbd>PAE</kbd>'
4177 normalized) from a single comparison run. </p>
4179 <p>To print a complete list of metrics, use the <a href="#list">-list
4180 metrics</a> option.</p>
4183 <div style="margin: auto;">
4184 <h4><a name="minimum" id="minimum"></a>-minimum</h4>
4187 <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>
4190 <div style="margin: auto;">
4191 <h4><a name="mode" id="mode"></a>-mode <em class="arg">value</em></h4>
4194 <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="../www/montage.html">montage</a>]</td></tr></table>
4196 <p>Choose the <em class="arg">value</em> from these styles: <kbd>Frame,
4197 Unframe, or Concatenate</kbd></p>
4199 <p>Use the <a href="#list" >-list</a> option with a '<kbd>Mode</kbd>' argument
4200 for a list of <a href="#mode" >-mode</a> arguments available in your
4201 ImageMagick installation.</p>
4204 <div style="margin: auto;">
4205 <h4><a name="modulate" id="modulate"></a>-modulate <em class="arg">brightness</em>[,<em class="arg">saturation</em>,<em class="arg">hue</em>]</h4>
4208 <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
4209 class="arg">saturation</em>, and <em class="arg">hue</em> of an image.</td><td style='text-align:right;'></td></tr></table>
4211 <p>The arguments are given as a percentages of variation. A value of 100 means
4212 no change, and any missing values are taken to mean 100.</p>
4214 <p>The <em class="arg">brightness</em> is a multiplier of the overall
4215 brightness of the image, so 0 means pure black, 50 is half as bright, 200 is
4216 twice as bright. To invert its meaning <a href="#negate">-negate</a> the image
4217 before and after. </p>
4219 <p>The <em class="arg">saturation</em> controls the amount of color in an
4220 image. For example, 0 produce a grayscale image, while a large value such as
4221 200 produce a very colorful, 'cartoonish' color.</p>
4223 <p>The <em class="arg">hue</em> argument causes a "rotation" of the colors
4224 within the image by the amount specified. For example, 50 results in
4225 a counter-clockwise rotation of 90, mapping red shades to purple, and so on.
4226 A value of either 0 or 200 results in a complete 180 degree rotation of the
4227 image. Using a value of 300 is a 360 degree rotation resulting in no change to
4228 the original image. </p>
4230 <p>For example, to increase the color brightness by 20% and decrease the color
4231 saturation by 10% and leave the hue unchanged, use <a
4232 href="#modulate">-modulate 120,90</a>.</p>
4234 <p>Use <a href="#set">-set</a> attribute of '<kbd
4235 class="arg">option:modulate:colorspace</kbd>' to specify which colorspace to
4236 modulate. Choose from <kbd>HSB</kbd>, <kbd>HSL</kbd> (the default), or
4237 <kbd>HWB</kbd>. For example,</p>
4239 <p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert image.png -set option:modulate:colorspace hsb -modulate 120,90 modulate.png</span></p>
4241 <div style="margin: auto;">
4242 <h4><a name="monitor" id="monitor"></a>-monitor</h4>
4245 <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>
4248 <div style="margin: auto;">
4249 <h4><a name="monochrome" id="monochrome"></a>-monochrome</h4>
4252 <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>
4255 <div style="margin: auto;">
4256 <h4><a name="morph" id="morph"></a>-morph <em class="arg">frames</em></h4>
4259 <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>
4261 <p>Both the image pixels and size are linearly interpolated to give the
4262 appearance of a meta-morphosis from one image to the next, over all the images
4263 in the current image list. The added images are the equivalent of a <a
4264 href="#blend">-blend</a> composition. The <em class="arg">frames</em>
4265 argument determine how many images to interpolate between each image. </p>
4268 <div style="margin: auto;">
4269 <h4><a name="morphology" id="morphology"></a>-morphology</h4>
4270 <h4><a name="morphology" id="morphology"></a>-morphology <em class="arg">method</em> <em class="arg">kernel</em></h4>
4273 <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>
4275 Until I get around to writing a option summary for this, see <A
4276 HREF="http://www.imagemagick.org/Usage/morphology/" >IM Usage Examples,
4277 Morphology</A>. </P>
4280 <div style="margin: auto;">
4281 <h4><a name="mosaic" id="mosaic"></a>-mosaic</h4>
4284 <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="#layers" >-layers</a> method "mosaic"</td><td style='text-align:right;'></td></tr></table>
4287 <div style="margin: auto;">
4288 <h4><a name="motion-blur" 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></h4>
4291 <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>
4293 <p>Blur with the given radius, standard deviation (sigma), and angle. The
4294 angle given is the angle toward which the image is blurred. That is the
4295 direction people would consider the object is coming from. </p>
4297 <p>Note that the blur is not uniform distribution, giving the motion a
4298 definite sense of direction of movement. </p>
4300 <p>The <a href="#virtual-pixel">-virtual-pixel</a> setting will determine how
4301 pixels which are outside the image proper are blurred into the final result.
4304 <div style="margin: auto;">
4305 <h4><a name="name" id="name"></a>-name</h4>
4308 <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>
4309 <div style="margin: auto;">
4310 <h4><a name="negate" id="negate"></a>-negate</h4>
4313 <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>
4315 <p>The red, green, and blue intensities of an image are negated. White becomes black, yellow becomes blue, etc. Use <a href="#negate">+negate</a> to only negate the grayscale pixels of the image.</p>
4317 <div style="margin: auto;">
4318 <h4><a name="noise" id="noise"></a>-noise <em class="arg">radius</em><br/>
4319 +noise <em class="arg">type</em></h4>
4322 <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>
4324 <p>The principal function of noise peak elimination filter is to smooth the objects within an image without losing edge information and without creating undesired structures. The central idea of the algorithm is to replace a pixel with its next neighbor in value within a pixel window, if this pixel has been found to be noise. A pixel is defined as noise if and only if this pixel is a maximum or minimum within the pixel window.</p>
4326 <p>Use <kbd><a href="#noise">-noise</a> <em class="arg">radius</em></kbd> to specify the width of the neighborhood when reducing noise.</p>
4328 <p>Use <a href="#noise">+noise</a> followed by a noise <em class="arg">type</em> to add noise to an image. Choose from these noise types:</p>
4340 <p>To print a complete list of noises, use the <a href="#list">-list noise</a> option.</p>
4342 <p>Also see the <a href="#evaluate">-evaluate</a> noise functions that allos
4343 the use of a controlling value to specify teh amount of noise that should be
4344 added to an image. </p>
4347 <div style="margin: auto;">
4348 <h4><a name="normalize" id="normalize"></a>-normalize</h4>
4351 <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>
4353 <p>The intensity values are stretched to cover the entire range of possible
4354 values. While doing so, black-out at most <em>2%</em> of the pixels and
4355 white-out at most <em>1%</em> of the pixels.</p>
4357 <p>Note that as of ImageMagick 6.4.7-0, <a href="#normalize" >-normalize</a>
4358 is equivalent to <a href="#contrast-stretch" >-contrast-stretch 2%x1%</a>.
4359 (Before this version, it was equivalent to <a href="#contrast-stretch"
4360 >-contrast-stretch 2%x99%</a>).</p>
4362 <p>All the channels are normalized in concert by the came amount so as to
4363 preserve color integrity, when the default <a href="#channel" >+channel</a>
4364 setting is in use. Specifying any other <a href="#channel" >-channel</a>
4365 setting will normalize the RGB channels independently.</p>
4367 <p>See <a href="#contrast-stretch" >-contrast-stretch</A> for more details.
4368 Also see <a href="#auto-level" >-auto-level</a> for a 'perfect' normalization
4369 that is better suited to mathematically generated images. </p>
4371 <p>This operator is under review for re-development. </p>
4374 <div style="margin: auto;">
4375 <h4><a name="ordered-dither" id="ordered-dither"></a>-ordered-dither <em class="arg">threshold_map</em>{,<em class="arg">level</em>...}</h4>
4378 <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
4379 class="arg">threshold map</em> specified, and a uniform color map with the
4380 given number of <em class="arg">levels</em> per color channel . </td><td style='text-align:right;'></td></tr></table>
4382 <p>You can choose from these standard threshold maps:</p>
4385 threshold 1x1 Threshold 1x1 (non-dither)
4386 checks 2x1 Checkerboard 2x1 (dither)
4387 o2x2 2x2 Ordered 2x2 (dispersed)
4388 o3x3 3x3 Ordered 3x3 (dispersed)
4389 o4x4 4x4 Ordered 4x4 (dispersed)
4390 o8x8 8x8 Ordered 8x8 (dispersed)
4391 h4x4a 4x1 Halftone 4x4 (angled)
4392 h6x6a 6x1 Halftone 6x6 (angled)
4393 h8x8a 8x1 Halftone 8x8 (angled)
4394 h4x4o Halftone 4x4 (orthogonal)
4395 h6x6o Halftone 6x6 (orthogonal)
4396 h8x8o Halftone 8x8 (orthogonal)
4397 h16x16o Halftone 16x16 (orthogonal)
4398 c5x5b c5x5 Circles 5x5 (black)
4399 c5x5w Circles 5x5 (white)
4400 c6x6b c6x6 Circles 6x6 (black)
4401 c6x6w Circles 6x6 (white)
4402 c7x7b c7x7 Circles 7x7 (black)
4403 c7x7w Circles 7x7 (white)
4406 <p> The <kbd>checks</kbd> pattern produces a 3 level checkerbord dither
4407 pattern. Or you can define your own <em class="arg" >threshold map</em> in a
4408 personal or system <kbd>thresholds.xml</kbd> XML file. </p>
4410 <p>To print a complete list of threshold, use the <a href="#list" >-list
4411 threshold</a> option.</p>
4413 <p>It is recommended that the <a href="#map" >+map</a> operator be used after
4414 applying <a href="#ordered-dither" >-ordered-dither</a> to reduce the number of
4415 colors an animated image sequence, to less that 256 colors. This ensures that
4416 a common or global color table is used when saving the result to a color
4417 limited file format such as GIF. </p>
4419 <p>Note that at this time the exact same threshold dithering map is used for
4420 all color channels, no attempt is made to offset or rotate the map for
4421 different channels is made, to create an offset printing effect. (possible
4422 future expansion) </p>
4425 <div style="margin: auto;">
4426 <h4><a name="opaque" id="opaque"></a>-opaque <em class="arg">color</em></h4>
4429 <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>
4431 <p>The <em class="arg">color</em> argument is defined using the format
4432 described under the <a href="#fill" >-fill</a> option. The <a href="#fuzz"
4433 >-fuzz</a> setting can be used to match and replace colors similar to the one
4436 <p>Use <a href="#opaque">+opaque</a> to paint any pixel that does not match
4437 the target color. </p>
4439 <p>The <a href="#transparent">-transparent</a> operator is exactly the same
4440 as <a href="#opaque" >-opaque</a> but replaces the matching color with
4441 transparency rather than the current <a href="#fill">-fill</a> color setting.
