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47 <p class="text-center"><a href="command-line-options.html#adaptive-blur">‑adaptive‑blur</a> • <a href="command-line-options.html#adaptive-resize">‑adaptive‑resize</a> • <a href="command-line-options.html#adaptive-sharpen">‑adaptive‑sharpen</a> • <a href="command-line-options.html#adjoin">‑adjoin</a> • <a href="command-line-options.html#affine">‑affine</a> • <a href="command-line-options.html#alpha">‑alpha</a> • <a href="command-line-options.html#annotate">‑annotate</a> • <a href="command-line-options.html#antialias">‑antialias</a> • <a href="command-line-options.html#append">‑append</a> • <a href="command-line-options.html#attenuate">‑attenuate</a> • <a href="command-line-options.html#authenticate">‑authenticate</a> • <a href="command-line-options.html#auto-gamma">‑auto‑gamma</a> • <a href="command-line-options.html#auto-level">‑auto‑level</a> • <a href="command-line-options.html#auto-orient">‑auto‑orient</a> • <a href="command-line-options.html#backdrop">‑backdrop</a> • <a href="command-line-options.html#background">‑background</a> • <a href="command-line-options.html#bench">‑bench</a> • <a href="command-line-options.html#bias">‑bias</a> • <a href="command-line-options.html#black-point-compensation">‑black‑point‑compensation</a> • <a href="command-line-options.html#black-threshold">‑black‑threshold</a> • <a href="command-line-options.html#blend">‑blend</a> • <a href="command-line-options.html#blue-primary">‑blue‑primary</a> • <a href="command-line-options.html#blue-shift">‑blue‑shift</a> • <a href="command-line-options.html#blur">‑blur</a> • <a href="command-line-options.html#border">‑border</a> • <a href="command-line-options.html#bordercolor">‑bordercolor</a> • <a href="command-line-options.html#borderwidth">‑borderwidth</a> • <a href="command-line-options.html#brightness-contrast">‑brightness‑contrast</a> • <a href="command-line-options.html#cache">‑cache</a> • <a href="command-line-options.html#canny">‑canny</a> • <a href="command-line-options.html#caption">‑caption</a> • <a href="command-line-options.html#cdl">‑cdl</a> • <a href="command-line-options.html#channel">‑channel</a> • <a href="command-line-options.html#charcoal">‑charcoal</a> • <a href="command-line-options.html#chop">‑chop</a> • <a href="command-line-options.html#clamp">‑clamp</a> • <a href="command-line-options.html#clip">‑clip</a> • <a href="command-line-options.html#clip-mask">‑clip‑mask</a> • <a href="command-line-options.html#clip-path">‑clip‑path</a> • <a href="command-line-options.html#clone">‑clone</a> • <a href="command-line-options.html#clut">‑clut</a> • <a href="command-line-options.html#coalesce">‑coalesce</a> • <a href="command-line-options.html#colorize">‑colorize</a> • <a href="command-line-options.html#colormap">‑colormap</a> • <a href="command-line-options.html#color-matrix">‑color‑matrix</a> • <a href="command-line-options.html#colors">‑colors</a> • <a href="command-line-options.html#colorspace">‑colorspace</a> • <a 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href="command-line-options.html#storage-type">‑storage‑type</a> • <a href="command-line-options.html#stretch">‑stretch</a> • <a href="command-line-options.html#strip">‑strip</a> • <a href="command-line-options.html#stroke">‑stroke</a> • <a href="command-line-options.html#strokewidth">‑strokewidth</a> • <a href="command-line-options.html#style">‑style</a> • <a href="command-line-options.html#subimage-search">‑subimage‑search</a> • <a href="command-line-options.html#swap">‑swap</a> • <a href="command-line-options.html#swirl">‑swirl</a> • <a href="command-line-options.html#synchronize">‑synchronize</a> • <a href="command-line-options.html#taint">‑taint</a> • <a href="command-line-options.html#text-font">‑text‑font</a> • <a href="command-line-options.html#texture">‑texture</a> • <a href="command-line-options.html#threshold">‑threshold</a> • <a href="command-line-options.html#thumbnail">‑thumbnail</a> • <a href="command-line-options.html#tile">‑tile</a> • <a href="command-line-options.html#tile-offset">‑tile‑offset</a> • <a href="command-line-options.html#tint">‑tint</a> • <a href="command-line-options.html#title">‑title</a> • <a href="command-line-options.html#transform">‑transform</a> • <a href="command-line-options.html#transparent">‑transparent</a> • <a href="command-line-options.html#transparent-color">‑transparent‑color</a> • <a href="command-line-options.html#transpose">‑transpose</a> • <a href="command-line-options.html#transverse">‑transverse</a> • <a href="command-line-options.html#treedepth">‑treedepth</a> • <a href="command-line-options.html#trim">‑trim</a> • <a href="command-line-options.html#type">‑type</a> • <a href="command-line-options.html#undercolor">‑undercolor</a> • <a href="command-line-options.html#unique-colors">‑unique‑colors</a> • <a href="command-line-options.html#units">‑units</a> • <a href="command-line-options.html#unsharp">‑unsharp</a> • <a href="command-line-options.html#update">‑update</a> • <a href="command-line-options.html#verbose">‑verbose</a> • <a href="command-line-options.html#version">‑version</a> • <a href="command-line-options.html#view">‑view</a> • <a href="command-line-options.html#vignette">‑vignette</a> • <a href="command-line-options.html#virtual-pixel">‑virtual‑pixel</a> • <a href="command-line-options.html#visual">‑visual</a> • <a href="command-line-options.html#watermark">‑watermark</a> • <a href="command-line-options.html#wave">‑wave</a> • <a href="command-line-options.html#weight">‑weight</a> • <a href="command-line-options.html#white-point">‑white‑point</a> • <a href="command-line-options.html#white-threshold">‑white‑threshold</a> • <a href="command-line-options.html#window">‑window</a> • <a href="command-line-options.html#window-group">‑window‑group</a> • <a href="command-line-options.html#write">‑write</a> • <a href="command-line-options.html#write-mask">‑write‑mask</a> </p>
49 <p class="lead magick-description">Below is list of command-line options recognized by the ImageMagick <a href="command-line-tools.html">command-line tools</a>. If you want a description of a particular option, click on the option name in the navigation bar above and you will go right to it. Unless otherwise noted, each option is recognized by the commands: <a href="convert.html">convert</a> and <a href="mogrify.html">mogrify</a>.</p>
51 <div style="margin: auto;">
52 <h3 class="magick-header"><a id="adaptive-blur"></a>-adaptive-blur <var>radius</var>[x<var>sigma</var>]</h3>
55 <p class="magick-description">Adaptively blur pixels, with decreasing effect near edges.</p>
57 <p>A Gaussian operator of the given radius and standard deviation (<var>sigma</var>) is used. If <var>sigma</var> is not given it
60 <div style="margin: auto;">
61 <h3 class="magick-header"><a id="adaptive-resize"></a>-adaptive-resize <var>geometry</var></h3>
64 <p class="magick-description">Resize the image using data-dependent triangulation.</p>
66 <p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument. The <a href="command-line-options.html#adaptive-resize">-adaptive-resize</a>
67 option defaults to data-dependent triangulation. Use the <a href="command-line-options.html#filter">-filter</a> to choose a different resampling algorithm.
68 Offsets, if present in the geometry string, are ignored, and the <a href="command-line-options.html#gravity">-gravity</a> option has no effect.</p>
70 <div style="margin: auto;">
71 <h3 class="magick-header"><a id="adaptive-sharpen"></a>-adaptive-sharpen <var>radius</var>[x<var>sigma</var>]</h3>
74 <p class="magick-description">Adaptively sharpen pixels, with increasing effect near edges.</p>
76 <p>A Gaussian operator of the given radius and standard deviation
77 (<var>sigma</var>) is used. If <var>sigma</var> is not given it
80 <div style="margin: auto;">
81 <h3 class="magick-header"><a id="adjoin"></a>-adjoin</h3>
84 <p class="magick-description">Join images into a single multi-image file.</p>
86 <p>This option is enabled by default. An attempt is made to save all images of
87 an image sequence into the given output file. However, some formats, such as
88 JPEG and PNG, do not support more than one image per file, and in that case
89 ImageMagick is forced to write each image as a separate file. As such, if
90 more than one image needs to be written, the filename given is modified by
91 adding a <a href="command-line-options.html#scene">-scene</a> number before the suffix, in order to
92 make distinct names for each image. </p>
94 <p>Use <a href="command-line-options.html#adjoin">+adjoin</a> to force each image to be written to
95 separate files, whether or not the file format allows multiple images per file
96 (for example, GIF, MIFF, and TIFF). </p>
98 <p>Including a C-style integer format string in the output filename will
99 automagically enable <a href="command-line-options.html#adjoin">+adjoin</a> and are used to specify
100 where the <a href="command-line-options.html#scene">-scene</a> number is placed in the filenames. These
101 strings, such as '<code>%d</code>' or '<code>%03d</code>', are familiar to those
102 who have used the standard <code>printf()</code>' C-library function. As an
103 example, the command</p>
106 convert logo: rose: -morph 15 my%02dmorph.jpg
109 <p>will create a sequence of 17 images (the two given plus 15 more created by
110 <a href="command-line-options.html#morph">-morph</a>), named: my00morph.jpg, my01morph.jpg,
111 my02morph.jpg, ..., my16morph.jpg. </p>
113 <p>In summary, ImageMagick tries to write all images to one file, but will
114 save to multiple files, if any of the following conditions exist...</p>
116 <li>the output image's file format does not allow multi-image files,</li>
117 <li>the <a href="command-line-options.html#adjoin">+adjoin</a> option is given, or</li>
118 <li>a printf() integer format string (eg: "%d") is present in the output
123 <div style="margin: auto;">
124 <h3 class="magick-header"><a id="affine"></a>-affine
125 <var>s<sub>x</sub></var>,<var>r<sub>x</sub></var>,<var>r<sub>y</sub></var>,<var>s<sub>y</sub></var>[,<var>t<sub>x</sub></var>,<var>t<sub>y</sub></var>]</h3>
128 <p class="magick-description">Set the drawing transformation matrix for combined rotating and scaling.</p>
130 <p>This option sets a transformation matrix, for use by subsequent <a href="command-line-options.html#draw">-draw</a> or <a href="command-line-options.html#transform">-transform</a> options. </p>
132 <p>The matrix entries are entered as comma-separated numeric values either in
133 quotes or without spaces. </p>
135 <p>Internally, the transformation matrix has 3x3 elements, but three of them
136 are omitted from the input because they are constant. The new (transformed)
137 coordinates (<var>x'</var>, <var>y'</var>) of a pixel at
138 position (<var>x</var>, <var>y</var>) in the original
139 image are calculated using the following matrix equation.</p>
141 <p class="text-center"><img class="img-thumbnail" alt="affine transformation" src="../images/affine.png"> </p>
143 <p> The size of the resulting image is that of the smallest rectangle that
144 contains the transformed source image. The parameters
145 <var>t<sub>x</sub></var> and <var>t<sub>y</sub></var>
146 subsequently shift the image pixels so that those that are moved out of the
147 image area are cut off.</p>
149 <p>The transformation matrix complies with the left-handed pixel coordinate
150 system: positive <var>x</var> and <var>y</var> directions
151 are rightward and downward, resp.; positive rotation is clockwise.</p>
153 <p> If the translation coefficients <var>t<sub>x</sub></var> and
154 <var>t<sub>y</sub></var> are omitted they default to 0,0. Therefore,
155 four parameters suffice for rotation and scaling without translation.</p>
157 <p>Scaling by the factors <var>s<sub>x</sub></var> and
158 <var>s<sub>y</sub></var> in the <var>x</var> and <var>y</var> directions,
159 respectively, is accomplished with the following.</p>
161 <p>See <a href="command-line-options.html#transform">-transform</a>, and the <a href="command-line-options.html#distort">-distort</a> method '<code>Affineprojection</code> for more
166 -affine <var>s<sub>x</sub></var>,0,0,<var>s<sub>y</sub></var>
169 <p>Translation by a displacement (<var>t<sub>x</sub></var>, <var>t<sub>y</sub></var>) is accomplished like so:</p>
172 -affine 1,0,0,1,<var>t<sub>x</sub></var>,<var>t<sub>y</sub></var>
175 <p>Rotate clockwise about the origin (the upper left-hand corner) by an angle
176 <var>a</var> by letting <var>c</var> = cos(<var>a</var>), <var>s</var>
177 = sin(<var>a</var>), and using the following.</p>
180 -affine <var>c</var>,<var>s</var>,-<var>s</var>,<var>c</var>
183 <p>The cumulative effect of a sequence of <a href="command-line-options.html#affine">-affine</a>
184 transformations can be accomplished by instead by a single <a href="command-line-options.html#affine">-affine</a> operation using the matrix equal to the product of the matrices
185 of the individual transformations.</p>
187 <p>An attempt is made to detect near-singular transformation matrices. If the
188 matrix determinant has a sufficiently small absolute value it is rejected.</p>
190 <div style="margin: auto;">
191 <h3 class="magick-header"><a id="alpha"></a>-alpha <var>type</var></h3>
194 <p class="magick-description">Gives control of the alpha/matte channel of an image.</p>
196 <p>Used to set a flag on an image indicating whether or not to use existing alpha
197 channel data, to create an alpha channel, or to perform other operations on the alpha channel. Choose the argument <var>type</var> from the list below.</p>
199 <dl class="dl-horizontal">
202 Enable the image's transparency channel. Note normally Set
203 should be used instead of this, unless you specifically need to
204 preserve existing (but specifically turned Off) transparency
209 associate the alpha channel with the image.</dd>
213 Disables the image's transparency channel. Does not delete or change the
214 existing data, just turns off the use of that data.</dd>
216 <dt>Disassociate</dt>
218 disassociate the alpha channel from the image.</dd>
222 Activates the alpha/matte channel. If it was previously turned off
223 then it also resets the channel to opaque. If the image already had
224 the alpha channel turned on, it will have no effect.</dd>
228 Enables the alpha/matte channel and forces it to be fully opaque.
233 Activates the alpha/matte channel and forces it to be fully
234 transparent. This effectively creates a fully transparent image the
235 same size as the original and with all its original RGB data still
236 intact, but fully transparent. </dd>
240 Copies the alpha channel values into all the color channels and turns
241 'Off' the the image's transparency, so as to generate
242 a gray-scale mask of the image's shape. The alpha channel data is left
243 intact just deactivated. This is the inverse of 'Copy'.
248 Turns 'On' the alpha/matte channel, then copies the
249 gray-scale intensity of the image, into the alpha channel, converting
250 a gray-scale mask into a transparent shaped mask ready to be colored
251 appropriately. The color channels are not modified. </dd>
255 As per 'Copy' but also colors the resulting shape mask with
256 the current background color. That is the RGB color channels is
257 replaced, with appropriate alpha shape.
262 Composite the image over the background color.
267 Set any fully-transparent pixel to the background color, while leaving
268 it fully-transparent. This can make some image file formats, such as
269 PNG, smaller as the RGB values of transparent pixels are more uniform,
270 and thus can compress better.
274 <p>Note that while the obsolete <code>+matte</code> operation was the
275 same as "<code><a href="command-line-options.html#alpha">-alpha</a> Off</code>", the <code>
276 >-matte</code> operation was the same as "<code><a href="command-line-options.html#alpha">-alpha</a>
277 Set</code>" and not "<code><a href="command-line-options.html#alpha">-alpha</a> On</code>". </p>
280 <div style="margin: auto;">
281 <h3 class="magick-header"><a id="annotate"></a>
282 -annotate <var>degrees</var> <var>text</var><br>
283 -annotate <var>Xdegrees</var>x<var>Ydegrees</var> <var>text</var><br> -annotate <var>Xdegrees</var>x<var>Ydegrees</var> {+-}<var>t<sub>x</sub></var>{+-}<var>t<sub>y</sub></var> <var>text</var><br> -annotate {+-}<var>t<sub>x</sub></var>{+-}<var>t<sub>y</sub></var> <var>text</var></h3>
286 <p class="magick-description">Annotate an image with text</p>
288 <p>This is a convenience for annotating an image with text. For more precise
289 control over text annotations, use <a href="command-line-options.html#draw">-draw</a>.</p>
292 <p>The values <var>Xdegrees</var> and <var>Ydegrees</var>
293 control the shears applied to the text, while <var>t<sub>x</sub></var> and <var>t<sub>y</sub></var> are offsets that give the location of the text relative any <a href="command-line-options.html#gravity">-gravity</a> setting and defaults to the upper left corner of the image.</p>
295 <p>Using <a href="command-line-options.html#annotate">-annotate</a> <var>degrees</var>
296 or <a href="command-line-options.html#annotate">-annotate</a> <var>degrees</var>x<var>degrees</var> produces an unsheared rotation of the text. The
297 direction of the rotation is positive, which means a clockwise rotation if <var>degrees</var> is positive. (This conforms to the usual mathematical
298 convention once it is realized that the positive <var>y</var>–direction is
299 conventionally considered to be <var>downward</var> for images.)</p>
301 <p>The new (transformed) coordinates (<var>x'</var>, <var>y'</var>) of a pixel at position (<var>x</var>, <var>y</var>) in the image are calculated using the following matrix
304 <p class="text-center"><img class="img-thumbnail" alt="annotate transformation" src="../images/annotate.png"></p>
306 <p>If <var>t<sub>x</sub></var> and <var>t<sub>y</sub></var> are omitted, they default to 0. This makes the
307 bottom-left of the text becomes the upper-left corner of the image, which is
308 probably undesirable. Adding a <a href="command-line-options.html#gravity">-gravity</a> option in this
309 case leads to nice results.</p>
311 <p>Text is any UTF-8 encoded character sequence. If <var>text</var>
312 is of the form '@mytext.txt', the text is read from the file
313 <code>mytext.txt</code>. Text in a file is taken literally; no embedded
314 formatting characters are recognized.</p>
316 <div style="margin: auto;">
317 <h3 class="magick-header"><a id="antialias"></a>-antialias</h3>
320 <p class="magick-description">Enable/Disable of the rendering of anti-aliasing pixels when drawing fonts and lines.</p>
322 <p>By default, objects (e.g. text, lines, polygons, etc.) are antialiased when
323 drawn. Use <a href="command-line-options.html#antialias">+antialias</a> to disable the addition of
324 antialiasing edge pixels. This will then reduce the number of colors added to
325 an image to just the colors being directly drawn. That is, no mixed colors
326 are added when drawing such objects. </p>
328 <div style="margin: auto;">
329 <h3 class="magick-header"><a id="append"></a>-append</h3>
332 <p class="magick-description">Join current images vertically or horizontally.</p>
334 <p>This option creates a single longer image, by joining all the current
335 images in sequence top-to-bottom. Use <a href="command-line-options.html#append">+append</a> to
336 stack images left-to-right. </p>
338 <p>If they are not of the same width, narrower images are padded with the
339 current <a href="command-line-options.html#background">-background</a> color setting, and their
340 position relative to each other can be controlled by the current <a href="command-line-options.html#gravity">-gravity</a> setting. </p>
343 <div style="margin: auto;">
344 <h3 class="magick-header"><a id="attenuate"></a>-attenuate <var>value</var></h3>
347 <p class="magick-description">Lessen (or intensify) when adding noise to an image.</p>
349 <p>If unset the value is equivalent to 1.0, or a maximum noise addition</p>
351 <div style="margin: auto;">
352 <h3 class="magick-header"><a id="authenticate"></a>-authenticate <var>password</var></h3>
355 <p class="magick-description">Decrypt a PDF with a password.</p>
357 <p>Use this option to supply a <var>password</var> for decrypting
358 a PDF that has been encrypted using Microsoft Crypto API (MSC API). The
359 encrypting using the MSC API is not supported.</p>
361 <p>For a different encryption method, see <a href="command-line-options.html#encipher">-encipher</a>
362 and <a href="command-line-options.html#decipher">-decipher</a>. </p>
365 <div style="margin: auto;">
366 <h3 class="magick-header"><a id="auto-gamma"></a>-auto-gamma</h3>
369 <p class="magick-description">Automagically adjust gamma level of image.</p>
371 <p>This calculates the mean values of an image, then applies a calculated <a href="command-line-options.html#gamma">-gamma</a> adjustment so that is the mean color exists in the
372 image it will get a have a value of 50%. </p>
374 <p>This means that any solid 'gray' image becomes 50% gray. </p>
376 <p>This works well for real-life images with little or no extreme dark and
377 light areas, but tend to fail for images with large amounts of bright sky or
378 dark shadows. It also does not work well for diagrams or cartoon like images.
381 <p>It uses the <a href="command-line-options.html#channel">-channel</a> setting, (including the
382 '<var>sync</var>' flag for channel synchronization), to determine which color
383 values is used and modified. As the default <a href="command-line-options.html#channel">-channel</a> setting is '<var>RGB,sync</var>', channels are modified
384 together by the same gamma value, preserving colors. </p>
388 <div style="margin: auto;">
389 <h3 class="magick-header"><a id="auto-level"></a>-auto-level</h3>
392 <p class="magick-description">Automagically adjust color levels of image.</p>
394 <p>This is a 'perfect' image normalization operator. It finds the exact
395 minimum and maximum color values in the image and then applies a <a href="command-line-options.html#level">-level</a> operator to stretch the values to the full range of
398 <p>The operator is not typically used for real-life images, image scans, or
399 JPEG format images, as a single 'out-rider' pixel can set a bad min/max values
400 for the <a href="command-line-options.html#level">-level</a> operation. On the other hand it is the
401 right operator to use for color stretching gradient images being used to
402 generate Color lookup tables, distortion maps, or other 'mathematically'
405 <p>The operator is very similar to the <a href="command-line-options.html#normalize">-normalize</a>, <a href="command-line-options.html#contrast-stretch">-contrast-stretch</a>, and <a href="command-line-options.html#linear-stretch">-linear-stretch</a> operators, but without 'histogram binning' or 'clipping'
406 problems that these operators may have. That is <a href="command-line-options.html#auto-level">-auto-level</a> is the perfect or ideal version these operators. </p>
408 <p>It uses the <a href="command-line-options.html#channel">-channel</a> setting, (including the
409 special '<var>sync</var>' flag for channel synchronization), to determine
410 which color values are used and modified. As the default <a href="command-line-options.html#channel">+channel</a> setting is '<var>RGB,sync</var>', the
411 '<var>sync</var>' ensures that the color channels will are modified
412 together by the same gamma value, preserving colors, and ignoring
416 <div style="margin: auto;">
417 <h3 class="magick-header"><a id="auto-orient"></a>-auto-orient</h3>
420 <p class="magick-description">adjusts an image so that its orientation is suitable for viewing (i.e. top-left orientation).</p>
422 <p>This operator reads and resets the EXIF image profile setting 'Orientation'
423 and then performs the appropriate 90 degree rotation on the image to orient
424 the image, for correct viewing. </p>
426 <p>This EXIF profile setting is usually set using a gravity sensor in digital
427 camera, however photos taken directly downward or upward may not have an
428 appropriate value. Also images that have been orientation 'corrected' without
429 reseting this setting, may be 'corrected' again resulting in a incorrect
430 result. If the EXIF profile was previously stripped, the <a href="command-line-options.html#auto-orient">-auto-orient</a> operator will do nothing. </p>
433 <div style="margin: auto;">
434 <h3 class="magick-header"><a id="average"></a>-average</h3>
437 <p class="magick-description">Average a set of images.</p>
439 <p>An error results if the images are not identically sized.</p>
442 <div style="margin: auto;">
443 <h3 class="magick-header"><a id="backdrop"></a>-backdrop</h3>
446 <p class="magick-description">Display the image centered on a backdrop.</p>
448 <p>This backdrop covers the entire workstation screen and is useful for hiding
449 other X window activity while viewing the image. The color of the backdrop is
450 specified as the background color. The color is specified using the format
451 described under the <a href="command-line-options.html#fill">-fill</a> option.</p>
453 <div style="margin: auto;">
454 <h3 class="magick-header"><a id="background"></a>-background <var>color</var></h3>
457 <p class="magick-description">Set the background color.</p>
459 <p>The color is specified using the format described under the <a href="command-line-options.html#fill">-fill</a> option. The default background color (if none is
460 specified or found in the image) is white.</p>
462 <div style="margin: auto;">
463 <h3 class="magick-header"><a id="bench"></a>-bench <var>iterations</var></h3>
466 <p class="magick-description">Measure performance.</p>
468 <p>Repeat the entire command for the given number of <var>iterations</var> and report the user-time and elapsed time. For instance,
469 consider the following command and its output. Modify the benchmark with the
470 -duration to run the benchmark for a fixed number of seconds and -concurrent
471 to run the benchmark in parallel (requires the OpenMP feature).</p>
474 -> convert logo: -resize 1000% -bench 5 logo.png
475 Performance[4]: 5i 0.875657ips 6.880u 0:05.710
478 <p>In this example, 5 iterations were completed at 0.875657 iterations per
479 second, using 4 threads and 6.88 seconds of the user's allotted time, for
480 a total elapsed time of 5.71 seconds.</p>
482 <div style="margin: auto;">
483 <h3 class="magick-header"><a id="bias"></a>-bias <var>value</var>{<var>%</var>}</h3>
486 <p class="magick-description">Add bias when convolving an image.</p>
488 <p>This option shifts the output of <a href="command-line-options.html#convolve">‑convolve</a> so that
489 positive and negative results are relative to the specified bias value. </p>
491 <p>This is important for non-HDRI compilations of ImageMagick when dealing
492 with convolutions that contain negative as well as positive values. This is
493 especially the case with convolutions involving high pass filters or edge
494 detection. Without an output bias, the negative values are clipped at
497 <p>When using an ImageMagick with the HDRI compile-time setting, <a href="command-line-options.html#bias">‑bias</a> is not needed, as ImageMagick is able to store/handle any
498 negative results without clipping to the color value range
499 (0..QuantumRange).</p>
501 <p>See the discussion on HDRI implementations of ImageMagick on the page <a href="high-dynamic-range.html">High Dynamic-Range Images</a>. For more
502 about HDRI go the ImageMagick <a href="http://www.imagemagick.org/Usage/basics/#hdri">Usage</a> pages or this
503 <a href="http://en.wikipedia.org/wiki/High_dynamic_range_imaging">Wikipedia</a>
506 <div style="margin: auto;">
507 <h3 class="magick-header"><a id="black-point-compensation"></a>-black-point-compensation</h3>
510 <p class="magick-description">Use black point compensation.</p>
512 <div style="margin: auto;">
513 <h3 class="magick-header"><a id="black-threshold"></a>-black-threshold <var>value</var>{<var>%</var>}</h3>
516 <p class="magick-description">Force to black all pixels below the threshold while leaving all pixels at or above the threshold unchanged.</p>
518 <p> The threshold value can be given as a percentage or as an absolute integer
519 value within [0, <var>QuantumRange</var>] corresponding to the
520 desired <a href="command-line-options.html#channel">‑channel</a> value. See <a href="command-line-options.html#threshold">‑threshold</a>for more details on thresholds and resulting values. </p>
523 <div style="margin: auto;">
524 <h3 class="magick-header"><a id="blend"></a>-blend <var>geometry</var></h3>
527 <p class="magick-description">blend an image into another by the given absolute value or percent.</p>
529 <p>Blend will average the images together ('plus') according to the
530 percentages given and each pixels transparency. If only a single percentage
531 value is given it sets the weight of the composite or 'source' image, while
532 the background image is weighted by the exact opposite amount. That is a
533 <code>-blend 30%</code> merges 30% of the 'source' image with 70% of the
534 'destination' image. Thus it is equivalent to <code>-blend 30x70%</code>.</p>
537 <div style="margin: auto;">
538 <h3 class="magick-header"><a id="blue-primary"></a>-blue-primary <var>x</var>,<var>y</var></h3>
541 <p class="magick-description">Set the blue chromaticity primary point.</p>
543 <div style="margin: auto;">
544 <h3 class="magick-header"><a id="blue-shift"></a>-blue-shift <var>factor</var></h3>
547 <p class="magick-description">simulate a scene at nighttime in the moonlight. Start with a factor of 1.5</p>
549 <div style="margin: auto;">
551 <div style="margin: auto;">
552 <h3 class="magick-header"><a id="blur"></a>-blur <var>radius</var><br>-blur <var>radius</var>x<var>sigma</var></h3>
555 <p class="magick-description">Reduce image noise and reduce detail levels.</p>
557 <p>Convolve the image with a Gaussian or normal distribution using the given
558 <var>Sigma</var> value. The formula is:</p>
560 <p class="text-center"><img class="img-thumbnail" alt="gaussian distribution" width="243px" height="42px" src="../images/gaussian-blur.png"></p>
562 <p>The <var>Sigma</var> value is the important argument, and
563 determines the actual amount of blurring that will take place. </p>
565 <p>The <var>Radius</var> is only used to determine the size of the
566 array which will hold the calculated Gaussian distribution. It should be an
567 integer. If not given, or set to zero, IM will calculate the largest possible
568 radius that will provide meaningful results for the Gaussian distribution.
571 <p>The larger the <var>Radius</var> the slower the
572 operation is. However too small a <var>Radius</var>, and sever
573 aliasing effects may result. As a guideline, <var>Radius</var>
574 should be at least twice the <var>Sigma</var> value, though three
575 times will produce a more accurate result. </p>
577 <p>This option differs from <a href="command-line-options.html#gaussian-blur">-gaussian-blur</a> simply
578 by taking advantage of the separability properties of the distribution. Here
579 we apply a single-dimensional Gaussian matrix in the horizontal direction,
580 then repeat the process in the vertical direction.</p>
582 <p>The <a href="command-line-options.html#virtual-pixel">-virtual-pixel</a> setting will determine how
583 pixels which are outside the image proper are blurred into the final result.
587 <div style="margin: auto;">
588 <h3 class="magick-header">-blur <var>Width</var>[x<var>Height</var>[+<var>Angle</var>]]</h3>
591 <p class="magick-description">Variably blur an image according to the overlay mapping.</p>
593 <p>Each pixel in the overlaid region is replaced with an Elliptical Weighted
594 Average (EWA) of the source image, scaled according to the grayscale
597 <p>The ellipse is weighted with sigma set to the given <var>Width</var> and <var>Height</var>. The <var>Height</var>
598 defaults to the <var>Width</var> for a normal circular Gaussian
599 weighting. The <var>Angle</var> will rotate the ellipse from
600 horizontal clock-wise. </p>
602 <p>The <a href="command-line-options.html#virtual-pixel">-virtual-pixel</a> setting will determine how
603 pixels which are outside the image proper are blurred into the final result.
607 <div style="margin: auto;">
608 <h3 class="magick-header"><a id="border"></a>-border <var>geometry</var></h3>
611 <p class="magick-description">Surround the image with a border of color. </p>
613 <p>Set the width and height using the <var>size</var> portion of the
614 <var>geometry</var> argument. See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument. Offsets are
617 <p>As of IM 6.7.8-8, the <var>geometry</var> arguments behave as follows:</p>
619 <dl class="dl-horizontal">
620 <dt><var>value</var></dt>
621 <dd>value is added to both left/right and top/bottom</dd>
622 <dt><var>value-x</var><kbd>x</kbd></dt>
623 <dd>value-x is added only to left/right and top/bottom are unchanged</dd>
624 <dt><kbd>x</kbd><var>value-y</var></dt>
625 <dd>value-y is added only to top/bottom and left/right are unchanged</dd>
626 <dt><var>value-x</var><kbd>x</kbd><var>value-y</var></dt>
627 <dd>value-x is added to left/right and value-y added to top/bottom</dd>
628 <dt><var>value-x</var><kbd>x</kbd>0</dt>
629 <dd>value-x is added only to left/right and top/bottom are unchanged</dd>
630 <dt>0<kbd>x</kbd><var>value-y</var></dt>
631 <dd>value-y is added only to top/bottom and left/right are unchanged</dd>
632 <dt><var>value</var>%</dt>
633 <dd>value % of width is added to left/right and value % of height is added to top/bottom</dd>
634 <dt><var>value-x</var><kbd>x</kbd>%</dt>
635 <dd>value-x % of width is added to left/right and to top/bottom</dd>
636 <dt>x<var>value-y</var>%</dt>
637 <dd>value-y % of height is added to top/bottom and to left/right</dd>
638 <dt><var>value-x</var>%<kbd>x</kbd><var>value-y</var>%</dt>
639 <dd>value-x % of width is added to left/right and value-y % of height is added to top/bottom</dd>
640 <dt><var>value-x</var>%<kbd>x</kbd>0%</dt>
641 <dd>value-x % of width is added to left/right and top/bottom are unchanged</dd>
642 <dt>0%<kbd>x</kbd><var>value-y</var>%</dt>
643 <dd>value-y % of height is added to top/bottom and left/right are unchanged</dd>
646 <p>Set the border color by preceding with the <a href="command-line-options.html#bordercolor">-bordercolor</a> setting.</p>
648 <p>The <a href="command-line-options.html#border">-border</a> operation is affected by the current <a href="command-line-options.html#compose">-compose</a> setting and assumes that this is using the default
649 '<code>Over</code>' composition method. It generates an image of the appropriate
650 size colors by the current <a href="command-line-options.html#bordercolor">-bordercolor</a> before
651 overlaying the original image in the center of this net image. This means that
652 with the default compose method of '<code>Over</code>' any transparent parts may
653 be replaced by the current <a href="command-line-options.html#bordercolor">-bordercolor</a> setting.</p>
654 <p>See also the <a href="command-line-options.html#frame">-frame</a> option, which has more
657 <div style="margin: auto;">
658 <h3 class="magick-header"><a id="bordercolor"></a>-bordercolor <var>color</var></h3>
661 <p class="magick-description">Set the border color.</p>
663 <p>The color is specified using the format described under the <a href="command-line-options.html#fill">-fill</a> option.</p>
665 <p>The default border color is <code>#DFDFDF</code>, <span style="background-color: #dfdfdf;">this shade of gray</span>.</p>
667 <div style="margin: auto;">
668 <h3 class="magick-header"><a id="borderwidth"></a>-borderwidth <var>geometry</var> </h3>
671 <p class="magick-description">Set the border width.</p>
673 <div style="margin: auto;">
674 <h3 class="magick-header"><a id="brightness-contrast"></a>-brightness-contrast <var>brightness</var><br>-brightness-contrast <var>brightness</var>{x<var>contrast</var>}{<var>%</var>}}</h3>
677 <p class="magick-description">Adjust the brightness and/or contrast of the image.</p>
679 <p>Brightness and Contrast values apply changes to the input image. They are
680 not absolute settings. A brightness or contrast value of zero means no change.