4442 To ensure that it can do this it also ensures that the image has an alpha
4443 channel enabled, as per "<kbd><a href="#alpha" >-alpha</a> set</kbd>", for
4444 the new transparent colors, and does not require you to modify the <a
4445 href="#channel">-channel</a> to enable alpha channel handling. </p>
4448 <div style="margin: auto;">
4449 <h4><a name="orient" id="orient"></a>-orient <em class="arg">image orientation</em></h4>
4452 <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>
4454 <p>Choose from these orientations:</p>
4468 <p>To print a complete list of orientations, use the <a href="#list" >-list
4469 orientation</a> option.</p>
4472 <div style="margin: auto;">
4473 <h4><a name="page" id="page"></a>-page <em class="arg">geometry</em><br/>
4474 -page <em class="arg">media</em>[<em class="arg">offset</em>][{<em class="arg">^!<></em>}]<br/>
4479 <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>
4481 <p>See <a href="../www/command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
4483 <p>For convenience you can specify the page size using <em class="arg">media</em> (see below). Offsets can then be added as with other <em class="arg">geometry</em> arguments (e.g. <a href="#page">-page</a> <kbd>Letter+43+43</kbd>).</p>
4485 <p>Use <em class="arg">media</em> as shorthand to specify the dimensions (<em class="arg">width</em>x<em class="arg">height</em>) of the <em class="arg">PostScript</em> page in dots per inch or a TEXT page in pixels. The choices for a PostScript page are:</p>
4486 <table id="geometryTable" cellpadding="2" cellspacing="0" border="1" width="50%" style="margin-left: auto; margin-right: auto;">
4489 <th align="center"><em class="arg">media</em></th>
4490 <th align="center"><em class="arg">width</em></th>
4491 <th align="center"><em class="arg">height</em></th>
4495 <tr><td align="left"> 11x17 </td> <td align="right"> 792</td> <td align="right"> 1224</td> </tr>
4496 <tr><td align="left"> Ledger </td> <td align="right"> 1224</td> <td align="right"> 792</td> </tr>
4497 <tr><td align="left"> Legal </td> <td align="right"> 612</td> <td align="right"> 1008</td> </tr>
4498 <tr><td align="left"> Letter </td> <td align="right"> 612</td> <td align="right"> 792</td> </tr>
4499 <tr><td align="left"> LetterSmall</td> <td align="right"> 612</td> <td align="right"> 792</td> </tr>
4500 <tr><td align="left"> ArchE </td> <td align="right"> 2592</td> <td align="right"> 3456</td> </tr>
4501 <tr><td align="left"> ArchD </td> <td align="right"> 1728</td> <td align="right"> 2592</td> </tr>
4502 <tr><td align="left"> ArchC </td> <td align="right"> 1296</td> <td align="right"> 1728</td> </tr>
4503 <tr><td align="left"> ArchB </td> <td align="right"> 864</td> <td align="right"> 1296</td> </tr>
4504 <tr><td align="left"> ArchA </td> <td align="right"> 648</td> <td align="right"> 864</td> </tr>
4505 <tr><td align="left"> A0 </td> <td align="right"> 2380</td> <td align="right"> 3368</td> </tr>
4506 <tr><td align="left"> A1 </td> <td align="right"> 1684</td> <td align="right"> 2380</td> </tr>
4507 <tr><td align="left"> A2 </td> <td align="right"> 1190</td> <td align="right"> 1684</td> </tr>
4508 <tr><td align="left"> A3 </td> <td align="right"> 842</td> <td align="right"> 1190</td> </tr>
4509 <tr><td align="left"> A4 </td> <td align="right"> 595</td> <td align="right"> 842</td> </tr>
4510 <tr><td align="left"> A4Small </td> <td align="right"> 595</td> <td align="right"> 842</td> </tr>
4511 <tr><td align="left"> A5 </td> <td align="right"> 421</td> <td align="right"> 595</td> </tr>
4512 <tr><td align="left"> A6 </td> <td align="right"> 297</td> <td align="right"> 421</td> </tr>
4513 <tr><td align="left"> A7 </td> <td align="right"> 210</td> <td align="right"> 297</td> </tr>
4514 <tr><td align="left"> A8 </td> <td align="right"> 148</td> <td align="right"> 210</td> </tr>
4515 <tr><td align="left"> A9 </td> <td align="right"> 105</td> <td align="right"> 148</td> </tr>
4516 <tr><td align="left"> A10 </td> <td align="right"> 74</td> <td align="right"> 105</td> </tr>
4517 <tr><td align="left"> B0 </td> <td align="right"> 2836</td> <td align="right"> 4008</td> </tr>
4518 <tr><td align="left"> B1 </td> <td align="right"> 2004</td> <td align="right"> 2836</td> </tr>
4519 <tr><td align="left"> B2 </td> <td align="right"> 1418</td> <td align="right"> 2004</td> </tr>
4520 <tr><td align="left"> B3 </td> <td align="right"> 1002</td> <td align="right"> 1418</td> </tr>
4521 <tr><td align="left"> B4 </td> <td align="right"> 709</td> <td align="right"> 1002</td> </tr>
4522 <tr><td align="left"> B5 </td> <td align="right"> 501</td> <td align="right"> 709</td> </tr>
4523 <tr><td align="left"> C0 </td> <td align="right"> 2600</td> <td align="right"> 3677</td> </tr>
4524 <tr><td align="left"> C1 </td> <td align="right"> 1837</td> <td align="right"> 2600</td> </tr>
4525 <tr><td align="left"> C2 </td> <td align="right"> 1298</td> <td align="right"> 1837</td> </tr>
4526 <tr><td align="left"> C3 </td> <td align="right"> 918</td> <td align="right"> 1298</td> </tr>
4527 <tr><td align="left"> C4 </td> <td align="right"> 649</td> <td align="right"> 918</td> </tr>
4528 <tr><td align="left"> C5 </td> <td align="right"> 459</td> <td align="right"> 649</td> </tr>
4529 <tr><td align="left"> C6 </td> <td align="right"> 323</td> <td align="right"> 459</td> </tr>
4530 <tr><td align="left"> Flsa </td> <td align="right"> 612</td> <td align="right"> 936</td> </tr>
4531 <tr><td align="left"> Flse </td> <td align="right"> 612</td> <td align="right"> 936</td> </tr>
4532 <tr><td align="left"> HalfLetter </td> <td align="right"> 396</td> <td align="right"> 612</td> </tr>
4539 <p>This option is also used to place subimages when writing to a multi-image format that supports offsets, such as GIF89 and MNG. When used for this purpose the offsets are always measured from the top left corner of the canvas and are not affected by the <a href="#gravity">-gravity</a> option. To position a GIF or MNG image, use <a href="#page">-page</a><em class="arg">{+-}x{+-}y</em> (e.g. -page +100+200). When writing to a MNG file, a <a href="#page">-page</a> option appearing ahead of the first image in the sequence with nonzero width and height defines the width and height values that are written in the <kbd>MHDR</kbd> chunk. Otherwise, the MNG width and height are computed from the bounding box that contains all images in the sequence. When writing a GIF89 file, only the bounding box method is used to determine its dimensions.</p>
4541 <p>For a PostScript page, the image is sized as in <a href="#geometry">-geometry</a> but positioned relative to the <em>lower left-hand corner</em> of the page by {+-}<kbd>x</kbd><em class="arg">offset</em>{+-}<kbd>y</kbd> <em class="arg">offset</em>. Use <a href="#page">-page 612x792</a>, for example, to center the image within the page. If the image size exceeds the PostScript page, it is reduced to fit the page. The default gravity for the <a href="#page">-page</a> option is <em class="arg">NorthWest</em>, i.e., positive <kbd>x</kbd> and <kbd>y</kbd> <em class="arg">offset</em> are measured rightward and downward from the top left corner of the page, unless the <a href="#gravity">-gravity</a> option is present with a value other than <em class="arg">NorthWest</em>.</p>
4543 <p>The default page dimensions for a TEXT image is 612x792.</p>
4545 <p>This option is used in concert with <a href="#density">-density</a>.</p>
4547 <p>Use <a href="#page">+page</a> to remove the page settings for an image.</p>
4549 <div style="margin: auto;">
4550 <h4><a name="paint" id="paint"></a>-paint <em class="arg">radius</em></h4>
4553 <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>
4555 <p>Each pixel is replaced by the most frequent color in a circular neighborhood whose width is specified with <em class="arg">radius</em>.</p>
4557 <div style="margin: auto;">
4558 <h4><a name="path" id="path"></a>-path <em class="arg">path</em></h4></div>
4560 <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>
4562 <div style="margin: auto;">
4563 <h4><a name="pause_animate_" id="pause_animate_"></a>-pause <em class="arg">seconds</em></h4>
4566 <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="../www/animate.html">animate</a>]</td></tr></table>
4568 <p>Pause for the specified number of seconds before repeating the animation.</p>