681 The range of values is -100 to +100 on each. Positive values increase the
682 brightness or contrast and negative values decrease the brightness or contrast.
683 To control only contrast, set the brightness=0. To control only brightness,
684 set contrast=0 or just leave it off.</p>
686 <p>You may also use <a href="command-line-options.html#fill">-channel</a> to control which channels to
687 apply the brightness and/or contrast change. The default is to apply the same
688 transformation to all channels.</p>
690 <p>Brightness and Contrast arguments are converted to offset and slope of a
691 linear transform and applied
692 using <a href="command-line-options.html#fill">-function polynomial "slope,offset"</a>.</p>
694 <p>The slope varies from 0 at contrast=-100 to almost vertical at
695 contrast=+100. For brightness=0 and contrast=-100, the result are totally
696 midgray. For brightness=0 and contrast=+100, the result will approach but
697 not quite reach a threshold at midgray; that is the linear transformation
698 is a very steep vertical line at mid gray.</p>
700 <p>Negative slopes, i.e. negating the image, are not possible with this
701 function. All achievable slopes are zero or positive.</p>
703 <p>The offset varies from -0.5 at brightness=-100 to 0 at brightness=0 to +0.5
704 at brightness=+100. Thus, when contrast=0 and brightness=100, the result is
705 totally white. Similarly, when contrast=0 and brightness=-100, the result is
708 <p>As the range of values for the arguments are -100 to +100, adding the '%'
709 symbol is no different than leaving it off.</p>
711 <div style="margin: auto;">
712 <h3 class="magick-header"><a id="cache"></a>-cache <var>threshold</var></h3>
715 <p class="magick-description">(This option has been replaced by the <a href="command-line-options.html#limit">-limit</a> option).</p>
717 <div style="margin: auto;">
718 <h3 class="magick-header"><a id="canny"></a>-canny <var>radius</var><br>-canny <var>radius</var>x<var>sigma</var>{<var>+lower-percent</var>}{<var>+upper-percent</var>}</h3>
721 <p class="magick-description">Canny edge detector uses a multi-stage algorithm to detect a wide range of edges in the image.</p>
723 <p>The thresholds range from 0 to 100% (e.g. -canny 0x1+10%+30%) with {<var>+lower-percent</var>} < {<var>+upper-percent</var>}. If {<var>+upper-percent</var>} is increased but {<var>+lower-percent</var>} remains the same, lesser edge components will be detected, but their lengths will be the same. If {<var>+lower-percent</var>} is increased but {<var>+upper-percent</var>} is the same, the same number of edge components will be detected but their lengths will be shorter. The default thresholds are shown. The <var>radius</var>x<var>sigma</var> controls a gaussian blur applied to the input image to reduce noise and smooth the edges.</p>
725 <div style="margin: auto;">
726 <h3 class="magick-header"><a id="caption"></a>-caption <var>string</var></h3>
729 <p class="magick-description">Assign a caption to an image.</p>
731 <p>This option sets the caption meta-data of an image read in after this
732 option has been given. To modify a caption of images already in memory use
733 "<code><a href="command-line-options.html#set">-set</a> caption</code>". </p>
735 <p>The caption can contain special format characters listed in the <a href="escape.html">Format and
736 Print Image Properties</a>. These attributes are expanded when the caption
737 is finally assigned to the individual images. </p>
739 <p>If the first character of <var>string</var> is <var>@</var>, the image caption is read from a file titled by the
740 remaining characters in the string. Comments read in from a file are literal;
741 no embedded formatting characters are recognized.</p>
743 <p>Caption meta-data is not visible on the image itself. To do that use the
744 <a href="command-line-options.html#annotate">-annotate</a> or <a href="command-line-options.html#draw">-draw</a> options
750 -caption "%m:%f %wx%h" bird.miff
753 <p>produces an image caption of <code>MIFF:bird.miff 512x480</code> (assuming
754 that the image <code>bird.miff</code> has a width of 512 and a height of
758 <div style="margin: auto;">
759 <h3 class="magick-header"><a id="cdl"></a>-cdl <var>filename</var></h3>
762 <p class="magick-description">color correct with a color decision list.</p>
764 <p>Here is an example color correction collection:</p>
767 <?xml version="1.0" encoding="UTF-8"?>
768 <ColorCorrectionCollection xmlns="urn:ASC:CDL:v1.2">
769 <ColorCorrection id="cc06668">
771 <Slope> 0.9 1.2 0.5 </Slope>
772 <Offset> 0.4 -0.5 0.6 </Offset>
773 <Power> 1.0 0.8 1.5 </Power>
776 <Saturation> 0.85 </Saturation>
778 </ColorCorrection>
779 </ColorCorrectionCollection>
782 <div style="margin: auto;">
783 <h3 class="magick-header"><a id="channel"></a>-channel <var>type</var></h3>
786 <p class="magick-description">Specify those image color channels to which subsequent operators are limited.</p>
788 <p>Choose from: <code>Red</code>, <code>Green</code>, <code>Blue</code>,
789 <code>Alpha</code>, <code>Gray</code>, <code>Cyan</code>, <code>Magenta</code>,
790 <code>Yellow</code>, <code>Black</code>, <code>Opacity</code>,
791 <code>Index</code>, <code>RGB</code>, <code>RGBA</code>, <code>CMYK</code>, or
792 <code>CMYKA</code>.</p>
794 <p>The channels above can also be specified as a comma-separated list or can be
795 abbreviated as a concatenation of the letters '<code>R</code>', '<code>G</code>',
796 '<code>B</code>', '<code>A</code>', '<code>O</code>', '<code>C</code>',
797 '<code>M</code>', '<code>Y</code>', '<code>K</code>'.
799 For example, to only select the <code>Red</code> and <code>Blue</code> channels
800 you can either use </p>
804 <p>or you can use the short hand form</p>
809 <p>All the channels that are present in an image can be specified using the
810 special channel type <code>All</code>. Not all operators are 'channel capable',
811 but generally any operators that are generally 'grey-scale' image operators,
812 will understand this setting. See individual operator documentation. </p>
816 <p>On top of the normal channel selection an extra flag can be specified,
817 '<code>Sync</code>'. This is turned on by default and if set means that
818 operators that understand this flag should perform: cross-channel
819 synchronization of the channels. If not specified, then most grey-scale
820 operators will apply their image processing operations to each individual
821 channel (as specified by the rest of the <a href="command-line-options.html#channel">-channel</a>
822 setting) completely independently from each other. </p>
824 <p>For example for operators such as <a href="command-line-options.html#auto-level">-auto-level</a> and
825 <a href="command-line-options.html#auto-gamma">-auto-gamma</a> the color channels are modified
826 together in exactly the same way so that colors will remain in-sync. Without
827 it being set, then each channel is modified separately and
828 independently, which may produce color distortion. </p>
830 <p>The <a href="command-line-options.html#morphology">-morphology</a> '<code>Convolve</code>' method
831 and the <a href="command-line-options.html#compose">-compose</a> mathematical methods, also understands
832 the '<code>Sync</code>' flag to modify the behaviour of pixel colors according
833 to the alpha channel (if present). That is to say it will modify the image
834 processing with the understanding that fully-transparent colors should not
835 contribute to the final result. </p>
837 <p>Basically, by default, operators work with color channels in synchronous, and
838 treats transparency as special, unless the <a href="command-line-options.html#channel">-channel</a>
839 setting is modified so as to remove the effect of the '<code>Sync</code>' flag.
840 How each operator does this depends on that operators current implementation.
841 Not all operators understands this flag at this time, but that is changing.
844 <p>To print a complete list of channel types, use <a href="command-line-options.html#list">-list
847 <p>By default, ImageMagick sets <a href="command-line-options.html#channel">-channel</a> to the value
848 '<code>RGBK,sync</code>', which specifies that operators act on all color
849 channels except the transparency channel, and that all the color channels are
850 to be modified in exactly the same way, with an understanding of transparency
851 (depending on the operation being applied). The 'plus' form <a href="command-line-options.html#channel">+channel</a> will reset the value back to this default. </p>
853 <p>Options that are affected by the <a href="command-line-options.html#channel">-channel</a> setting
854 include the following.
856 <a href="command-line-options.html#auto-gamma">-auto-gamma</a>,
857 <a href="command-line-options.html#auto-level">-auto-level</a>,
858 <a href="command-line-options.html#black-threshold">-black-threshold</a>,
859 <a href="command-line-options.html#blur">-blur</a>,
860 <a href="command-line-options.html#clamp">-clamp</a>,
861 <a href="command-line-options.html#clut">-clut</a>,
862 <a href="command-line-options.html#combine">-combine</a>,
863 <a href="command-line-options.html#composite">-composite</a> (Mathematical compose methods only),
864 <a href="command-line-options.html#convolve">-convolve</a>,
865 <a href="command-line-options.html#contrast-stretch">-contrast-stretch</a>,
866 <a href="command-line-options.html#evaluate">-evaluate</a>,
867 <a href="command-line-options.html#function">-function</a>,
868 <a href="command-line-options.html#fx">-fx</a>,
869 <a href="command-line-options.html#gaussian-blur">-gaussian-blur</a>,
870 <a href="command-line-options.html#hald-clut">-hald-clut</a>,
871 <a href="command-line-options.html#motion-blur">-motion-blur</a>,
872 <a href="command-line-options.html#morphology">-morphology</a>,
873 <a href="command-line-options.html#negate">-negate</a>,
874 <a href="command-line-options.html#normalize">-normalize</a>,
875 <a href="command-line-options.html#ordered-dither">-ordered-dither</a>,
876 <a href="command-line-options.html#radial-blur">-radial-blur</a>,
877 <a href="command-line-options.html#random-threshold">-random-threshold</a>,
878 <a href="command-line-options.html#separate">-separate</a>,
879 <a href="command-line-options.html#threshold">-threshold</a>, and
880 <a href="command-line-options.html#white-threshold">-white-threshold</a>.
883 <p>Warning, some operators behave differently when the <a href="command-line-options.html#channel">+channel</a> default setting is in effect, verses ANY user defined <a href="command-line-options.html#channel">-channel</a> setting (including the equivalent of the
884 default). These operators have yet to be made to understand the newer 'Sync'
887 <p>For example <a href="command-line-options.html#threshold">-threshold</a> will by default gray-scale
888 the image before thresholding, if no <a href="command-line-options.html#channel">-channel</a> setting
889 has been defined. This is not 'Sync flag controlled, yet. </p>
891 <p>Also some operators such as <a href="command-line-options.html#blur">-blur</a>, <a href="command-line-options.html#gaussian-blur">-gaussian-blur</a>, will modify their handling of the
892 color channels if the '<code>alpha</code>' channel is also enabled by <a href="command-line-options.html#channel">-channel</a>. Generally this done to ensure that
893 fully-transparent colors are treated as being fully-transparent, and thus any
894 underlying 'hidden' color has no effect on the final results. Typically
895 resulting in 'halo' effects. The newer <a href="command-line-options.html#morphology">-morphology</a>
896 convolution equivalents however does have a understanding of the 'Sync' flag
897 and will thus handle transparency correctly by default. </p>
899 <p>As a alpha channel is optional within images, some operators will read the
900 color channels of an image as a greyscale alpha mask, when the image has no
901 alpha channel present, and the <a href="command-line-options.html#channel">-channel</a> setting tells
902 the operator to apply the operation using alpha channels. The <a href="command-line-options.html#clut">-clut</a> operator is a good example of this. </p>
906 <div style="margin: auto;">
907 <h3 class="magick-header"><a id="charcoal"></a>-charcoal <var>factor</var></h3>
910 <p class="magick-description">Simulate a charcoal drawing.</p>
912 <div style="margin: auto;">
913 <h3 class="magick-header"><a id="chop"></a>-chop <var>geometry</var></h3>
916 <p class="magick-description">Remove pixels from the interior of an image.</p>
918 <p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument. The <var>width</var>
919 and <var>height</var> given in the of the <var>size</var>
920 portion of the <var>geometry</var> argument give the number of
921 columns and rows to remove. The <var>offset</var> portion of
922 the <var>geometry</var> argument is influenced by
923 a <a href="command-line-options.html#gravity">-gravity</a> setting, if present.</p>
925 <p>The <a href="command-line-options.html#chop">-chop</a> option removes entire rows and columns,
926 and moves the remaining corner blocks leftward and upward to close the gaps.</p>
928 <p>While it can remove internal rows and columns of pixels, it is more
929 typically used with as <a href="command-line-options.html#gravity">-gravity</a> setting and zero
930 offsets so as to remove a single edge from an image. Compare this to <a href="command-line-options.html#shave">-shave</a> which removes equal numbers of pixels from oppisite
931 sides of the image. </p>
933 <p>Using <a href="command-line-options.html#chop">-chop</a> effectively undoes the results of a <a href="command-line-options.html#splice">-splice</a> that was given the same <var>geometry</var> and <a href="command-line-options.html#gravity">-gravity</a> settings. </p>
935 <div style="margin: auto;">
936 <h3 class="magick-header"><a id="clamp"></a>-clamp</h3>
939 <p class="magick-description">set each pixel whose value is below zero to zero and any the pixel whose value is above the quantum range to the quantum range (e.g. 65535) otherwise the pixel value remains unchanged.</p>
941 <div style="margin: auto;">
942 <h3 class="magick-header"><a id="clip"></a>-clip</h3>
945 <p class="magick-description">Apply the clipping path if one is present.</p>
947 <p>If a clipping path is present, it is applied to subsequent operations.</p>
949 <p>For example, in the command</p>
952 convert cockatoo.tif -clip -negate negated.tif
955 <p>only the pixels within the clipping path are negated.</p>
957 <p>The <a href="command-line-options.html#clip">-clip</a> feature requires SVG support. If the SVG
958 delegate library is not present, the option is ignored.</p>
960 <p>Use <a href="command-line-options.html#clip">+clip</a> to disable clipping for subsequent operations.</p>
962 <div style="margin: auto;">
963 <h3 class="magick-header"><a id="clip-mask"></a>-clip-mask</h3>
966 <p class="magick-description">Clip the image as defined by this mask.</p>
968 <p>Use the alpha channel of the current image as a mask. Any areas that is
969 white is not modified by any of the 'image processing operators' that follow,
970 until the mask is removed. Pixels in the black areas of the clip mask are
971 modified per the requirements of the operator. </p>
973 <p>In some ways this is similar to (though not the same) as defining
974 a rectangular <a href="command-line-options.html#region">-region</a>, or using the negative of the
975 mask (third) image in a three image <a href="command-line-options.html#composite">-composite</a>,
978 <p>Use <a href="command-line-options.html#clip-mask">+clip-mask</a> to disable clipping for subsequent operations.</p>
980 <div style="margin: auto;">
981 <h3 class="magick-header"><a id="clip-path"></a>-clip-path <var>id</var></h3>
984 <p class="magick-description">Clip along a named path from the 8BIM profile.</p>
986 <p>This is identical to <a href="command-line-options.html#clip">-clip</a> except choose a specific clip path in the event the image has more than one path available. </p>
988 <p>Use <a href="command-line-options.html#clip-path">+clip-path</a> to disable clipping for subsequent operations.</p>
990 <div style="margin: auto;">
991 <h3 class="magick-header"><a id="clone"></a>-clone <var>index(s)</var></h3>
994 <p class="magick-description">make a clone of an image (or images).</p>
996 <p>Inside parenthesis (where the operator is normally used) it will make a
997 clone of the images from the last 'pushed' image sequence, and adds them to
998 the end of the current image sequence. Outside parenthesis
999 (not recommended) it clones the images from the current image sequence. </p>
1001 <p>Specify the image by its index in the sequence. The first image is index
1002 0. Negative indexes are relative to the end of the sequence; for
1003 example, <code>−1</code>
1004 represents the last image of the sequence. Specify a range of images with a
1005 dash (e.g. <code>0−4</code>). Separate multiple indexes with commas but no
1006 spaces (e.g. <code>0,2,5</code>). A value of '<code>0−−1</code> will
1007 effectively clone all the images. </p>
1009 <p>The <a href="command-line-options.html#clone">+clone</a> will simply make a copy of the last image
1010 in the image sequence, and is thus equivalent to using a argument of
1011 '<code>−1</code>'. </p>
1013 <div style="margin: auto;">
1014 <h3 class="magick-header"><a id="clut"></a>-clut</h3>
1017 <p class="magick-description">Replace the channel values in the first image using each corresponding channel in the second image as a <b>c</b>olor <b>l</b>ook<b>u</b>p <b>t</b>able.</p>
1019 <p>The second (LUT) image is ordinarily a gradient image containing the
1020 histogram mapping of how each channel should be modified. Typically it is a
1021 either a single row or column image of replacement color values. If larger
1022 than a single row or column, values are taken from a diagonal line from
1023 top-left to bottom-right corners.</p>
1025 <p>The lookup is further controlled by the <a href="command-line-options.html#interpolate">-interpolate</a> setting, which is especially handy for an
1026 LUT which is not the full length needed by the ImageMagick installed Quality
1027 (Q) level. Good settings for this are the '<code>bilinear</code>' and
1028 '<code>bicubic</code>' interpolation settings, which give smooth color
1029 gradients, and the '<code>integer</code>' setting for a direct, unsmoothed
1030 lookup of color values. </p>
1032 <p>This operator is especially suited to replacing a grayscale image with a
1033 specific color gradient from the CLUT image. </p>
1035 <p>Only the channel values defined by the <a href="command-line-options.html#channel">-channel</a>
1036 setting will have their values replaced. In particular, since the default <a href="command-line-options.html#channel">-channel</a> setting is <code>RGB</code>, this means that
1037 transparency (alpha/matte channel) is not affected, unless the <a href="command-line-options.html#channel">-channel</a> setting is modified. When the alpha channel is
1038 set, it is treated by the <a href="command-line-options.html#clut">-clut</a> operator in the same way
1039 as the other channels, implying that alpha/matte values are replaced using the
1040 alpha/matte values of the original image. </p>
1042 <p>If either the image being modified, or the lookup image, contains no
1043 transparency (i.e. <a href="command-line-options.html#alpha">-alpha</a> is turned 'off') but the <a href="command-line-options.html#channel">-channel</a> setting includes alpha replacement, then it is
1044 assumed that image represents a gray-scale gradient which is used for the
1045 replacement alpha values. That is you can use a gray-scale CLUT image to
1046 adjust a existing images alpha channel, or you can color a gray-scale image
1047 using colors form CLUT containing the desired colors, including transparency.
1050 <p>See also <a href="command-line-options.html#hald-clut">-hald-clut</a> which replaces colors
1051 according to the lookup of the full color RGB value from a 2D representation
1052 of a 3D color cube. </p>
1055 <div style="margin: auto;">
1056 <h3 class="magick-header"><a id="coalesce"></a>-coalesce</h3>
1059 <p class="magick-description">Fully define the look of each frame of an GIF animation sequence, to form a 'film strip' animation.</p>
1061 <p>Overlay each image in an image sequence according to
1062 its <a href="command-line-options.html#dispose">-dispose</a> meta-data, to reproduce the look of
1063 an animation at each point in the animation sequence. All images should be
1064 the same size, and are assigned appropriate GIF disposal settings for the
1065 animation to continue working as expected as a GIF animation. Such frames
1066 are more easily viewed and processed than the highly optimized GIF overlay
1069 <p>The animation can be re-optimized after processing using
1070 the <a href="command-line-options.html#layers">-layers</a> method '<code>optimize</code>', although
1071 there is no guarantee that the restored GIF animation optimization is
1072 better than the original. </p>
1075 <div style="margin: auto;">
1076 <h3 class="magick-header"><a id="colorize"></a>-colorize <var>value</var></h3>
1079 <p class="magick-description">Colorize the image by an amount specified by <var>value</var> using the color specified by the most recent <a href="command-line-options.html#fill">-fill</a> setting.</p>
1081 <p>Specify the amount of colorization as a percentage. Separate colorization
1082 values can be applied to the red, green, and blue channels of the image with
1083 a comma-delimited list of colorization
1084 values (e.g., <code>-colorize 0,0,50</code>).</p>
1086 <div style="margin: auto;">
1087 <h3 class="magick-header"><a id="colormap"></a>-colormap <var>type</var></h3>
1090 <p class="magick-description">Define the colormap type.</p>
1092 <p>The <var>type</var> can be <code>shared</code> or <code>private</code>.</p>
1094 <p>This option only applies when the default X server visual
1095 is <code>PseudoColor</code> or <code>GrayScale</code>. Refer
1096 to <a href="command-line-options.html#visual">-visual</a> for more details. By default,
1097 a shared colormap is allocated. The image shares colors with
1098 other X clients. Some image colors could be approximated,
1099 therefore your image may look very different than intended.
1100 If <code>private</code> is chosen, the image colors appear exactly
1101 as they are defined. However, other clients may go <var>technicolor</var>
1102 when the image colormap is installed.</p>
1104 <div style="margin: auto;">
1105 <h3 class="magick-header"><a id="colors"></a>-colors <var>value</var></h3>
1108 <p class="magick-description">Set the preferred number of colors in the image.</p>
1110 <p>The actual number of colors in the image may be less than your request,
1111 but never more. Note that this a color reduction option. Images with fewer
1112 unique colors than specified by <var>value</var> will have any
1113 duplicate or unused colors removed. The ordering of an existing color
1114 palette may be altered. When converting an image from color to grayscale,
1115 it is more efficient to convert the image to the gray colorspace before
1116 reducing the number of colors. Refer to
1117 the <a href="quantize.html">
1118 color reduction algorithm</a> for more details.</p>
1120 <div style="margin: auto;">
1121 <h3 class="magick-header"><a id="color-matrix"></a>-color-matrix <var>matrix</var></h3>
1124 <p class="magick-description">apply color correction to the image.</p>
1126 <p>This option permits saturation changes, hue rotation, luminance to alpha,
1127 and various other effects. Although variable-sized transformation matrices
1128 can be used, typically one uses a 5x5 matrix for an RGBA image and a 6x6
1129 for CMYKA (or RGBA with offsets). The matrix is similar to those used by
1130 Adobe Flash except offsets are in column 6 rather than 5 (in support of
1131 CMYKA images) and offsets are normalized (divide Flash offset by 255).</p>
1133 <p>As an example, to add contrast to an image with offsets, try this command:</p>
1136 convert kittens.jpg -color-matrix \
1137 " 1.5 0.0 0.0 0.0, 0.0, -0.157 \
1138 0.0 1.5 0.0 0.0, 0.0, -0.157 \
1139 0.0 0.0 1.5 0.0, 0.0, -0.157 \
1140 0.0 0.0 0.0 1.0, 0.0, 0.0 \
1141 0.0 0.0 0.0 0.0, 1.0, 0.0 \
1142 0.0 0.0 0.0 0.0, 0.0, 1.0" kittens.png
1144 <div style="margin: auto;">
1145 <h3 class="magick-header"><a id="colorspace"></a>-colorspace <var>value</var></h3>
1148 <p class="magick-description">Set the image colorspace.</p>
1157 OHTA Rec601YCbCr Rec709YCbCr RGB
1158 scRGB sRGB Transparent xyY
1163 <p>To print a complete list of colorspaces, use <a href="command-line-options.html#list">-list colorspace</a>.</p>
1165 <p>For a more accurate color conversion to or from the linear RGB, CMYK, or grayscale colorspaces, use the <a href="command-line-options.html#profile">-profile</a> option. Note, ImageMagick assumes the sRGB colorspace if the image format does not indicate otherwise. For colorspace conversion, the gamma function is first removed to produce linear RGB.</p>
1167 <table class="table table-condensed table-striped">
1168 <caption>Conversion of RGB to Other Color Spaces</caption>
1169 <tr><th valign="middle">CMY</th></tr>
1170 <tr><td valign="middle">C=<var>QuantumRange</var>−R</td></tr>
1171 <tr><td valign="middle">M=<var>QuantumRange</var>−G</td></tr>
1172 <tr><td valign="middle">Y=<var>QuantumRange</var>−B</td></tr>
1173 <tr><th valign="middle">CMYK — starts with CMY from above</th></tr>
1174 <tr><td valign="middle">K=min(C,Y,M)</td></tr>
1175 <tr><td valign="middle">C=<var>QuantumRange</var>*(C−K)/(<var>QuantumRange</var>−K)</td></tr>
1176 <tr><td valign="middle">M=<var>QuantumRange</var>*(M−K)/(<var>QuantumRange</var>−K)</td></tr>
1177 <tr><td valign="middle">Y=<var>QuantumRange</var>*(Y−K)/(<var>QuantumRange</var>−K)</td></tr>
1179 <tr><th valign="middle">Gray</th></tr>
1180 <tr><td valign="middle">Gray = 0.298839*R+0.586811*G+0.114350*B</td></tr>
1182 <tr><th valign="middle">HSB — Hue, Saturation, Brightness; like a cone peak downward</th></tr>
1183 <tr><td valign="middle">H=angle around perimeter (0 to 360 deg); H=0 is red; increasing angles toward green</td></tr>
1184 <tr><td valign="middle">S=distance from axis outward</td></tr>
1185 <tr><td valign="middle">B=distance along axis from bottom upward; B=max(R,G,B); <var>intensity-like</var></td></tr>
1187 <tr><th valign="middle">HSL — Hue, Saturation, Lightness; like a double cone end-to-end with peaks at very top and bottom</th></tr>
1188 <tr><td valign="middle">H=angle around perimeter (0 to 360 deg); H=0 is red; increasing angles toward green</td></tr>
1189 <tr><td valign="middle">S=distance from axis outward</td></tr>
1190 <tr><td valign="middle">L=distance along axis from bottom upward; L=0.5*max(R,G,B) + 0.5*min(R,G,B); <var>intensity-like</var></td></tr>
1192 <tr><th valign="middle">HWB — Hue, Whiteness, Blackness</th></tr>
1193 <tr><td valign="middle">Hue (complicated equation)</td></tr>
1194 <tr><td valign="middle">Whiteness (complicated equation)</td></tr>
1195 <tr><td valign="middle">Blackness (complicated equation)</td></tr>
1197 <tr><th valign="middle">LAB</th></tr>
1198 <tr><td valign="middle">L (complicated equation relating X,Y,Z)</td></tr>
1199 <tr><td valign="middle">A (complicated equation relating X,Y,Z)</td></tr>
1200 <tr><td valign="middle">B (complicated equation relating X,Y,Z)</td></tr>
1202 <tr><th valign="middle">LOG</th></tr>
1203 <tr><td valign="middle">I1 (complicated equation involving logarithm of R)</td></tr>
1204 <tr><td valign="middle">I2 (complicated equation involving logarithm of G)</td></tr>
1205 <tr><td valign="middle">I3 (complicated equation involving logarithm of B)</td></tr>
1207 <tr><th valign="middle">OHTA — approximates principal components transformation</th></tr>
1208 <tr><td valign="middle">I1=0.33333*R+0.33334*G+0.33333*B; <var>intensity-like</var></td></tr>
1209 <tr><td valign="middle">I2=(0.50000*R+0.00000*G−0.50000*B)*(<var>QuantumRange</var>+1)/2</td></tr>
1210 <tr><td valign="middle">I3=(−0.25000*R+0.50000*G−0.25000*B)*(<var>QuantumRange</var>+1)/2</td></tr>
1212 <tr><th valign="middle">Rec601Luma</th></tr>
1213 <tr><td valign="middle">Gray = 0.298839*R+0.586811*G+0.114350*B</td></tr>
1215 <tr><th valign="middle">Rec601YCbCr</th></tr>
1216 <tr><td valign="middle">Y=0.2988390*R+0.5868110*G+0.1143500*B; <var>intensity-like</var></td></tr>
1217 <tr><td valign="middle">Cb=(−0.168736*R-0.331264*G+0.500000*B)*(<var>QuantumRange</var>+1)/2</td></tr>
1218 <tr><td valign="middle">Cr=(0.500000*R−0.418688*G−0.081312*B)*(<var>QuantumRange</var>+1)/2</td></tr>
1220 <tr><th valign="middle">Rec709Luma</th></tr>
1221 <tr><td valign="middle">Gray=0.212656*R+0.715158*G+0.072186*B</td></tr>
1223 <tr><th valign="middle">Rec709YCbCr</th></tr>
1224 <tr><td valign="middle">Y=0.212656*R+0.715158*G+0.072186*B; <var>intensity-like</var></td></tr>
1225 <tr><td valign="middle">Cb=(−0.114572*R−0.385428*G+0.500000*B)+(<var>QuantumRange</var>+1)/2</td></tr>
1226 <tr><td valign="middle">Cr=(0.500000*R−0.454153*G−0.045847*B)+(<var>QuantumRange</var>+1)/2</td></tr>
1228 <tr><th valign="middle">sRGB</th></tr>
1229 <tr><td valign="middle">if R ≤ .0.0031308 then Rs=R/12.92 else Rs=1.055 R ^ (1.0 / 2.4) ? 0.055</td></tr>
1230 <tr><td valign="middle">if G ≤ .0.0031308 then Gs=B/12.92 else Gs=1.055 R ^ (1.0 / 2.4) ? 0.055</td></tr>
1231 <tr><td valign="middle">if B ≤ .0.0031308 then Bs=B/12.92 else Bs=1.055 R ^ (1.0 / 2.4) ? 0.055</td></tr>
1233 <tr><th valign="middle">XYZ</th></tr>
1234 <tr><td valign="middle">X=0.4124564*R+0.3575761*G+0.1804375*B</td></tr>
1235 <tr><td valign="middle">Y=0.2126729*R+0.7151522*G+0.0721750*B</td></tr>
1236 <tr><td valign="middle">Z=0.0193339*R+0.1191920*G+0.9503041*B</td></tr>
1238 <tr><th valign="middle">YCC</th></tr>
1239 <tr><td valign="middle">Y=(0.298839*R+0.586811*G+0.114350*B) (with complicated scaling); <var>intensity-like</var></td></tr>
1240 <tr><td valign="middle">C1=(−0.298839*R−0.586811*G+0.88600*B) (with complicated scaling)</td></tr>
1241 <tr><td valign="middle">C2=(0.70100*R−0.586811*G−0.114350*B) (with complicated scaling)</td></tr>
1243 <tr><th valign="middle">YCbCr</th></tr>
1244 <tr><td valign="middle">Y=0.2988390*R+0.5868110*G+0.1143500*B; <var>intensity-like</var></td></tr>
1245 <tr><td valign="middle">Cb=(−0.168736*R−0.331264*G+0.500000*B)*(<var>QuantumRange</var>+1)/2</td></tr>
1246 <tr><td valign="middle">Cr=(0.500000*R−0.418688*G−0.081312*B)*(<var>QuantumRange</var>+1)/2</td></tr>
1248 <tr><th valign="middle">YIQ</th></tr>
1249 <tr><td valign="middle">Y=0.298839*R+0.586811*G+0.114350*B; <var>intensity-like</var></td></tr>
1250 <tr><td valign="middle">I=(0.59600*R−0.27400*G−0.32200*B)*(<var>QuantumRange</var>+1)/2</td></tr>
1251 <tr><td valign="middle">Q=(0.21100*R−0.52300*G+0.31200*B)*(<var>QuantumRange</var>+1)/2</td></tr>
1253 <tr><th valign="middle">YPbPr</th></tr>
1254 <tr><td valign="middle">Y=0.2988390*R+0.5868110*G+0.1143500*B; <var>intensity-like</var></td></tr>
1255 <tr><td valign="middle">Pb=(−0.168736*R−0.331264*G+0.500000*B)*(<var>QuantumRange</var>+1)/2</td></tr>
1256 <tr><td valign="middle">Pr=(0.500000*R−0.418688*G−0.081312*B)*(<var>QuantumRange</var>+1)/2</td></tr>
1258 <tr><th valign="middle">YUV</th></tr>
1259 <tr><td valign="middle">Y=0.298839*R+0.586811*G+0.114350*B; <var>intensity-like</var></td></tr>
1260 <tr><td valign="middle">U=(−0.14740*R−0.28950*G+0.43690*B)*(<var>QuantumRange</var>+1)/2</td></tr>
1261 <tr><td valign="middle">V=(0.61500*R−0.51500*G−0.10000*B)*(<var>QuantumRange</var>+1)/2</td></tr>
1264 <p>Note the scRGB colorspace requires HDRI support otherwise it behaves just like linear RGB.</p>
1266 <div style="margin: auto;">
1267 <h3 class="magick-header"><a id="combine"></a>-combine</h3>
1270 <p class="magick-description">Combine one or more images into a single image.</p>
1272 <p>The channels (previously set by <a href="command-line-options.html#channel">-channel</a>) of the
1273 combined image are taken from the grayscale values of each image in the
1274 sequence, in order. For the default -channel setting of <code>RGB</code>, this
1275 means the first image is assigned to the <code>Red</code> channel, the second
1276 to the <code>Green</code> channel, the third to the <code>Blue</code>.</p>
1278 <p>This option can be thought of as the inverse to <a href="command-line-options.html#separate">-separate</a>, so long as the channel settings are the same.
1279 Thus, in the following example, the final image should be a copy of the
1283 convert original.png -channel RGB -separate sepimage.png
1284 convert sepimage-0.png sepimage-1.png sepimage-2.png -channel RGB \
1285 -combine imagecopy.png
1288 <div style="margin: auto;">
1289 <h3 class="magick-header"><a id="comment"></a>-comment <var>string</var></h3>
1292 <p class="magick-description">Embed a comment in an image.</p>
1294 <p>This option sets the comment meta-data of an image read in after this
1295 option has been given. To modify a comment of images already in memory use
1296 "<code><a href="command-line-options.html#set">-set</a> comment</code>". </p>
1298 <p>The comment can contain special format characters listed in the <a href="escape.html">Format and
1299 Print Image Properties</a>. These attributes are expanded when the comment
1300 is finally assigned to the individual images. </p>
1302 <p>If the first character of <var>string</var> is <var>@</var>, the image comment is read from a file titled by the
1303 remaining characters in the string. Comments read in from a file are literal;
1304 no embedded formatting characters are recognized.</p>
1306 <p>Comment meta-data are not visible on the image itself. To do that use the
1307 <a href="command-line-options.html#annotate">-annotate</a> or <a href="command-line-options.html#draw">-draw</a> options
1313 -comment "%m:%f %wx%h" bird.miff
1316 <p>produces an image comment of <code>MIFF:bird.miff 512x480</code> (assuming
1317 that the image <code>bird.miff</code> has a width of 512 and a height of
1320 <div style="margin: auto;">
1321 <h3 class="magick-header"><a id="compare"></a>-compare</h3>
1324 <p class="magick-description">mathematically and visually annotate the difference between an image and its reconstruction</p>
1326 <p>This is a convert version of "<code>compare</code>" for two same sized images. The syntax is as follows, but other metrics are allowed.</p>
1329 convert image.png reference.png -metric RMSE -compare \ <br> difference.png
1332 <p>To get the metric value use the string format "%[distortion]".</p>
1335 convert image.png reference.png -metric RMSE -compare -format \
1336 "%[distortion]" info:
1339 <div style="margin: auto;">
1340 <h3 class="magick-header"><a id="complex"></a>-complex <var>operator</var></h3>
1343 <p class="magick-description">perform complex mathematics on an image sequence</p>
1345 Choose from these operators:
1357 <p>Optionally specify the <code>divide</code> operator SNR with <code><a href="command-line-options.html#define">-define</a> complex:snr=float</code>.</p>
1359 <div style="margin: auto;">
1360 <h3 class="magick-header"><a id="compose"></a>-compose <var>operator</var></h3>
1363 <p class="magick-description">Set the type of image composition.</p>
1365 <p>See <a href="compose.html">Alpha Compositing</a> for
1366 a detailed discussion of alpha compositing.</p>
1368 <p>This setting effects image processing operators that merge two (or more)
1369 images together in some way. This includes the operators,
1370 <a href="command-line-options.html#composite">-compare</a>,
1371 <a href="command-line-options.html#composite">-composite</a>,
1372 <a href="command-line-options.html#layers">-layers</a> composite,
1373 <a href="command-line-options.html#flatten">-flatten</a>,
1374 <a href="command-line-options.html#mosaic">-mosaic</a>,
1375 <a href="command-line-options.html#layers">-layers</a> merge,
1376 <a href="command-line-options.html#border">-border</a>,
1377 <a href="command-line-options.html#frame">-frame</a>,
1378 and <a href="command-line-options.html#extent">-extent</a>. </p>
1380 <p>It is also one of the primary options for the "<code>composite</code>"
1384 <div style="margin: auto;">
1385 <h3 class="magick-header"><a id="composite"></a>-composite</h3>
1388 <p class="magick-description">Perform alpha composition on two images and an optional mask</p>
1390 <p>Take the first image 'destination' and overlay the second 'source' image
1391 according to the current <a href="command-line-options.html#compose">-compose</a> setting. The location
1392 of the 'source' or 'overlay' image is controlled according to <a href="command-line-options.html#geometry">-geometry</a>, and <a href="command-line-options.html#geometry">-geometry</a>
1395 <p>If a third image is given this is treated as a gray-scale blending 'mask' image
1396 relative to the first 'destination' image. This mask is blended with the
1397 source image. However for the '<code>displace</code>' compose method, the
1398 mask is used to provide a separate Y-displacement image instead. </p>
1400 <p>If a <a href="command-line-options.html#compose">-compose</a> method requires extra numerical
1401 arguments or flags these can be provided by setting the <a href="command-line-options.html#set">-set</a> '<code>option:compose:args</code>'
1402 appropriately for the compose method. </p>
1404 <p>Some <a href="command-line-options.html#compose">-compose</a> methods can modify the 'destination'
1405 image outside the overlay area. You can disable this by setting the special <a href="command-line-options.html#set">-set</a> '<code>option:compose:outside-overlay</code>'
1406 to '<code>false</code>'. </p>
1408 <p>The SVG compositing specification requires that color and opacity values range between zero and QuantumRange inclusive. You can permit values outside this range with this option: <a href="command-line-options.html#set">-set</a> '<code>option:compose:clamp=false</code></p>
1411 <div style="margin: auto;">
1412 <h3 class="magick-header"><a id="compress"></a>-compress <var>type</var></h3>
1415 <p class="magick-description">Use pixel compression specified by <var>type</var> when writing the image.</p>
1417 <p>Choices are: <code>None</code>, <code>BZip</code>, <code>Fax</code>, <code>Group4</code>, <code>JPEG</code>, <code>JPEG2000</code>, <code>Lossless</code>, <code>LZW</code>, <code>RLE</code> or <code>Zip</code>.</p>
1419 <p>To print a complete list of compression types, use <a href="command-line-options.html#list">-list
1422 <p>Specify <a href="command-line-options.html#compress">+compress</a> to store the binary image in an
1423 uncompressed format. The default is the compression type of the specified
1426 <p>If <code>LZW</code> compression is specified but LZW compression has not been
1427 enabled, the image data is written in an uncompressed LZW format that can be
1428 read by LZW decoders. This may result in larger-than-expected GIF files.</p>
1430 <p><code>Lossless</code> refers to lossless JPEG, which is only available if the
1431 JPEG library has been patched to support it. Use of lossless JPEG is generally
1432 not recommended.</p>
1435 When writing an ICO file, you may request that the images be encoded in
1436 PNG format, by specifying <code>Zip</code> compression.</p>
1439 When writing a JNG file, specify <code>Zip</code> compression to request that
1440 the alpha channel be encoded in PNG "IDAT" format, or <code>JPEG</code>
1441 to request that it be encoded in JPG "JDAA" format.</p>
1443 <p>Use the <a href="command-line-options.html#quality">-quality</a> option to set the compression level
1444 to be used by JPEG, PNG, MIFF, and MPEG encoders.
1445 Use the <a href="command-line-options.html#sampling-factor">-sampling-factor</a> option to set the
1446 sampling factor to be used by JPEG, MPEG, and YUV encoders for down-sampling
1447 the chroma channels.</p>
1449 <div style="margin: auto;">
1450 <h3 class="magick-header"><a id="connected-components"></a>-connected-components <var>connectivity</var></h3>
1453 <p class="magick-description">connected-components uniquely labeled, choose from 4 or 8 way connectivity.</p>
1455 <p>Use <code><a href="command-line-options.html#define">-define</a> connected-components:verbose=true</code> to output statistics associated with each unique label.</p>
1457 <div style="margin: auto;">
1458 <h3 class="magick-header"><a id="contrast"></a>-contrast</h3>
1461 <p class="magick-description">Enhance or reduce the image contrast.</p>
1463 <p>This option enhances the intensity differences between the lighter and
1464 darker elements of the image. Use <a href="command-line-options.html#contrast">-contrast</a> to enhance
1465 the image or <a href="command-line-options.html#contrast">+contrast</a> to reduce the image
1468 <p>For a more pronounced effect you can repeat the option:</p>
1471 convert rose: -contrast -contrast rose_c2.png
1474 <div style="margin: auto;">
1475 <h3 class="magick-header"><a id="contrast-stretch"></a>-contrast-stretch <var>black-point</var><br>-contrast-stretch <var>black-point</var>{x<var>white-point</var>}{<var>%</var>}}</h3>
1478 <p class="magick-description">Increase the contrast in an image by <var>stretching</var> the range of intensity values.</p>
1480 <p>While performing the stretch, black-out at most <var>black-point</var> pixels and white-out at most <var>white-point</var> pixels. Or, if percent is used, black-out at most
1481 <var>black-point %</var> pixels and white-out at most <var>white-point %</var> pixels.</p>
1483 <p>Prior to ImageMagick 6.4.7-0, <a href="command-line-options.html#contrast-stretch">-contrast-stretch</a> will black-out at most <var>black-point</var> pixels and white-out at most <var>total pixels
1484 minus white-point</var> pixels. Or, if percent is used, black-out at most <var>black-point %</var> pixels and white-out at most <var>100% minus white-point %</var> pixels.</p>
1486 <p>Note that <code>-contrast-stretch 0</code> will modify the image such that
1487 the image's min and max values are stretched to 0 and <var>QuantumRange</var>, respectively, without any loss of data due to burn-out or
1488 clipping at either end. This is not the same as <a href="command-line-options.html#normalize">-normalize</a>, which is equivalent to <code>-contrast-stretch 0.15x0.05%</code> (or
1489 prior to ImageMagick 6.4.7-0, <code>-contrast-stretch 2%x99%</code>).</p>
1491 <p>Internally operator works by creating a histogram bin, and then uses that
1492 bin to modify the image. As such some colors may be merged together when they
1493 originally fell into the same 'bin'. </p>
1495 <p>All the channels are normalized in concert by the came amount so as to
1496 preserve color integrity, when the default <a href="command-line-options.html#channel">+channel</a>
1497 setting is in use. Specifying any other <a href="command-line-options.html#channel">-channel</a>
1498 setting will normalize the RGB channels independently.</p>
1500 <p>See also <a href="command-line-options.html#auto-level">-auto-level</a> for a 'perfect'
1501 normalization of mathematical images. </p>
1503 <p>This operator is under review for re-development. </p>
1506 <div style="margin: auto;">
1507 <h3 class="magick-header"><a id="convolve"></a>-convolve <var>kernel</var></h3>
1510 <p class="magick-description">Convolve an image with a user-supplied convolution kernel.</p>
1512 <p>The <var>kernel</var> is a matrix specified as
1513 a comma-separated list of integers (with no spaces), ordered left-to right,
1514 starting with the top row. Presently, only odd-dimensioned kernels are
1515 supported, and therefore the number of entries in the specified <var>kernel</var> must be 3<sup>2</sup>=9, 5<sup>2</sup>=25,
1516 7<sup>2</sup>=49, etc. </p>
1518 <p>Note that the <a href="command-line-options.html#convolve">‑convolve</a> operator supports the <a href="command-line-options.html#bias">‑bias</a> setting. This option shifts the convolution so that
1519 positive and negative results are relative to a user-specified bias value.
1520 This is important for non-HDRI compilations of ImageMagick when dealing with
1521 convolutions that contain negative as well as positive values. This is
1522 especially the case with convolutions involving high pass filters or edge
1523 detection. Without an output bias, the negative values is clipped at zero.
1526 <p>When using an ImageMagick with the HDRI compile-time setting, <a href="command-line-options.html#bias">‑bias</a> is not needed, as ImageMagick is able to store/handle any
1527 negative results without clipping to the color value range (0..QuantumRange).
1528 See the discussion on HDRI implementations of ImageMagick on the page <a href="high-dynamic-range.html">High
1529 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
1530 <a href="http://en.wikipedia.org/wiki/High_dynamic_range_imaging">Wikipedia</a>
1534 <div style="margin: auto;">
1535 <h3 class="magick-header"><a id="copy"></a>-copy <var>geometry</var> <var>offset</var></h3>
1538 <p class="magick-description">copy pixels from one area of an image to another.</p>
1540 <div style="margin: auto;">
1541 <h3 class="magick-header"><a id="crop"></a>-crop <var>geometry</var>{<var>@</var>}{<var>!</var>}</h3>
1544 <p class="magick-description">Cut out one or more rectangular regions of the image.</p>
1546 <p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
1548 <p>The <var>width</var> and <var>height</var> of the <var>geometry</var> argument give the size of the image that remains
1549 after cropping, and <var>x</var> and <var>y</var> in the
1550 <var>offset</var> (if present) gives the location of the top left
1551 corner of the cropped image with respect to the original image. To specify the
1552 amount to be removed, use <a href="command-line-options.html#shave">-shave</a> instead.</p>
1554 <p>If the <var>x</var> and <var>y</var> offsets are
1555 present, a single image is generated, consisting of the pixels from the
1556 cropping region. The offsets specify the location of the upper left corner of
1557 the cropping region measured downward and rightward with respect to the upper
1558 left corner of the image. If the <a href="command-line-options.html#gravity">-gravity</a> option is
1559 present with <code>NorthEast</code>, <code>East</code>, or <code>SouthEast</code>
1560 gravity, it gives the distance leftward from the right edge of the image to
1561 the right edge of the cropping region. Similarly, if the <a href="command-line-options.html#gravity">-gravity</a> option is present with <code>SouthWest</code>,
1562 <code>South</code>, or <code>SouthEast</code> gravity, the distance is measured
1563 upward between the bottom edges.</p>
1565 <p>If the <var>x</var> and <var>y</var> offsets are
1566 omitted, a set of tiles of the specified geometry, covering the entire input
1567 image, is generated. The rightmost tiles and the bottom tiles are smaller if
1568 the specified geometry extends beyond the dimensions of the input image.</p>
1570 <p>You can add the <var>@</var> to the geometry argument to equally divide the image into the number of tiles generated.</p>
1572 <p>By adding a exclamation character flag to the geometry argument, the
1573 cropped images virtual canvas page size and offset is set as if the
1574 geometry argument was a viewport or window. This means the canvas page size
1575 is set to exactly the same size you specified, the image offset set
1576 relative top left corner of the region cropped. </p>
1578 <p>If the cropped image 'missed' the actual image on its virtual canvas, a
1579 special single pixel transparent 'missed' image is returned, and a 'crop
1580 missed' warning given. </p>
1582 <p>It might be necessary to <a href="command-line-options.html#repage">+repage</a> the image prior to
1583 cropping the image to ensure the crop coordinate frame is relocated to the
1584 upper-left corner of the visible image.
1586 Similarly you may want to use <a href="command-line-options.html#repage">+repage</a> after cropping to
1587 remove the page offset that will be left behind. This is especially true when
1588 you are going to write to an image format such as PNG that supports an image
1591 <div style="margin: auto;">
1592 <h3 class="magick-header"><a id="cycle"></a>-cycle <var>amount</var></h3>
1595 <p class="magick-description">displace image colormap by amount.</p>
1597 <p><var>Amount</var> defines the number of positions each
1598 colormap entry is shifted.</p>
1601 <div style="margin: auto;">
1602 <h3 class="magick-header"><a id="debug"></a>-debug <var>events</var></h3>
1605 <p class="magick-description">enable debug printout.</p>
1607 <p>The <code>events</code> parameter specifies which events are to be logged. It
1608 can be either <code>None</code>, <code>All</code>, <code>Trace</code>, or
1609 a comma-separated list consisting of one or more of the following domains:
1610 <code>Accelerate</code>, <code>Annotate</code>, <code>Blob</code>, <code>Cache</code>,
1611 <code>Coder</code>, <code>Configure</code>, <code>Deprecate</code>,
1612 <code>Exception</code>, <code>Locale</code>, <code>Render</code>,
1613 <code>Resource</code>, <code>Security</code>, <code>TemporaryFile</code>,
1614 <code>Transform</code>, <code>X11</code>, or <code>User</code>. </p>
1617 <p>For example, to log cache and blob events, use.</p>
1620 convert -debug "Cache,Blob" rose: rose.png
1623 <p>The <code>User</code> domain is normally empty, but developers can log user
1624 events in their private copy of ImageMagick.</p>
1626 <p>To print the complete list of debug methods, use <a href="command-line-options.html#list">-list
1629 <p>Use the <a href="command-line-options.html#log">-log</a> option to specify the format for debugging
1632 <p>Use <a href="command-line-options.html#debug">+debug</a> to turn off all logging.</p>
1634 <p>Debugging may also be set using the <code>MAGICK_DEBUG</code> <a href="resources.html#environment">environment variable</a>. The allowed values for the <code>MAGICK_DEBUG</code>
1635 environment variable are the same as for the <a href="command-line-options.html#debug">-debug</a>
1639 <div style="margin: auto;">
1640 <h3 class="magick-header"><a id="decipher"></a>-decipher <var>filename</var></h3>
1643 <p class="magick-description">Decipher and restore pixels that were previously transformed by <a href="command-line-options.html#encipher">-encipher</a>.</p>
1645 <p>Get the passphrase from the file specified by <var>filename</var>.</p>
1647 <p>For more information, see the webpage, <a href="http://www.imagemagick.org/www/cipher.html">ImageMagick: Encipher or
1648 Decipher an Image</a>.</p>
1651 <div style="margin: auto;">
1652 <h3 class="magick-header"><a id="deconstruct"></a>-deconstruct</h3>
1655 <p class="magick-description">find areas that has changed between images </p>
1657 <p>Given a sequence of images all the same size, such as produced by <a href="command-line-options.html#coalesce">-coalesce</a>, replace the second and later images, with
1658 a smaller image of just the area that changed relative to the previous image.
1661 <p>The resulting sequence of images can be used to optimize an animation
1662 sequence, though will not work correctly for GIF animations when parts of the
1663 animation can go from opaque to transparent. </p>
1665 <p>This option is actually equivalent to the <a href="command-line-options.html#layers">-layers</a>
1666 method '<code>compare-any</code>'. </p>
1669 <div style="margin: auto;">
1670 <h3 class="magick-header"><a id="define"></a>-define <var>key</var>{<var>=value</var>}<var>...</var></h3>
1673 <p class="magick-description">add specific global settings generally used to control coders and image processing operations.</p>
1675 <p>This option creates one or more definitions for coders and decoders to use
1676 while reading and writing image data. Definitions are generally used to
1677 control image file format coder modules, and image processing operations,
1678 beyond what is provided by normal means. Defined settings are listed in <a href="command-line-options.html#verbose">-verbose</a> information ("<code>info:</code>" output format)
1679 as "Artifacts". </p>
1681 <p>If <var>value</var> is missing for a definition, an empty-valued
1682 definition of a flag is created with that name. This used to control on/off
1683 options. Use <a href="command-line-options.html#define">+define key</a> to remove definitions
1684 previously created. Use <a href="command-line-options.html#define">+define "*"</a> to remove all
1685 existing definitions.</p>
1687 <p>The same 'artifact' settings can also be defined using the <a href="command-line-options.html#set">-set "option:<var>key</var>" "<var>value</var>"</a> option, which also allows the use of <a href="escape.html">Format and Print Image
1688 Properties</a> in the defined value. </p>
1690 <p>The <var>option</var> and <var>key</var> are case-independent (they are
1691 converted to lowercase for use within the decoders) while the <var>value</var>
1692 is case-dependent.</p>
1694 <p>Such settings are global in scope, and affect all images and operations. </p>
1696 <p>The following definitions are just some of the artifacts that are
1699 <table class="table table-condensed table-striped">
1701 <td>bmp:format=<var>value</var></td>
1702 <td> valid values are <var>bmp2</var>, <var>bmp3</var>,
1703 and <var>bmp4</var>. This option can be useful when the
1704 method of prepending "BMP2:" to the output filename is inconvenient or
1705 is not available, such as when using the <a href="mogrify.html">mogrify</a> utility.</td>
1709 <td>colorspace:auto-grayscale=<var>on|off</var></td>
1710 <td>prevent automatic conversion to grayscale inside coders that support grayscale.</td>
1714 <td>complex:snr=<var>value</var></td>
1715 <td>Set the divide SNR constant<a href="command-line-options.html#complex">-complex</a></td>
1719 <td>compose:args=<var>arguments</var></td>
1720 <td>Sets certain compose argument values when using convert ... -compose ...
1721 -composite. See <a href="http://www.imagemagick.org/www/compose.html">Image Composition</a></td>
1725 <td>compose:clamp=<var>on|off</var></td>
1726 <td>set each pixel whose value is below zero to zero and any the pixel whose value is above the quantum range to the quantum range (e.g. 65535) otherwise the pixel value remains unchanged. Define supported in ImageMagick 6.9.1-3 and above.</td>
1730 <td>convolve:scale=<var>{kernel_scale}[!^] [,{origin_addition}] [%]</var></td>
1731 <td>Defines the kernel scaling. The special flag ! automatically scales to
1732 full dynamic range. The ! flag can be used in combination with a factor or
1733 percent. The factor or percent is then applied after the automatic scaling.
1734 An example is 50%!. This produces a result 50% darker than full dynamic
1735 range scaling. The ^ flag assures the kernel is 'zero-summing', for
1736 example when some values are positive and some are negative as in edge
1737 detection kernels. The origin addition adds that value to the center
1738 pixel of the kernel. This produces and effect that is like adding the image
1739 that many times to the result of the filtered image. The typical value
1740 is 1 so that the original image is added to the result of the convolution.
1741 The default is 0.</td>
1745 <td>convolve:showkernel=<var>1</var></td>
1746 <td>Outputs (to 'standard error') all the information about a specified <a href="command-line-options.html#morphology">-morphology convolve</a> kernel.</td>
1750 <td>dcm:display-range=<var>reset</var></td>
1751 <td>Sets the display range to the minimum and maximum pixel values for the
1752 DCM image format.</td>
1756 <td>dds:cluster-fit=<var>true|false</var></td>
1757 <td>Enables the dds cluster-fit.</td>
1761 <td>dds:compression=<var>dxt1|dxt5|none</var></td>
1762 <td>Sets the dds compression.</td>
1766 <td>dds:mipmaps=<var>value</var></td>
1767 <td>Sets the dds number of mipmaps.</td>
1771 <td>dds:weight-by-alpha=<var>true|false</var></td>
1772 <td>Enables the dds alpha weighting.</td>
1776 <td>delegate:bimodal=<var>true</var></td>
1777 <td>Specifies direct conversion from Postscript to PDF.</td>
1781 <td>distort:scale=<var>value</var></td>
1782 <td>Sets the output scaling factor for use with <a href="command-line-options.html#distort">-distort</a></td>
1786 <td>distort:viewport=<var>WxH+X+Y</var></td>
1787 <td>Sets the viewport for use with <a href="command-line-options.html#distort">-distort</a></td>
1791 <td>dot:layout-engine=<var>value</var></td>
1792 <td>Specifies the layout engine for the DOT image format (e.g.
1793 <code>neato</code>).</td>
1797 <td>filter:option=<var>value</var></td>
1798 <td>Set a filter option for use with <a href="command-line-options.html#resize">-resize</a>.
1799 See <a href="command-line-options.html#filter">-filter</a> for details.</td>
1803 <td>fourier:normalize=<var>inverse</var></td>
1804 <td>Sets the location for the FFT/IFT normalization as use by
1805 <a href="command-line-options.html#fft">+-fft</a> and <a href="command-line-options.html#ift">+-ift</a>. The default is
1810 <td>icon:auto-resize</td>
1811 <td>Automatically stores multiple sizes when writing an ico image
1812 (requires a 256x256 input image).</td>
1816 <td>jp2:layer-number=<var>value</var></td>
1817 <td>Sets the maximum number of quality layers to decode. Same for JPT, JC2,
1822 <td>jp2:number-resolutions=<var>value</var></td>
1823 <td>Sets the number of resolutions to encode.Same for JPT, JC2, and J2K</td>
1827 <td>jp2:progression-order=<var>value</var></td>
1828 <td>choose from LRCP, RLCP, RPCL, PCRL or CPRL. Same for JPT, JC2, and
1833 <td>jp2:quality=<var>value,value...</var></td>
1834 <td>Sets the quality layer PSNR, given in dB. The order is from left to
1835 right in ascending order. The default is a single lossless quality layer.
1836 Same for JPT, JC2, and J2K</td>
1840 <td>jp2:rate=<var>value</var></td>
1841 <td>Specify the compression factor to use while writing JPEG-2000 files. The
1842 compression factor is the reciprocal of the compression ratio. The valid
1843 range is 0.0 to 1.0, with 1.0 indicating lossless compression. If defined,
1844 this value overrides the -quality setting. A quality setting of 75
1845 results in a rate value of 0.06641. Same for JPT, JC2, and J2K</td>
1849 <td>jp2:reduce-factor=<var>value</var></td>
1850 <td>Sets the number of highest resolution levels to be discarded.Same for
1851 JPT, JC2, and J2K</td>
1855 <td>jpeg:block-smoothing=<var>on|off</var></td>
1860 <td>jpeg:colors=<var>value</var></td>
1861 <td>Set the desired number of colors and let the JPEG encoder do the
1866 <td>jpeg:dct-method=<var>value</var></td>
1867 <td>Choose from <code>default</code>, <code>fastest</code>,
1868 <code>float</code>, <code>ifast</code>, and <code>islow</code>.</td>
1872 <td>jpeg:extent=<var>value</var></td>
1873 <td>Restrict the maximum JPEG file size, for example <code>-define
1874 jpeg:extent=400KB</code>. The JPEG encoder will search for the highest
1875 compression quality level that results in an output file that does not
1876 exceed the value. The <code>-quality</code> option is ignored if it
1877 is also present.</td>
1881 <td>jpeg:fancy-upsampling=<var>on|off</var></td>
1886 <td>jpeg:optimize-coding=<var>on|off</var></td>
1891 <td>jpeg:q-table=<var>table</var></td>
1896 <td>jpeg:sampling-factor=<var>sampling-factor-string</var></td>
1901 <td>jpeg:size=<var>geometry</var></td>
1902 <td>Set the size hint of a JPEG image, for
1903 example, <code>-define jpeg:size=128x128</code>.
1904 It is most useful for increasing performance and reducing the memory
1905 requirements when reducing the size of a large JPEG image.</td>
1909 <td>json:features</td>
1910 <td>includes features in verbose information</td>
1919 <td>json:locate</td>
1924 <td>json:moments</td>
1925 <td>includes image moments in verbose information</td>
1929 <td>mng:need-cacheoff</td>
1930 <td>turn playback caching off for streaming MNG.</td>
1934 <td>morphology:compose=<var>compose-method</var></td>
1935 <td>Specifies how to merge results generated by multiple<a href="command-line-options.html#morphology">-morphology</a> kernel. The default is none. One
1936 typical value is 'lighten' as used, for example, with the sobel edge
1941 <td>morphology:showkernel=<var>1</var></td>
1942 <td>Outputs (to 'standard error') all the information about a generated <a href="command-line-options.html#morphology">-morphology</a> kernel.</td>
1946 <td>pcl:fit-to-page=<var>true</var></td>
1949 <td>pdf:fit-page=<var>geometry</var></td>
1950 <td> geometry specifies the scaling dimensions for resizing when the PDF is
1951 being read. The geometry is either WxH{%} or page size. No offsets are
1952 allowed. (introduced in IM 6.8.8-8)</td>
1956 <td>pdf:fit-to-page=<var>true</var></td>
1961 <td>pdf:use-cropbox=<var>true</var></td>
1966 <td>pdf:use-trimbox=<var>true</var></td>
1971 <td>png:bit-depth=<var>value</var></td>
1975 <td>png:color-type=<var>value</var></td>
1976 <td>desired bit-depth and color-type for PNG output. You can force the PNG
1977 encoder to use a different bit-depth and color-type than it would have
1978 normally selected, but only if this does not cause any loss of image
1979 quality. Any attempt to reduce image quality is treated as an error and no
1980 PNG file is written. E.g., if you have a 1-bit black-and-white image, you
1981 can use these "defines" to cause it to be written as an 8-bit grayscale,
1982 indexed, or even a 64-bit RGBA. But if you have a 16-million color image,
1983 you cannot force it to be written as a grayscale or indexed PNG. If you
1984 wish to do this, you must use the appropriate <a href="command-line-options.html#depth">-depth</a>,
1985 <a href="command-line-options.html#colors">-colors</a>, or <a href="command-line-options.html#type">-type</a> directives to
1986 reduce the image quality prior to using the PNG encoder. Note that in
1987 indexed PNG files, "bit-depth" refers to the number of bits per index,
1988 which can be 1, 2, 4, or 8. In such files, the color samples always have
1993 <td>png:compression-filter=<var>value</var></td>
1994 <td> valid values are 0 through 9. 0-4 are the corresponding PNG filters,
1995 5 means adaptive filtering except for images with a colormap, 6 means
1996 adaptive filtering for all images, 7 means MNG "loco" compression, 8 means
1997 Z_RLE strategy with adaptive filtering, and 9 means Z_RLE strategy with no
2002 <td>png:compression-level=<var>value</var></td>
2003 <td> valid values are 0 through 9, with 0 providing the least but fastest
2004 compression and 9 usually providing the best and always the slowest.</td>
2008 <td>png:compression-strategy=<var>value</var></td>
2009 <td> valid values are 0 through 4, meaning default, filtered, huffman_only,
2010 rle, and fixed ZLIB compression strategy. If you are using an old zlib
2011 that does not support Z_RLE (before 1.2.0) or Z_FIXED (before 1.2.2.2),
2012 values 3 and 4, respectively, will use the zlib default strategy
2017 <td>png:format=<var>value</var></td>
2018 <td> valid values are <var>png8</var>, <var>png24</var>,
2019 <var>png32</var>, <var>png48</var>,
2020 <var>png64</var>, and <var>png00</var>.
2021 This property can be useful for specifying
2022 the specific PNG format to be used, when the usual method of prepending the
2023 format name to the output filename is inconvenient, such as when writing
2024 a PNG-encoded ICO file or when using <a href="mogrify.html">mogrify</a>.
2025 Value = <var>png8</var> reduces the number of colors to 256,
2026 only one of which may be fully transparent, if necessary. The other
2027 values do not force any reduction of quality; it is an error to request
2028 a format that cannot represent the image data without loss (except that
2029 it is allowed to reduce the bit-depth from 16 to 8 for all formats).
2030 Value = <var>png24</var> and <var>png48</var>
2031 allow transparency, only if a single color is fully transparent and that
2032 color does not also appear in an opaque pixel; such transparency is
2033 written in a PNG <code>tRNS</code> chunk.
2034 Value = <var>png00</var> causes the image to inherit its
2035 color-type and bit-depth from the input image, if the input was also
2040 <td>png:exclude-chunk=<var>value</var></td>
2043 <td>png:include-chunk=<var>value</var></td>
2044 <td>ancillary chunks to be excluded from or included in PNG output.
2046 <p>The <var>value</var> can be the name of a PNG chunk-type such
2047 as <var>bKGD</var>, a comma-separated list of chunk-names
2048 (which can include the word <var>date</var>, the word
2049 <var>all</var>, or the word <var>none</var>).
2050 Although PNG chunk-names are case-dependent, you can use all lowercase
2051 names if you prefer.</p>
2053 <p>The "include-chunk" and "exclude-chunk" lists only affect the behavior
2054 of the PNG encoder and have no effect on the PNG decoder.</p>
2056 <p>As a special case, if the <code>sRGB</code> chunk is excluded and
2057 the <code>gAMA</code> chunk is included, the <code>gAMA</code> chunk will
2058 only be written if gamma is not 1/2.2, since most decoders assume
2059 sRGB and gamma=1/2.2 when no colorspace information is included in
2060 the PNG file. Because the list is processed from left to right, you
2061 can achieve this with a single define:</p>
2064 -define png:include-chunk=none,gAMA
2067 <p>As a special case, if the <code>sRGB</code> chunk is not excluded and
2068 the PNG encoder recognizes that the image contains the sRGB ICC profile,
2069 the PNG encoder will write the <code>sRGB</code> chunk instead of the
2070 entire ICC profile. To force the PNG encoder to write the sRGB
2071 profile as an <code>iCCP</code> chunk in the output PNG instead of the
2072 <code>sRGB</code> chunk, exclude the <code>sRGB</code> chunk.</p>
2074 <p>The critical PNG chunks <code>IHDR</code>, <code>PLTE</code>,
2075 <code>IDAT</code>, and <code>IEND</code> cannot be excluded. Any such
2076 entries appearing in the list will be ignored.</p>
2078 <p>If the ancillary PNG <code>tRNS</code> chunk is excluded and the
2079 image has transparency, the PNG colortype is forced to be 4 or 6
2080 (GRAY_ALPHA or RGBA). If the image is not transparent, then the
2081 <code>tRNS</code> chunk isn't written anyhow, and there is no effect
2082 on the PNG colortype of the output image.</p>
2084 <p>The <a href="command-line-options.html#strip">-strip</a> option does the equivalent of the
2085 following for PNG output:</p>
2088 -define png:exclude-chunk=EXIF,iCCP,iTXt,sRGB,tEXt,zCCP,zTXt,date
2091 <p>The default behavior is to include all known PNG ancillary chunks
2092 plus ImageMagick's private <code>vpAg</code> ("virtual page") chunk,
2093 and to exclude all PNG chunks that are unknown to ImageMagick,
2094 regardless of their PNG "copy-safe" status as described in the
2095 PNG specification.</p>
2097 <p>Any chunk names that are not known to ImageMagick are ignored
2098 if they appear in either the "include-chunk" or "exclude-chunk" list.
2099 The ancillary chunks currently known to ImageMagick are
2100 <code>bKGD</code>, <code>cHRM</code>, <code>gAMA</code>, <code>iCCP</code>,
2101 <code>oFFs</code>, <code>pHYs</code>, <code>sRGB</code>, <code>tEXt</code>,
2102 <code>tRNS</code>, <code>vpAg</code>, and <code>zTXt</code>.</p>
2104 <p>You can also put <code>date</code> in the list to include or exclude
2105 the "Date:create" and "Date:modify" text chunks that ImageMagick normally
2106 inserts in the output PNG.</p></td>
2110 <td>png:preserve-colormap[=<var>true</var>]</td>
2111 <td>Use the existing image->colormap. Normally the PNG encoder will
2112 try to optimize the palette, eliminating unused entries and putting
2113 the transparent colors first. If this flag is set, that behavior
2118 <td>png:preserve-iCCP[=<var>true</var>]</td>
2119 <td>By default, the PNG decoder and encoder examine any ICC profile
2120 that is present, either from an <code>iCCP</code> chunk in the PNG
2121 input or supplied via an option, and if the profile is recognized
2122 to be the sRGB profile, converts it to the <code>sRGB</code> chunk.