4570 <div style="margin: auto;">
4571 <h4><a name="pause_import_" id="pause_import_"></a>-pause <em class="arg">seconds</em></h4>
4574 <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="../www/import.html">import</a>]</td></tr></table>
4576 <p>Pause for the specified number of seconds before taking the next snapshot.</p>
4578 <div style="margin: auto;">
4579 <h4><a name="ping" id="ping"></a>-ping</h4>
4582 <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>
4584 <div style="margin: auto;">
4585 <h4><a name="pointsize" id="pointsize"></a>-pointsize <em class="arg">value</em></h4>
4588 <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>
4590 <div style="margin: auto;">
4591 <h4><a name="polaroid" id="polaroid"></a>-polaroid <em class="arg">angle</em></h4>
4594 <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>
4596 <p>Use <kbd>+polaroid</kbd> to rotate the image at a random angle between -15 and +15 degrees.</p>
4598 <div style="margin: auto;">
4599 <h4><a name="posterize" id="posterize"></a>-posterize <em class="arg">levels</em></h4>
4602 <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.</td><td style='text-align:right;'></td></tr></table>
4604 <div style="margin: auto;">
4605 <h4><a name="precision" id="precision"></a>-precision <em class="arg">value</em></h4>
4608 <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>
4610 <div style="margin: auto;">
4611 <h4><a name="preview" id="preview"></a>-preview <em class="arg">type</em></h4>
4614 <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>
4616 <p>Use this option to affect the preview operation of an image (e.g. <kbd>convert file.png -preview Gamma Preview:gamma.png</kbd>). Choose from these previews:</p>
4650 <p>To print a complete list of previews, use the <a href="#list">-list preview</a> option.</p>
4652 <p>The default preview is <kbd>JPEG</kbd>.</p>
4654 <div style="margin: auto;">
4655 <h4><a name="print" id="print"></a>-print <em class="arg">string</em></h4>
4658 <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>
4660 <div style="margin: auto;">
4661 <h4><a name="process" id="process"></a>-process <em class="arg">command</em></h4>
4664 <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>
4666 <p>The command arguments has the form <kbd>"module arg1 arg2 arg3 ... argN"</kbd> where <kbd>module</kbd> is the name of the module to invoke (e.g. "Analyze") and arg1 arg2 arg3 ... argN are an arbitrary number of arguments to pass to the process module.</p>
4668 <div style="margin: auto;">
4669 <h4><a name="profile" id="profile"></a>-profile <em class="arg">filename</em><br/>
4670 +profile <em class="arg">profile_name</em></h4>
4673 <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>
4675 <p>Using <a href="#profile">-profile</a> <em class="arg">filename</em> adds an ICM (ICC color management), IPTC (newswire information), or a generic profile to the image.</p>
4677 <p>Use <a href="#profile">+profile <em class="arg">profile_name</em></a> to remove the indicated profile. ImageMagick uses standard filename globbing, so wildcard expressions may be used to remove more than one profile. Here we remove all profiles from the image except for the XMP profile: <kbd>+profile "!xmp,*"</kbd>. </p>
4679 <p>Use <kbd>identify -verbose</kbd> to find out which profiles are in the image file. Use <a href="#strip">-strip</a> to remove all profiles (and comments).</p>
4681 <p>To extract a profile, the <a href="#profile">-profile</a> option is not used. Instead, simply write the file to an image format such as <em class="arg">APP1, 8BImageMagick, ICM,</em> or <em class="arg">IPTC</em>.</p>
4683 <p>For example, to extract the Exif data (which is stored in JPEG files in the <em class="arg">APP1</em> profile), use.</p>
4685 <p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert cockatoo.jpg profile.exif</span></p>
4686 <p>It is important to note that results may depend on whether or not the original image already has an included profile. Also, keep in mind that <a href="#profile">-profile</a> is an "operator" (as opposed to a "setting") and therefore a conversion is made each time it is encountered, in order, in the command-line. For instance, in the following example, if the original image is CMYK with profile, a CMYK-CMYK-RGB conversion results.</p>
4688 <p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert CMYK.tif -profile "CMYK.icc" -profile "RGB.icc" RGB.tiff</span></p>
4689 <p>Furthermore, since ICC profiles are not necessarily symmetric, extra conversion steps can yield unwanted results.
4690 CMYK profiles are often very asymmetric since they involve 3−>4 and 4−>3 channel mapping.
4693 <div style="margin: auto;">
4694 <h4><a name="quality" id="quality"></a>-quality <em class="arg">value</em></h4>
4697 <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>
4699 <p>For the JPEG and MPEG image formats, quality is 1 (lowest image quality and highest compression) to 100 (best quality but least effective compression). The default is to use the estimate quality of your input image otherwise 92. Use the <a href="#sampling-factor">-sampling-factor</a> option to specify the factors for chroma downsampling.</p>
4701 <p>For the MIFF image format, quality/10 is the zlib compression level, which is 0 (worst but fastest compression) to 9 (best but slowest). It has no effect on the image appearance, since the compression is always lossless.</p>
4703 <p>For the JPEG-2000 image format, quality is mapped using a non-linear equation to the compression ratio required by the Jasper library. This non-linear equation is intended to loosely approximate the quality provided by the JPEG v1 format. The default quality value 100, a request for non-lossy compression. A quality of 75 results in a request for 16:1 compression.</p>
4705 <p>For the MNG and PNG image formats, the quality value sets the zlib compression level (quality / 10) and filter-type (quality % 10). For compression level 0, the Huffman-only strategy is used, which is fastest but not necessarily the worst compression. The default PNG compression is 75.</p>
4707 <p>If filter-type is 4 or less, the specified filter-type is used for all scanlines:</p>
4717 <p>If filter-type is 5, adaptive filtering is used when quality is greater than 50 and the image does not have a color map, otherwise no filtering is used.</p>
4719 <p>If filter-type is 6, adaptive filtering with <em class="arg">minimum-sum-of-absolute-values</em> is used.</p>
4721 <p>Only if the output is MNG, if filter-type is 7, the LOCO color transformation and adaptive filtering with <em class="arg">minimum-sum-of-absolute-values</em> are used.</p>
4723 <p>The quality setting has no effect on the appearance of PNG and MNG images, since the compression is always lossless.</p>
4725 <p>For further information, see the <a href="http://www.w3.org/pub/WWW/TR">PNG</a> specification.</p>
4727 <div style="margin: auto;">
4728 <h4><a name="quantize" id="quantize"></a>-quantize <em class="arg">colorspace</em></h4>
4731 <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>
4733 <p>This setting defines the colorspace used to sort out and reduce the number
4734 of colors needed by an image (for later dithering) by operators such as <a
4735 href="#colors" >-colors</a>, Note that color reducion also happens
4736 automatically when saving images to color-limited image file formats, such as
4740 <div style="margin: auto;">
4741 <h4><a name="quiet" id="quiet"></a>-quiet</h4>
4744 <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>
4746 <div style="margin: auto;">
4747 <h4><a name="radial-blur" id="radial-blur"></a>-radial-blur <em class="arg">angle</em></h4>
4750 <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>
4752 <p>Note that this is actually a rotational blur rather than a radial and as
4753 such actually mis-named. </p>
4755 <p>The <a href="#virtual-pixel">-virtual-pixel</a> setting will determine how
4756 pixels which are outside the image proper are blurred into the final result.
4760 <div style="margin: auto;">
4761 <h4><a name="raise" id="raise"></a>-raise <em class="arg">thickness</em></h4>
4764 <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>
4766 <p>This will create a 3-D effect. Use <a href="#raise">-raise</a> to create a raised effect, otherwise use <a href="#raise">+raise</a>.