2123 You can use <code>-define png:preserve-iCCP</code> to prevent
2124 this from happening; in such cases the <code>iCCP</code> chunk
2125 will be read or written and no <code>sRGB</code> chunk will be
2126 written. There are some ICC profiles that claim to be sRGB but
2127 have various errors that cause them to be rejected by libpng16; such
2128 profiles are recognized anyhow and converted to the <code>sRGB</code>
2129 chunk, but are rejected if the <code>-define png:preserve-iCCP</code>
2130 is present. Note that not all "sRGB" ICC profiles are recognized
2131 yet; we will add them to the list as we encounter them.</td>
2135 <td>png:swap-bytes[=<var>true</var>]</td>
2136 <td>The PNG specification requires that any multi-byte integers be stored in
2137 network byte order (MSB-LSB endian). This option allows you to
2138 fix any invalid PNG files that have 16-bit samples stored incorrectly
2139 in little-endian order (LSB-MSB). The "-define png:swap-bytes" option
2140 must appear before the input filename on the commandline. The swapping
2141 is done during the libpng decoding operation.</td>
2145 <td>profile:skip=<var>name1,name2,...</var></td>
2146 <td>Skip the named profile[s] when reading the image. Use skip="*" to
2147 skip all named profiles in the image. Many named profiles exist,
2148 including ICC, EXIF, APP1, IPTC, XMP, and others.</td>
2152 <td>ps:imagemask</td>
2153 <td>If the ps:imagemask flag is defined, the PS3 and EPS3 coders will create
2154 Postscript files that render bilevel images with the Postscript imagemask
2155 operator instead of the image operator.</td>
2159 <td>quantum:format=<var>type</var></td>
2160 <td>Set the type to <code>floating-point</code> to specify a floating-point
2161 format for raw files (e.g. GRAY:) or for MIFF and TIFF images in HDRI mode
2162 to preserve negative values. If <a href="command-line-options.html#depth">-depth</a> 16 is
2163 included, the result is a single precision floating point format.
2164 If <a href="command-line-options.html#depth">-depth</a> 32 is included, the result is
2165 double precision floating point format.</td>
2169 <td>quantum:polarity=<var>photometric-interpretation</var></td>
2170 <td>Set the photometric-interpretation of an image (typically for TIFF image
2171 file format) to either <code>min-is-black</code> (default) or
2172 <code>min-is-white</code>.</td>
2176 <td>sample:offset=<var>geometry</var></td>
2177 <td>Location of the sampling point within the sub-region being sampled,
2178 expressed as percentages (see <a href="command-line-options.html#sample">-sample</a>).</td>
2182 <td>showkernel=<var>1</var></td>
2183 <td>Outputs (to 'standard error') all the information about a generated <a href="command-line-options.html#morphology">-morphology</a> kernel.</td>
2187 <td>stream:buffer-size=<var>value</var></td>
2188 <td>Set the stream buffer size. Select 0 for unbuffered I/O.</td>
2192 <td>tiff:alpha=<var>associated|unassociated|unspecified</var></td>
2193 <td>Specify the alpha extra samples as associated, unassociated or unspecified </td>
2197 <td>tiff:endian=<var>msb|lsb</var></td>
2202 <td>tiff:exif-properties=<var>false</var></td>
2203 <td>Skips reading the EXIF properties.</td>
2207 <td>tiff:fill-order=<var>msb|lsb</var></td>
2212 <td>tiff:ignore-tags=<var>comma-separate-list-of-tag-IDs</var></td>
2213 <td>Allows one or more tag ID values to be ignored.</td>
2217 <td>tiff:rows-per-strip=<var>value</var></td>
2218 <td>Sets the number of rows per strip</td>
2222 <td>tiff:tile-geometry=<var>WxH</var></td>
2223 <td>Sets the tile size for pyramid tiffs. Requires the suffix
2224 PTIF: before the outputname</td>
2228 <p>For example, to create a postscript file that will render only the black
2229 pixels of a bilevel image, use:</p>
2232 convert bilevel.tif -define ps:imagemask eps3:stencil.ps
2235 <p>Set attributes of the image registry by prefixing the value with
2236 <code>registry:</code>. For example, to set a temporary path to put work files,
2240 -define registry:temporary-path=/data/tmp
2243 <div style="margin: auto;">
2244 <h3 class="magick-header"><a id="delay"></a>-delay <var>ticks</var> <br>-delay <var>ticks</var>x<var>ticks-per-second</var> {<var><</var>} {<var>></var>}</h3>
2247 <p class="magick-description">display the next image after pausing.</p>
2249 <p>This option is useful for regulating the animation of image sequences
2250 <var>ticks/ticks-per-second</var> seconds must expire before the display of the
2251 next image. The default is no delay between each showing of the image
2252 sequence. The default ticks-per-second is 100.</p>
2254 <p>Use <code>></code> to change the image delay <var>only</var> if its current
2255 value exceeds the given delay. <code><</code> changes the image delay
2256 <var>only</var> if current value is less than the given delay. For example, if
2257 you specify <code>30></code> and the image delay is 20, the image delay does
2258 not change. However, if the image delay is 40 or 50, the delay it is changed
2259 to 30. Enclose the given delay in quotation marks to prevent the
2260 <code><</code> or <code>></code> from being interpreted by your shell as
2261 a file redirection.</p>
2264 <div style="margin: auto;">
2265 <h3 class="magick-header"><a id="delete"></a>-delete <var>indexes</var></h3>
2268 <p class="magick-description">delete the images specified by index, from the image sequence.</p>
2270 <p>Specify the image by its index in the sequence. The first image is index
2271 0. Negative indexes are relative to the end of the sequence, for example, -1
2272 represents the last image of the sequence. Specify a range of images with
2273 a dash (e.g. 0-4). Separate indexes with a comma (e.g. 0,2). Use
2274 <code>+delete</code> to delete the last image in the current image sequence.</p>
2277 <div style="margin: auto;">
2278 <h3 class="magick-header"><a id="density"></a>-density <var>width</var><br>-density <var>width</var>x<var>height</var></h3>
2281 <p class="magick-description">Set the horizontal and vertical resolution of an image for rendering to devices.</p>
2283 <p>This option specifies the image resolution to store while encoding a raster
2284 image or the canvas resolution while rendering (reading) vector formats such
2285 as Postscript, PDF, WMF, and SVG into a raster image. Image resolution
2286 provides the unit of measure to apply when rendering to an output device or
2287 raster image. The default unit of measure is in dots per inch (DPI). The <a href="command-line-options.html#units">-units</a> option may be used to select dots per centimeter
2290 <p>The default resolution is 72 dots per inch, which is equivalent to one
2291 point per pixel (Macintosh and Postscript standard). Computer screens are
2292 normally 72 or 96 dots per inch, while printers typically support 150, 300,
2293 600, or 1200 dots per inch. To determine the resolution of your display, use
2294 a ruler to measure the width of your screen in inches, and divide by the
2295 number of horizontal pixels (1024 on a 1024x768 display).</p>
2297 <p>If the file format supports it, this option may be used to update the
2298 stored image resolution. Note that Photoshop stores and obtains image
2299 resolution from a proprietary embedded profile. If this profile is not
2300 stripped from the image, then Photoshop will continue to treat the image using
2301 its former resolution, ignoring the image resolution specified in the standard
2304 <p>The <a href="command-line-options.html#density">-density</a> option sets an <var>attribute</var> and
2305 does not alter the underlying raster image. It may be used to adjust the
2306 rendered size for desktop publishing purposes by adjusting the scale applied
2307 to the pixels. To resize the image so that it is the same size at a different
2308 resolution, use the <a href="command-line-options.html#resample">-resample</a> option.</p>
2310 <div style="margin: auto;">
2311 <h3 class="magick-header"><a id="depth"></a>-depth <var>value</var></h3>
2314 <p class="magick-description">depth of the image.</p>
2316 <p>This the number of bits in a color sample within a pixel. Use this option
2317 to specify the depth of raw images whose depth is unknown such as GRAY, RGB,
2318 or CMYK, or to change the depth of any image after it has been read.</p>
2320 <div style="margin: auto;">
2321 <h3 class="magick-header"><a id="descend"></a>-descend</h3>
2324 <p class="magick-description">obtain image by descending window hierarchy.</p>
2326 <div style="margin: auto;">
2327 <h3 class="magick-header"><a id="deskew"></a>-deskew <var>threshold</var></h3>
2330 <p class="magick-description">straighten an image. A threshold of 40% works for most images.</p>
2332 <p>Use <a href="command-line-options.html#set">-set</a> <code>option:deskew:auto-crop
2333 <var>width</var></code> to auto crop the image. The set argument is the pixel
2334 width of the image background (e.g 40).</p>
2336 <div style="margin: auto;">
2337 <h3 class="magick-header"><a id="despeckle"></a>-despeckle</h3>
2340 <p class="magick-description">reduce the speckles within an image.</p>
2342 <div style="margin: auto;">
2343 <h3 class="magick-header"><a id="direction"></a>-direction <var>type</var></h3>
2346 <p class="magick-description">render text right-to-left or left-to-right.</p>
2348 <div style="margin: auto;">
2349 <h3 class="magick-header"><a id="displace"></a>-displace <var>horizontal-scale</var><br>-displace <var>horizontal-scale</var>x<var>vertical-scale</var></h3>
2352 <p class="magick-description">shift image pixels as defined by a displacement map.</p>
2354 <p>With this option, the 'overlay' image, and optionally the 'mask' image,
2355 is used as a displacement map, which is used to displace the lookup of
2356 what part of the 'background' image is seen at each point of the overlaid
2357 area. Much like the displacement map is a 'lens' that redirects light shining
2358 through it so as to present a distorted view the original 'background' image
2361 <p>Any perfect grey areas of the displacement map produce a zero
2362 displacement of the image. Black areas produce the given maximum negative
2363 displacement of the lookup point, while white produce a maximum positive
2364 displacement of the lookup. </p>
2366 <p>Note that it is the lookup of the 'background' that is displaced, not a
2367 displacement of the image itself. As such an area of the displacement map
2368 containing 'white' will have the lookup point 'shifted' by a positive amount,
2369 and thus generating a copy of the destination image to the right/downward from
2370 the correct position. That is the image will look like it may have been
2371 'shifted' in a negative left/upward direction. Understanding this is a very
2372 important in understanding how displacement maps work. </p>
2374 <p>The given arguments define the maximum amount of displacement in pixels
2375 that a particular map can produce. If the displacement scale is large enough
2376 it is also possible to lookup parts of the 'background' image that lie well
2377 outside the bounds of the displacement map itself. That is you could very
2378 easily copy a section of the original image from outside the overlay area
2379 into the overlay area. </p>
2381 <p>The '%' flag makes the displacement scale relative to the size of the
2382 overlay image (100% = half width/height of image). Using '!' switches
2383 percentage arguments to refer to the destination image size instead.
2384 these flags were added as of IM v6.5.3-5.</p>
2386 <p>Normally a single grayscale displacement map is provided, which with the
2387 given scaling values will determine a single direction (vector) in which
2388 displacements can occur (positively or negatively). However, if you also
2389 specify a third image which is normally used as a <var>mask</var>,
2390 the <var>composite image</var> is used for horizontal X
2391 displacement, while the <var>mask image</var> is used for vertical Y
2392 displacement. This allows you to define completely different displacement
2393 values for the X and Y directions, and allowing you to lookup any point within
2394 the <var>scale</var> bounds. In other words each pixel can lookup
2395 any other nearby pixel, producing complex 2 dimensional displacements, rather
2396 than a simple 1 dimensional vector displacements. </p>
2398 <p>Alternatively rather than supplying two separate images, as of IM v6.4.4-0,
2399 you can use the 'red' channel of the overlay image to specify the horizontal
2400 or X displacement, and the 'green' channel for the vertical or Y displacement.
2403 <p>As of IM v6.5.3-5 any alpha channel in the overlay image is used as a
2404 mask the transparency of the destination image. However areas outside the
2405 overlaid areas will not be effected. </p>
2408 <div style="margin: auto;">
2409 <h3 class="magick-header"><a id="display"></a>-display <var>host:display[.screen]</var></h3>
2412 <p class="magick-description">Specifies the X server to contact.</p>
2414 <p>This option is used with convert for obtaining image or font from this
2415 X server. See <var>X(1)</var>.</p>
2417 <div style="margin: auto;">
2418 <h3 class="magick-header"><a id="dispose"></a>-dispose <var>method</var></h3>
2421 <p class="magick-description">define the GIF disposal image setting for images that are being created or read in. </p>
2423 <p>The layer disposal method defines the way each the displayed image is to be
2424 modified after the current 'frame' of an animation has finished being
2425 displayed (after its 'delay' period), but before the next frame on an
2426 animation is to be overlaid onto the display. </p>
2428 <p>Here are the valid methods:</p>
2430 <dl class="dl-horizontal">
2431 <dt>Undefined</dt><dd>0: No disposal specified (equivalent to '<code>none</code>').</dd>
2432 <dt>None</dt><dd>1: Do not dispose, just overlay next frame image.</dd>
2433 <dt>Background</dt><dd>2: Clear the frame area with the background color.</dd>
2434 <dt>Previous</dt><dd>3: Clear to the image prior to this frames overlay.</dd>
2437 <p>You can also use the numbers given above, which is what the GIF format
2438 uses internally to represent the above settings. </p>
2440 <p>To print a complete list of dispose methods, use <a href="command-line-options.html#list">-list dispose</a>.</p>
2442 <p>Use <a href="command-line-options.html#dispose">+dispose</a>, turn off the setting and prevent
2443 resetting the layer disposal methods of images being read in. </p>
2445 <p>Use <a href="command-line-options.html#set">-set</a> '<code>dispose</code>' method to set the image
2446 disposal method for images already in memory.</p>
2448 <div style="margin: auto;">
2449 <h3 class="magick-header"><a id="dissimilarity-threshold"></a>-dissimilarity-threshold <var>value</var></h3>
2452 <p class="magick-description">maximum RMSE for subimage match (default 0.2).</p>
2455 <div style="margin: auto;">
2456 <h3 class="magick-header"><a id="dissolve"></a>-dissolve <var>src_percent</var>[x<var>dst_percent</var>]</h3>
2459 <p class="magick-description">dissolve an image into another by the given percent.</p>
2461 <p>The opacity of the composite image is multiplied by the given percent, then
2462 it is composited 'over' the main image. If <var>src_percent</var>
2463 is greater than 100, start dissolving the main image so it becomes
2464 transparent at a value of '<code>200</code>'. If both percentages
2465 are given, each image are dissolved to the percentages given. </p>
2467 <p>Note that dissolve percentages do not add, two opaque images dissolved
2468 '50,50', produce a 75% transparency. For a 50% + 50% blending of the two
2469 images, you would need to use dissolve values of '50,100'. </p>
2471 <div style="margin: auto;">
2472 <h3 class="magick-header"><a id="distort"></a>-distort <var>method arguments</var></h3>
2475 <p class="magick-description">distort an image, using the given <var>method</var> and its required <var>arguments</var>.</p>
2477 <p>The <var>arguments</var> is a single string containing a list
2478 of floating point numbers separated by commas or spaces. The number of
2479 and meaning of the floating point values depends on the distortion <var>method</var> being used. </p>
2481 <p>Choose from these distortion types:</p>
2483 <table class="table table-condensed table-striped">
2485 <th style="width: 8%">Method</th>
2486 <th>Description</th>
2490 <td>ScaleRotateTranslate <br> SRT</td>
2492 Distort image by first scaling and rotating about a given 'center',
2493 before translating that 'center' to the new location, in that order. It
2494 is an alternative method of specifying a 'Affine' type of
2495 distortion, but without shearing effects. It also provides a good way
2496 of rotating and displacing a smaller image for tiling onto a larger
2497 background (IE 2-dimensional animations). <br>
2499 The number of arguments determine the specific meaning of each
2500 argument for the scales, rotation, and translation operations. <br>
2502 <dl class="dl-horizontal">
2503 <dt>2:</dt><dd><var>Scale Angle</var></dd>
2504 <dt>3:</dt><dd><var>X,Y Angle</var></dd>
2505 <dt>4:</dt><dd><var>X,Y Scale Angle</var></dd>
2506 <dt>5:</dt> <dd><var>X,Y ScaleX,ScaleY Angle</var></dd>
2507 <dt>6:</dt> <dd><var>X,Y Scale Angle NewX,NewY</var></dd>
2508 <dt>7:</dt> <dd><var>X,Y ScaleX,ScaleY Angle NewX,NewY</var></dd>
2511 This is actually an alternative way of specifying a 2 dimensional linear
2512 'Affine' or 'AffineProjection' distortion. </td> </tr>
2517 Distort the image linearly by moving a list of at least 3 or more sets
2518 of control points (as defined below). Ideally 3 sets or 12 floating
2519 point values are given allowing the image to be linearly scaled,
2520 rotated, sheared, and translated, according to those three points. See
2521 also the related 'AffineProjection' and 'SRT'
2524 More than 3 sets given control point pairs (12 numbers) is least
2525 squares fitted to best match a linear affine distortion. If only 2
2526 control point pairs (8 numbers) are given a two point image translation
2527 rotation and scaling is performed, without any possible shearing,
2528 flipping or changes in aspect ratio to the resulting image. If only one
2529 control point pair is provides the image is only translated, (which may
2530 be a floating point non-integer translation). <br>
2532 This distortion does not include any form of perspective distortion.
2538 <td>AffineProjection</td>
2540 Linearly distort an image using the given Affine Matrix of 6
2541 pre-calculated coefficients forming a set of Affine Equations to map
2542 the source image to the destination image.
2544 <p class="text-center"><var>
2545 s<sub>x</sub>, r<sub>x</sub>,
2546 r<sub>y</sub>, s<sub>y</sub>,
2547 t<sub>x</sub>, t<sub>y</sub>
2550 See <a href="command-line-options.html#affine">-affine</a> setting for more detail, and
2551 meanings of these coefficients. <br>
2553 The distortions 'Affine' and 'SRT' provide
2554 alternative methods of defining this distortion, with ImageMagick doing
2555 the calculations needed to generate the required coefficients. You can
2556 see the internally generated coefficients, by using a <a href="command-line-options.html#verbose">-verbose</a> setting with those other variants. </td>
2561 <td>BilinearForward<br>
2562 BilinearReverse</td>
2564 Bilinear Distortion, given a minimum of 4 sets of coordinate pairs, or
2565 16 values (see below). Not that lines may not appear straight after
2566 distortion, though the distance between coordinates will remain
2569 The 'BilinearForward' is used to map rectangles to any
2570 quadrilateral, while the 'BilinearReverse' form maps any
2571 quadrilateral to a rectangle, while preserving the straight line edges
2574 Note that 'BilinearForward' can generate invalid pixels
2575 which will be colored using the <a href="command-line-options.html#mattecolor">-mattecolor</a>
2576 color setting. Also if the quadrilateral becomes 'flipped' the image
2579 There are future plans to produce a true Bilinear distortion that will
2580 attempt to map any quadrilateral to any other quadrilateral, while
2581 preserving edges (and edge distance ratios).
2587 <td>Perspective</td>
2589 Perspective distort the images, using a list of 4 or more sets of
2590 control points (as defined below). More that 4 sets (16 numbers) of
2591 control points provide least squares fitting for more accurate
2592 distortions (for the purposes of image registration and panorama
2593 effects). Less than 4 sets will fall back to a 'Affine'
2594 linear distortion. <br>
2596 Perspective Distorted images ensures that straight lines remain
2597 straight, but the scale of the distorted image will vary. The horizon
2598 is anti-aliased, and the 'sky' color may be set using the
2599 <a href="command-line-options.html#mattecolor">-mattecolor</a> setting. </td>
2603 <td>PerspectiveProjection </td>
2605 Do a 'Perspective' distortion biased on a set of 8
2606 pre-calculated coefficients. You can get these coefficients by looking
2607 at the <a href="command-line-options.html#verbose">-verbose</a> output of a
2608 'Perspective' distortion, or by calculating them yourself.
2609 If the last two perspective scaling coefficients are zero, the
2610 remaining 6 represents a transposed 'Affine Matrix'. </td>
2617 Arc the image (variation of polar mapping) over the angle given around
2620 <p></p><dl class="dl-horizontal">
2622 <dd>The angle over which to arc the image side-to-side</dd>
2623 <dt>rotate_angle</dt>
2624 <dd>Angle to rotate resulting image from vertical center</dd>
2626 <dd>Set top edge of source image at this radius</dd>
2627 <dt>bottom_radius </dt>
2628 <dd>Set bottom edge to this radius (radial scaling)</dd>
2631 The resulting image is always resized to best fit the resulting image,
2632 (as if using <a href="command-line-options.html#distort">+distort</a>) while attempting to
2633 preserve scale and aspect ratio of the original image as much as
2634 possible with the arguments given by the user. All four arguments will
2635 be needed to change the overall aspect ratio of an 'Arc'ed image. <br>
2637 This a variation of a polar distortion designed to try to preserve the
2638 aspect ratio of the image rather than direct Cartesian to Polar
2645 Like 'Arc' but do a complete Cartesian to Polar mapping of
2646 the image. that is the height of the input image is mapped to the
2647 radius limits, while the width is wrapped around between the
2650 Arguments: <var>Rmax,Rmin CenterX,CenterY, start,end_angle</var> <br>
2652 All arguments are optional. With <var>Rmin</var> defaulting to zero, the
2653 center to the center of the image, and the angles going from -180 (top)
2654 to +180 (top). If <var>Rmax</var> is given the special value of
2655 '0', the the distance from the center to the nearest edge
2656 is used for the radius of the output image, which will ensure the whole
2657 image is visible (though scaled smaller). However a special value of
2658 '-1' will use the distance from the center to the furthest
2659 corner, This may 'clip' the corners from the input rectangular image,
2660 but will generate the exact reverse of a 'DePolar' with
2661 the same arguments. <br>
2663 If the plus form of distort (<a href="command-line-options.html#distort">+distort</a>) is used
2664 output image center will default to 0,0 of the virtual
2665 canvas, and the image size adjusted to ensure the whole input image is
2666 made visible in the output image on the virtual canvas. </td>
2673 Uses the same arguments and meanings as a 'Polar' distortion
2674 but generates the reverse Polar to Cartesian distortion. <br>
2676 The special <var>Rmax</var> setting of '0' may however clip
2677 the corners of the input image. However using the special
2678 <var>Rmax</var> setting of '-1' (maximum center to corner
2679 distance) will ensure the whole distorted image is preserved in the
2680 generated result, so that the same argument to 'Polar' will
2681 reverse the distortion re-producing the original.
2683 Note that as this distortion requires the area resampling of a circular
2684 arc, which can not be handled by the builtin EWA resampling function.
2685 As such the normal EWA filters are turned off. It is recommended some
2686 form of 'super-sampling' image processing technique be used to produce
2687 a high quality result. </td>
2694 Given the four coefficients (A,B,C,D) as defined by <a href="http://wiki.panotools.org/Lens_correction_model">Helmut
2695 Dersch</a>, perform a barrel or pin-cushion distortion appropriate to
2696 correct radial lens distortions. That is in photographs, make straight
2697 lines straight again. <br>
2699 <p class="text-center">Arguments: <var>A B C</var> [ <var>D</var> [
2700 <var>X</var> , <var>Y</var> ] ] <br>
2701 or <var>A<sub>x</sub> B<sub>x</sub> C<sub>x</sub> D<sub>x</sub>
2702 A<sub>y</sub> B<sub>y</sub> C<sub>y</sub> D<sub>y</sub></var>
2703 [ <var>X</var> , <var>Y</var> ] </p>
2704 So that it forms the function
2705 <p class="text-center">Rsrc = r * ( <var>A</var>*r<sup>3</sup> + <var>B</var>*r<sup>2</sup> +
2706 <var>C</var>*r + <var>D</var> )</p>
2708 Where <var>X</var>,<var>Y</var> is the optional center of the distortion
2709 (defaulting to the center of the image). <br>
2710 The second form is typically used to distort images, rather than
2711 correct lens distortions. <br>
2717 <td>BarrelInverse</td>
2719 This is very similar to 'Barrel' with the same set of
2720 arguments, and argument handling. However it uses the inverse
2721 of the radial polynomial,
2722 so that it forms the function
2723 <p class="text-center">Rsrc = r / ( <var>A</var>*r<sup>3</sup> + <var>B</var>*r<sup>2</sup> +
2724 <var>C</var>*r + <var>D</var> )</p>
2725 Note that this is not the reverse of the 'Barrel'
2726 distortion, just a different barrel-like radial distortion method.
2734 Distort the given list control points (any number) using an Inverse
2735 Squared Distance Interpolation Method (<a href="http://en.wikipedia.org/wiki/Shepard%27s_method">Shepards
2736 Method</a>). The control points in effect do 'localized' displacement
2737 of the image around the given control point (preserving the look and
2738 the rotation of the area near the control points. For best results
2739 extra control points should be added to 'lock' the positions of the
2740 corners, edges and other unchanging parts of the image, to prevent
2741 their movement. <br>
2743 The distortion has been likened to 'taffy pulling' using nails, or
2744 pins' stuck in a block of 'jelly' which is then moved to the new
2745 position, distorting the surface of the jelly. <br>
2747 Internally it is equivalent to generating a displacement map (see <a href="command-line-options.html#displace">-displace</a>) for source image color look-up using
2748 the <a href="command-line-options.html#sparse-color">-sparse-color</a> method of the same name.
2755 <p>To print a complete list of distortion methods, use <a href="command-line-options.html#list">-list
2758 <p>Many of the above distortion methods such as '<code>Affine</code>',
2759 '<code>Perspective</code>', and '<code>Shepards</code>' use a list control points
2760 defining how these points in the given image should be distorted in the
2761 destination image. Each set of four floating point values represent a source
2762 image coordinate, followed immediately by the destination image coordinate.
2763 This produces a list of values such as...</p>
2764 <p class="text-center"><var>
2765 U<sub>1</sub>,V<sub>1</sub> X<sub>1</sub>,Y<sub>1</sub>
2766 U<sub>2</sub>,V<sub>2</sub> X<sub>2</sub>,Y<sub>2</sub>
2767 U<sub>3</sub>,V<sub>3</sub> X<sub>3</sub>,Y<sub>3</sub>
2769 U<sub>n</sub>,V<sub>n</sub> X<sub>n</sub>,Y<sub>n</sub>
2771 <p>where <var>U,V</var> on the source image is mapped to <var>X,Y</var> on the
2772 destination image. </p>
2774 <p>For example, to warp an image using '<code>perspective</code>' distortion,
2775 needs a list of at least 4 sets of coordinates, or 16 numbers. Here is the
2776 perspective distortion of the built-in "rose:" image. Note how spaces were
2777 used to group the 4 sets of coordinate pairs, to make it easier to read and
2781 convert rose: -virtual-pixel black \
2782 -distort Perspective '0,0,0,0 0,45,0,45 69,0,60,10 69,45,60,35' \
2783 rose_3d_rotated.gif"
2786 <p>If more that the required number of coordinate pairs are given for
2787 a distortion, the distortion method is 'least squares' fitted to produce the
2788 best result for all the coordinate pairs given. If less than the ideal number
2789 of points are given, the distort will generally fall back to a simpler form of
2790 distortion that can handles the smaller number of coordinates (usually a linear
2791 '<code>Affine</code>' distortion). </p>
2793 <p>By using more coordinates you can make use of image registration tool to
2794 find matching coordinate pairs in overlapping images, so as to improve the
2795 'fit' of the distortion. Of course a bad coordinate pair can also make the
2796 'fit' worse. Caution is always advised. </p>
2798 <p>Colors are acquired from the source image according to a cylindrical
2799 resampling <a href="command-line-options.html#filter">-filter</a>, using a special technique known as
2800 EWA resampling. This produces very high quality results, especially when
2801 images become smaller (minified) in the output, which is very common when
2802 using '<code>perspective</code>' distortion. For example here we view
2803 a infinitely tiled 'plane' all the way to the horizon. </p>
2806 convert -size 90x90 pattern:checkerboard -normalize -virtual-pixel tile \
2807 -distort perspective '0,0,5,45 89,0,45,46 0,89,0,89 89,89,89,89' \
2811 <p>Note that a infinitely tiled perspective images involving the horizon can
2812 be very slow, because of the number of pixels that are compressed to generate
2813 each individual pixel close to the 'horizon'. You can turn off EWA
2814 resampling, by specifing the special <a href="command-line-options.html#filter">-filter</a> setting of
2815 '<code>point</code>' (recommended if you plan to use super-sampling instead).
2818 <p>If an image generates <i>invalid pixels</i>, such as the 'sky' in the last
2819 example, <a href="command-line-options.html#distort">-distort</a> will use the current <a href="command-line-options.html#mattecolor">-mattecolor</a> setting for these pixels. If you do not
2820 what these pixels to be visible, set the color to match the rest of the
2823 <p>The output image size will by default be the same as the input image. This
2824 means that if the part of the distorted image falls outside the viewed area of
2825 the 'distorted space', those parts is clipped and lost. However if you use
2826 the plus form of the operator (<a href="command-line-options.html#distort">+distort</a>) the operator
2827 will attempt (if possible) to show the whole of the distorted image, while
2828 retaining a correct 'virtual canvas' offset, for image layering. This offset
2829 may need to be removed using <a href="command-line-options.html#repage">+repage</a>, to remove if it
2832 <p>Setting <a href="command-line-options.html#verbose">-verbose</a> setting, will cause <a href="command-line-options.html#distort">-distort</a> to attempt to output the internal coefficients,
2833 and the <a href="command-line-options.html#fx">-fx</a> equivalent to the distortion, for expert study,
2834 and debugging purposes. This many not be available for all distorts. </p>
2836 <p>You can alternatively specify a special "<code><a href="command-line-options.html#define">-define</a> distort:viewport={geometry_string}</code>" setting which will
2837 specify the size and the offset of the generated 'viewport' image of the
2838 distorted image space.</p>
2840 <p>Setting a "<code><a href="command-line-options.html#define">-define</a>
2841 distort:scale={scale_factor}</code>" will scale the output image (viewport or
2842 otherwise) by that factor without changing the viewed contents of the
2843 distorted image. This can be used either for 'super-sampling' the image for
2844 a higher quality result, or for panning and zooming around the image (with
2845 appropriate viewport changes, or post-distort cropping and resizing). </p>
2847 <p>Setting "<code><a href="command-line-options.html#define">-define</a> resample:verbose=1</code>"
2848 will output the cylindrical filter lookup table created by the EWA (Elliptical
2849 Weighted Average) resampling algorithm. Note this table uses a squared radius
2850 lookup value. This is typically only used for debugging EWA resampling. </p>
2853 <div style="margin: auto;">
2854 <h3 class="magick-header"><a id="distribute-cache"></a>-distribute-cache <var>port</var></h3>
2857 <p class="magick-description">launch a distributed pixel cache server. </p>
2859 <div style="margin: auto;">
2860 <h3 class="magick-header"><a id="dither"></a>-dither <var>method</var></h3>
2863 <p class="magick-description">Apply a Riemersma or Floyd-Steinberg error diffusion dither to
2864 images when general color reduction is applied via an option, or automagically
2865 when saving to specific formats. This enabled by default.</p>
2867 <p>Dithering places two or more colors in neighboring pixels so that to the
2868 eye a closer approximation of the images original color is reproduced. This
2869 reduces the number of colors needed to reproduce the image but at the cost of
2870 a lower level pattern of colors. Error diffusion dithers can use any set of
2871 colors (generated or user defined) to an image. </p>
2873 <p>Dithering is turned on by default, to turn it off use the plus form of the
2874 setting, <a href="command-line-options.html#dither">+dither</a>. This will also also render PostScript
2875 without text or graphic aliasing. Disabling dithering often (but not always)
2876 leads to faster process, a smaller number of colors, but more cartoon like
2877 image coloring. Generally resulting in 'color banding' effects in areas with
2878 color gradients. </p>
2880 <p>The color reduction operators <a href="command-line-options.html#colors">-colors</a>, <a href="command-line-options.html#monochrome">-monochrome</a>, <a href="command-line-options.html#remap%20">-remap</a>, and <a href="command-line-options.html#posterize">-posterize</a>, apply dithering to images using the reduced
2881 color set they created. These operators are also used as part of automatic
2882 color reduction when saving images to formats with limited color support, such
2883 as <code>GIF:</code>, <code>XBM:</code>, and others, so dithering may also be used
2884 in these cases. </p>
2886 <p>Alternatively you can use <a href="command-line-options.html#random-threshold">-random-threshold</a>
2887 to generate purely random dither. Or use <a href="command-line-options.html#ordered-dither">-ordered-dither</a> to apply threshold mapped dither
2888 patterns, using uniform color maps, rather than specific color maps. </p>
2891 <div style="margin: auto;">
2892 <h3 class="magick-header"><a id="draw"></a>-draw <var>string</var></h3>
2895 <p class="magick-description">Annotate an image with one or more graphic primitives.</p>
2897 <p>Use this option to annotate or decorate an image with one or more graphic
2898 primitives. The primitives include shapes, text, transformations, and pixel
2901 <p>The shape primitives:</p>
2903 <dl class="dl-horizontal">
2904 <dt>point</dt><dd> x,y</dd>
2905 <dt>line</dt><dd> x0,y0 x1,y1</dd>
2906 <dt>rectangle</dt><dd> x0,y0 x1,y1</dd>
2907 <dt>roundRectangle</dt><dd> x0,y0 x1,y1 wc,hc</dd>
2908 <dt>arc</dt><dd> x0,y0 x1,y1 a0,a1</dd>
2909 <dt>ellipse</dt><dd> x0,y0 rx,ry a0,a1</dd>
2910 <dt>circle</dt><dd> x0,y0 x1,y1</dd>
2911 <dt>polyline</dt><dd> x0,y0 ... xn,yn</dd>
2912 <dt>polygon</dt><dd> x0,y0 ... xn,yn</dd>
2913 <dt>bezier</dt><dd> x0,y0 ... xn,yn</dd>
2914 <dt>path</dt><dd>specification </dd>
2915 <dt>image</dt><dd> operator x0,y0 w,h filename</dd>
2918 <p>The text primitive:</p>
2920 <dl class="dl-horizontal">
2921 <dt>text</dt><dd>x0,y0 string</dd>
2923 <p>The text gravity primitive:</p>
2925 <dl class="dl-horizontal">
2926 <dt>gravity</dt><dd>NorthWest, North, NorthEast, West, Center, East, SouthWest, South, or SouthEast</dd>
2929 <p>The text gravity primitive only affects the placement of text and does not
2930 interact with the other primitives. It is equivalent to using the <a href="command-line-options.html#gravity">-gravity</a> command-line option, except that it is limited in
2931 scope to the <a href="command-line-options.html#draw">-draw</a> option in which it appears.</p>
2933 <p>The transformation primitives:</p>
2935 <dl class="dl-horizontal">
2936 <dt>rotate</dt><dd>degrees</dd>
2937 <dt>translate</dt><dd>dx,dy</dd>
2938 <dt>scale</dt><dd>sx,sy</dd>
2939 <dt>skewX</dt><dd>degrees</dd>
2940 <dt>skewY</dt><dd>degrees</dd>
2943 <p>The pixel operation primitives:</p>
2945 <dl class="dl-horizontal">
2946 <dt>color</dt><dd>x0,y0 method</dd>
2947 <dt>matte</dt><dd>x0,y0 method</dd>
2950 <p>The shape primitives are drawn in the color specified by the preceding <a href="command-line-options.html#fill">-fill</a> setting. For unfilled shapes, use <a href="command-line-options.html#fill">-fill none</a>. You can optionally control the stroke (the
2951 "outline" of a shape) with the <a href="command-line-options.html#stroke">-stroke</a> and <a href="command-line-options.html#strokewidth">-strokewidth</a> settings.</p>
2953 <p>A <code>point</code> primitive is specified by a single <var>point</var> in the
2954 pixel plane, that is, by an ordered pair of integer coordinates,
2955 <var>x</var>,<var>y</var>. (As it involves only a single pixel, a <code>point</code>
2956 primitive is not affected by <a href="command-line-options.html#stroke">-stroke</a> or <a href="command-line-options.html#strokewidth">-strokewidth</a>.)</p>
2958 <p>A <code>line</code> primitive requires a start point and end point.</p>
2960 <p>A <code>rectangle</code> primitive is specified by the pair of points at the
2961 upper left and lower right corners.</p>
2963 <p>A <code>roundRectangle</code> primitive takes the same corner points as
2964 a <code>rectangle</code> followed by the width and height of the rounded corners
2967 <p>The <code>circle</code> primitive makes a disk (filled) or circle (unfilled).