4769 <p>Unlike the similar <a href="#frame">-frame</a> option, <a href="#raise">-raise</a> does not alter the dimensions of the image.</p>
4771 <div style="margin: auto;">
4772 <h4><a name="random-threshold" id="random-threshold"></a>-random-threshold <em class="arg">low</em>x<em class="arg">high</em></h4>
4775 <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>
4777 <div style="margin: auto;">
4778 <h4><a name="red-primary" id="red-primary"></a>-red-primary <em class="arg">x,y</em></h4>
4781 <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>
4783 <div style="margin: auto;">
4784 <h4><a name="regard-warnings" id="regard-warnings"></a>-regard-warnings</h4>
4787 <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>
4789 <div style="margin: auto;">
4790 <h4><a name="remap" id="remap"></a>-remap <em class="arg">filename</em></h4>
4793 <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>
4795 <p>If the <a href="#dither">-dither</a> setting is enabled (the default) then
4796 the given colors are dithered over the image as necessary, otherwise the closest
4797 color (in RGB colorspace) is selected to replace that pixel in the image. </p>
4799 <p>As a side effect of applying a <a href="#remap">-remap</a> of colors across all
4800 images in the current image sequence, all the images will have the same color
4801 table. That means that when saved to a file format such as GIF, it will use
4802 that color table as a single common or global color table, for all the images,
4803 without requiring extra local color tables. </p>
4805 <p>Use <a href="#remap">+remap</a> to reduce all images in the current image
4806 sequence to use a common color map over all the images. This equivalent to
4807 appending all the images together (without extra background colors) and color
4808 reducing those images using <a href="#colors">-colors</a> with a 256 color
4809 limit, then <a href="#remap">-remap</a> those colors over the original list of
4810 images. This ensures all the images follow a single color map. </p>
4812 <p>If the number of colors over all the images is less than 256, then <a
4813 href="#remap">+remap</a> should not perform any color reduction or dithering, as
4814 no color changes are needed. In that case, its only effect is to force the use
4815 of a global color table. This recommended after using either <a
4816 href="#colors">-colors</a> or <a href="#ordered-dither">-ordered-dither</a> to
4817 reduce the number of colors in an animated image sequence. </p>
4819 <div style="margin: auto;">
4820 <h4><a name="region" id="region"></a>-region <em class="arg">geometry</em></h4>
4823 <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>
4825 <p>The <em class="arg">x</em> and <em class="arg">y</em> offsets are treated in the same manner as in <a href="#crop">-crop</a>.</p>
4827 <p>See <a href="../www/command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
4829 <div style="margin: auto;">
4830 <h4><a name="remote" id="remote"></a>-remote</h4>
4833 <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>
4835 <p>The only command recognized is the name of an image file to load.</p>
4837 <p>If you have more than one <a href="../www/display.html">display</a> application running simultaneously, use the <a href="#window"> window</a> option to specify which application to control.</p>
4839 <div style="margin: auto;">
4840 <h4><a name="render" id="render"></a>-render</h4>
4843 <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>
4845 <p>Use <a href="#render">+render</a> to turn off rendering vector operations. This useful when saving the result to vector formats such as MVG or SVG.</p>
4847 <div style="margin: auto;">
4848 <h4><a name="repage" id="repage"></a>-repage <em class="arg">geometry</em></h4>
4851 <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>
4853 <p>This option is like <a href="#page">-page</a> but acts as an image operator
4854 rather than a setting. You can separately set the canvas size or the offset
4855 of the image on that canvas by only providing those components. </p>
4857 <p>See <a href="../www/command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
4859 <p>If a <kbd>!</kbd> flag is given the offset given is added to the existing
4860 offset to move the image relative to its previous position. This useful for
4861 animation sequences. </p>
4863 <p>A given a canvas size of zero such as '<kbd>0x0</kbd>' forces it to
4864 recalculate the canvas size so the image (at its current offset) will appear
4865 completely on that canvas (unless it has a negative offset).</p>
4867 <p>Use <a href="#repage">+repage</a> to completely remove/reset the virtual
4868 canvas meta-data from the images. </p>
4870 <p>The <a href="#set">-set</a> '<kbd>page</kbd>' option can be used to
4871 directly assign virtual canvas meta-data. </p>
4874 <div style="margin: auto;">
4875 <h4><a name="resample" id="resample"></a>-resample <em class="arg">horizontal</em>x<em class="arg">vertical</em></h4>
4878 <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>
4880 <p>Resize the image so that its rendered size remains the same as the original at the specified target resolution. For example, if a 300 DPI image renders at 3 inches by 2 inches on a 300 DPI device, when the image has been resampled to 72 DPI, it will render at 3 inches by 2 inches on a 72 DPI device. Note that only a small number of image formats (e.g. JPEG, PNG, and TIFF) are capable of storing the image resolution. For formats which do not support an image resolution, the original resolution of the image must be specified via <a href="#density">-density</a> on the command line prior to specifying the resample resolution.</p>
4882 <p>Note that Photoshop stores and obtains image resolution from a proprietary embedded profile. If this profile exists in the image, then Photoshop will continue to treat the image using its former resolution, ignoring the image resolution specified in the standard file header.</p>
4884 <div style="margin: auto;">
4885 <h4><a name="resize" id="resize"></a>-resize <em class="arg">geometry</em></h4>
4888 <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>
4890 <p>See <a href="../www/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 ignored, and the <a href="#gravity">-gravity</a> option has no effect.</p>
4892 <p>If the <a href="#filter">-filter</a> option precedes the <a href="#resize">-resize</a> option, the image is resized with the specified filter.</p>
4894 <p>Many image processing algorithms assume your image is in a linear-light coding. If your image is gamma-corrected, you can remove the nonlinear gamma correction, apply the transform, then restore it like this:</p>
4896 <p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert portrait.jpg -gamma .45455 -resize 25% -gamma 2.2 \ <br/> -quality 92 passport.jpg</span></p>
4897 <div style="margin: auto;">
4898 <h4><a name="respect-parentheses" id="respect-parentheses"></a>-respect-parentheses</h4>
4901 <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>
4903 <div style="margin: auto;">
4904 <h4><a name="reverse" id="reverse"></a>-reverse</h4>
4907 <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>
4910 <div style="margin: auto;">
4911 <h4><a name="roll" id="roll"></a>-roll {<em class="arg">+-</em>}<em class="arg">x</em>{<em class="arg">+-</em>}<em class="arg">y</em></h4>
4914 <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>
4916 <p>A negative <em class="arg">x</em> offset rolls the image left-to-right. A negative <em class="arg">y</em> offset rolls the image top-to-bottom.</p>
4919 <div style="margin: auto;">
4920 <h4><a name="rotate" id="rotate"></a>-rotate <em class="arg">degrees</em>{<em class="arg"><</em>}{<em class="arg">></em>}</h4>
4923 <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>
4925 <p>Use <kbd>></kbd> to rotate the image only if its width exceeds the height. <kbd><</kbd> rotates the image <em>only</em> if its width is less than the height. For example, if you specify <kbd>-rotate "-90>"</kbd> and the image size is 480x640, the image is not rotated. However, if the image is 640x480, it is rotated by -90 degrees. If you use <kbd>></kbd> or <kbd><</kbd>, enclose it in quotation marks to prevent it from being misinterpreted as a file redirection.</p>
4927 <p>Empty triangles in the corners, left over from rotating the image, are
4928 filled with the <kbd>background</kbd> color. </p>
4930 <p>See also the <a href="#distort">-distort</a> operator and specifically the
4931 '<kbd>ScaleRotateTranslate</kbd>' distort method. </p>
4934 <div style="margin: auto;">
4935 <h4><a name="sample" id="sample"></a>-sample <em class="arg">geometry</em></h4>
4938 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>minify/magnify the image using pixel subsampling and pixel replication, respectively.</td><td style='text-align:right;'></td></tr></table>
4940 <p>Change the image size simply by directly sampling the pixels original
4941 image. When magnifying, pixels are replicated in blocks. When minifying,
4942 pixels are sub-sampled (i.e., some rows and columns are skipped over). </p>
4944 <p>The results are thus equivalent to using <a href="#resize">-resize</a> with
4945 a <a href="#filter">-filter</a> setting of <kbd>point</kbd> (nearest
4946 neighbour), though <a href="#sample">-sample</a> is a lot faster, as it
4947 avoids all the filter processing of the image. As such it completely ignores
4948 the current <a href="#filter">-filter</a> setting. </p>
4950 <p>The key feature of the <a href="#sample">-sample</a> is that no new colors
4951 will be added to the resulting image, though some colors may disappear. </p>
4953 <p>See <a href="../www/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
4954 ignored, unlike <a href="#resize">-resize</a>. </p>
4957 <div style="margin: auto;">
4958 <h4><a name="sampling-factor" id="sampling-factor"></a>-sampling-factor <em class="arg">horizontal-factor</em>x<em class="arg">vertical-factor</em></h4>
4961 <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>
4963 <p>This option specifies the sampling factors to be used by the JPEG encoder for chroma downsampling. If this option is omitted, the JPEG library will use its own default values. When reading or writing the YUV format and when writing the M2V (MPEG-2) format, use <a href="#sampling-factor">-sampling-factor 2x1</a> or <a href="#sampling-factor">-sampling-factor 4:2:2</a> to specify the 4:2:2 downsampling method.</p>
4965 <div style="margin: auto;">
4966 <h4><a name="scale" id="scale"></a>-scale <em class="arg">geometry</em></h4>
4969 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>minify/magnify the image using pixel block averaging and pixel replication, respectively.</td><td style='text-align:right;'></td></tr></table>
4971 <p>Change the image size simply by replacing pixels by averaging pixels
4972 together when minifying, or replacing pixels when magnifing. </p>
4974 <p>The results are thus equivalent to using <a href="#resize">-resize</a> with
4975 a <a href="#filter">-filter</a> setting of <kbd>box</kbd>. Though it is a lot
4976 faster, as it avoids all the filter processing of the image. As such it
4977 completely ignores the current <a href="#filter">-filter</a> setting. </p>
4979 <p>If when shrinking (minifying) images the original image is some integer
4980 multiple of the new image size, the number of pixels avergaed together to
4981 produce the new pixel color is the same across the whole image. This is
4982 a special case known as 'binning' and is often used as a method of reducing
4983 noise in image such as those generated by digital cameras, especially in low
4984 light conditions. </p>
4987 <div style="margin: auto;">
4988 <h4><a name="scene" id="scene"></a>-scene <em class="arg">value</em></h4>
4991 <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>
4993 <p>This option sets the scene number of an image or the first image in an image sequence.</p>
4995 <div style="margin: auto;">
4996 <h4><a name="screen" id="screen"></a>-screen</h4>
4999 <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>
5001 <p>This option indicates that the GetImage request used to obtain the image should be done on the root window, rather than directly on the specified window. In this way, you can obtain pieces of other windows that overlap the specified window, and more importantly, you can capture menus or other popups that are independent windows but appear over the specified window.</p>
5003 <div style="margin: auto;">
5004 <h4><a name="seed" id="seed"></a>-seed</h4>
5007 <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>
5009 <div style="margin: auto;">
5010 <h4><a name="segment" id="segment"></a>-segment <em class="arg">cluster-threshold</em>x<em class="arg">smoothing-threshold</em></h4>
5013 <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>
5015 <p>Segment an image by analyzing the histograms of the color components and identifying units that are homogeneous with the fuzzy c-means technique. This is part of the ImageMagick color quantization routines. </p>
5017 <p>Specify <em class="arg">cluster threshold</em> as the number of pixels in each cluster that must exceed the cluster threshold to be considered valid. <em class="arg">Smoothing threshold</em> eliminates noise in the second derivative of the histogram. As the value is increased, you can expect a smoother second derivative. The default is 1.5.</p>
5019 <p>If the <a href="#verbose">-verbose</a> setting is defined, a detailed report
5020 of the color clusters is returned.</p>
5023 <div style="margin: auto;">
5024 <h4><a name="selective-blur" id="selective-blur"></a>-selective-blur <em class="arg">geometry</em></h4>
5027 <div style="margin: auto;">
5028 <h4><a name="selective-blur" id="selective-blur"></a>-selective-blur <em class="arg">radius</em><br />-unsharp <em class="arg">radius</em>x<em class="arg">sigma</em>{<em class="arg">+threshold</em>}</h4>
5031 <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>
5033 <p>Blurs those pixels that are less than or equal to the threshold in contrast. The threshold may be expressed as a fraction of <em class="QR">QuantumRange</em> or as a percentage.</p>
5035 <div style="margin: auto;">
5036 <h4><a name="separate" id="separate"></a>-separate</h4>
5039 <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="#channel">-channel</a>.</td><td style='text-align:right;'></td></tr></table>
5041 <div style="margin: auto;">
5042 <h4><a name="sepia-tone" id="sepia-tone"></a>-sepia-tone <em class="arg">threshold</em></h4>
5045 <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>
5047 <p>Specify <em class="arg">threshold</em> as the percent threshold of the intensity (0 - 99.9%).</p>
5049 <p>This option applies a special effect to the image, similar to the effect achieved in a photo darkroom by sepia toning. Threshold ranges from 0 to <em class="QR">QuantumRange</em> and is a measure of the extent of the sepia toning. A threshold of 80% is a good starting point for a reasonable tone.</p>
5053 <div style="margin: auto;">
5054 <h4><a name="set" id="set"></a>-set <em class="arg">key value</em></h4>
5055 <h4><a name="set" id="set"></a>+set <em class="arg">key</em></h4>
5058 <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
5059 image sequence.</td><td style='text-align:right;'></td></tr></table>
5061 <p>This will assign (or modify) specific settings attached to all the images
5062 in the current image sequence. Using the <a href="#set">+set</a> form of the
5063 option will either remove, or reset that setting to a default state, as
5066 <p>For example, it will modify specific well known image meta-data
5067 'attributes' such as those normally overridden by: the options <a
5068 href="#delay" >-delay</a>, <a href="#dispose" >-dispose</a>, and <a
5069 href="#page" >-page</a>, <a href="#colorspace" >-colorspace</a>; generally
5070 assigned before the image is read in, by using a <em class="arg">key</em> of
5073 <p>If the given <em class="arg">key</em> does not match a specific known
5074 'attribute ', such as shown above, the setting is stored as a a free form
5075 'properity' string. Such settings are listed in <a href="#verbose"
5076 >-verbose</a> information ("<kbd>info:</kbd>" output format) as "Properties".