2968 Give the center and any point on the perimeter (boundary).</p>
2970 <p>The <code>arc</code> primitive is used to inscribe an elliptical segment in
2971 to a given rectangle. An <code>arc</code> requires the two corners used for
2972 <code>rectangle</code> (see above) followed by the start and end angles of the
2973 arc of the segment segment (e.g. 130,30 200,100 45,90). The start and end
2974 points produced are then joined with a line segment and the resulting segment
2975 of an ellipse is filled.</p>
2977 <p>Use <code>ellipse</code> to draw a partial (or whole) ellipse. Give the
2978 center point, the horizontal and vertical "radii" (the <var>semi-axes</var> of
2979 the ellipse) and start and end angles in degrees (e.g. 100,100 100,150
2982 <p>The <code>polyline</code> and <code>polygon</code> primitives require three or
2983 more points to define their perimeters. A <code>polyline</code> is simply
2984 a <code>polygon</code> in which the final point is not stroked to the start
2985 point. When unfilled, this is a <var>polygonal line</var>. If the <a href="command-line-options.html#stroke">-stroke</a> setting is <code>none</code> (the default), then
2986 a <code>polyline</code> is identical to a <code>polygon</code>. </p>
2988 <p>A <var>coordinate</var> is a pair of integers separated by a space or
2989 optional comma. </p>
2991 <p>As an example, to define a circle centered at 100,100 that extends to
2995 -draw 'circle 100,100 150,150'
2998 <p>The <code>Bezier</code> primitive creates a spline curve and requires three
2999 or points to define its shape. The first and last points are the
3000 <var>knots</var> and these points are attained by the curve, while any
3001 intermediate coordinates are <var>control points</var>. If two control points
3002 are specified, the line between each end knot and its sequentially respective
3003 control point determines the tangent direction of the curve at that end. If
3004 one control point is specified, the lines from the end knots to the one
3005 control point determines the tangent directions of the curve at each end. If
3006 more than two control points are specified, then the additional control points
3007 act in combination to determine the intermediate shape of the curve. In order
3008 to draw complex curves, it is highly recommended either to use the
3009 <code>path</code> primitive or to draw multiple four-point bezier segments with
3010 the start and end knots of each successive segment repeated. For example:</p>
3013 -draw 'bezier 20,50 45,100 45,0 70,50'
3014 -draw 'bezier 70,50 95,100 95,0 120,50'
3017 <p>A <code>path</code> represents an outline of an object, defined in terms of
3018 moveto (set a new current point), lineto (draw a straight line), curveto (draw
3019 a Bezier curve), arc (elliptical or circular arc) and closepath (close the
3020 current shape by drawing a line to the last moveto) elements. Compound paths
3021 (i.e., a path with subpaths, each consisting of a single moveto followed by
3022 one or more line or curve operations) are possible to allow effects such as
3023 <var>donut holes</var> in objects. (See <a href="http://www.w3.org/TR/SVG/paths.html">Paths</a>.)</p>
3025 <p>Use <code>image</code> to composite an image with another image. Follow the
3026 image keyword with the composite operator, image location, image size, and
3030 -draw 'image SrcOver 100,100 225,225 image.jpg'
3033 <p>You can use 0,0 for the image size, which means to use the actual
3034 dimensions found in the image header. Otherwise, it is scaled to the given
3035 dimensions. See <a href="compose.html">Alpha Compositing</a> for
3036 a detailed discussion of alpha composition methods that are available. </p>
3038 <p>The "special augmented compose operators" such as "dissolve" that require
3039 arguments cannot be used at present with the <code>-draw image</code> option.
3042 <p>Use <code>text</code> to annotate an image with text. Follow the text
3043 coordinates with a string. If the string has embedded spaces, enclose it in
3044 single or double quotes.</p>
3046 <p>For example, the following annotates the image with <code>Works like
3047 magick!</code> for an image titled <code>bird.miff</code>. </p>
3050 -draw "text 100,100 'Works like magick!' "
3053 <p>See the <a href="command-line-options.html#annotate">-annotate</a> option for another convenient way
3054 to annotate an image with text.</p>
3056 <p>The <code>rotate</code> primitive rotates subsequent shape primitives and
3057 text primitives about the origin of the main image. If the <a href="command-line-options.html#region">-region</a> option precedes the <a href="command-line-options.html#draw">-draw</a>
3058 option, the origin for transformations is the upper left corner of the
3061 <p>The <code>translate</code> primitive translates subsequent shape and text
3064 <p>The <code>scale</code> primitive scales them.</p>
3066 <p>The <code>skewX</code> and <code>skewY</code> primitives skew them with respect
3067 to the origin of the main image or the region.</p>
3069 <p>The transformations modify the current affine matrix, which is initialized
3070 from the initial affine matrix defined by the <a href="command-line-options.html#affine">-affine</a>
3071 option. Transformations are cumulative within the <a href="command-line-options.html#draw">-draw</a>
3072 option. The initial affine matrix is not affected; that matrix is only changed
3073 by the appearance of another <a href="command-line-options.html#affine">-affine</a> option. If another
3074 <a href="command-line-options.html#draw">-draw</a> option appears, the current affine matrix is
3075 reinitialized from the initial affine matrix.</p>
3077 <p>Use the <code>color</code> primitive to change the color of a pixel to the
3078 fill color (see <a href="command-line-options.html#fill">-fill</a>). Follow the pixel coordinate with
3089 <p>Consider the target pixel as that specified by your coordinate. The
3090 <code>point</code> method recolors the target pixel. The <code>replace</code>
3091 method recolors any pixel that matches the color of the target pixel.
3092 <code>Floodfill</code> recolors any pixel that matches the color of the target
3093 pixel and is a neighbor, whereas <code>filltoborder</code> recolors any neighbor
3094 pixel that is not the border color. Finally, <code>reset</code> recolors all
3097 <p>Use <code>matte</code> to the change the pixel matte value to transparent.
3098 Follow the pixel coordinate with a method (see the <code>color</code> primitive
3099 for a description of methods). The <code>point</code> method changes the matte
3100 value of the target pixel. The <code>replace</code> method changes the matte
3101 value of any pixel that matches the color of the target pixel.
3102 <code>Floodfill</code> changes the matte value of any pixel that matches the
3103 color of the target pixel and is a neighbor, whereas <code>filltoborder</code>
3104 changes the matte value of any neighbor pixel that is not the border color (<a href="command-line-options.html#bordercolor">-bordercolor</a>). Finally <code>reset</code> changes the
3105 matte value of all pixels.</p>
3107 <p>You can set the primitive color, font, and font bounding box color with <a href="command-line-options.html#fill">-fill</a>, <a href="command-line-options.html#font">-font</a>, and <a href="command-line-options.html#box">-box</a>
3108 respectively. Options are processed in command line order so be sure to use
3109 these options <var>before</var> the <a href="command-line-options.html#draw">-draw</a> option.</p>
3111 <p>Strings that begin with a number must be quoted (e.g. use '1.png' rather
3114 <p>Drawing primitives conform to the <a href="magick-vector-graphics.html">Magick
3115 Vector Graphics</a> format.</p>
3118 <div style="margin: auto;">
3119 <h3 class="magick-header"><a id="duplicate"></a>-duplicate <var>count,indexes</var></h3>
3122 <p class="magick-description">duplicate an image one or more times.</p>
3124 <p>Specify the count and the image to duplicate by its index in the sequence.
3125 The first image is index 0. Negative indexes are relative to the end of the
3126 sequence, for example, -1 represents the last image of the sequence. Specify
3127 a range of images with a dash (e.g. 0-4). Separate indexes with a comma (e.g.
3128 0,2). Use <code>+duplicate</code> to duplicate the last image in the current
3131 <div style="margin: auto;">
3132 <h3 class="magick-header"><a id="edge"></a>-edge <var>radius</var></h3>
3135 <p class="magick-description">detect edges within an image.</p>
3137 <div style="margin: auto;">
3138 <h3 class="magick-header"><a id="emboss"></a>-emboss <var>radius</var></h3>
3141 <p class="magick-description">emboss an image.</p>
3143 <div style="margin: auto;">
3144 <h3 class="magick-header"><a id="encipher"></a>-encipher <var>filename</var></h3>
3147 <p class="magick-description">Encipher pixels for later deciphering by <a href="command-line-options.html#decipher">-decipher</a>.</p>
3149 <p>Get the passphrase from the file specified by <var>filename</var>.</p>
3151 <p>For more information, see the webpage, <a href="http://www.imagemagick.org/www/cipher.html">ImageMagick: Encipher or
3152 Decipher an Image</a>.</p>
3156 <div style="margin: auto;">
3157 <h3 class="magick-header"><a id="encoding"></a>-encoding <var>type</var></h3>
3160 <p class="magick-description">specify the text encoding.</p>
3165 AdobeCustom AdobeExpert
3166 AdobeStandard AppleRoman
3173 <div style="margin: auto;">
3174 <h3 class="magick-header"><a id="endian"></a>-endian <var>type</var></h3>
3177 <p class="magick-description">Specify endianness (<code>MSB</code> or <code>LSB</code>) of the image.</p>
3179 <p>To print a complete list of endian types, use the <a href="command-line-options.html#list">-list endian</a> option.</p>
3181 <p>Use <a href="command-line-options.html#endian">+endian</a> to revert to unspecified endianness.</p>
3184 <div style="margin: auto;">
3185 <h3 class="magick-header"><a id="enhance"></a>-enhance</h3>
3188 <p class="magick-description">Apply a digital filter to enhance a noisy image.</p>
3191 <div style="margin: auto;">
3192 <h3 class="magick-header"><a id="equalize"></a>-equalize</h3>
3195 <p class="magick-description">perform histogram equalization on the image channel-by-channel.</p>
3197 <p>To perform histogram equalization on all channels in concert, transform the
3198 image into some other color space, such as HSL, OHTA, YIQ or YUV, then
3199 equalize the appropriate intensity-like channel, then convert back to RGB.</p>
3201 <p>For example using HSL, we have: ... <code>-colorspace HSL -channel lightness
3202 -equalize -colorspace RGB</code> ...</p>
3204 <p>For YIQ, YUV and OHTA use the red channel. For example, OHTA is a principal
3205 components transformation that puts most of the information in the first
3206 channel. Here we have ... <code>-colorspace OHTA -channel red -equalize
3207 -colorspace RGB</code> ...</p>
3209 <div style="margin: auto;">
3210 <h3 class="magick-header"><a id="evaluate"></a>-evaluate <var>operator value</var></h3>
3213 <p class="magick-description">Alter channel pixels by evaluating an arithmetic, relational, or logical expression.</p>
3215 <p>(See the <a href="command-line-options.html#function">-function</a> operator for some
3216 multi-parameter functions. See the <a href="command-line-options.html#fx">-fx</a> operator if more
3217 elaborate calculations are needed.)</p>
3219 <p>The behaviors of each <var>operator</var> are summarized in the
3220 following list. For brevity, the numerical value of a "pixel" referred to
3221 below is the value of the corresponding channel of that pixel, while
3222 a "normalized pixel" is that number divided by the maximum
3223 (installation-dependent) value <var>QuantumRange</var>. (If
3224 normalized pixels are used, they are restored, following the other
3225 calculations, to the full range by multiplying by <var>QuantumRange</var>.)</p>
3227 <table class="table table-condensed table-striped">
3232 <th><var>operator</var></th>
3233 <th>Summary (see further below for details)</th>
3238 <tr><td>Abs </td> <td>Add <var>value</var> to pixels and return absolute value. </td></tr>
3239 <tr><td>Add </td> <td>Add <var>value</var> to pixels. </td></tr>
3240 <tr><td>AddModulus </td> <td>Add <var>value</var> to pixels modulo <var>QuantumRange</var>.</td></tr>
3241 <tr><td>And </td> <td>Binary AND of pixels with <var>value</var>.</td></tr>
3242 <tr><td>Cos, Cosine </td> <td>Apply cosine to pixels with frequency <var>value</var> with 50% bias added.</td></tr>
3243 <tr><td>Divide </td> <td>Divide pixels by <var>value</var>.</td></tr>
3244 <tr><td>Exp </td> <td>base-e exponential function</td></tr>
3245 <tr><td>Exponential </td> <td>base-e exponential function</td></tr>
3246 <tr><td>LeftShift </td> <td>Shift the pixel values left by <var>value</var> bits (i.e., multiply pixels by 2<sup><var>value</var></sup>).</td></tr>
3247 <tr><td>Log </td> <td>Apply scaled logarithm to normalized pixels.</td></tr>
3248 <tr><td>Max </td> <td>Set pixels to maximum of <var>value</var> and current pixel <var>value</var> (i.e. set any pixels currently less than <var>value</var> to <var>value</var>).</td></tr>
3249 <tr><td>Mean </td> <td>Add the <var>value</var> and divide by 2.</td></tr>
3250 <tr><td>Median </td> <td>Choose the median value from an image sequence.</td></tr>
3251 <tr><td>Min </td> <td>Set pixels to minimum of <var>value</var> and current pixel <var>value</var> (i.e. set any pixels currently greater than <var>value</var> to <var>value</var>).</td></tr>
3252 <tr><td>Multiply </td> <td>Multiply pixels by <var>value</var>.</td></tr>
3253 <tr><td>Or </td> <td>Binary OR of pixels with <var>value</var>.</td></tr>
3254 <tr><td>Pow </td> <td>Raise normalized pixels to the power <var>value</var>.</td></tr>
3255 <tr><td>RightShift </td> <td>Shift the pixel values right by <var>value</var> bits (i.e., divide pixels by 2<sup><var>value</var></sup>).</td></tr>
3256 <tr><td>RMS</td> <td>Square the pixel and add the <var>value</var>.</td></tr>
3257 <tr><td>RootMeanSquare</td> <td>Square the pixel and add the <var>value</var>.</td></tr>
3258 <tr><td>Set </td> <td>Set pixel equal to <var>value</var>.</td></tr>
3259 <tr><td>Sin, Sine </td> <td>Apply sine to pixels with frequency <var>value</var> with 50% bias added.</td></tr>
3260 <tr><td>Subtract </td> <td>Subtract <var>value</var> from pixels.</td></tr>
3261 <tr><td>Xor </td> <td>Binary XOR of pixels with <var>value.</var></td></tr>
3263 <tr><td> </td><td> </td></tr>
3265 <tr><td>Gaussian-noise</td><td> </td></tr>
3266 <tr><td>Impulse-noise</td><td> </td></tr>
3267 <tr><td>Laplacian-noise</td><td> </td></tr>
3268 <tr><td>Multiplicative-noise</td> <td>(These are equivalent to the corresponding <a href="command-line-options.html#noise">-noise</a> operators.)</td></tr>
3269 <tr><td>PoissonNoise</td><td> </td></tr>
3270 <tr><td>Uniform-noise</td><td> </td></tr>
3272 <tr><td> </td><td> </td></tr>
3274 <tr><td>Threshold </td> <td>Threshold pixels larger than <var>value</var>.</td></tr>
3275 <tr><td>ThresholdBlack </td> <td>Threshold pixels to zero values equal to or below <var>value</var>.</td></tr>
3276 <tr><td>ThresholdWhite </td> <td>Threshold pixels to maximum values above <var>value</var>. </td></tr>
3280 <p>The specified functions are applied only to each previously set <a href="command-line-options.html#channel">-channel</a> in the image. If necessary, the results of the
3281 calculations are truncated (clipped) to fit in the interval [0, <var>QuantumRange</var>]. The transparency channel of the image is
3282 represented as a 'alpha' values (0 = fully transparent), so, for example, a
3283 <code>Divide</code> by 2 of the alpha channel will make the image
3284 semi-transparent. Append the percent symbol '<code>%</code>' to specify a value
3285 as a percentage of the <var>QuantumRange</var>.</p>
3287 <p>To print a complete list of <a href="command-line-options.html#evaluate">-evaluate</a> operators, use
3288 <a href="command-line-options.html#list">-list evaluate</a>.</p>
3290 <p>The results of the <code>Add</code>, <code>Subtract</code> and
3291 <code>Multiply</code> methods can also be achieved using either the <a href="command-line-options.html#level">-level</a> or the <a href="command-line-options.html#level">+level</a> operator, with
3292 appropriate argument, to linearly modify the overall range of color values.
3293 Please note, however, that <a href="command-line-options.html#level">-level</a> treats transparency as
3294 'matte' values (0 = opaque), while <a href="command-line-options.html#level">-evaluate</a> works with
3297 <p><code>AddModulus</code> has been added as of ImageMagick 6.4.8-4 and provides
3298 addition modulo the <var>QuantumRange</var>. It is therefore
3299 equivalent to <code>Add</code> unless the resulting pixel value is outside the
3300 interval [0, <var>QuantumRange</var>]. </p>
3302 <p><code>Exp or Exponential</code> has been added as of ImageMagick 6.6.5-1 and
3303 works on normalized pixel values. The <var>value</var> used with
3304 <code>Exp</code> should be negative so as to produce a decaying exponential
3305 function. Non-negative values will always produce results larger unity and
3306 thus outside the interval [0, <var>QuantumRange</var>]. The
3307 formula is expressed below. </p>
3309 <p class="text-center">
3310 exp(<var>value</var> × <b><var>u</var></b>)
3313 <p> If the input image is squared, for example, using <a href="command-line-options.html#-function">-function polynomial "2 0 0"</a>, then a decaying Gaussian function will be
3316 <p><code>Log</code> has been added as of ImageMagick 6.4.2-1 and works on
3317 normalized pixel values. This a <var>scaled</var> log function. The <var>value</var> used with <code>Log</code> provides a <var>scaling
3318 factor</var> that adjusts the curvature in the graph of the log function. The
3319 formula applied to a normalized value <b><var>u</var></b> is below. </p>
3321 <p class="text-center">
3322 log(<var>value</var> × <b><var>u</var></b> + 1) / log(<var>value</var> + 1)
3325 <p><code>Pow</code> has been added as of ImageMagick 6.4.1-9, and works on
3326 normalized pixel values. Note that <code>Pow</code> is related to the <a href="command-line-options.html#gamma">-gamma</a> operator. For example, <b>-gamma 2</b> is equivalent
3327 to <b>-evaluate pow 0.5</b>, i.e., a 'square root' function. The value used
3328 with <a href="command-line-options.html#gamma">-gamma</a> is simply the reciprocal of the value used
3329 with <code>Pow</code>.</p>
3331 <p><code>Cosine</code> and <code>Sine</code> was added as of IM v6.4.8-8 and
3332 converts the image values into a value according to a (co)sine wave function.
3333 The synonyms <code>Cos</code> and <code>Sin</code> may also be used. The output
3334 is biased 50% and normalized by 50% so as to fit in the respective color value
3335 range. The <var>value</var> scaling of the <var>period</var> of the
3336 function (its frequency), and thus determines the number of 'waves' that will
3337 be generated over the input color range. For example, if the <var>value</var> is 1, the effective period is simply the <var>QuantumRange</var>; but if the <var>value</var> is 2,
3338 then the effective period is the <var>half</var> the <var>QuantumRange</var>.</p>
3340 <p class="text-center">
3341 0.5 + 0.5 × cos(2 π <b><var>u</var></b> × <var>value</var>).
3344 <p>See also the <a href="command-line-options.html#function">-function</a> operator, which is a
3345 multi-value version of evaluate. </p>
3347 <div style="margin: auto;">
3348 <h3 class="magick-header"><a id="evaluate-sequence"></a>-evaluate-sequence <var>operator</var></h3>
3351 <p class="magick-description">Alter channel pixels by evaluating an arithmetic, relational, or
3352 logical expression over a sequence of images.</p>
3354 <p>To print a complete list of <a href="command-line-options.html#evaluate-sequence">-evaluate-sequence</a> operators, use <a href="command-line-options.html#list">-list evaluate</a>.</p>
3356 <div style="margin: auto;">
3357 <h3 class="magick-header"><a id="extent"></a>-extent <var>geometry</var></h3>
3360 <p class="magick-description">Set the image size and offset.</p>
3362 <p>If the image is enlarged, unfilled areas are set to the background color.
3363 To position the image, use offsets in the <var>geometry</var>
3364 specification or precede with a <a href="command-line-options.html#gravity">-gravity</a> setting. To
3365 specify how to compose the image with the background, use <a href="command-line-options.html#compose">-compose</a>.</p>
3367 <p>This command reduces or expands a JPEG image to fit on an 800x600
3368 display. If the aspect ratio of the input image isn't exactly 4:3, then the
3369 image is centered on an 800x600 black canvas: </p>
3372 convert input.jpg -resize 800x600 -background black -compose Copy \
3373 -gravity center -extent 800x600 -quality 92 output.jpg
3376 <p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
3378 <div style="margin: auto;">
3379 <h3 class="magick-header"><a id="extract"></a>-extract <var>geometry</var></h3>
3382 <p class="magick-description">Extract the specified area from image.</p>
3384 <p>This option is most useful for extracting a subregion of a very large raw
3385 image. Note that these two commands are equivalent:</p>
3388 convert -size 16000x16000 -depth 8 -extract 640x480+1280+960 \
3389 image.rgb image.png",
3390 convert -size 16000x16000 -depth 8 'image.rgb[640x480+1280+960]' \
3391 image.rgb image.png"
3394 <p>If you omit the offsets, as in</p>
3397 convert -size 16000x16000 -depth 8 -extract 640x480 \
3401 <p>the image is <var>resized</var> to the specified dimensions instead,
3405 convert -size 16000x16000 -depth 8 -resize 640x480 image.rgb image.png
3408 <p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
3410 <div style="margin: auto;">
3411 <h3 class="magick-header"><a id="family"></a>-family <var>fontFamily</var></h3>
3414 <p class="magick-description">Set a font family for text.</p>
3416 <p>This setting suggests a font family that ImageMagick should try to use for
3417 rendering text. If the family can be found it is used; if not, a default font
3418 (e.g., "Arial") or a family known to be similar is substituted (e.g.,
3419 "Courier" might be used if "System" is requested but not found). </p>
3421 <p>For other settings that affect fonts, see the options <a href="command-line-options.html#font">-font</a>, <a href="command-line-options.html#stretch">-stretch</a>, <a href="command-line-options.html#style">-style</a>, and <a href="command-line-options.html#weight">-weight</a>. </p>
3423 <div style="margin: auto;">
3424 <h3 class="magick-header"><a id="features"></a>-features <var>distance</var></h3>
3427 <p class="magick-description">display (cooccurrence matrix) texture measure features for each channel in the image in each of four directions (horizontal, vertical, left and right diagonals) for the specified distance.</p>
3430 Angular Second Moment Sum Entropy
3432 Correlation Difference Variance
3433 Sum of Squares Variance Difference Entropy
3434 Inverse Difference Moment Information Measure of Correlation 1
3435 Sum Average Information Measure of Correlation 2
3436 Sum Variance Maximum Correlation Coefficient
3439 <div style="margin: auto;">
3440 <h3 class="magick-header"><a id="fft"></a>-fft</h3>
3443 <p class="magick-description">implements the forward discrete Fourier transform (DFT).</p>
3445 <p>This option is new as of ImageMagick 6.5.4-3 (and now working for Windows
3446 users in ImageMagick 6.6.0-9). It transforms an image from the normal
3447 (spatial) domain to the frequency domain. In the frequency domain, an image is
3448 represented as a superposition of complex sinusoidal waves of varying
3449 amplitudes. The image x and y coordinates are the possible frequencies along
3450 the x and y directions, respectively, and the pixel intensity values are
3451 complex numbers that correspond to the sinusoidal wave amplitudes. See for
3452 example, <a href="http://en.wikipedia.org/wiki/Fourier_transform">Fourier
3453 Transform</a>, <a href="http://en.wikipedia.org/wiki/DFT">Discrete Fourier
3454 Transform</a> and <a href="http://en.wikipedia.org/wiki/FFT">Fast Fourier
3457 <p>A single image name is provided as output for this option. However, the
3458 output result will have two components. It is either a two-frame image or two
3459 separate images, depending upon whether the image format specified supports
3460 multi-frame images. The reason that we get a dual output result is because the
3461 frequency domain represents an image using complex numbers, which cannot be
3462 visualized directly. Therefore, the complex values are automagically separated
3463 into a two-component image representation. The first component is the
3464 magnitude of the complex number and the second is the phase of the complex
3465 number. See for example, <a href="http://en.wikipedia.org/wiki/Complex_numbers">Complex Numbers</a>.</p>
3467 <p>The magnitude and phase component images must be specified using image
3468 formats that do not limit the color or compress the image. Thus, MIFF, TIF,
3469 PFM, EXR and PNG are the recommended image formats to use. All of these
3470 formats, except PNG support multi-frame images. So for example,</p>
3473 convert image.png -fft fft_image.miff
3476 <p>generates a magnitude image as <code>fft_image.miff[0]</code> and a phase
3477 image as <code>fft_image.miff[1]</code>. Similarly,</p>
3480 convert image.png -fft fft_image.png
3483 <p>generates a magnitude image as <code>fft_image-0.png</code> and a phase image
3484 as <code>fft_image-1.png</code>. If you prefer this representation, then you can
3485 force any of the other formats to produce two output images by including <a href="command-line-options.html#adjoin">+adjoin</a> following -fft in the command line.</p>
3487 <p>The input image can be any size, but if not square and even-dimensioned, it
3488 is padded automagically to the larger of the width or height of the input
3489 image and to an even number of pixels. The padding will occur at the bottom
3490 and/or right sides of the input image. The resulting output magnitude and
3491 phase images is square at this size. The kind of padding relies on the <a href="command-line-options.html#virtual-pixel">-virtual-pixel</a> setting.</p>
3493 <p>Both output components will have dynamic ranges that fit within
3494 [0, <var>QuantumRange</var>], so that HDRI need not be enabled.
3495 Phase values nominally range from 0 to 2*π, but is scaled to span the full
3496 dynamic range. (The first few releases had non-HDRI scaled but HDRI not
3497 scaled). The magnitude image is not scaled and thus generally will contain
3498 very small values. As such, the image normally will appear totally black. In
3499 order to view any detail, the magnitude image typically is enhanced with a log
3500 function into what is usually called the spectrum. A log function is used to
3501 enhance the darker values more in comparison to the lighter values. This can
3502 be done, for example, as follows:</p>
3505 convert fft_image.miff[0] -contrast-stretch 0 \
3506 -evaluate log 1000 fft_image_spectrum.png"
3509 <p>where either <a href="command-line-options.html#contrast-stretch">-contrast-stretch</a> 0 or <a href="command-line-options.html#auto-level">-auto-level</a> is used to scale the image to full dynamic
3510 range, first. The argument to the <a href="command-line-options.html#evaluate">-evaluate</a> log
3511 typically is specified between 100 and 10,000, depending upon the amount of
3512 detail that one wants to bring out in the spectrum. Larger values produce more
3513 visible detail. Too much detail, however, may hide the important features.</p>
3515 <p>The <a href="http://www.fftw.org/">FFTW</a> delegate library is required to
3516 use <a href="command-line-options.html#fft">-fft</a>.</p>
3518 <p>Use <a href="command-line-options.html#fft">+fft</a> to produce two output images that are the real
3519 and imaginary components of the complex valued Fourier transform.</p>
3521 <p>However, as the real and imaginary components can contain negative values,
3522 this requires that IM be configured with HDRI enabled. In this case, you must
3523 use either MIFF, TIF, PFM or MPC formats for the real and imaginary component
3524 results, since they are formats that preserve both negative and fractional
3525 values without clipping them or truncating the fractional part. With either
3526 MIFF or TIF, one should add -define quantum:format=32, to allow those image
3527 types to work properly in HDRI mode without clipping.</p>
3529 <p>The real and imaginary component images resulting from <a href="command-line-options.html#fft">+fft</a> are also square, even dimensioned images due to the same
3530 padding that was discussed above for the magnitude and phase component
3533 <p>See the discussion on HDRI implementations of ImageMagick on the page <a href="high-dynamic-range.html">High Dynamic-Range Images</a>. For more
3534 about HDRI go the ImageMagick <a href="http://www.imagemagick.org/Usage/basics/#hdri">Usage</a> pages, <a href="http://www.fmwconcepts.com/imagemagick/fourier_transforms/fourier.html">Fred's Fourier Processing With ImageMagick page</a> or this <a href="http://en.wikipedia.org/wiki/High_dynamic_range_imaging">Wikipedia</a>
3537 <p>By default the FFT is normalized (and the IFT is not). Use "<code><a href="command-line-options.html#define">-define</a> fourier:normalize=forward</code> to explicityly normalize the FFT and unnormalize the IFT.</p>
3540 <div style="margin: auto;">
3541 <h3 class="magick-header"><a id="fill"></a>-fill <var>color</var></h3>
3544 <p class="magick-description">color to use when filling a graphic primitive.</p>
3546 <p>This option accepts a color name, a hex color, or a numerical RGB, RGBA,
3547 HSL, HSLA, CMYK, or CMYKA specification. See <a href="color.html">Color Names</a> for
3548 a description of how to properly specify the color argument.</p>
3550 <p>Enclose the color specification in quotation marks to prevent the "#" or
3551 the parentheses from being interpreted by your shell.</p>
3558 -fill "rgb(255,255,255)"
3561 <p>See <a href="command-line-options.html#draw">-draw</a> for further details.</p>
3563 <p>To print a complete list of color names, use the <a href="command-line-options.html#list">-list color</a> option.</p>
3565 <div style="margin: auto;">
3566 <h3 class="magick-header"><a id="filter"></a>-filter <var>type</var></h3>
3569 <p class="magick-description">Use this <var>type</var> of filter when resizing or distorting an image.</p>
3571 <p>Use this option to affect the resizing operation of an image during
3572 operations such as <a href="command-line-options.html#resize">-resize</a> and <a href="command-line-options.html#distort">-distort</a>. For example you can use a simple resize filter such as:</p>
3577 Triangle Quadratic Mitchell
3580 <p>The <code>Bessel</code> and <code>Sinc</code> filter is also provided (as well
3581 as a faster <code>SincFast</code> equivalent form). However these filters are
3582 generally useless on their own as they are infinite filters that are being
3583 clipped to the filters support size. Their direct use is not recommended
3584 except via expert settings (see below). </p>
3586 <p>Instead these special filter functions are typically windowed by a windowing
3587 function that the <a href="command-line-options.html#filter">-filter</a> setting defines. That is
3588 using these functions will define a 'Windowed' filter, appropriate to the
3589 operator involved. Windowed filters include: </p>
3592 Lanczos Hamming Parzen
3593 Blackman Kaiser Welsh
3594 Hanning Bartlett Bohman
3597 <p>Also one special self-windowing filter is also provided
3598 <code>Lagrange</code>, which will automagically re-adjust its function depending
3599 on the current 'support' or 'lobes' expert settings (see below).</p>
3601 <p>If you do not select a filter with this option, the filter defaults to
3602 <code>Mitchell</code> for a colormapped image, an image with a matte channel, or
3603 if the image is enlarged. Otherwise the filter default to
3604 <code>Lanczos</code>.</p>
3606 <p>To print a complete list of resize filters, use the <a href="command-line-options.html#list">-list
3607 filter</a> option.</p>
3609 <p>You can modify how the filter behaves as it scales your image through the
3610 use of these expert settings (see also <a href="command-line-options.html#define">-define</a> and <a href="command-line-options.html#set">-set</a>):-</p>
3612 <table class="table table-condensed table-striped">
3614 <td>-define filter:blur=<var>factor</var></td>
3615 <td>Scale the X axis of the filter (and its window). Use > 1.0 for
3616 blurry or < 1.0 for sharp. This should only be used with Gaussian and
3617 Gaussian-like filters simple filters, or you may not get the expected
3622 <td>-define filter:support=<var>radius</var></td>
3623 <td>Set the filter support radius. Defines how large the filter should be and
3624 thus directly defines how slow the filtered resampling process is. All
3625 filters have a default 'prefered' support size. Some filters like
3626 <code>Lagrange</code> and windowed filters adjust themselves depending on
3627 this value. With simple filters this value either does nothing (but slow
3628 the resampling), or will clip the filter function in a detrimental way.