5079 <p>This includes string 'properities' that are set by and assigned to images
5080 using the options <a href="#comment" >-comment</a>, <a href="#label"
5081 >-label</a>, <a href="#caption" >-caption</a>. These options actually assign
5082 a global 'artifact' which are automatically assigned (and any <a href="../www/escape.html" >Format Percent
5083 Escapes</a> expanded) to images as they are read in. For example:</p>
5085 <p class='crt'><span class="crtprompt"> $magick> </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"> $magick> </span><span class='crtin'>Rose is a rose is a rose is a rose</span></p>
5086 <p>The set value can also make use of <a href="../www/escape.html" >Format and Print Image
5087 Properties</a> in the defined value. For example:</p>
5089 <p class='crt'><span class="crtprompt"> $magick> </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"> $magick> </span><span class='crtin'>Old size = 70x46 New size = 35x23</span></p>
5090 <p>Other well known 'properities' that can be include:
5091 '<kbd>date:create</kbd>' and '<kbd>date:modify</kbd>' and
5092 '<kbd>signature</kbd>'. </p>
5094 <p>The <a href="#repage">-repage</a> operator will also allow you to modify
5095 the '<kbd>page</kbd>' attribute of an image for images already in memory (also
5096 see <a href="#repage">-page</a>). However it is designed to provide a finer
5097 control of the sub-parts of this 'attribute'. The <a href="#set">-set page</a>
5098 option will only provide a direct, unmodified assignment of '<kbd>page</kbd>'
5101 <p>This option can also associate a colorspace or profile with your image.
5104 <p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert image.psd -set profile ISOcoated_v2_eci.icc image-icc.psd</span></p>
5105 <p>Some 'properties' must be defined in a specific way to be used. For
5106 example only 'properties' prefixed with "<kbd>filename:</kbd>" can be used to
5107 modify the output filename of an image. For example</p>
5109 <p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert rose: -set filename:mysize '%wx%h' 'rose_%[filename:mysize].png'</span></p>
5110 <p>If the setting value is prefixed with "<kbd>option:</kbd>" the setting will
5111 be saved as a global "Artifact" exactly as if it was set using the <a
5112 href="#define" >-define</a> option. As such settings are globel in scope, they
5113 can be used to pass 'attributes' and 'properities' of one specific image,
5114 in a way that allows you to use them in a completely different image, even if
5115 the original image has long since been modified or destroyed. For example: </p>
5117 <p class='crt'><span class="crtprompt"> $magick> </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>
5118 <p>Note that <a href="../www/escape.html" >Format Percent Escapes</a> will only match
5119 a 'artifact' if the given <em class="arg">key</em> does not match an existing
5120 'attribute' or 'properity'. </p>
5122 <p>You can set the attributes of the image registry by prefixing the value
5123 with <kbd>registry:</kbd>.</p>
5127 <div style="margin: auto;">
5128 <h4><a name="shade" id="shade"></a>-shade <em class="arg">azimuth</em>x<em class="arg">elevation</em></h4>
5131 <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>
5133 <p>Specify <em class="arg">azimuth</em> and <em class="arg">elevation</em> as the position of the light source. Use <a href="#shade">+shade</a> to return the shading results as a grayscale image.</p>
5135 <div style="margin: auto;">
5136 <h4><a name="shadow" 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>
5139 <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>
5141 <div style="margin: auto;">
5142 <h4><a name="shared-memory"
5143 id="shared-memory"></a>-shared-memory</h4>
5146 <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>
5148 <p>This option specifies whether the utility should attempt to use shared memory for pixmaps. ImageMagick must be compiled with shared memory support, and the display must support the <em class="arg">MIT-SHM</em> extension. Otherwise, this option is ignored. The default is <kbd>True</kbd>.</p>
5150 <div style="margin: auto;">
5151 <h4><a name="sharpen" id="sharpen"></a>-sharpen <em class="arg">radius</em>{x<em class="arg">sigma</em>}</h4>
5154 <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>
5156 <p>Use a Gaussian operator of the given radius and standard deviation (sigma).</p>
5158 <div style="margin: auto;">
5159 <h4><a name="shave" id="shave"></a>-shave <em class="arg">geometry</em></h4>
5162 <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>
5164 <p>The <em class="arg">size</em> portion of the <em class="arg">geometry</em> argument specifies the width of the region to be removed from both sides of the image and the height of the regions to be removed from top and bottom. Offsets are ignored.</p>
5166 <p>See <a href="../www/command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
5168 <div style="margin: auto;">
5169 <h4><a name="shear" id="shear"></a>-shear <em class="arg">Xdegrees</em>[x<em class="arg">Ydegrees</em>]</h4>
5172 <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>
5174 <p>The shear angles may be positive, negative, or zero. When <em class="arg">Ydegrees</em> is omitted it defaults to 0. When both angles are given, the horizontal component of the shear is performed before the vertical component.</p>
5176 <p>Shearing slides one edge of an image along the x-axis or y-axis (i.e., horizontally or vertically, respectively),creating a parallelogram. The amount of each is controlled by the respective shear angle. For horizontal shears, <em class="arg">Xdegrees</em> is measured clockwise relative to "up" (the negative y-axis), sliding the top edge to the right when 0°<<em class="arg">Xdegrees</em><90° and to the left when 90°<<em class="arg">Xdegrees</em><180°. For vertical shears <em class="arg">Ydegrees</em> is measured clockwise relative to "right" (the positive x-axis), sliding the right edge down when 0°<<em class="arg">Ydegrees</em><90° and up when 90°<<em class="arg">Ydegrees</em><180°.</p>
5178 <p>Empty triangles left over from shearing the image are filled with the color defined by the <a href="#fill">-background</a> option. The color is specified using the format described under the <a href="#fill">-fill</a> option.</p>
5180 <p>The horizontal shear is performed before the vertical part. This is important to note, since horizontal and vertical shears do not <em>commute</em>, i.e., the order matters in a sequence of shears. For example, the following two commands are not equivalent.</p>
5182 <p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert logo: -shear 20x0 -shear 0x60 logo-sheared.png</span><span class='crtout'></span><span class="crtprompt"> $magick> </span><span class='crtin'>convert logo: -shear 0x60 -shear 20x0 logo-sheared.png</span></p>
5183 <p>The first of the two commands above is equivalent to the following, except for the amount of empty space created; the command that follows generates a smaller image, and so is a better choice in terms of time and space.</p>
5185 <p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert logo: -shear 20x60 logo-sheared.png</span></p>
5186 <div style="margin: auto;">
5187 <h4><a name="sigmoidal" id="sigmoidal-contrast"></a>-sigmoidal-contrast <em class="arg">contrast</em>x<em class="arg">mid-point</em></h4>
5190 <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>
5192 <p>Increase the contrast of the image using a sigmoidal transfer function without saturating highlights or shadows. <em class="arg">Contrast</em> indicates how much to increase the contrast (0 is none; 3 is typical; 20 is a lot); <em class="arg">mid-point</em> indicates where midtones fall in the resultant image (0 is white; 50% is middle-gray; 100% is black). By default the image contrast is increased, use <em class="arg">+sigmoidal-contrast</em> to decrease the contrast.</p>
5194 <div style="margin: auto;">
5195 <h4><a name="silent" id="silent"></a>-silent</h4>
5198 <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>
5200 <div style="margin: auto;">
5201 <h4><a name="size" id="size"></a>-size <em class="arg">width</em>[x<em class="arg">height</em>][<em class="arg">+offset</em>]</h4>
5204 <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>
5206 <p>Use this option to specify the width and height of raw images whose dimensions are unknown such as <kbd>GRAY</kbd>, <kbd>RGB</kbd>, or <kbd>CMYK</kbd>. In addition to width and height, use <a href="#size">-size</a> with an offset to skip any header information in the image or tell the number of colors in a <kbd>MAP</kbd> image file, (e.g. -size 640x512+256).</p>
5208 <p>For Photo CD images, choose from these sizes:</p>
5218 <div style="margin: auto;">
5219 <h4><a name="sketch" 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>
5222 <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>
5224 <p>Sketch with the given radius, standard deviation (sigma), and angle. The angle given is the angle toward which the image is sketched. That is the direction people would consider the object is coming from. </p>
5226 <div style="margin: auto;">
5227 <h4><a name="snaps" id="snaps"></a>-snaps <em class="arg">value</em></h4>
5230 <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="../www/import.html">import</a>]</td></tr></table>
5232 <p>Use this option to grab more than one image from the X server screen, to create an animation sequence.</p>
5234 <div style="margin: auto;">
5235 <h4><a name="solarize" id="solarize"></a>-solarize <em class="arg">threshold</em></h4>
5238 <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>
5240 <p>Specify <em class="arg">factor</em> as the percent threshold of the intensity (0 - 99.9%).</p>
5242 <p>This option produces a <em class="arg">solarization</em> effect seen when exposing a photographic film to light during the development process.</p>
5244 <div style="margin: auto;">
5245 <h4><a name="sparse-color" id="sparse-color"></a>-sparse-color <em
5246 class="arg">method</em> '<em class="arg">x</em>,<em class="arg">y</em> <em class="arg">color</em> ...'</h4>
5249 <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>
5255 <th align="left" style="width: 8%">Method</th>
5256 <th align="left">Description</th>
5260 <td valign="top">voronoi</td>
5261 <td valign="top">Simply map each pixel to the to nearest color point
5262 given. The result are polygonal 'cells' of solid color. </td>
5266 <td valign="top">shepards</td>
5267 <td valign="top">Colors points biased on the ratio of inverse distance
5268 squared. Generating spots of color in a sea of the average of
5273 <td valign="top">barycentric</td>
5274 <td valign="top">three point triangle of color given 3 points.