3633 <td>-define filter:lobes=<var>count</var></td>
3634 <td>Set the number of lobes to use for the Sinc/Bessel filter. This an
3635 alternative way of specifying the 'support' range of the filter, that is
3636 designed to be more suited to windowed filters, especially when used for
3637 image distorts.</td>
3641 <td>-define filter:sigma=<var>value</var></td>
3642 <td>The 'sigma' value used to define the <code>Gaussian</code> filter. Default
3643 sigma value is '<code>0.5</code>'. It only effects <code>Gaussian</code> but
3644 does not shrink (but may enlarge) the filter's 'support'. It can be used
3645 to generate very small blurs but without the filter 'missing' pixels due
3646 to using a small support setting. A larger value of '<code>0.707</code>'
3647 (a value of '1/sqrt(2)') is another common setting. </td>
3651 <td>-define filter:b=<var>b-spline_factor</var></td>
3653 <td>-define filter:c=<var>keys_alpha_factor</var></td>
3654 <td>Redefine the values used for cubic filters such as <code>Cubic</code>,
3655 <code>Catrom</code>, <code>Mitchel</code>, and <code>Hermite</code>, as well as
3656 the <code>Parzen</code> cubic windowing function. If only one of the values
3657 are defined, the other is set so as to generate a 'Cubic-Keys' filter.
3658 The values meaning was defined by a research paper by
3659 Mitchell-Netravali.</td>
3663 <td>-define filter:kaiser-beta=<var>value</var></td>
3664 <td>The 'alpha' value used to as part of the Kaiser Windowing function.
3665 Default value is '6.5'. It only effects Kaiser windowing function, and
3666 does not effect any other attributes.
3667 Before ImageMagick v6.7.6-10, this option was known as "filter:alpha", (an
3668 inheritance from the very old "zoom" program). It was changed to bring the
3669 function in line with more modern academic research usage, and better
3670 assign it be more definitive. </td>
3674 <td>-define filter:kaiser-alpha=<var>value</var></td>
3675 <td>This value when multiplied by 'PI' is equivalent to "kaiser-beta", and
3676 will override that setting. It only effects Kaiser windowing function,
3677 and does not effect any other attributes. </td>
3681 <td>-define filter:filter=<var>filter_function</var></td>
3682 <td>Use this function directly as the weighting filter. This will allow
3683 you to directly use a windowing function such as <code>Blackman</code>,
3684 as a resampling filter, rather than as its normal usage as a windowing
3685 function. If defined, no windowing function also defined, the window function is set
3686 to <code>Box</code>). Directly specifying <code>Sinc</code> or <code>Jinc</code>
3687 as a filter will also do this. </td>
3691 <td>-define filter:window=<var>filter_function</var></td>
3692 <td>The IIR (infinite impulse response) filters <code>Sinc</code> and
3693 <code>Jinc</code> are windowed (brought down to zero over the defined
3694 support range) with the given filter. This allows you to specify a filter
3695 function to be used as a windowing function for these IIR filters.
3696 Many of the defined filters are actually windowing functions for these IIR
3697 filters. A typical choices is <code>Box</code>, (which effectively turns
3698 off the windowing function). </td>
3702 <td>-define filter:win-support=<var>radius</var></td>
3703 <td>Scale windowing function to this size instead. This causes the windowing
3704 (or self-windowing Lagrange filter) to act is if the support window is
3705 larger than what is actually supplied to the calling operator. The filter
3706 however is still clipped to the real support size given. If unset this
3707 will equal the normal filter support size. </td>
3711 <td>-define filter:verbose=<var>1</var></td>
3712 <td>This causes IM to print information on the final internal filter
3713 selection to standard output. This includes a commented header on the
3714 filter settings being used, and data allowing the filter weights to be
3715 easily graphed. Note however that some filters are internally defined in terms of other filters. The <code>Lanczos</code> filter for example is defined in terms of
3716 a <code>SincFast</code> windowed <code>SincFast</code> filter, while
3717 <code>Mitchell</code> is defined as a general <code>Cubic</code> family filter
3718 with specific 'B' and 'C' settings. </td>
3723 <p>For example, to get a 8 lobe jinc windowed sinc filter (Genseng filter?):</p>
3728 -set filter:window=jinc \
3729 -set filter:lobes=8 \
3730 -resize 150% image.jpg"
3733 <p>Or a raw un-windowed Sinc filter with 4 lobes:</p>
3737 -set filter:filter=sinc \
3738 -set filter:lobes=4 \
3739 -resize 150% image.jpg"
3742 <p>To extract the data for a raw windowing function, combine it with
3743 a '<code>Box</code>' filter. For example the '<code>Welch</code> parabolic
3744 windowing function. </p>
3747 convert null: -define filter:filter=Box \
3748 -define filter:window=Welch \
3749 -define filter:support=1.0 \
3750 -define filter:verbose=1 \
3751 -resize 2 null: > window_welch.dat
3754 plot \"window_welch.dat\" with lines
3757 <p>Note that the use of expert options is provided for image processing experts
3758 who have studied and understand how resize filters work. Without this
3759 knowledge, and an understanding of the definition of the actual filters
3760 involved, using expert settings are more likely to be detrimental to your image
3764 <div style="margin: auto;">
3765 <h3 class="magick-header"><a id="flatten"></a>-flatten</h3>
3768 <p class="magick-description">This is a simple alias for the <a href="command-line-options.html#layers">-layers</a> method "flatten".</p>
3771 <div style="margin: auto;">
3772 <h3 class="magick-header"><a id="flip"></a>-flip</h3>
3775 <p class="magick-description">create a <var>mirror image</var></p>
3777 <p>reflect the scanlines in the vertical direction. The image will be mirrored
3781 <div style="margin: auto;">
3782 <h3 class="magick-header"><a id="floodfill"></a>-floodfill {<var>+-</var>}<var>x</var>{<var>+-</var>}<var>y</var> <var>color</var></h3>
3785 <p class="magick-description">floodfill the image with color at the specified offset.</p>
3787 <p>Flood fill starts from the given 'seed point' which is not gravity effected.
3788 Any color that matches within <a href="command-line-options.html#fuzz">-fuzz</a> color distance of the
3789 given <var>color</var> argument, connected to that 'seed point'
3790 will be replaced with the current <a href="command-line-options.html#fill">-fill</a> color. </p>
3792 <p>Note that if the pixel at the 'seed point' does not itself match the given
3793 <var>color</var> (according to <a href="command-line-options.html#fuzz">-fuzz</a>), then no
3794 action will be taken. </p>
3796 <p>This operator works more like the <a href="command-line-options.html#opaque">-opaque</a> option, than
3797 a more general flood fill that reads the matching color directly at the 'seed
3798 point'. For this form of flood fill, look at <a href="command-line-options.html#draw">-draw</a> and
3799 its 'color floodfill' drawing method. </p>
3802 <div style="margin: auto;">
3803 <h3 class="magick-header"><a id="flop"></a>-flop</h3>
3806 <p class="magick-description">create a <var>mirror image</var>.</p>
3808 <p>Reflect the scanlines in the horizontal direction, just like the image in
3809 a vertical mirror. </p>
3812 <div style="margin: auto;">
3813 <h3 class="magick-header"><a id="font"></a>-font <var>name</var></h3>
3816 <p class="magick-description">set the font to use when annotating images with text, or creating labels.</p>
3818 <p>To print a complete list of fonts, use the <a href="command-line-options.html#list">-list font</a>
3819 option (for versions prior to 6.3.6, use 'type' instead of 'font').</p>
3821 <p>In addition to the fonts specified by the above pre-defined list, you can
3822 also specify a font from a specific source. For example <code>Arial.ttf</code>
3823 is a TrueType font file, <code>ps:helvetica</code> is PostScript font, and
3824 <code>x:fixed</code> is X11 font.</p>
3826 <p>For other settings that affect fonts, see the options <a href="command-line-options.html#family">-family</a>, <a href="command-line-options.html#stretch">-stretch</a>, <a href="command-line-options.html#style">-style</a>, and <a href="command-line-options.html#weight">-weight</a>. </p>
3829 <div style="margin: auto;">
3830 <h3 class="magick-header"><a id="foreground"></a>-foreground <var>color</var></h3>
3833 <p class="magick-description">Define the foreground color for menus.", "display</p>
3835 <p>The color is specified using the format described under the <a href="command-line-options.html#fill">-fill</a> option.</p>
3837 <p>The default foreground color is black.</p>
3839 <div style="margin: auto;">
3840 <h3 class="magick-header"><a id="format"></a>-format <var>type</var></h3>
3843 <p class="magick-description">the image format type.</p>
3845 <p>When used with the <code>mogrify</code> utility, this option converts any
3846 image to the image <a href="formats.html">format</a> you specify.
3847 For a list of image format types supported by ImageMagick, use <a href="command-line-options.html#list">-list format</a>.</p>
3849 <p>By default the file is written to its original name. However, if the
3850 filename extension matches a supported format, the extension is replaced with
3851 the image format type specified with <a href="command-line-options.html#format">-format</a>. For
3852 example, if you specify <var>tiff</var> as the format type and the
3853 input image filename is <var>image.gif</var>, the output image
3854 filename becomes <var>image.tiff</var>.</p>
3856 <div style="margin: auto;">
3857 <h3 class="magick-header"><a id="format_identify_"></a>-format <var>string</var></h3>
3860 <p class="magick-description">output formatted image characteristics.</p>
3862 <p>See <a href="escape.html">Format and Print Image
3863 Properties</a> for an explanation on how to specify the argument to this
3866 <div style="margin: auto;">
3867 <h3 class="magick-header"><a id="frame"></a>-frame <var>geometry</var></h3>
3870 <p class="magick-description">Surround the image with a border or beveled frame.</p>
3872 <p>The color of the border is specified with the <a href="command-line-options.html#mattecolor">-mattecolor</a> command line option. </p>
3874 <p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument. The <var>size</var> portion of the <var>geometry</var> argument indicates the amount of extra width and
3875 height that is added to the dimensions of the image. If no offsets are given
3876 in the <var>geometry</var> argument, then the border added is
3877 a solid color. Offsets <var>x</var> and <var>y</var>, if present, specify that
3878 the width and height of the border is partitioned to form an outer bevel of
3879 thickness <var>x</var> pixels and an inner bevel of thickness
3880 <var>y</var> pixels. Negative offsets make no sense as frame arguments.
3883 <p>The <a href="command-line-options.html#frame">-frame</a> option is affected by the current <a href="command-line-options.html#compose">-compose</a> setting and assumes that this is using the default
3884 '<code>Over</code>' composition method. It generates an image of the appropriate
3885 size with the current <a href="command-line-options.html#bordercolor">-bordercolor</a> setting, and then
3886 draws the frame of four distinct colors close to the current <a href="command-line-options.html#mattecolor">-mattecolor</a>. The original image is then overlaid onto
3887 center of this image. This means that with the default compose method of
3888 '<code>Over</code>' any transparent parts may be replaced by the current <a href="command-line-options.html#bordercolor">-bordercolor</a> setting.</p>
3890 <p>The image composition is not
3891 affected by the <a href="command-line-options.html#gravity">-gravity</a> option.</p>
3894 <div style="margin: auto;">
3895 <h3 class="magick-header"><a id="frame_import_"></a>-frame</h3>
3898 <p class="magick-description">include the X window frame in the imported image. </p>
3899 <div style="margin: auto;">
3900 <h3 class="magick-header"><a id="function"></a>-function <var>function</var> <var>parameters</var></h3>
3903 <p class="magick-description">Apply a function to channel values.</p>
3905 <p>This operator performs calculations based on the given arguments to modify
3906 each of the color values for each previously set <a href="command-line-options.html#channel">-channel</a> in the image. See <a href="command-line-options.html#evaluate">-evaluate</a> for details concerning how the results of the
3907 calculations are handled.</p>
3909 <p>This is can be considered a multi-argument version of the <a href="command-line-options.html#evaluate">-evaluate</a> operator. (Added in
3910 ImageMagick 6.4.8−8.)</p>
3912 <p>Here, <var>parameters</var> is a comma-separated list of
3913 numerical values. The number of values varies depending on which <var>function</var> is selected. Choose the <var>function</var> from:</p>
3922 <p>To print a complete list of <a href="command-line-options.html#function">-function</a> operators,
3923 use <a href="command-line-options.html#list">-list function</a>. Descriptions follow.</p>
3925 <dl class="dl-horizontal">
3927 <dd><p>The <code>Polynomial</code> function takes an arbitrary number of parameters,
3928 these being the coefficients of a polynomial, in decreasing order of degree.
3929 That is, entering</p>
3932 -function Polynomial <var>a</var><sub><var>n</var></sub>,<var>a</var><sub><var>n</var>-1</sub>,...<var>a</var><sub>1</sub>,<var>a</var><sub>0</sub>
3935 <p>will invoke a polynomial function given by</p>
3938 <var>a</var><sub><var>n</var></sub> <b><var>u</var></b><sup><var>n</var></sup> + <var>a</var><sub><var>n</var>-1</sub> <b><var>u</var></b><sup><var>n</var>-1</sup> + ··· <var>a</var><sub>1</sub> <b><var>u</var></b> + <var>a</var><sub>0</sub>,
3941 <p>where <b><var>u</var></b> is pixel's original normalized channel value.</p>
3943 <p>The <code>Polynomial</code> function can be used in place of <code>Set</code>
3944 (the <var>constant</var> polynomial) and <code>Add</code>, <code>Divide</code>,
3945 <code>Multiply</code>, and <code>Subtract</code> (some <var>linear</var>
3946 polynomials) of the <a href="command-line-options.html#evaluate">-evaluate</a> operator. The <a href="command-line-options.html#level">-level</a> operator also affects channels linearly. Some
3947 correspondences follow.</p>
3949 <table class="table table-condensed table-striped">
3951 <td>-evaluate Set <var>value</var> </td>
3952 <td>-function Polynomial <var>value</var></td>
3953 <td>(Constant functions; set <var>value</var>×100% gray when channels are RGB.)</td>
3956 <td>-evaluate Add <var>value</var> </td>
3957 <td>-function Polynomial 1,<var>value</var></td>
3960 <td>-evaluate Subtract <var>value</var> </td>
3961 <td>-function Polynomial 1,−<var>value</var></td>
3964 <td>-evaluate Multiply <var>value</var> </td>
3965 <td>-function Polynomial <var>value</var>,0</td>
3968 <td>+level black% x white%</td>
3969 <td>-function Polynomial A,B</td>
3970 <td>(Reduce contrast. Here, A=(white-black)/100 and B=black/100.)</td>
3974 <p>The <code>Polynomial</code> function gives great versatility, since
3975 polynomials can be used to fit any continuous curve to any degree of accuracy
3981 <p>The <code>Sinusoid</code> function can be used to vary the channel values
3982 sinusoidally by setting frequency, phase shift, amplitude, and a bias. These
3983 values are given as one to four parameters, as follows,</p>
3986 -function <code>Sinusoid</code> <var>freq</var>,[<var>phase</var>,[<var>amp</var>,[<var>bias</var>]]]
3989 <p>where <var>phase</var> is in degrees. (The domain [0,1] of the function
3990 corresponds to 0 through <var>freq</var>×360 degrees.)
3991 The result is that if a pixel's normalized channel value is originally
3992 <b><var>u</var></b>, its resulting normalized value is given by </p>
3995 <var>amp</var> * sin(2*π* (<var>freq</var> * <b><var>u</var></b> + <var>phase</var> / 360)) + <var>bias</var>
3998 <p> For example, the following generates a curve that starts and ends at 0.9
3999 (when <b><var>u</var></b>=0 and 1, resp.), oscillating three times between
4000 .7−.2=.5 and .7+.2=.9. </p>
4003 -function Sinusoid 3,-90,.2,.7
4006 <p>The default values of <var>amp</var> and <var>bias</var> are both .5. The default for <var>phase</var>
4009 <p>The <code>Sinusoid</code> function generalizes <code>Sin</code> and
4010 <code>Cos</code> of the <a href="command-line-options.html#evaluate">-evaluate</a> operator by allowing
4011 varying amplitude, phase and bias. The correspondence is as follows.</p>
4013 <table class="table table-condensed table-striped">
4015 <td>-evaluate Sin <var>freq</var> </td>
4016 <td>-function Sinusoid <var>freq</var>,0 </td>
4019 <td>-evaluate Cos <var>freq</var> </td>
4020 <td>-function Sinusoid <var>freq</var>,90 </td>
4026 <p>The <code>ArcSin</code> function generates the inverse curve of a Sinusoid,
4027 and can be used to generate cylindrical distortion and displacement maps.
4028 The curve can be adjusted relative to both the input values and output range
4032 -function <code>ArcSin</code> <var>width</var>,[<var>center</var>,[<var>range</var>,[<var>bias</var>]]]
4035 <p>with all values given in terms of normalized color values (0.0 for black,
4036 1.0 for white). Defaulting to values covering the full range from 0.0 to 1.0
4037 for bout input (<var>width</var>), and output (<var>width</var>) values. '<code>1.0,0.5,1.0,0.5</code>' </p>
4040 <var>range</var>/π * asin( 2/<var>width</var> * ( <b><var>u</var></b> - <var>center</var> ) ) + <var>bias</var>
4046 <p>The <code>ArcTan</code> function generates a curve that smooth crosses from
4047 limit values at infinities, though a center using the given slope value.
4048 All these values can be adjusted via the arguments.</p>
4051 -function <code>ArcTan</code> <var>slope</var>,[<var>center</var>,[<var>range</var>,[<var>bias</var>]]]
4054 <p>Defaulting to '<code>1.0,0.5,1.0,0.5</code>'.
4058 <var>range</var>/π * atan( <var>slope</var>*π * ( <b><var>u</var></b> - <var>center</var> ) ) + <var>bias</var>
4066 <div style="margin: auto;">
4067 <h3 class="magick-header"><a id="fuzz"></a>-fuzz <var>distance</var>{<var>%</var>}</h3>
4070 <p class="magick-description">Colors within this <var>distance</var> are considered equal.</p>
4072 <p>A number of algorithms search for a target color. By default the color must
4073 be exact. Use this option to match colors that are close to the target color
4074 in RGB space. For example, if you want to automagically trim the edges of an
4075 image with <a href="command-line-options.html#trim">-trim</a> but the image was scanned and the target
4076 background color may differ by a small amount. This option can account for
4077 these differences.</p>
4079 <p>The <var>distance</var> can be in absolute intensity units or, by
4080 appending <code>%</code> as a percentage of the maximum possible intensity (255,
4081 65535, or 4294967295).</p>
4083 <p>Use <a href="command-line-options.html#fuzz">+fuzz</a> to reset the fuzz value to 0.</p>
4086 <div style="margin: auto;">
4087 <h3 class="magick-header"><a id="fx"></a>-fx <var>expression</var></h3>
4090 <p class="magick-description">apply a mathematical expression to an image or image channels.</p>
4092 <p>If the first character of <var>expression</var> is <code>@</code>,
4093 the expression is read from a file titled by the remaining characters in the
4096 <p>See <a href="fx.html">FX,
4097 The Special Effects Image Operator</a> for a detailed discussion of this
4101 <div style="margin: auto;">
4102 <h3 class="magick-header"><a id="gamma"></a>-gamma <var>value</var></h3>
4105 <p class="magick-description">level of gamma correction.</p>
4107 <p>The same color image displayed on two different workstations may look
4108 different due to differences in the display monitor. Use gamma correction to
4109 adjust for this color difference. Reasonable values extend from
4110 <code>0.8</code> to <code>2.3</code>. Gamma less than 1.0 darkens the image and
4111 gamma greater than 1.0 lightens it. Large adjustments to image gamma may
4112 result in the loss of some image information if the pixel quantum size is only
4113 eight bits (quantum range 0 to 255).</p>
4115 <p>Gamma adjusts the image's channel values pixel-by-pixel according to
4116 a power law, namely, pow(pixel,1/gamma) or pixel^(1/gamma), where pixel is the
4117 normalized or 0 to 1 color value. For example, using a value of gamma=2 is the
4118 same as taking the square root of the image.</p>
4120 <p>You can apply separate gamma values to the red, green, and blue channels of
4121 the image with a gamma value list delimited with commas (e.g.,
4122 <code>1.7,2.3,1.2</code>).</p>
4124 <p>Use <a href="command-line-options.html#gamma">+gamma <var>value</var></a> to set the
4125 image gamma level without actually adjusting the image pixels. This option
4126 is useful if the image is of a known gamma but not set as an image attribute
4127 (e.g. PNG images). Write the "file gamma" which is the reciprocal of the
4128 display gamma; e.g., if your image is sRGB and you want to write a PNG gAMA
4132 convert input.png +gamma .45455 output.png
4135 <p>(0.45455 is 1/2.2)</p>
4137 <p>Note that gamma adjustments are also available via the <a href="command-line-options.html#level">-level</a> operator.</p>
4139 <div style="margin: auto;">
4140 <h3 class="magick-header"><a id="gaussian-blur"></a>-gaussian-blur <var>radius</var><br>-gaussian-blur <var>radius</var>x<var>sigma</var></h3>
4143 <p class="magick-description">Blur the image with a Gaussian operator.</p>
4145 <p>Convolve the image with a Gaussian or normal distribution using the given
4146 <var>Sigma</var> value. The formula is:</p>
4148 <p class="text-center"><img class="img-thumbnail" alt="gaussian distribution" width="243px" height="42px" src="../images/gaussian-blur.png"> </p>
4150 <p>The <var>Sigma</var> value is the important argument, and
4151 determines the actual amount of blurring that will take place. </p>
4153 <p>The <var>Radius</var> is only used to determine the size of the
4154 array which will hold the calculated Gaussian distribution. It should be an
4155 integer. If not given, or set to zero, IM will calculate the largest possible
4156 radius that will provide meaningful results for the Gaussian distribution.
4159 <p>The larger the <var>Radius</var> the radius the slower the
4160 operation is. However too small a <var>Radius</var>, and sever
4161 aliasing effects may result. As a guideline, <var>Radius</var>
4162 should be at least twice the <var>Sigma</var> value, though three
4163 times will produce a more accurate result. </p>
4165 <p>This differs from the faster <a href="command-line-options.html#blur">-blur</a> operator in that a
4166 full 2-dimensional convolution is used to generate the weighted average of the
4167 neighboring pixels. </p>
4169 <p>The <a href="command-line-options.html#virtual-pixel">-virtual-pixel</a> setting will determine how
4170 pixels which are outside the image proper are blurred into the final result.
4174 <div style="margin: auto;">
4175 <h3 class="magick-header"><a id="geometry"></a>-geometry <var>geometry</var></h3>
4178 <p class="magick-description">Set the preferred size and location of the image.</p>
4180 <p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
4182 <div style="margin: auto;">
4183 <h3 class="magick-header"><a id="gravity"></a>-gravity <var>type</var></h3>
4186 <p class="magick-description">Sets the current gravity suggestion for various other settings and options.</p>
4188 <p>Choices include: <code>NorthWest</code>, <code>North</code>,
4189 <code>NorthEast</code>, <code>West</code>, <code>Center</code>, <code>East</code>,
4190 <code>SouthWest</code>, <code>South</code>, <code>SouthEast</code>. Use <a href="command-line-options.html#list">-list gravity</a> to get a complete list of <a href="command-line-options.html#gravity">-gravity</a> settings available in your ImageMagick
4193 <p>The direction you choose specifies where to position text or subimages. For
4194 example, a gravity of <code>Center</code> forces the text to be centered within
4195 the image. By default, the image gravity is <code>NorthWest</code>. See <a href="command-line-options.html#draw">-draw</a> for more details about graphic primitives. Only the
4196 text primitive of <a href="command-line-options.html#draw">-draw</a> is affected by the <a href="command-line-options.html#gravity">-gravity</a> option.</p>
4198 <p>The <a href="command-line-options.html#gravity">-gravity</a> option is also used in concert with the
4199 <a href="command-line-options.html#geometry">-geometry</a> setting and other settings or options that
4200 take <var>geometry</var> as an argument, such as the <a href="command-line-options.html#crop">-crop</a> option. </p>
4202 <p>If a <a href="command-line-options.html#gravity">-gravity</a> setting occurs before another option
4203 or setting having a <var>geometry</var> argument that specifies an
4204 offset, the offset is usually applied to the point within the image suggested
4205 by the <a href="command-line-options.html#gravity">-gravity</a> argument. Thus, in the following
4206 command, for example, suppose the file <code>image.png</code> has dimensions
4207 200x100. The offset specified by the argument to <a href="command-line-options.html#region">-region</a>
4208 is (−40,+20). The argument to <a href="command-line-options.html#gravity">-gravity</a> is
4209 <code>Center</code>, which suggests the midpoint of the image, at the point
4210 (100,50). The offset (−40,20) is applied to that point, giving
4211 (100−40,50+20)=(60,70), so the specified 10x10 region is located at
4212 that point. (In addition, the <a href="command-line-options.html#gravity">-gravity</a> affects the
4213 region itself, which is <var>centered</var> at the pixel
4214 coordinate (60,70). (See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.)</p>
4217 convert image.png -gravity Center -region 10x10-40+20 \
4221 <p>When used as an option to <a href="composite.html">composite</a>, <a href="command-line-options.html#gravity">-gravity</a> gives the direction that the image gravitates
4222 within the composite.</p>
4224 <p>When used as an option to <a href="montage.html">montage</a>, <a href="command-line-options.html#gravity">-gravity</a> gives the direction that an image gravitates
4225 within a tile. The default gravity is <code>Center</code> for this purpose.</p>
4228 <div style="margin: auto;">
4229 <h3 class="magick-header"><a id="grayscale"></a>-grayscale <var>method</var></h3>
4232 <p class="magick-description">convert image to grayscale.</p>
4234 <p>This will use one of the <a href="command-line-options.html#intensity">-intensity</a> methods to
4235 convert the given image into a linear-grayscale image. </p>
4237 <p>For example, to convert an image to (linear) Rec709Luminance grayscale, type:</p>
4240 convert in.png -grayscale Rec709Luminance out.png
4243 <p>which is equivalent to:</p>
4246 convert in.png -colorspace gray out.png
4249 <p>Similarly, to convert an image to (non-linear) Rec709Luma grayscale, type:</p>
4252 convert in.png -grayscale Rec709Luma out.png
4255 <p>which is equivalent to:</p>
4258 convert in.png -set colorspace RGB -colorspace gray out.png
4261 <p>Note that a 'colorspace' intensity method will produce the same result
4262 regardless of the current colorpsace of the image. But a 'mathematical'
4263 intensity method will depend on the current colorspace the image is currently
4266 <p>While this operation uses an <a href="command-line-options.html#intensity">-intensity</a> method,
4267 it does not use or set the <a href="command-line-options.html#intensity">-intensity</a> setting, so
4268 will not effect other operations that may use that setting.</p>
4271 <div style="margin: auto;">
4272 <h3 class="magick-header"><a id="green-primary"></a>-green-primary <var>x,y</var></h3>
4275 <p class="magick-description">green chromaticity primary point.</p>
4278 <div style="margin: auto;">
4279 <h3 class="magick-header"><a id="hald-clut"></a>-hald-clut</h3>
4282 <p class="magick-description">apply a Hald color lookup table to the image.</p>
4284 <p>A Hald color lookup table is a 3-dimensional color cube mapped to 2
4285 dimensions. Create it with the <code>HALD:</code> prefix (e.g. HALD:8). You
4286 can apply any color transformation to the Hald image and then use this option
4287 to apply the transform to the image. </p>
4290 convert image.png hald.png -hald-clut transform.png
4293 <p>This option provides a convenient method for you to use Gimp or Photoshop
4294 to make color corrections to the Hald CLUT image and subsequently apply them
4295 to multiple images using an ImageMagick script. </p>
4297 <p>Note that the representation is only of the normal RGB color space and that
4298 the whole color value triplet is used for the interpolated lookup of the
4299 represented Hald color cube image. Because of this the operation is not <a href="command-line-options.html#channel">-channel</a> setting effected, nor can it adjust or modify an
4300 images transparency or alpha/matte channel.</p>
4302 <p>See also <a href="command-line-options.html#clut">-clut</a> which provides color value replacement
4303 of the individual color channels, usually involving a simpler gray-scale
4304 image. E.g: gray-scale to color replacement, or modification by a histogram
4308 <div style="margin: auto;">
4309 <h3 class="magick-header"><a id="help"></a>-help</h3>
4312 <p class="magick-description">print usage instructions.</p>
4314 <div style="margin: auto;">
4315 <h3 class="magick-header"><a id="highlight-color"></a>-highlight-color <var>color</var></h3>
4318 <p class="magick-description">when comparing images, emphasize pixel differences with this color.</p>
4320 <div style="margin: auto;">
4321 <h3 class="magick-header"><a id="hough-lines"></a>-hough-lines <var>width</var>x<var>height</var>{<var>+threshold</var>}</h3>
4324 <p class="magick-description">identify straight lines in the image (e.g. -hough-lines 9x9+195).</p>
4326 <p>Use the Hough line detector with any binary edge extracted image to locate and draw any straight lines that it finds.</p>
4328 <p>The process accumulates counts for every white pixel in the binary edge image for every possible orientation (for angles from 0 to 179 in 1 deg increments) and distance from the center of the image to the corners (in 1 px increments). It stores the counts in an accumulator matrix of angle vs distance. The size of the accumulator will be 180x(diagonal/2). Next it searches the accumulator for peaks in counts and converts the locations of the peaks to slope and intercept in the normal x,y input image space. The algorithm uses slope/intercepts to find the endpoints clipped to the bounds of the image. The lines are drawn from the given endpoints. The counts are a measure of the length of the lines.</p>.
4330 <p>The WxH arguments specify the filter size for locating the peaks in the Hough accumulator. The threshold excludes lines whose counts are less than the threshold value.</p>
4332 <p>Use <code><a href="command-line-options.html#background">-background</a></code> to specify the color of the background onto which the lines will be drawn. The default is black.</p>
4334 <p>Use <code><a href="command-line-options.html#fill">-fill</a></code> to specify the color of the lines. The default is black.</p>
4336 <p>Use <code><a href="command-line-options.html#stroke">-stroke</a></code> and <code><a href="command-line-options.html#strokewidth">-strokewidth</a></code> to specify the thickness of the lines. The default is black and no strokewidth.</p>
4338 <p>A text file listing the endpoints and counts may be created by using the suffix, .mvg, for the output image.</p>
4340 <p>Use <code><a href="command-line-options.html#define">-define</a> hough-lines:accumulator=true</code> to return the accumulator image in addition to the lines image.</p>
4342 <div style="margin: auto;">
4343 <h3 class="magick-header"><a id="iconGeometry"></a>-iconGeometry <var>geometry</var></h3>
4346 <p class="magick-description">specify the icon geometry.</p>
4348 <p>Offsets, if present in the geometry specification, are handled in the same
4349 manner as the <a href="command-line-options.html#geometry">-geometry</a> option, using X11 style to
4350 handle negative offsets.</p>
4352 <p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
4354 <div style="margin: auto;">
4355 <h3 class="magick-header"><a id="iconic"></a>-iconic</h3>
4358 <p class="magick-description">start in icon mode in X Windows", 'animate', 'display</p>
4360 <div style="margin: auto;">
4361 <h3 class="magick-header"><a id="identify"></a>-identify</h3>
4364 <p class="magick-description">identify the format and characteristics of the image.</p>
4366 <p>This information is printed: image scene number; image name; image size;
4367 the image class (<var>DirectClass</var> or <var>PseudoClass</var>); the total number of unique colors; and the
4368 number of seconds to read and transform the image. Refer to <a href="miff.html">MIFF</a> for
4369 a description of the image class.</p>
4371 <p>If <a href="command-line-options.html#colors">-colors</a> is also specified, the total unique colors
4372 in the image and color reduction error values are printed. Refer to <a href="quantize.html">color
4373 reduction algorithm</a> for a description of these values.</p>
4375 <p>If <a href="command-line-options.html#verbose">-verbose</a> precedes this option, copious
4376 amounts of image properties are displayed including image statistics, profiles,
4377 image histogram, and others.</p>
4379 <div style="margin: auto;">
4380 <h3 class="magick-header"><a id="ift"></a>-ift</h3>
4383 <p class="magick-description">implements the inverse discrete Fourier transform (DFT).</p>
4385 <p>This option is new as of ImageMagick 6.5.4-3 (and now working for Windows
4386 users in ImageMagick 6.6.0-9). It transforms a pair of magnitude and phase
4387 images from the frequency domain to a single image in the normal or spatial
4388 domain. See for example, <a href="http://en.wikipedia.org/wiki/Fourier_transform">Fourier Transform</a>,
4389 <a href="http://en.wikipedia.org/wiki/DFT">Discrete Fourier Transform</a> and
4390 <a href="http://en.wikipedia.org/wiki/FFT">Fast Fourier Transform</a>.</p>
4392 <p>For example, depending upon the image format used to store the result of
4393 the <a href="command-line-options.html#fft">-fft</a>, one would use either</p>
4396 convert fft_image.miff -ift fft_image_ift.png
4402 convert fft_image-0.png fft_image-1.png -ift fft_image_ift.png
4405 <p>The resulting image may need to be cropped due to padding introduced when
4406 the original image, prior to the <a href="command-line-options.html#fft">-fft</a> or <a href="command-line-options.html#fft">+fft</a>, was not square or even dimensioned. Any padding is at
4407 the right and/or bottom sides of the image.</p>
4409 <p>The <a href="http://www.fftw.org/">FFTW</a> delegate library is required to
4410 use <a href="command-line-options.html#ift">-ift</a>.</p>
4412 <p>Use <a href="command-line-options.html#ift">+ift</a> (with HDRI enabled) to transform a pair of real
4413 and imaginary images from the frequency domain to a single image in the normal
4414 (spatial) domain.</p>
4416 <p>By default the IFT is not normalized (and the FFT is). Use "<code><a href="command-line-options.html#define">-define</a> fourier:normalize=inverse</code> to explictly normalize the IFT and unnormalize the FFT.</p>
4418 <div style="margin: auto;">
4419 <h3 class="magick-header"><a id="immutable"></a>-immutable</h3>
4422 <p class="magick-description">make image immutable.</p>
4424 <div style="margin: auto;">
4425 <h3 class="magick-header"><a id="implode"></a>-implode <var>factor</var></h3>
4428 <p class="magick-description">implode image pixels about the center.</p>
4430 <div style="margin: auto;">
4431 <h3 class="magick-header"><a id="insert"></a>-insert <var>index</var></h3>
4434 <p class="magick-description">insert the last image into the image sequence.</p>
4436 <p>This option takes last image in the current image sequence and inserts it
4437 at the given index. If a negative index is used, the insert position is
4438 calculated before the last image is removed from the sequence. As such
4439 <code>-insert -1</code> will result in no change to the image sequence.</p>
4441 <p>The <code>+insert</code> option is equivalent to <code>-insert -1</code>. In
4442 other words, insert the last image, at the end of the current image sequence.
4443 Consequently this has no effect on the image sequence order.</p>
4445 <div style="margin: auto;">
4446 <h3 class="magick-header"><a id="intensity"></a>-intensity <var>method</var></h3>
4449 <p class="magick-description">method to generate intensity value from pixel.</p>
4451 <p>ImageMagick provides a number of methods used in situations where an
4452 operatory needs to determine a single grayscale value for some purpose, from
4453 an image with red, green, and blue pixel components. Typically the linear
4454 <code>Rec709Luminance</code> formula is used, which is the same formula used when
4455 converting images to <code>-colorspace gray</code>. </p>
4457 <p>The following formulas are currently provided, and will first convert
4458 the pixel values to linear-RGB or non-linear sRGB colorspace before
4459 being applied to calulate the final greyscale value. </p>
4461 <dl class="dl-horizontal">
4462 <dt>Rec601Luma</dt><dd> 0.298839R' + 0.586811G'+ 0.114350B'</dd>
4463 <dt>Rec601Luminance</dt><dd> 0.298839R + 0.586811G + 0.114350B</dd>
4464 <dt>Rec709Luma</dt><dd> 0.212656R' + 0.715158G' + 0.072186B'</dd>
4465 <dt>Rec709Luminance</dt><dd> 0.212656R + 0.715158G + 0.072186B</dd>
4466 <dt>Brightness</dt><dd> max(R', G', B')</dd>
4467 <dt>Lightness</dt><dd> (min(R', G', B') + max(R', G', B')) / 2.0</dd>
4470 <p>Note that the above R,G,B values is the image's linear-RGB values, while
4471 R',G',B' are sRGB non-linear values. </p>
4473 <p>These intensity methods are mathematical in nature and will use the
4474 current value in the images respective R,G,B channel regardless of
4475 what that is, or what colorspace the image is currently using.</p>
4477 <dl class="dl-horizontal">
4478 <dt>Average</dt><dd>(R + G + B) / 3.0</dd>
4479 <dt>MS</dt><dd>(R^2 + G^2 + B^2) / 3.0</dd>
4480 <dt>RMS</dt><dd>sqrt( (R^2 + G^2 + B^2) / 3.0 )</dd>
4483 <p>These methods are often used for other purposes, such as generating a
4484 grayscale difference image between two color images (using <a href="command-line-options.html#compose">-compose</a> '<code>Difference</code>' composition. </p>
4486 <p> For example The 'MS' (Mean Squared) setting is good for minimizing color
4487 error comparisions. While... The method 'RMS' (Root Mean Squared) for
4488 example is appropriate for calculating color vector distance, from a color
4489 difference image. This is equivalent to the color only component of the <a href="command-line-options.html#fuzz">-fuzz</a> factor color compare setting. </p>
4491 <p>See also <a href="command-line-options.html#grayscale">-grayscale</a> which applies one of the above
4492 grayscaling formula directly to an image without setting the <a href="command-line-options.html#intensity">-intensity</a> setting.</p>
4494 <p>The <a href="command-line-options.html#colorspace">-colorspace gray</a> image conversion also uses
4495 the current intensity setting, but will always convert the image to the
4496 appropriate sRGB or linear-RGB colorspace before appling the above
4499 <p>To print a complete list of posible pixel intensity setting methods, use <a href="command-line-options.html#list">-list intensity</a>.</p>
4501 <p>Operators affected by the <a href="command-line-options.html#intensity">-intensity</a> setting include:</p>
4507 -clut (when mapping greyscale CLUT image to alpha channel if set by -channels)
4508 -colors for gray colorspace
4509 -compose {LightenIntensity, DarkenIntensity, CopyOpacity, CopyBlack}
4511 -distort {ErodeIntensity, DilateIntensity}
4521 <div style="margin: auto;">
4522 <h3 class="magick-header"><a id="intent"></a>-intent <var>type</var></h3>
4525 <p class="magick-description">use this type of rendering intent when managing the image color.</p>
4527 <p>Use this option to affect the color management operation of an image (see
4528 <a href="command-line-options.html#profile">-profile</a>). Choose from these intents: <code>Absolute,
4529 Perceptual, Relative, Saturation</code>.</p>
4531 <p>The default intent is Perceptual for the sRGB colorspace and undefined for the RGB and gray colorspaces.</p>
4533 <p>To print a complete list of rendering intents, use <a href="command-line-options.html#list">-list intent</a>.</p>
4535 <div style="margin: auto;">
4536 <h3 class="magick-header"><a id="interlace"></a>-interlace <var>type</var></h3>
4539 <p class="magick-description">the type of interlacing scheme.</p>
4553 <p>This option is used to specify the type of interlacing scheme for raw image
4554 formats such as <code>RGB</code> or <code>YUV</code>.</p>
4556 <p><code>None</code> means do not interlace (RGBRGBRGBRGBRGBRGB...),</p>
4558 <p><code>Line</code> uses scanline interlacing (RRR...GGG...BBB...RRR...GGG...BBB...), and.</p>
4560 <p><code>Plane</code> uses plane interlacing (RRRRRR...GGGGGG...BBBBBB...).</p>
4562 <p><code>Partition</code> is like plane except the different planes are saved to
4563 individual files (e.g. image.R, image.G, and image.B).</p>
4565 <p>Use <code>Line</code> or <code>Plane</code> to create an <code>interlaced
4566 PNG</code> or <code>GIF</code> or <code>progressive JPEG</code> image.</p>
4568 <p>To print a complete list of interlacing schemes, use <a href="command-line-options.html#list">-list
4571 <div style="margin: auto;">
4572 <h3 class="magick-header"><a id="interpolate"></a>-interpolate <var>type</var></h3>
4575 <p class="magick-description">Set the pixel color interpolation method to use when looking up a color based on a floating point or real value.</p>
4577 <p>When looking up the color of a pixel using a non-integer floating point
4578 value, you typically fall in between the pixel colors defined by the source
4579 image. This setting determines how the color is determined from the colors of
4580 the pixels surrounding that point. That is how to determine the color of a
4581 point that falls between two, or even four different colored pixels. </p>
4583 <dl class="dl-horizontal">
4585 <dd>The color of the top-left pixel (floor function)</dd>
4586 <dt>nearest-neighbor</dt>
4587 <dd>The nearest pixel to the lookup point (rounded function)</dd>
4589 <dd>The average color of the surrounding four pixels</dd>
4591 <dd>A double linear interpolation of pixels (the default)</dd>
4593 <dd>Divide area into two flat triangular interpolations</dd>
4595 <dd>Fitted bicubic-spines of surrounding 16 pixels</dd>
4597 <dd>Direct spline curves (colors are blurred)</dd>
4599 <dd>Use resize <a href="command-line-options.html#filter">-filter</a> settings</dd>
4602 <p>This most important for distortion operators such as <a href="command-line-options.html#distort">-distort</a>, <a href="command-line-options.html#implode">-implode</a>, <a href="command-line-options.html#transform">-transform</a> and <a href="command-line-options.html#fx">-fx</a>. </p>
4604 <p>To print a complete list of interpolation methods, use <a href="command-line-options.html#list">-list interpolate</a>.</p>
4606 <p>See also <a href="command-line-options.html#virtual-pixel">-virtual-pixel</a>, for control of the
4607 lookup for positions outside the boundaries of the image. </p>
4610 <div style="margin: auto;">
4611 <h3 class="magick-header"><a id="interline-spacing"></a>-interline-spacing <var>value</var></h3>
4614 <p class="magick-description">the space between two text lines.</p>
4616 <div style="margin: auto;">
4617 <h3 class="magick-header"><a id="interword-spacing"></a>-interword-spacing <var>value</var></h3>
4620 <p class="magick-description">the space between two words.</p>
4622 <div style="margin: auto;">
4623 <h3 class="magick-header"><a id="kerning"></a>-kerning <var>value</var></h3>
4626 <p class="magick-description">the space between two letters.</p>
4628 <div style="margin: auto;">
4629 <h3 class="magick-header"><a id="kuwahara"></a>-kuwahara <var>radius</var><br>-kuwahara <var>radius</var>x<var>sigma</var></h3>
4632 <p class="magick-description">edge preserving noise reduction filter.</p>
4634 <p>The <var>radius</var> is more important than the <var>sigma</var>. If <var>sigma</var> is left off, it will be computed automatically from the <var>radius</var> as <var>sigma</var>=<var>radius</var>-0.5. The <var>sigma</var> provides a bit of additional smoothing control.</p>
4637 <div style="margin: auto;">
4638 <h3 class="magick-header"><a id="label"></a>-label <var>name</var></h3>
4641 <p class="magick-description">assign a label to an image.</p>
4643 <p>Use this option to assign a specific label to the image, as it is read in
4644 or created. You can use the <a href="command-line-options.html#set">-set</a> operation to re-assign
4645 a the labels of images already read in. Image formats such as TIFF, PNG,
4646 MIFF, supports saving the label information with the image.</p>
4648 <p>When saving an image to a <var>PostScript</var> file, any label
4649 assigned to an image is used as a header string to print above the postscript
4652 <p>You can include the image filename, type, width, height, or other image
4653 attribute by embedding special format character. See <a href="escape.html">Format and Print Image
4654 Properties</a> for details of the percent escape codes.</p>
4659 -label "%m:%f %wx%h" bird.miff
4662 <p>assigns an image label of <code>MIFF:bird.miff 512x480</code> to the
4663 "<code>bird.miff</code>" image and whose width is 512 and height is 480, as it
4664 is read in. If a <a href="command-line-options.html#label">+label</a> option was used instead, any
4665 existing label present in the image would be used. You can remove all labels
4666 from an image by assigning the empty string. </p>
4668 <p>A label is not drawn on the image, but is embedded in the image datastream
4669 via <var>Label</var> tag or similar mechanism. If you want the label to be
4670 visible on the image itself, use the <a href="command-line-options.html#draw">-draw</a> option, or
4671 during the final processing in the creation of an image montage.</p>
4673 <p>If the first character of <var>string</var> is <var>@</var>, the image label is read from a file titled by the
4674 remaining characters in the string. Labels in a file are literal, no embedded
4675 formatting characters are recognized.</p>
4678 <div style="margin: auto;">
4679 <h3 class="magick-header"><a id="lat"></a>-lat <var>width</var><br>-lat <var>width</var>x<var>height</var>{<var>+-</var>}<var>offset</var>{<var>%</var>}</h3>
4682 <p class="magick-description">perform local adaptive threshold.</p>
4684 <p>Adaptively threshold each pixel based on the value of pixels in a
4685 surrounding window. If the current pixel is lighter than this average plus
4686 the optional <code>offset</code>, then it is made white, otherwise it is made
4687 black. Small variations in pixel values such as found in scanned documents
4688 can be ignored if offset is positive. A negative offset will make it more
4689 sensitive to those small variations. </p>
4691 <p>This is commonly used to threshold images with an uneven background. It is
4692 based on the assumption that average color of the small window is the
4693 the local background color, from which to separate the foreground color. </p>
4696 <div style="margin: auto;">
4697 <h3 class="magick-header"><a id="layers"></a>-layers <var>method</var></h3>
4700 <p class="magick-description">handle multiple images forming a set of image layers or animation frames.</p>
4702 <p>Perform various image operation methods to a ordered sequence of images
4703 which may represent either a set of overlaid 'image layers', a GIF disposal
4704 animation, or a fully-'coalesced' animation sequence. </p>
4706 <table class="table table-condensed table-striped">
4709 <th style="width: 8%">Method</th>
4710 <th>Description</th>
4714 <td>compare-any</td>
4715 <td>Crop the second and later frames to the smallest rectangle
4716 that contains all the differences between the two images. No GIF <a href="command-line-options.html#dispose">-dispose</a> methods are taken into account. </td>
4719 <tr><td></td><td>This exactly the same as the <a href="command-line-options.html#deconstruct">-deconstruct</a> operator, and does not preserve animations normal
4720 working, especially when animation used layer disposal methods such as
4721 '<code>Previous</code>' or '<code>Background</code>'. </td>
4725 <td>compare-clear</td>
4726 <td>As '<code>compare-any</code>' but crop to the bounds of any
4727 opaque pixels which become transparent in the second frame. That is the
4728 smallest image needed to mask or erase pixels for the next frame. </td>
4732 <td>compare-overlay</td>
4733 <td>As '<code>compare-any</code>' but crop to pixels that add
4734 extra color to the next image, as a result of overlaying color pixels.
4735 That is the smallest single overlaid image to add or change colors. </td>
4738 <tr><td></td><td>This can be used with the <a href="command-line-options.html#compose">-compose</a> alpha
4739 composition method '<code>change-mask</code>', to reduce the image to
4740 just the pixels that need to be overlaid. </td>
4745 <td>Equivalent to a call to the <a href="command-line-options.html#coalesce">-coalesce</a> operator. Apply the layer disposal methods set in the
4746 current image sequence to form a fully defined animation sequence, as
4747 it should be displayed. Effectively converting a GIF animation into a
4748 'film strip'-like animation. </td>
4753 <td>Alpha Composition of two image lists, separated by a
4754 "<code>null:</code>" image, with the destination image list first, and
4755 the source images last. An image from each list are composited
4756 together until one list is finished. The separator image and source
4757 image lists are removed. </td>
4762 <td>The <a href="command-line-options.html#geometry">-geometry</a> offset is adjusted according
4763 to <a href="command-line-options.html#gravity">-gravity</a> in accordance of the virtual
4764 canvas size of the first image in each list. Unlike a normal <a href="command-line-options.html#composite">-composite</a> operation, the canvas offset is also
4765 added to the final composite positioning of each image. </td> </tr>
4768 <td>If one of the image lists only contains one image, that image is
4769 applied to all the images in the other image list, regardless of which
4770 list it is. In this case it is the image meta-data of the list which
4777 <td>This like '<code>coalesce</code>' but shows the look of
4778 the animation after the layer disposal method has been applied, before
4779 the next sub-frame image is overlaid. That is the 'dispose' image that
4780 results from the application of the GIF <a href="command-line-options.html#dispose">-dispose</a> method. This allows you to check what
4781 is going wrong with a particular animation you may be developing.
4787 <td>Create a canvas the size of the first images virtual
4788 canvas using the current <a href="command-line-options.html#background">-background</a> color,
4789 and <a href="command-line-options.html#compose">-compose</a> each image in turn onto that
4790 canvas. Images falling outside that canvas is clipped. Final
4791 image will have a zero virtual canvas offset. </td>
4795 <td>This usually used as one of the final 'image layering' operations
4796 overlaying all the prepared image layers into a final image. </td>
4800 <td>For a single image this method can also be used to fillout a virtual
4801 canvas with real pixels, or to underlay an opaque color to remove
4802 transparency from an image.</td>
4808 <td>As 'flatten' method but merging all the given image
4809 layers to create a new layer image just large enough to hold all the
4810 image without clipping or extra space. The new images virtual offset
4811 will preserve the position of the new layer, even if this offset is
4812 negative. The virtual canvas size of the first image is preserved.
4816 <tr><td></td><td>Caution is advised when handling image layers with
4817 negative offsets as few image file formats handle them correctly.
4818 Following this operation method with <a href="command-line-options.html#repage">+repage</a>
4819 will remove the layer offset, and create an image in which all the
4820 overlaid image positions relative to each other is preserved, though
4821 not necessarily exactly where you specified them.
4825 <tr><td></td><td>See also 'trim-bounds' below which is closely related but
4826 without doing the'flatten' to merge the images together. </td>
4831 <td>As 'flatten' method but expanding the initial canvas size
4832 of the first image in a positive direction only so as to hold all the
4833 image layers. However as a virtual canvas is 'locked' to the origin,
4834 by its own definition, image layers with a negative offsets will still
4835 become clipped by the top and left edges. See 'merge' or 'trim-bounds'
4836 if this could be a problem. </td>
4840 <tr><td></td><td>This method is commonly used to layout individual image
4841 using various offset but without knowing the final canvas size. The
4842 resulting image will, like 'flatten' not have any virtual offset, so
4843 can be saved to any image file format. </td>
4849 <td>Optimize a coalesced animation, into GIF animation using
4850 a number of general techniques. This currently a short cut to
4851 apply both the '<code>optimize-frame</code>', and
4852 '<code>optimize-transparency</code>' methods but may be expanded to
4853 include other optimization methods as they are developed. </td>
4857 <td>optimize-frame</td>
4858 <td>Optimize a coalesced animation, into GIF animation by
4859 reducing the number of pixels per frame as much as possible by
4860 attempting to pick the best layer disposal method to use, while ensuring
4861 the result will continue to animate properly. </td>
4864 <tr><td></td><td> There is no guarantee that the best optimization is found.
4865 But then no reasonably fast GIF optimization algorithm can do this.
4866 However this does seem to do better than most other GIF frame
4867 optimizers seen. </td>
4871 <td>optimize-plus</td>
4872 <td>As '<code>optimize-frame</code>' but attempt to improve the
4873 overall optimization by adding extra frames to the animation, without
4874 changing the final look or timing of the animation. The frames are
4875 added to attempt to separate the clearing of pixels from the
4876 overlaying of new additional pixels from one animation frame to the
4877 next. If this does not improve the optimization (for the next frame
4878 only), it will fall back to the results of the previous normal
4879 '<code>optimize-frame</code>' technique. </td>
4882 <tr><td></td><td>There is the possibility that the change in the disposal
4883 style will result in a worsening in the optimization of later frames,
4884 though this is unlikely. In other words there no guarantee that it is
4885 better than the normal '<code>optimize-frame</code>' technique. For some
4886 animations however you can get a vast improvement in the final
4887 animation size. </td>
4891 <td>optimize-transparency</td>
4892 <td>Given a GIF animation, replace any pixel in the sub-frame
4893 overlay images with transparency, if it does not change the resulting
4894 animation by more than the current <a href="command-line-options.html#fuzz">-fuzz</a> factor.
4898 <tr><td></td><td>This should allow a existing frame optimized GIF animation
4899 to compress into a smaller file size due to larger areas of one
4900 (transparent) color rather than a pattern of multiple colors repeating
4901 the current disposed image of the last frame. </td>
4905 <td>remove-dups</td>
4906 <td>Remove (and merge time delays) of duplicate consecutive
4907 images, so as to simplify layer overlays of coalesced animations.
4911 <tr><td></td><td>Usually this a result of using a constant time delay
4912 across the whole animation, or after a larger animation was split into
4913 smaller sub-animations. The duplicate frames could also have been
4914 used as part of some frame optimization methods. </td>
4918 <td>remove-zero</td>
4919 <td>Remove any image with a zero time delay, unless ALL the
4920 images have a zero time delay (and is not a proper timed animation, a
4921 warning is then issued). </td>
4924 <tr><td></td><td>In a GIF animation, such images are usually frames which
4925 provide partial intermediary updates between the frames that are
4926 actually displayed to users. These frames are usually added for
4927 improved frame optimization in GIF animations. </td>
4931 <td>trim-bounds</td>
4932 <td>Find the bounds of all the images in the current
4933 image sequence, then adjust the offsets so all images are contained on
4934 a minimal positive canvas. None of the image data is modified or
4935 merged, only the individual image virtual canvas size and offset.
4936 All the images is given the same canvas size, and and will have
4937 a positive offset, but will remain in the same position relative to
4938 each other. As a result of the minimal canvas size at least one image
4939 will touch every edge of that canvas. The image data touching those
4940 edges however may be transparent. </td>
4943 <tr><td></td><td>The result is much like if you used 'merge' followed by a
4944 <a href="command-line-options.html#repage">+repage</a> option, except that all the images
4945 have been kept separate. If 'flatten' is used after using
4946 'trim-bounds' you will get the same result. </td>
4952 <p>To print a complete list of layer types, use <a href="command-line-options.html#list">-list layers</a>.</p>
4954 <p>The operators <a href="command-line-options.html#coalesce">-coalesce</a>, <a href="command-line-options.html#deconstruct">-deconstruct</a>, <a href="command-line-options.html#flatten">-flatten</a>, and <a href="command-line-options.html#mosaic">-mosaic</a> are only aliases for the above methods and may be depreciated in
4955 the future. Also see <a href="command-line-options.html#page">-page</a>, <a href="command-line-options.html#repage">-repage</a> operators, the <a href="command-line-options.html#compose">-compose</a> setting, and the
4956 GIF <a href="command-line-options.html#dispose">-dispose</a> and <a href="command-line-options.html#delay">-delay</a>
4960 <div style="margin: auto;">
4961 <h3 class="magick-header"><a id="level"></a>-level <var>black_point</var>{,<var>white_point</var>}{<var>%</var>}{,<var>gamma</var>}</h3>
4964 <p class="magick-description">adjust the level of image channels.</p>
4966 <p>Given one, two or three values delimited with commas: black-point,
4967 white-point, gamma (for example: 10,250,1.0 or 2%,98%,0.5). The black and
4968 white points range from 0 to <var>QuantumRange</var>, or from 0 to
4969 100%; if the white point is omitted it is set to (<var>QuantumRange</var> - black_point), so as to center contrast changes.
4970 If a <code>%</code> sign is present anywhere in the string, both black and white
4971 points are percentages of the full color range. Gamma will do a <a href="command-line-options.html#gamma">-gamma</a> adjustment of the values. If it is omitted, the
4972 default of 1.0 (no gamma correction) is assumed.</p>
4974 <p>In normal usage (<code>-level</code>) the image values are stretched so that
4975 the given '<code>black_point</code>' value in the original image is set to zero
4976 (or black), while the given '<code>white_point</code>' value is set to <var>QuantumRange</var> (or white). This provides you with direct
4977 contrast adjustments to the image. The '<code>gamma</code>' of the resulting
4978 image will then be adjusted. </p>
4980 <p>From ImageMagick v6.4.1-9 using the plus form of the operator
4981 (<code>+level</code>) or adding the special '!' flag anywhere in the argument
4982 list, will cause the operator to do the reverse of the level adjustment. That
4983 is a zero, or <var>QuantumRange</var> value (black, and white, resp.)
4984 in the original image, is adjusted to the given level values, allowing you to
4985 de-contrast, or compress the channel values within the image. The
4986 '<code>gamma</code>' is adjusted before the level adjustment to de-contrast the
4989 <p>Only the channels defined by the current <a href="command-line-options.html#channel">-channel</a>
4990 setting are adjusted (defaults to RGB color channels only), allowing you to
4991 limit the effect of this operator. </p>
4993 <p>Please note that the transparency channel is treated as 'matte'
4994 values (0 is opaque) and not as 'alpha' values (0 is transparent).</p>
4997 <div style="margin: auto;">
4998 <h3 class="magick-header"><a id="level-colors"></a>-level-colors {<var>black_color</var>}{,}{<var>white_color</var>}</h3>
5001 <p class="magick-description">adjust the level of an image using the provided dash separated colors.</p>
5003 <p>This function is exactly like <a href="command-line-options.html#level">-level</a>, except that the
5004 value value for each color channel is determined by the
5005 '<code>black_color</code>' and '<code>white_color</code>' colors given (as
5006 described under the <a href="command-line-options.html#fill">-fill</a> option). </p>
5008 <p>This effectually means the colors provided to <code>-level-colors</code>
5009 is mapped to become 'black' and 'white' respectively, with all the other
5010 colors linearly adjusted (or clipped) to match that change. Each channel is
5011 adjusted separately using the channel values of the colors specified. </p>
5013 <p>On the other hand the plus form of the operator (<code>+level-colors</code>)
5014 will map the image color 'black' and 'white' to the given colors
5015 respectively, resulting in a gradient (de-contrasting) tint of the image to
5016 those colors. This can also be used to convert a plain gray-scale image into a
5017 one using the gradient of colors specified. </p>
5019 <p>By supplying a single color with a comma separator either before or after
5020 that color, will just replace the respective 'black' or 'white' point
5021 respectively. But if no comma separator is provided, the given color is
5022 used for both the black and white color points, making the operator either
5023 threshold the images around that color (- form) or set all colors to that
5024 color (+ form). </p>
5027 <div style="margin: auto;">
5028 <h3 class="magick-header"><a id="limit"></a>-limit <var>type value</var></h3>
5031 <p class="magick-description">Set the pixel cache resource limit.</p>
5033 <p>Choose from: <code>area</code>, <code>disk</code>, <code>file</code>,
5034 <code>map</code>, <code>memory</code>, <code>thread</code>, or <code>time</code>.</p>
5036 <p>The value for <code>file</code> is in number of files. The other limits are
5037 in bytes. Define arguments for the memory, map, area, and disk resource limits
5038 with SI prefixes (.e.g 100MB).</p>
5040 <p>By default the limits are 768 files, 3GB of image area, 1.5GiB memory, 3GiB
5041 memory map, and 18.45EB of disk. These limits are adjusted relative to the
5042 available resources on your computer if this information is available. When
5043 any limit is reached, ImageMagick fails in some fashion but attempts to take
5044 compensating actions, if possible. For example, the following limits
5048 -limit memory 32MiB -limit map 64MiB
5051 <p>Use <a href="command-line-options.html#list">-list resource</a> to list the current limits. For example, our system shows these limits:</p>
5054 -> identify -list resource
5068 <p>Requests for pixel storage to keep intermediate images are satisfied by one
5069 of three resource categories: in-memory pool, memory-mapped files pool, and
5070 disk pool (in that order) depending on the <a href="command-line-options.html#limit">‑limit</a> settings
5071 and whether the system honors a resource request. If the total size of
5072 allocated pixel storage in the given pool reaches the corresponding limit, the
5073 request is passed to the next pool. Additionally, requests that exceed the
5074 <code>area</code> limit automagically are allocated on disk.</p>
5076 <p>To illustrate how ImageMagick utilizes resource limits, consider a typical
5077 image resource request. First, ImageMagick tries to allocate the pixels in
5078 memory. The request might be denied if the resource request exceeds the
5079 <code>memory</code> limit or if the system does not honor the request. If
5080 a memory request is not honored, the pixels are allocated to disk and the file
5081 is memory-mapped. However, if the allocation request exceeds the
5082 <code>map</code> limit, the resource allocation goes to disk. In all cases, if
5083 the resource request exceeds the <code>area</code> limit, the pixels are
5084 automagically cached to disk. If the disk has a hard limit, the program
5087 <p>In most cases you simply do not need to concern yourself with resource
5088 limits. ImageMagick chooses reasonable defaults and most images do not tax
5089 your computer resources. Where limits do come in handy is when you process
5090 images that are large or on shared systems where ImageMagick can consume all
5091 or most of the available memory. In this case, the ImageMagick workflow slows
5092 other processes or, in extreme cases, brings the system to a halt. Under
5093 these circumstances, setting limits give some assurances that the ImageMagick
5094 workflow will not interfere with other concurrent uses of the computer. For
5095 example, assume you have a web interface that processes images uploaded from
5096 the Internet. To assure ImageMagick does not exceed 10MiB of memory you can
5097 simply set the area limit to 10MiB:</p>
5103 <p>Now whenever a large image is processed, the pixels are automagically
5104 cached to disk instead of memory. This of course implies that large images
5105 typically process very slowly, simply because pixel processing in memory can
5106 be an order of magnitude faster than on disk. Because your web site users
5107 might inadvertently upload a huge image to process, you should set a disk
5111 -limit area 10MB -limit disk 500MB
5114 <p>Here ImageMagick stops processing if an image requires more than 500MB of disk storage.</p>
5116 <p>In addition to command-line resource limit option, resources can be set
5117 with <a href="resources.html#environment">environment variables</a>. Set the
5118 environment variables <code>MAGICK_AREA_LIMIT</code>,
5119 <code>MAGICK_DISK_LIMIT</code>, <code>MAGICK_FILE_LIMIT</code>,
5120 <code>MAGICK_MEMORY_LIMIT</code>, <code>MAGICK_MAP_LIMIT</code>,
5121 <code>MAGICK_THREAD_LIMIT</code>, <code>MAGICK_TIME_LIMIT</code> for limits of
5122 image area, disk space, open files, heap memory, memory map, number of threads
5123 of execution, and maximum elapsed time in seconds respectively.</p>
5125 <p> Inquisitive users can try adding <a href="command-line-options.html#debug">-debug cache</a> to
5126 their commands and then scouring the generated output for references to the
5127 pixel cache, in order to determine how the pixel cache was allocated and how
5128 resources were consumed. Advanced Unix/Linux users can pipe that output
5129 through <code>grep memory|open|destroy|disk</code> for more readable sifting.
5132 <p>For more about ImageMagick's use of resources, see the section <b>Cache
5133 Storage and Resource Requirements</b> on the <a href="architecture.html#cache%0A">Architecture</a> page. </p>
5135 <div style="margin: auto;">
5136 <h3 class="magick-header"><a id="linear-stretch"></a>-linear-stretch <var>black-point</var><br>-linear-stretch <var>black-point</var>{x<var>white-point</var>}{<var>%</var>}}</h3>
5139 <p class="magick-description">Linear with saturation stretch.</p>
5141 <p>This is very similar to <a href="command-line-options.html#contrast-stretch">-contrast-stretch</a>,
5142 and uses a 'histogram bin' to determine the range of color values that needs to
5143 be stretched. However it then stretches those colors using the <a href="command-line-options.html#level">-level</a> operator.</p>
5145 <p>As such while the initial determination may have 'binning' round off
5146 effects, the image colors are stretched mathematically, rather than using the
5147 histogram bins. This makes the operator more accurate. </p>
5149 <p>note however that a <a href="command-line-options.html#linear-stretch">-linear-stretch</a> of
5150 '<code>0</code>' does nothing, while a value of '<code>1</code>' does a near
5151 perfect stretch of the color range. </p>
5153 <p>See also <a href="command-line-options.html#auto-level">-auto-level</a> for a 'perfect'
5154 normalization of mathematical images. </p>
5156 <p>This operator is under review for re-development. </p>
5159 <div style="margin: auto;">
5160 <h3 class="magick-header"><a id="linewidth"></a>-linewidth</h3>
5163 <p class="magick-description">the line width for subsequent draw operations.</p>
5165 <div style="margin: auto;">
5166 <h3 class="magick-header"><a id="liquid-rescale"></a>-liquid-rescale <var>geometry</var></h3>
5169 <p class="magick-description">rescale image with seam-carving.</p>
5171 <p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
5173 <div style="margin: auto;">
5174 <h3 class="magick-header"><a id="list"></a>-list <var>type</var></h3>
5177 <p class="magick-description">Print a list of supported arguments for various options or settings. Choose from these list types:</p>
5179 <pre class="pre-scrollable">
5252 <p>These lists vary depending on your version of ImageMagick. Use "<code>-list
5253 list</code>" to get a complete listing of all the "<code>-list</code>" arguments
5260 <div style="margin: auto;">
5261 <h3 class="magick-header"><a id="log"></a>-log <var>string</var></h3>
5264 <p class="magick-description">Specify format for debug log.</p>
5266 <p>This option specifies the format for the log printed when the <a href="command-line-options.html#debug">-debug</a> option is active.</p>
5268 <p>You can display the following components by embedding special format
5271 <dl class="dl-horizontal">
5272 <dt>%d</dt><dd>domain</dd>
5273 <dt>%e</dt><dd>event</dd>
5274 <dt>%f</dt><dd>function</dd>
5275 <dt>%l</dt><dd>line</dd>
5276 <dt>%m</dt><dd>module</dd>
5277 <dt>%p</dt><dd>process ID</dd>
5278 <dt>%r</dt><dd>real CPU time</dd>
5279 <dt>%t</dt><dd>wall clock time</dd>
5280 <dt>%u</dt><dd>user CPU time</dd>
5281 <dt>%%</dt><dd>percent sign</dd>
5282 <dt>\n</dt><dd>newline</dd>
5283 <dt>\r</dt><dd>carriage return</dd>
5289 convert -debug coders -log "%u %m:%l %e" in.gif out.png
5292 <p>The default behavior is to print all of the components.</p>
5294 <div style="margin: auto;">
5295 <h3 class="magick-header"><a id="loop"></a>-loop <var>iterations</var></h3>
5298 <p class="magick-description">add Netscape loop extension to your GIF animation.</p>
5300 <p>Set iterations to zero to repeat the animation an infinite number of times,
5301 otherwise the animation repeats itself up to <var>iterations</var>
5304 <div style="margin: auto;">
5305 <h3 class="magick-header"><a id="lowlight-color"></a>-lowlight-color <var>color</var></h3>
5308 <p class="magick-description">when comparing images, de-emphasize pixel differences with this color.</p>
5310 <div style="margin: auto;">
5311 <h3 class="magick-header"><a id="magnify"></a>-magnify</h3>
5314 <p class="magick-description">double the size of the image with pixel art scaling.</p>
5317 <div style="margin: auto;">
5318 <h3 class="magick-header"><a id="map"></a>-map <var>type</var></h3>
5321 <p class="magick-description">Display image using this <var>type</var>.</p>
5323 <p>Choose from these <var>Standard Colormap</var> types:</p>
5334 <p>The <var>X server</var> must support the <var>Standard
5335 Colormap</var> you choose, otherwise an error occurs. Use <code>list</code> as
5336 the type and <code>display</code> searches the list of colormap types in
5337 <code>top-to-bottom</code> order until one is located. See <var>xstdcmap(1)</var> for one way of creating Standard Colormaps.</p>
5340 <div style="margin: auto;">
5341 <h3 class="magick-header"><a id="map_stream_"></a>-map <var>components</var></h3>
5344 <p class="magick-description">pixel map.</p>
5346 <p>Here are the valid components of a map:</p>
5348 <dl class="dl-horizontal">
5349 <dt>r</dt><dd> red pixel component</dd>
5350 <dt>g</dt><dd> green pixel component</dd>
5351 <dt>b</dt><dd> blue pixel component</dd>
5352 <dt>a</dt><dd> alpha pixel component (0 is transparent)</dd>
5353 <dt>o</dt><dd> opacity pixel component (0 is opaque)</dd>
5354 <dt>i</dt><dd> grayscale intensity pixel component</dd>
5355 <dt>c</dt><dd> cyan pixel component</dd>
5356 <dt>m</dt><dd> magenta pixel component</dd>
5357 <dt>y</dt><dd> yellow pixel component</dd>
5358 <dt>k</dt><dd> black pixel component</dd>
5359 <dt>p</dt><dd> pad component (always 0)</dd>
5362 <p>You can specify as many of these components as needed in any order (e.g.