5275 Giving only 2 points will form a linear gradient between those points.
5276 Gradient is however not restricted to just the triangle or line. </td>
5280 <td valign="top">bilinear</td>
5281 <td valign="top">Like barycentric but for 4 points. Less than 4 points
5282 fall back to barycentric. </td>
5288 <p>The points are placed according to the images location on the virtual
5289 canvas (<a href="#page" >-page</a> or <a href="#repage" >-repage</a>
5290 offset), and do not actually have to exist on the given image, but may be
5291 some point beyond the edge of the image. All points are floating point values.
5294 <p>Only the color channels defined by the <a href="#channel" >-channel</a> are
5295 modified, whcih means the matte/alpha transparency channel is not effected by
5296 default. If enabled, the image also needs a the matte/alpha channel to be
5297 enabled for this operator to effect an images transparency. This is typical
5298 transparency handling for images. </p>
5300 <p>All the above methods when given a single point of color will replace all
5301 the colors in the image with the color given, regardless of the point. This is
5302 logical, and provides an alternative technique to recolor a image to some
5306 <div style="margin: auto;">
5307 <h4><a name="splice" id="splice"></a>-splice <em class="arg">geometry</em></h4>
5310 <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>
5312 <p>See <a href="../www/command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument. See <a href="#background">-background</a> to reset the background color.</p>
5314 <div style="margin: auto;">
5315 <h4><a name="spread" id="spread"></a>-spread <em class="arg">amount</em></h4>
5318 <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>
5320 <p>The argument <em class="arg">amount</em> defines the size of the neighborhood around each pixel from which to choose a candidate pixel to swap.</p>
5322 <div style="margin: auto;">
5323 <h4><a name="stegano" id="stegano"></a>-stegano <em class="arg">offset</em></h4>
5326 <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>
5328 <p>Use an offset to start the image hiding some number of pixels from the beginning of the image. Note this offset and the image size. You will need this information to recover the steganographic image (e.g. display -size 320x256+35 stegano:image.png).</p>
5330 <div style="margin: auto;">
5331 <h4><a name="stereo" id="stereo"></a>-stereo <em class="arg">+x</em>{<em class="arg">+y</em>}</h4>
5334 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>composite two images to create a stereo anaglyph.</td><td style='text-align:right;'>[<a href="../www/composite.html">composite</a>]</td></tr></table>
5336 <p>The left side of the stereo pair is saved as the red channel of the output image. The right side is saved as the green channel. Red-green stereo glasses are required to properly view the stereo image.</p>
5338 <div style="margin: auto;">
5339 <h4><a name="storage-type" id="storage-type"></a>-storage-type <em class="arg">type</em></h4>
5342 <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>
5345 char store pixels as unsigned characters
5346 double store pixels as doubles
5347 float store pixels as floats
5348 integer store pixels as integers
5349 long store pixels as longs
5350 quantum store pixels in the native depth of your ImageMagick distribution
5351 short store pixels as unsigned shorts
5354 <p>Float and double types are normalized from 0.0 to 1.0 otherwise the pixels
5355 values range from 0 to the maximum value the storage type can support.</p>
5357 <div style="margin: auto;">
5358 <h4><a name="stretch" id="stretch"></a>-stretch <em class="arg">fontStretch</em></h4>
5361 <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>
5363 <p>This setting suggests a type of stretch that ImageMagick should try to apply to the currently selected font family. Select <em class="arg">fontStretch</em> from the following.</p>
5378 <p>To print a complete list of stretch types, use <a href="#list">-list stretch</a>.</p>
5380 <p>For other settings that affect fonts, see the options <a href="#font">-font</a>, <a href="#family">-family</a>, <a href="#style">-style</a>, and <a href="#weight">-weight</a>. </p>
5382 <div style="margin: auto;">
5383 <h4><a name="strip" id="strip"></a>-strip</h4>
5386 <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>
5388 <div style="margin: auto;">
5389 <h4><a name="stroke" id="stroke"></a>-stroke <em class="arg">color</em></h4>
5392 <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>
5394 <p>The color is specified using the format described under the <a href="#fill">-fill</a> option.</p>
5396 <p>See <a href="#draw">-draw</a> for further details.</p>
5398 <div style="margin: auto;">
5399 <h4><a name="strokewidth" id="strokewidth"></a>-strokewidth <em class="arg">value</em></h4>
5402 <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>
5404 <p>See <a href="#draw">-draw</a> for further details.</p>
5406 <div style="margin: auto;">
5407 <h4><a name="style" id="style"></a>-style <em class="arg">fontStyle</em></h4>
5410 <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>
5412 <p>This setting suggests a font style that ImageMagick should try to apply to
5413 the currently selected font family. Select <em class="arg">fontStyle</em> from
5423 <p>For other settings that affect fonts, see the options <a href="#font">-font</a>, <a href="#family">-family</a>, <a href="#stretch">-stretch</a>, and <a href="#weight">-weight</a>. </p>
5425 <div style="margin: auto;">
5426 <h4><a name="subimage-search" id="subimage-search"></a>-subimage-search</h4>
5429 <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="../www/compare.html">compare</a>]</td></tr></table>
5431 <p>This option is required to have compare search for the best match location
5432 of a small image within a larger image. This search will produce two images
5433 (or two frames). The first is the "difference" image and the second will
5434 be the "match score" image.</p>
5436 <p>The "match-score" image is smaller containing a pixel for ever possible
5437 position of the top-left corner of the given sub-image. that is its size will
5438 be the size of the larger_image - sub_image + 1. The brightest location in
5439 this image is the location s the locate on the best match that is also
5440 reported. Note that this may or may nor be a perfect match, and the actual
5441 brightness will reflect this. Other bright 'peaks' can be used to locate other
5442 possible matching loctions. </p>
5444 <p>Note that the search will try to compare teh sub-image at every possible
5445 location in the larger image, as such it can be very slow. The smaller the
5446 sub-image the faster this search is. </p>
5449 <div style="margin: auto;">
5450 <h4><a name="swap" id="swap"></a>-swap <em class="arg">index,index</em></h4>
5453 <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>
5455 <p>For example, <a href="#swap">-swap 0,2</a> swaps the first and the third
5456 images in the current image sequence. Use <a href="#swap">+swap</a> to switch
5457 the last two images in the sequence.</p>
5459 <div style="margin: auto;">
5460 <h4><a name="swirl" id="swirl"></a>-swirl <em class="arg">degrees</em></h4>
5463 <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>
5465 <p><em class="arg">Degrees</em> defines the tightness of the swirl.</p>
5467 <div style="margin: auto;">
5468 <h4><a name="synchronize" id="synchronize"></a>-synchronize</h4>
5471 <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>
5473 <div style="margin: auto;">
5474 <h4><a name="taint" id="taint"></a>-taint</h4>
5477 <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>
5479 <div style="margin: auto;">
5480 <h4><a name="text-font" id="text-font"></a>-text-font <em class="arg">name</em></h4>
5483 <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>
5485 <p>Specifies the name of the preferred font to use in fixed (typewriter style) formatted text. The default is 14 point <em class="arg">Courier</em>.</p>
5487 <p>You can tag a font to specify whether it is a PostScript, TrueType, or OPTION1 font. For example, <kbd>Courier.ttf</kbd> is a TrueType font and <kbd>x:fixed</kbd> is OPTION1.</p>
5489 <div style="margin: auto;">
5490 <h4><a name="texture" id="texture"></a>-texture <em class="arg">filename</em></h4>
5493 <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>
5495 <div style="margin: auto;">
5496 <h4><a name="threshold" id="threshold"></a>-threshold <em class="arg">value</em>{<em class="arg">%</em>}</h4>
5499 <!-- {<em class="arg">green,blue,opacity</em>}
5500 <p>If the green or blue value is omitted, these channels use the same value as the first one provided. If all three color values are the same, the result is a bi-level image. If the opacity threshold is omitted, OpaqueOpacity is used and any partially transparent pixel becomes fully transparent.</p>
5503 <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>
5505 <p>Any pixel values (more specifically, those channels set using <a href="../www/command-line-options.html#channel">‑channel</a>) that exceed the specified threshold are reassigned the maximum channel value, while all other values are assigned the minimum.</p>
5507 <p> The threshold value can be given as a percentage or as an absolute integer value corresponding to the desired channel value. When given as an integer, the minimum attainable value is 0 (corresponding to black when all channels are affected), but the maximum value (corresponding to white) is that of the <kbd>quantum depth</kbd> of the particular build of ImageMagick, and is therefore dependent on the installation. For that reason, a reasonable recommendation for most applications is to specify the threshold values as a percentage.
5510 <p> The following would force pixels with red values above 50% to have 100% red values, while those at or below 50% red would be set to 0 in the red channel. The green, blue, and alpha channels (if present) would be unchanged. </p>
5512 <p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert in.png -channel red -threshold 50% out.png</span></p>
5513 <p>As (possibly) impractical but instructive examples, the following would generate an all-black and an all-white image with the same dimensions as the input image.</p>
5516 <p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert in.png -threshold 100% black.png</span><span class='crtout'></span><span class="crtprompt"> $magick> </span><span class='crtin'>convert in.png -threshold -1 white.png</span></p>
5517 <p>Note that the values of the transparency channel is treated as 'matte'
5518 values (0 is opaque) and not as 'alpha' values (0 is transparent).</p>
5520 <p> See also <a href="../www/command-line-options.html#black-threshold">‑black‑threshold</a> and <a href="../www/command-line-options.html#white-threshold">‑white‑threshold</a>.
5523 <div style="margin: auto;">
5524 <h4><a name="thumbnail" id="thumbnail"></a>-thumbnail <em class="arg">geometry</em></h4>
5527 <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>
5529 <p>This is similar to <a href="#resize">-resize</a>, except it is optimized for speed and any image profile, other than a color profile, is removed to reduce the thumbnail size. To strip the color profiles as well, add <a href="#strip">-strip</a> just before of after this option.</p>
5531 <p>See <a href="../www/command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
5533 <div style="margin: auto;">
5534 <h4><a name="tile" id="tile"></a>-tile <em class="arg">filename</em></h4>
5537 <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>
5539 <div style="margin: auto;">
5540 <h4>-tile <em class="arg">geometry</em></h4>
5543 <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="../www/montage.html">montage</a>]</td></tr></table>
5545 <p>See <a href="../www/command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
5547 <div style="margin: auto;">
5551 <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="../www/composite.html">composite</a>]</td></tr></table>
5553 <div style="margin: auto;">
5554 <h4><a name="tile-offset" 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>
5557 <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>
5559 <p>This should be set before the tiling image is set by <a href="#tile" >-tile</a> or <a href="#texture" >-texture</a>, or directly applied for creating a tiled canvas using <kbd>TILE:</kbd> or <kbd>PATTERN:</kbd> input formats. </p>
5561 <p>Internally ImageMagick does a <a href="#roll" >-roll</a> of the tile image by the arguments given when the tile image is set. </p>
5563 <div style="margin: auto;">
5564 <h4><a name="tint" id="tint"></a>-tint <em class="arg">value</em></h4>
5567 <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>
5569 <p>Tint the image with the fill color.</p>
5571 <p>Specify the amount of tinting as a percentage. Pure colors like black, white red, yellow, will not be affected by -tint. Only mid-range colors such as the various shades of grey.</p>
5573 <div style="margin: auto;">
5574 <h4><a name="title" id="title"></a>-title <em class="arg">string</em></h4>
5577 <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="../www/animate.html">animate</a>, <a href="../www/display.html">display</a>, <a href="../www/montage.html">montage</a>]</td></tr></table>
5579 <p>Use this option to assign a specific title to the image. This assigned to the image window and is typically displayed in the window title bar. Optionally you can include the image filename, type, width, height, Exif data, or other image attribute by embedding special format characters described under the <a href="#format">-format</a> option.</p>
5584 -title "%m:%f %wx%h"
5587 <p>produces an image title of <kbd>MIFF:bird.miff 512x480</kbd> for an image titled <kbd>bird.miff</kbd> and whose width is 512 and height is 480.</p>
5590 <div style="margin: auto;">
5591 <h4><a name="transform" id="transform"></a>-transform</h4>
5594 <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>
5596 <p>This option applies the transformation matrix from a previous <a href="#affine">-affine</a> option.</p>
5598 <p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert -affine 2,2,-2,2,0,0 -transform bird.ppm bird.jpg</span></p>
5600 <p>This operator has been now been superseded by the <a
5601 href="#distort">-distort</a> '<kbd>AffineProjection</kbd>' method. </p>
5604 <div style="margin: auto;">
5605 <h4><a name="transparent" id="transparent"></a>-transparent <em class="arg">color</em></h4>
5608 <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>
5610 <p>The <em class="arg">color</em> argument is defined using the format
5611 described under the <a href="#fill">-fill</a> option. The <a href="#fuzz"
5612 >-fuzz</a> setting can be used to match and replace colors similar to the one
5615 <p>Use <a href="#transparent" >+transparent</a> to invert the pixels matched.
5616 that is make all non-matching colors transparent. </p>
5618 <p>The <a href="#opaque">-opaque</a> operator is exactly the same as <a
5619 href="#transparent" >-transparent</a> but replaces the matching color with the
5620 current <a href="#fill">-fill</a> color setting, rather than transparent.
5621 However the <a href="#transparent" >-transparent</a> operator also ensures
5622 that the image has an alpha channel enabled, as per "<kbd><a href="#alpha"
5623 >-alpha</a> set</kbd>", and does not require you to modify the <a
5624 href="#channel">-channel</a> to enable alpha channel handling. </p>
5626 <p>Note that this does not define the color as being the 'transparency color'
5627 used for color-mapped image formats, such as GIF. For that use <a
5628 href="#transparent-color" >-transparent-color</a> </p>
5631 <div style="margin: auto;">
5632 <h4><a name="transparent-color" id="transparent-color"></a>-transparent-color <em class="arg">color</em></h4>
5635 <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>
5637 <p>Sometimes this is used for saving to image formats such as
5638 GIF and PNG8 which uses this color to represent boolean transparency. This
5639 does not make a color transparent, it only defines what color the transparent
5640 color is in the color palette of the saved image. Use <a
5641 href="#transparent">-transparent</a> to make an opaque color transparent.</p>
5643 <p>This option allows you to have both an opaque visible color, as well as a
5644 transparent color of the same color value without conflict. That is, you can
5645 use the same color for both the transparent and opaque color areas within an
5646 image. This, in turn, frees to you to select a transparent color that is
5647 appropriate when an image is displayed by an application that does not handle a
5648 transparent color index, while allowing ImageMagick to correctly handle images of this
5651 <p>The default transparent color is <kbd>#00000000</kbd>, which is fully transparent black.</p>
5653 <div style="margin: auto;">
5654 <h4><a name="transpose" id="transpose"></a>-transpose</h4>
5657 <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>
5659 <p> This option mathematically transposes the pixel array. It is equivalent to the sequence <kbd>-flip -rotate 90</kbd>.
5662 <div style="margin: auto;">
5663 <h4><a name="transverse" id="transverse"></a>-transverse</h4>
5666 <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 <kbd>-flop -rotate 90</kbd>.</td><td style='text-align:right;'></td></tr></table>
5669 <div style="margin: auto;">
5670 <h4><a name="treedepth" id="treedepth"></a>-treedepth <em class="arg">value</em></h4>
5673 <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>
5675 <p>Normally, this integer value is zero or one. A value of zero or one causes the use of an optimal tree depth for the color reduction algorithm.</p>
5677 <p>An optimal depth generally allows the best representation of the source image with the fastest computational speed and the least amount of memory. However, the default depth is inappropriate for some images. To assure the best representation, try values between 2 and 8 for this parameter. Refer to the <a href="../www/quantize.html">color reduction algorithm</a> for more details.</p>
5679 <p>The <a href="#colors">-colors</a> or <a href="#monochrome">-monochrome</a> option, or writing to an image format which requires color reduction, is required for this option to take effect.</p>
5681 <div style="margin: auto;">
5682 <h4><a name="trim" id="trim"></a>-trim</h4>
5685 <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>
5687 <p>This option removes any edges that are exactly the same color as the corner pixels. Use <a href="#fuzz">-fuzz</a> to make <a href="#trim">-trim</a> remove edges that are nearly the same color as the corner pixels.</p>
5689 <p>The page or virtual canvas information of the image is preserved allowing
5690 you to extract the result of the <a href="#trim">-trim</a> operation from the
5691 image. Use a <a href="#repage">+repage</a> to remove the virtual canvas page
5692 information if it is unwanted.</p>
5694 <p>If the trimmed image 'disappears' an warning is produced, and a special
5695 single pixel transparent 'missed' image is returned, in the same way as when a
5696 <a href="#crop">-crop</a> operation 'misses' the image proper. </p>
5699 <div style="margin: auto;">
5700 <h4><a name="type" id="type"></a>-type <em class="arg">type</em></h4>
5703 <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>
5704 <p>Choose from: <kbd>Bilevel</kbd>, <kbd>Grayscale</kbd>, <kbd>GrayscaleMatte</kbd>, <kbd>Palette</kbd>, <kbd>PaletteMatte</kbd>, <kbd>TrueColor</kbd>, <kbd>TrueColorMatte</kbd>, <kbd>ColorSeparation</kbd>, or <kbd>ColorSeparationMatte</kbd>.</p>
5706 <p>Normally, when a format supports different subformats such as grayscale and truecolor, the encoder will try to choose an efficient subformat. The <a href="#type">-type</a> option can be used to overrride this behavior. For example, to prevent a JPEG from being written in grayscale format even though only gray pixels are present, use.</p>
5708 <p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert bird.png -type TrueColor bird.jpg</span></p>
5709 <p>Similarly, use <a href="#type">-type TrueColorMatte</a> to force the encoder to write an alpha channel even though the image is opaque, if the output format supports transparency.</p>
5711 <p>Use <a href="#type">-type optimize</a> to ensure the image is written in the smallest possible file size.</p>
5713 <div style="margin: auto;">
5714 <h4><a name="undercolor" id="undercolor"></a>-undercolor <em class="arg">color</em></h4>
5717 <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>
5719 <p>The color is specified using the format described under the <a href="#fill">-fill</a> option.</p>
5721 <p>See <a href="#draw">-draw</a> for further details.</p>
5724 <div style="margin: auto;">
5725 <h4><a name="update" id="update"></a>-update <em class="arg">seconds</em></h4>
5728 <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>
5730 <p>Suppose that while you are displaying an image the file that is currently displayed is over-written. <kbd>display</kbd> will automagically detect that the input file has been changed and update the displayed image accordingly.</p>
5733 <div style="margin: auto;">
5734 <h4><a name="unique-colors" id="unique-colors"></a>-unique-colors</h4>
5737 <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>
5740 <div style="margin: auto;">
5741 <h4><a name="units" id="units"></a>-units <em class="arg">type</em></h4>
5744 <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>
5746 <p>Choose from: <kbd>Undefined</kbd>, <kbd>PixelsPerInch</kbd>, or <kbd>PixelsPerCentimeter</kbd>. This option is normally used in conjunction with the <a href="#density">-density</a> option.</p>
5749 <div style="margin: auto;">
5750 <h4><a name="unsharp" 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">+amount</em>}{<em class="arg">+threshold</em>}</h4>
5753 <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>
5755 <p>The <a href="#unsharp">-unsharp</a> option sharpens an image. The image is convolved with a Gaussian operator of the given radius and standard deviation (sigma). For reasonable results, radius should be larger than sigma. Use a radius of 0 to have the method select a suitable radius.</p>
5757 <p>The parameters are:</p>
5760 radius: The radius of the Gaussian, in pixels, not counting the center
5762 sigma: The standard deviation of the Gaussian, in pixels (default 1.0).
5763 amount: The fraction of the difference between the original and the blur
5764 image that is added back into the original (default 1.0).
5765 threshold: The threshold, as a fraction of <em class="QR">QuantumRange</em>, needed to apply the
5766 difference amount (default 0.05).
5770 <div style="margin: auto;">
5771 <h4><a name="verbose" id="verbose"></a>-verbose</h4>
5774 <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 precedes the <a href="#identify">-identify</a> option or <kbd>info:</kbd>.</td><td style='text-align:right;'></td></tr></table>
5777 <div style="margin: auto;">
5778 <h4><a name="version" id="version"></a>-version</h4>
5781 <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>
5784 <div style="margin: auto;">
5785 <h4><a name="view" id="view"></a>-view <em class="arg">string</em></h4>
5788 <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>
5791 <div style="margin: auto;">
5792 <h4><a name="vignette" 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>
5795 <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>
5798 <div style="margin: auto;">
5799 <h4><a name="virtual-pixel" id="virtual-pixel"></a>-virtual-pixel <em class="arg">method</em></h4>
5802 <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>
5804 <p>This option defines what color source should be used if and when a color
5805 lookup completely 'misses' the source image. The color(s) that appear to
5806 surround the source image. Generally this color is derived from the source
5807 image, but could also be set to a specify background color. </p>
5809 <p>Choose from these methods:</p>
5812 background: the area surrounding the image is the background color
5813 black: the area surrounding the image is black
5814 checker-tile: alternate squares with image and background color
5815 dither: non-random 32x32 dithered pattern
5816 edge: extend the edge pixel toward infinity
5817 gray: the area surrounding the image is gray
5818 horizontal-tile: horizontally tile the image, background color above/below
5819 horizontal-tile-edge: horizontally tile the image and replicate the side edge pixels
5820 mirror: mirror tile the image
5821 random: choose a random pixel from the image
5822 tile: tile the image (default)
5823 transparent: the area surrounding the image is transparent blackness
5824 vertical-tile: vertically tile the image, sides are background color
5825 vertical-tile-edge: vertically tile the image and replicate the side edge pixels
5826 white: the area surrounding the image is white
5829 <p>The default value is "edge".</p>
5831 <p>This most important for distortion operators such as <a href="#distort"
5832 >-distort</a>, <a href="#implode" >-implode</a>, and <a href="#fx" >-fx</a>.
5833 However it also effects operations that may access pixels just outside the
5834 image proper, such as <a href="#convolve">-convolve</a>, <a
5835 href="#blur">-blur</a>, and <a href="#sharpen">-sharpen</a>. </p>
5837 <p>To print a complete list of virtual pixel types, use the <a href="#list">-list virtual-pixel</a> option.</p>
5840 <div style="margin: auto;">
5841 <h4><a name="visual" id="visual"></a>-visual <em class="arg">type</em></h4>
5844 <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="../www/animate.html">animate</a>, <a href="../www/display.html">display</a>]</td></tr></table>
5846 <p>Choose from these visual classes:</p>
5859 <p>The X server must support the visual you choose, otherwise an error occurs. If a visual is not specified, the visual class that can display the most simultaneous colors on the default screen is chosen.</p>
5862 <div style="margin: auto;">
5863 <h4><a name="watermark" id="watermark"></a>-watermark <em
5864 class="arg">brightness</em>x<em class="arg">saturation</em></h4>
5867 <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
5868 saturation.</td><td style='text-align:right;'>[<a href="../www/composite.html">composite</a>]</td></tr></table>
5870 <p>Take a grayscale image (with alpha mask) and modify the destination image's
5871 brightness according to watermark image's grayscale value and the <em
5872 class="arg">brightness</em> percentage. The destinations color saturation
5873 attribute is just direct modified by the <em class="arg">saturation</em>
5874 percentage, which defaults to 100 percent (no color change). </p>
5877 <div style="margin: auto;">
5878 <h4><a name="wave" id="wave"></a>-wave <em class="arg">amplitude</em><br />-wave <em class="arg">amplitude</em>x<em class="arg">wavelength</em></h4>
5881 <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>
5883 <p>Specify <em class="arg">amplitude</em> and <em class="arg">wavelength</em> of the wave.</p>
5885 <div style="margin: auto;">
5886 <h4><a name="weight" id="weight"></a>-weight <em class="arg">fontWeight</em></h4>
5889 <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>
5891 <p>This setting suggests a font weight that ImageMagick should try to apply to the currently selected font family. Use a positive integer for <em class="arg">fontWeight</em> or select from the following.</p>
5898 <th><em class="arg">fontWeight</em></th>
5899 <th>Description</th>
5903 <tr><td>All </td> <td>No effect. </td></tr>
5904 <tr><td>Bold </td> <td>Same as <em class="arg">fontWeight</em> = 700.</td></tr>
5905 <tr><td>Bolder </td> <td>Add 100 to font weight if currently ≤ 800.</td></tr>
5906 <tr><td>Lighter </td> <td>Subtract 100 to font weight if currently ≤ 100.</td></tr>
5907 <tr><td>Normal </td> <td>Same as <em class="arg">fontWeight</em> = 400.</td></tr>
5911 <p>To print a complete list of weight types, use <a href="#list">-list weight</a>.</p>
5913 <p>For other settings that affect fonts, see the options <a href="#font">-font</a>, <a href="#family">-family</a>, <a href="#stretch">-stretch</a>, and <a href="#style">-style</a>. </p>
5915 <div style="margin: auto;">
5916 <h4><a name="white-point" id="white-point"></a>-white-point <em class="arg">x,y</em></h4>
5919 <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>
5921 <div style="margin: auto;">
5922 <h4><a name="white-threshold" id="white-threshold"></a>-white-threshold <em class="arg">value</em>{<em class="arg">%</em>}</h4>
5925 <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 pixels at or below the threshold unchanged.</td><td style='text-align:right;'></td></tr></table>
5927 <p> The threshold value can be given as a percentage or as an absolute integer value within [0, <em class="QR">QuantumRange</em>] corresponding to the desired <a href="../www/command-line-options.html#channel">‑channel</a> value. See <a href="../www/command-line-options.html#threshold">‑threshold</a> for more details on thresholds and resulting values.
5930 <div style="margin: auto;">
5931 <h4><a name="window" id="window"></a>-window <em class="arg">id</em></h4>
5934 <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="../www/animate.html">animate</a>, <a href="../www/display.html">display</a>]</td></tr></table>
5936 <p><em class="arg">id</em> can be a window id or name. Specify <kbd>root</kbd> to select X's root window as the target window.</p>
5938 <p>By default the image is tiled onto the background of the target window. If <kbd>backdrop</kbd> or <a href="#geometry">-resize</a> are specified, the image is surrounded by the background color. Refer to <kbd>X RESOURCES</kbd> for details.</p>
5940 <p>The image will not display on the root window if the image has more unique colors than the target window colormap allows. Use <a href="#colors">-colors</a> to reduce the number of colors.</p>
5942 <div style="margin: auto;">
5943 <h4><a name="window-group" id="window-group"></a>-window-group</h4>
5946 <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>
5948 <div style="margin: auto;">
5949 <h4><a name="write" id="write"></a>-write <em class="arg">filename</em></h4>
5952 <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>
5953 <p>The image sequence preceding the <a href="#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="#write">+write</a> <em class="arg">filename</em> option.</p>
5955 <p>Use <a href="#compress">-compress</a> to specify the type of image compression.</p>
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