5363 bgr). The components can repeat as well (e.g. rgbr).</p>
5366 <div style="margin: auto;">
5367 <h3 class="magick-header"><a id="mattecolor"></a>-mattecolor <var>color</var></h3>
5370 <p class="magick-description">Specify the color to be used with the <a href="command-line-options.html#frame">-frame</a> option.</p>
5372 <p>The color is specified using the format described under the <a href="command-line-options.html#fill">-fill</a> option.</p>
5374 <p>The default matte color is <code>#BDBDBD</code>, <span style="background-color: #bdbdbd;">this shade of gray</span>.</p>
5376 <div style="margin: auto;">
5377 <h3 class="magick-header"><a id="maximum"></a>-maximum</h3>
5380 <p class="magick-description">return the maximum intensity of an image sequence.</p>
5382 <p>Select the 'maximum' value from all the surrounding pixels. </p>
5384 <p>This is legacy option from the <a href="command-line-options.html#statistic">method</a> of the same
5387 <div style="margin: auto;">
5388 <h3 class="magick-header"><a id="median"></a>-median <var>geometry</var></h3>
5391 <p class="magick-description">apply a median filter to the image.</p>
5393 <p>Select the 'middle' value from all the surrounding pixels. </p>
5395 <p>This is legacy option from the <a href="command-line-options.html#statistic">method</a> of the same
5398 <div style="margin: auto;">
5399 <h3 class="magick-header"><a id="mean-shift"></a>-mean-shift <var>width</var>x<var>height</var>{<var>+distance</var>{%}}</h3>
5402 <p class="magick-description">image noise removal and color reduction/segmentation (e.g. -mean-shift 7x7+10%).</p>
5404 <p><var>width</var>x<var>height</var> is the window size and <var>distance</var> is the color distance measured in the range 0 to 1 or 0 to 100%</p>
5406 <p>The mean shift algorithm is iterative and thus slower the larger the window size. For each pixel, it gets all the pixels in the window centered at the pixel and excludes those that are outside the <var>radius=sqrt((width-1)(height-1)/4)</var> surrounding the pixel. From those pixels, it finds which of them are within the specified squared color distance from the current mean. It then computes a new x,y centroid from those coordinates and a new mean. This new x,y centroid is used as the center for a new window. This process is iterated until it converges and the final mean is then used to replace the original pixel value. It repeats this process for the next pixel, etc, until it processes all pixels in the image. Results are better when using other colorspaces rather than RGB. Recommend YIQ, YUV or YCbCr, which seem to give equivalent results.</p>
5408 <div style="margin: auto;">
5409 <h3 class="magick-header"><a id="metric"></a>-metric <var>type</var></h3>
5412 <p class="magick-description">Output to STDERR a measure of the differences between images according to the <var>type</var> given metric.</p>
5416 <dl class="dl-horizontal">
5417 <dt>AE</dt><dd> absolute error count, number of different pixels (-fuzz effected)</dd>
5418 <dt>FUZZ</dt><dd> mean color distance</dd>
5419 <dt>MAE</dt><dd> mean absolute error (normalized), average channel error distance</dd>
5420 <dt>MEPP</dt><dd> mean error per pixel (normalized mean error, normalized peak error)</dd>
5421 <dt>MSE</dt><dd> mean error squared, average of the channel error squared</dd>
5422 <dt>NCC</dt><dd> normalized cross correlation</dd>
5423 <dt>PAE</dt><dd> peak absolute (normalized peak absolute)</dd>
5424 <dt>PHASH</dt><dd> perceptual hash</dd>
5425 <dt>PSNR</dt><dd> peak signal to noise ratio</dd>
5426 <dt>RMSE</dt><dd> root mean squared (normalized root mean squared)</dd>
5429 <p>Control the '<code>AE</code>', or absolute count of pixels that are different,
5430 with the <a href="command-line-options.html#fuzz">-fuzz</a> factor (ignore pixels which
5431 only changed by a small amount). Use '<code>PAE</code>' to find the
5432 size of the <a href="command-line-options.html#fuzz">-fuzz</a> factor needed to make all pixels
5433 'similar', while '<code>MAE</code>' determines the factor needed
5434 for about half the pixels to be similar. </p>
5436 <p>The '<code>MEPP</code>' metric returns three different metrics
5437 ('<code>MAE</code>', '<code>MAE</code>' normalized, and '<code>PAE</code>'
5438 normalized) from a single comparison run. </p>
5440 <p>To print a complete list of metrics, use the <a href="command-line-options.html#list">-list
5441 metric</a> option.</p>
5444 <div style="margin: auto;">
5445 <h3 class="magick-header"><a id="minimum"></a>-minimum</h3>
5448 <p class="magick-description">return the minimum intensity of an image sequence.</p>
5450 <p>Select the 'minimal' value from all the surrounding pixels. </p>
5452 <p>This is legacy option from the <a href="command-line-options.html#statistic">method</a> of the same
5457 <div style="margin: auto;">
5458 <h3 class="magick-header"><a id="mode"></a>-mode <var>geometry</var></h3>
5461 <p class="magick-description">make each pixel the \'predominant color\' of the neighborhood.'</p>
5463 <div style="margin: auto;">
5464 <h3 class="magick-header">-mode <var>value</var></h3>
5467 <p class="magick-description">Mode of operation.</p>
5469 <p>Choose the <var>value</var> from these styles: <code>Frame,
5470 Unframe, or Concatenate</code></p>
5472 <p>Use the <a href="command-line-options.html#list">-list</a> option with a '<code>Mode</code>' argument
5473 for a list of <a href="command-line-options.html#mode">-mode</a> arguments available in your
5474 ImageMagick installation.</p>
5477 <div style="margin: auto;">
5478 <h3 class="magick-header"><a id="modulate"></a>-modulate <var>brightness</var>[,<var>saturation</var>,<var>hue</var>]</h3>
5481 <p class="magick-description">Vary the <var>brightness</var>, <var>saturation</var>, and <var>hue</var> of an image.</p>
5483 <p>The arguments are given as a percentages of variation. A value of 100 means
5484 no change, and any missing values are taken to mean 100.</p>
5486 <p>The <var>brightness</var> is a multiplier of the overall
5487 brightness of the image, so 0 means pure black, 50 is half as bright, 200 is
5488 twice as bright. To invert its meaning <a href="command-line-options.html#negate">-negate</a> the image
5489 before and after. </p>
5491 <p>The <var>saturation</var> controls the amount of color in an
5492 image. For example, 0 produce a grayscale image, while a large value such as
5493 200 produce a very colorful, 'cartoonish' color.</p>
5495 <p>The <var>hue</var> argument causes a "rotation" of the colors
5496 within the image by the amount specified. For example, 50 results in
5497 a counter-clockwise rotation of 90, mapping red shades to purple, and so on.
5498 A value of either 0 or 200 results in a complete 180 degree rotation of the
5499 image. Using a value of 300 is a 360 degree rotation resulting in no change to
5500 the original image. </p>
5502 <p>For example, to increase the color brightness by 20% and decrease the color
5503 saturation by 10% and leave the hue unchanged, use <a href="command-line-options.html#modulate">-modulate 120,90</a>.</p>
5505 <p>Use <a href="command-line-options.html#set">-set</a> attribute of '<code>option:modulate:colorspace</code>' to specify which colorspace to
5506 modulate. Choose from <code>HCL</code>, <code>HCLp</code>, <code>HSB</code>, <code>HSI</code>, <code>HSL</code> (the default), <code>HSV</code>, <code>HWB</code>, or <code>LCH</code> (LCHuv). For example,</p>
5509 convert image.png -set option:modulate:colorspace hsb -modulate 120,90 modulate.png
5512 <div style="margin: auto;">
5513 <h3 class="magick-header"><a id="moments"></a>-moments</h3>
5516 <p class="magick-description">report image moments and perceptual hash.</p>
5519 <div style="margin: auto;">
5520 <h3 class="magick-header"><a id="monitor"></a>-monitor</h3>
5523 <p class="magick-description">monitor progress.</p>
5526 <div style="margin: auto;">
5527 <h3 class="magick-header"><a id="monochrome"></a>-monochrome</h3>
5530 <p class="magick-description">transform the image to black and white.</p>
5532 <div style="margin: auto;">
5533 <h3 class="magick-header"><a id="morph"></a>-morph <var>frames</var></h3>
5536 <p class="magick-description">morphs an image sequence.</p>
5538 <p>Both the image pixels and size are linearly interpolated to give the
5539 appearance of a metamorphosis from one image to the next, over all the images
5540 in the current image list. The added images are the equivalent of a <a href="command-line-options.html#blend">-blend</a> composition. The <var>frames</var>
5541 argument determine how many images to interpolate between each image. </p>
5544 <div style="margin: auto;">
5545 <h3 class="magick-header"><a id="morphology"></a>-morphology</h3>
5546 <h3 class="magick-header">-morphology <var>method</var> <var>kernel</var></h3>
5549 <p class="magick-description">apply a morphology method to the image.</p>
5551 <p>Until I get around to writing an option summary for this, see <a href="http://www.imagemagick.org/Usage/morphology/">IM Usage Examples,
5552 Morphology</a>. </p>
5555 <div style="margin: auto;">
5556 <h3 class="magick-header"><a id="mosaic"></a>-mosaic</h3>
5559 <p class="magick-description">an simple alias for the <a href="command-line-options.html#layers">-layers</a> method "mosaic"</p>
5562 <div style="margin: auto;">
5563 <h3 class="magick-header"><a id="motion-blur"></a>-motion-blur <var>radius</var><br>-motion-blur <var>radius</var>x<var>sigma</var>+<var>angle</var></h3>
5566 <p class="magick-description">simulate motion blur.</p>
5568 <p>Blur with the given radius, standard deviation (sigma), and angle. The
5569 angle given is the angle toward which the image is blurred. That is the
5570 direction people would consider the object is coming from. </p>
5572 <p>Note that the blur is not uniform distribution, giving the motion a
5573 definite sense of direction of movement. </p>
5575 <p>The <a href="command-line-options.html#virtual-pixel">-virtual-pixel</a> setting will determine how
5576 pixels which are outside the image proper are blurred into the final result.
5579 <div style="margin: auto;">
5580 <h3 class="magick-header"><a id="name"></a>-name</h3>
5583 <p class="magick-description">name an image.</p>
5584 <div style="margin: auto;">
5585 <h3 class="magick-header"><a id="negate"></a>-negate</h3>
5588 <p class="magick-description">replace each pixel with its complementary color.</p>
5590 <p>The red, green, and blue intensities of an image are negated. White becomes
5591 black, yellow becomes blue, etc. Use <a href="command-line-options.html#negate">+negate</a> to only
5592 negate the grayscale pixels of the image.</p>
5594 <div style="margin: auto;">
5595 <h3 class="magick-header"><a id="noise"></a>-noise <var>geometry</var><br>
5596 +noise <var>type</var></h3>
5599 <p class="magick-description">Add or reduce noise in an image.</p>
5601 <p>The principal function of noise peak elimination filter is to smooth the
5602 objects within an image without losing edge information and without creating
5603 undesired structures. The central idea of the algorithm is to replace a pixel
5604 with its next neighbor in value within a pixel window, if this pixel has been
5605 found to be noise. A pixel is defined as noise if and only if this pixel is
5606 a maximum or minimum within the pixel window.</p>
5608 <p>Use <code><a href="command-line-options.html#noise">-noise</a> <var>radius</var></code> to
5609 specify the width of the neighborhood when reducing noise. This is equivalent
5610 to using a <code><a href="command-line-options.html#statistic">-statistic</a> NonPeak</code> operation,
5611 which should be used in preference.</p>
5613 <p>Use <a href="command-line-options.html#noise">+noise</a> followed by a noise <var>type</var> to add noise to an image. Choose from these noise
5626 <p>The amount of noise added can be controled by the <code><a href="command-line-options.html#attunuuate">-attenuate</a></code> setting. If unset the value is
5627 equivalent to 1.0, or a maximum noise addition.</p>
5629 <p>Note that Random will replace the image with noise rather than add noise to the image. Use Uniform, if you wish to add random noise to the image.</p>
5631 <p>To print a complete list of noises, use the <a href="command-line-options.html#list">-list noise</a> option.</p>
5633 <p>Also see the <a href="command-line-options.html#evaluate">-evaluate</a> noise functions that allows
5634 the use of a controlling value to specify the amount of noise that should be
5635 added to an image. </p>
5638 <div style="margin: auto;">
5639 <h3 class="magick-header"><a id="normalize"></a>-normalize</h3>
5642 <p class="magick-description">Increase the contrast in an image by <var>stretching</var> the range of intensity values.</p>
5644 <p>The intensity values are stretched to cover the entire range of possible
5645 values. While doing so, black-out at most <var>2%</var> of the pixels and
5646 white-out at most <var>1%</var> of the pixels.</p>
5648 <p>Note that as of ImageMagick 6.4.7-0, <a href="command-line-options.html#normalize">-normalize</a>
5649 is equivalent to <a href="command-line-options.html#contrast-stretch">-contrast-stretch 2%x1%</a>.
5650 (Before this version, it was equivalent to <a href="command-line-options.html#contrast-stretch">-contrast-stretch 2%x99%</a>).</p>
5652 <p>All the channels are normalized in concert by the came amount so as to
5653 preserve color integrity, when the default <a href="command-line-options.html#channel">+channel</a>
5654 setting is in use. Specifying any other <a href="command-line-options.html#channel">-channel</a>
5655 setting will normalize the RGB channels independently.</p>
5657 <p>See <a href="command-line-options.html#contrast-stretch">-contrast-stretch</a> for more details.
5658 Also see <a href="command-line-options.html#auto-level">-auto-level</a> for a 'perfect' normalization
5659 that is better suited to mathematically generated images. </p>
5661 <p>This operator is under review for re-development. </p>
5664 <div style="margin: auto;">
5665 <h3 class="magick-header"><a id="opaque"></a>-opaque <var>color</var></h3>
5668 <p class="magick-description">change this color to the fill color within the image.</p>
5670 <p>The <var>color</var> argument is defined using the format
5671 described under the <a href="command-line-options.html#fill">-fill</a> option. The <a href="command-line-options.html#fuzz">-fuzz</a> setting can be used to match and replace colors similar to the one
5674 <p>Use <a href="command-line-options.html#opaque">+opaque</a> to paint any pixel that does not match
5675 the target color. </p>
5677 <p>The <a href="command-line-options.html#transparent">-transparent</a> operator is exactly the same
5678 as <a href="command-line-options.html#opaque">-opaque</a> but replaces the matching color with
5679 transparency rather than the current <a href="command-line-options.html#fill">-fill</a> color setting.
5680 To ensure that it can do this it also ensures that the image has an alpha
5681 channel enabled, as per "<code><a href="command-line-options.html#alpha">-alpha</a> set</code>", for
5682 the new transparent colors, and does not require you to modify the <a href="command-line-options.html#channel">-channel</a> to enable alpha channel handling. </p>
5685 <div style="margin: auto;">
5686 <h3 class="magick-header"><a id="ordered-dither"></a>-ordered-dither <var>threshold_map</var>{,<var>level</var>...}</h3>
5689 <p class="magick-description">dither the image using a pre-defined ordered dither <var>threshold map</var> specified, and a uniform color map with the
5690 given number of <var>levels</var> per color channel.</p>
5692 <p>You can choose from these standard threshold maps:</p>
5694 <pre class="pre-scrollable">
5695 threshold 1x1 Threshold 1x1 (non-dither)
5696 checks 2x1 Checkerboard 2x1 (dither)
5697 o2x2 2x2 Ordered 2x2 (dispersed)
5698 o3x3 3x3 Ordered 3x3 (dispersed)
5699 o4x4 4x4 Ordered 4x4 (dispersed)
5700 o8x8 8x8 Ordered 8x8 (dispersed)
5701 h3x4a 4x1 Halftone 4x4 (angled)
5702 h6x6a 6x1 Halftone 6x6 (angled)
5703 h8x8a 8x1 Halftone 8x8 (angled)
5704 h3x4o Halftone 4x4 (orthogonal)
5705 h6x6o Halftone 6x6 (orthogonal)
5706 h8x8o Halftone 8x8 (orthogonal)
5707 h36x16o Halftone 16x16 (orthogonal)
5708 c5x5b c5x5 Circles 5x5 (black)
5709 c5x5w Circles 5x5 (white)
5710 c6x6b c6x6 Circles 6x6 (black)
5711 c6x6w Circles 6x6 (white)
5712 c7x7b c7x7 Circles 7x7 (black)
5713 c7x7w Circles 7x7 (white)
5716 <p> The <code>threshold</code> generated a simple 50% threshold of the image.
5717 This could be used with <var>level</var> to do the equivalent of <a href="command-line-options.html#posterize">-posterize</a> to reduce an image to basic primary colors.
5720 <p>The <code>checks</code> pattern produces a 3 level checkerboard dither
5721 pattern. That is a grayscale will become a pattern of solid black, solid
5722 white, and mid-tone colors into a checkerboard pattern of black and white.
5725 <p>You can define your own <var>threshold map</var> for ordered
5726 dithering and halftoning your images, in either personal or system
5727 <code>thresholds.xml</code> XML file. See <a href="resources.html">Resources</a>
5728 for more details of configuration files. </p>
5730 <p>To print a complete list of the thresholds that have been defined, use the
5731 <a href="command-line-options.html#list">-list threshold</a> option.</p>
5733 <p>Note that at this time the same threshold dithering map is used for all
5734 color channels, no attempt is made to offset or rotate the map for different
5735 channels is made, to create an offset printing effect. Also as the maps are
5736 simple threshold levels, the halftone and circle maps will create incomplete
5737 circles along the edges of a colored area. Also all the effects are purely
5738 on/off boolean effects, without anti-aliasing to make the circles smooth
5739 looking. Large dots can be made to look better with a small amount of blurring
5740 after being created. </p>
5743 <div style="margin: auto;">
5744 <h3 class="magick-header"><a id="orient"></a>-orient <var>image orientation</var></h3>
5747 <p class="magick-description">specify orientation of a digital camera image.</p>
5749 <p>Choose from these orientations:</p>
5752 bottom-left right-top
5753 bottom-right top-left
5754 left-bottom top-right
5759 <p>To print a complete list of orientations, use the <a href="command-line-options.html#list">-list
5760 orientation</a> option.</p>
5763 <div style="margin: auto;">
5764 <h3 class="magick-header"><a id="page"></a>-page <var>geometry</var><br>
5765 -page <var>media</var>[<var>offset</var>][{<var>^!<></var>}]<br>
5770 <p class="magick-description">Set the size and location of an image on the larger virtual canvas.</p>
5772 <p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
5774 <p>For convenience you can specify the page size using <var>media</var> (see below). Offsets can then be added as with other
5775 <var>geometry</var> arguments (e.g. <a href="command-line-options.html#page">-page</a> <code>Letter+43+43</code>).</p>
5777 <p>Use <var>media</var> as shorthand to specify the dimensions (<var>width</var>x<var>height</var>) of the <var>PostScript</var> page in dots per inch or a TEXT page in pixels.
5778 The choices for a PostScript page are:</p>
5780 <dl class="dl-horizontal">
5781 <dt> 11x17 </dt> <dd> 792 x 1224</dd>
5782 <dt> Ledger </dt> <dd> 1224 x 792</dd>
5783 <dt> Legal </dt> <dd> 612 x 1008</dd>
5784 <dt> Letter </dt> <dd> 612 x 792</dd>
5785 <dt> LetterSmall</dt> <dd> 612 x 792</dd>
5786 <dt> ArchE </dt> <dd> 2592 x 3456</dd>
5787 <dt> ArchD </dt> <dd> 1728 x 2592</dd>
5788 <dt> ArchC </dt> <dd> 1296 x 1728</dd>
5789 <dt> ArchB </dt> <dd> 864 x 1296</dd>
5790 <dt> ArchA </dt> <dd> 648 x 864</dd>
5791 <dt> A0 </dt> <dd> 2380 x 3368</dd>
5792 <dt> A1 </dt> <dd> 1684 x 2380</dd>
5793 <dt> A2 </dt> <dd> 1190 x 1684</dd>
5794 <dt> A3 </dt> <dd> 842 x 1190</dd>
5795 <dt> A4 </dt> <dd> 595 x 842</dd>
5796 <dt> A4Small </dt> <dd> 595 x 842</dd>
5797 <dt> A5 </dt> <dd> 421 x 595</dd>
5798 <dt> A6 </dt> <dd> 297 x 421</dd>
5799 <dt> A7 </dt> <dd> 210 x 297</dd>
5800 <dt> A8 </dt> <dd> 148 x 210</dd>
5801 <dt> A9 </dt> <dd> 105 x 148</dd>
5802 <dt> A10 </dt> <dd> 74 x 105</dd>
5803 <dt> B0 </dt> <dd> 2836 x 4008</dd>
5804 <dt> B1 </dt> <dd> 2004 x 2836</dd>
5805 <dt> B2 </dt> <dd> 1418 x 2004</dd>
5806 <dt> B3 </dt> <dd> 1002 x 1418</dd>
5807 <dt> B4 </dt> <dd> 709 x 1002</dd>
5808 <dt> B5 </dt> <dd> 501 x 709</dd>
5809 <dt> C0 </dt> <dd> 2600 x 3677</dd>
5810 <dt> C1 </dt> <dd> 1837 x 2600</dd>
5811 <dt> C2 </dt> <dd> 1298 x 1837</dd>
5812 <dt> C3 </dt> <dd> 918 x 1298</dd>
5813 <dt> C4 </dt> <dd> 649 x 918</dd>
5814 <dt> C5 </dt> <dd> 459 x 649</dd>
5815 <dt> C6 </dt> <dd> 323 x 459</dd>
5816 <dt> Flsa </dt> <dd> 612 x 936</dd>
5817 <dt> Flse </dt> <dd> 612 x 936</dd>
5818 <dt> HalfLetter </dt> <dd> 396 x 612</dd>
5821 <p>This option is also used to place subimages when writing to a multi-image
5822 format that supports offsets, such as GIF89 and MNG. When used for this
5823 purpose the offsets are always measured from the top left corner of the canvas
5824 and are not affected by the <a href="command-line-options.html#gravity">-gravity</a> option. To
5825 position a GIF or MNG image, use <a href="command-line-options.html#page">-page</a><var>{+-}x{+-}y</var> (e.g. -page +100+200). When writing to a MNG
5826 file, a <a href="command-line-options.html#page">-page</a> option appearing ahead of the first image in
5827 the sequence with nonzero width and height defines the width and height values
5828 that are written in the <code>MHDR</code> chunk. Otherwise, the MNG width and
5829 height are computed from the bounding box that contains all images in the
5830 sequence. When writing a GIF89 file, only the bounding box method is used to
5831 determine its dimensions.</p>
5833 <p>For a PostScript page, the image is sized as in <a href="command-line-options.html#geometry">-geometry</a> but positioned relative to the <var>lower
5834 left-hand corner</var> of the page by {+-}<code>x</code><var>offset</var>{+-}<code>y</code> <var>offset</var>. Use <a href="command-line-options.html#page">-page 612x792</a>, for example, to center the image within the
5835 page. If the image size exceeds the PostScript page, it is reduced to fit the
5836 page. The default gravity for the <a href="command-line-options.html#page">-page</a> option is <var>NorthWest</var>, i.e., positive <code>x</code> and <code>y</code> <var>offset</var> are measured rightward and downward from the top left
5837 corner of the page, unless the <a href="command-line-options.html#gravity">-gravity</a> option is
5838 present with a value other than <var>NorthWest</var>.</p>
5840 <p>The default page dimensions for a TEXT image is 612x792.</p>
5842 <p>This option is used in concert with <a href="command-line-options.html#density">-density</a>.</p>
5844 <p>Use <a href="command-line-options.html#page">+page</a> to remove the page settings for an image.</p>
5846 <div style="margin: auto;">
5847 <h3 class="magick-header"><a id="paint"></a>-paint <var>radius</var></h3>
5850 <p class="magick-description">simulate an oil painting.</p>
5852 <p>Each pixel is replaced by the most frequent color in a circular
5853 neighborhood whose width is specified with <var>radius</var>.</p>
5855 <div style="margin: auto;">
5856 <h3 class="magick-header"><a id="path"></a>-path <var>path</var></h3></div>
5858 <p class="magick-description">write images to this path on disk.</p>
5860 <div style="margin: auto;">
5861 <h3 class="magick-header"><a id="pause_animate_"></a>-pause <var>seconds</var></h3>
5864 <p class="magick-description">Pause between animation loops</p>
5866 <p>Pause for the specified number of seconds before repeating the animation.</p>
5868 <div style="margin: auto;">
5869 <h3 class="magick-header"><a id="pause_import_"></a>-pause <var>seconds</var></h3>
5872 <p class="magick-description">Pause between snapshots.</p>
5874 <p>Pause for the specified number of seconds before taking the next snapshot.</p>
5876 <div style="margin: auto;">
5877 <h3 class="magick-header"><a id="perceptible"></a>-perceptible <var>epsilon</var></h3>
5880 <p class="magick-description">set each pixel whose value is less than |<var>epsilon</var>| to <var>-epsilon</var> or <var>epsilon</var> (whichever is closer) otherwise the pixel value remains unchanged.</p>
5882 <div style="margin: auto;">
5883 <h3 class="magick-header"><a id="ping"></a>-ping</h3>
5886 <p class="magick-description">efficiently determine image characteristics.</p>
5888 <div style="margin: auto;">
5889 <h3 class="magick-header"><a id="pointsize"></a>-pointsize <var>value</var></h3>
5892 <p class="magick-description">pointsize of the PostScript, OPTION1, or TrueType font.</p>
5894 <div style="margin: auto;">
5895 <h3 class="magick-header"><a id="polaroid"></a>-polaroid <var>angle</var></h3>
5898 <p class="magick-description">simulate a Polaroid picture.</p>
5900 <p>Use <code>+polaroid</code> to rotate the image at a random angle between -15 and +15 degrees.</p>
5902 <div style="margin: auto;">
5903 <h3 class="magick-header"><a id="poly"></a>-poly <var>"wt,exp ..."</var></h3>
5906 <p class="magick-description">combines multiple images according to a weighted sum of polynomials; one floating point weight (coefficient) and one floating point polynomial exponent (power) for each image expressed as comma separated pairs.</p>
5908 <p> The weights should typically be fractions between -1 and 1. But the sum of weights should be 1 or at least between 0 and 1 to avoid clamping in non-hdri mode at black and white.</p>
5910 <p>The exponents may be positive, negative or zero. A negative exponent is equivalent to 1 divided by the image raised to the corresponding positive exponent. A zero exponent always produces 1 scaled by quantumrange to white, i.e. wt*white, no matter what the image.</p>
5912 <p>The format is: <var>output = wt1*image1^exp1 + wt2*image2^exp2 </var>...</p>
5914 <p>Some simple uses are:</p>
5916 <li>A weighted sum of each image provided all weights add to unity and all exponents=1. If the the weights are all equal to 1/(number of images), then this is equivalent to <a href="command-line-options.html#profile">-evaluate-sequence</a> <var>mean</var>.</li>
5917 <li>The sum of squares of two or more images, provided the weights are equal (and sum to 1 to avoid clamping) and the exponents equal 2.</li>
5920 <p>Note that one may add a constant color to the expression simply by using xc:somecolor for one of the images and specifying the desired weight and exponent equal to 0.</p>
5922 <p>Similarly one may add white to the expression by simply using null: (or xc:white) for one of the images with the appropriate weight and exponent equal to 0.</p>
5925 <div style="margin: auto;">
5926 <h3 class="magick-header"><a id="posterize"></a>-posterize <var>levels</var></h3>
5929 <p class="magick-description">reduce the image to a limited number of color levels per channel.</p>
5931 <p>Very low values of <var>levels</var>, e.g., 2, 3, 4, have the most
5934 <div style="margin: auto;">
5935 <h3 class="magick-header"><a id="precision"></a>-precision <var>value</var></h3>
5938 <p class="magick-description">set the maximum number of significant digits to be printed.</p>
5940 <div style="margin: auto;">
5941 <h3 class="magick-header"><a id="preview"></a>-preview <var>type</var></h3>
5944 <p class="magick-description">image preview type.</p>
5946 <p>Use this option to affect the preview operation of an image (e.g.
5947 <code>convert file.png -preview Gamma Preview:gamma.png</code>). Choose from
5950 <pre class="pre-scrollable">
5982 <p>To print a complete list of previews, use the <a href="command-line-options.html#list">-list preview</a> option.</p>
5984 <p>The default preview is <code>JPEG</code>.</p>
5986 <div style="margin: auto;">
5987 <h3 class="magick-header"><a id="print"></a>-print <var>string</var></h3>
5990 <p class="magick-description">interpret string and print to console.</p>
5992 <div style="margin: auto;">
5993 <h3 class="magick-header"><a id="process"></a>-process <var>command</var></h3>
5996 <p class="magick-description">process the image with a custom image filter.</p>
5998 <p>The command arguments has the form <code>"module arg1 arg2 arg3 ...
5999 argN"</code> where <code>module</code> is the name of the module to invoke (e.g.
6000 "Analyze") and arg1 arg2 arg3 ... argN are an arbitrary number of arguments to
6001 pass to the process module.</p>
6003 <div style="margin: auto;">
6004 <h3 class="magick-header"><a id="profile"></a>-profile <var>filename</var><br>
6005 +profile <var>profile_name</var></h3>
6008 <p class="magick-description">Manage ICM, IPTC, or generic profiles in an image.</p>
6010 <p>Using <a href="command-line-options.html#profile">-profile</a> <var>filename</var> adds an
6011 ICM (ICC color management), IPTC (newswire information), or a generic profile
6014 <p>Use <a href="command-line-options.html#profile">+profile <var>profile_name</var></a> to
6015 remove the indicated profile. ImageMagick uses standard filename globbing, so
6016 wildcard expressions may be used to remove more than one profile. Here we
6017 remove all profiles from the image except for the XMP profile: <code>+profile
6018 "!xmp,*"</code>. </p>
6020 <p>Use <code>identify -verbose</code> to find out which profiles are in the
6021 image file. Use <a href="command-line-options.html#strip">-strip</a> to remove all profiles (and
6024 <p>To extract a profile, the <a href="command-line-options.html#profile">-profile</a> option is not
6025 used. Instead, simply write the file to an image format such as <var>APP1, 8BIM, ICM,</var> or <var>IPTC</var>.</p>
6027 <p>For example, to extract the Exif data (which is stored in JPEG files in the
6028 <var>APP1</var> profile), use.</p>
6031 convert cockatoo.jpg profile.exif
6034 <p>It is important to note that results may depend on whether or not the
6035 original image already has an included profile. Also, keep in mind that <a href="command-line-options.html#profile">-profile</a> is an "operator" (as opposed to a "setting") and
6036 therefore a conversion is made each time it is encountered, in order, in the
6037 command-line. For instance, in the following example, if the original image is
6038 CMYK with profile, a CMYK-CMYK-RGB conversion results.</p>
6041 convert CMYK.tif -profile "CMYK.icc" -profile "RGB.icc" RGB.tiff
6044 <p>Furthermore, since ICC profiles are not necessarily symmetric, extra
6045 conversion steps can yield unwanted results. CMYK profiles are often very
6046 asymmetric since they involve 3−>4 and 4−>3 channel mapping.
6049 <div style="margin: auto;">
6050 <h3 class="magick-header"><a id="quality"></a>-quality <var>value</var></h3>
6053 <p class="magick-description">JPEG/MIFF/PNG compression level.</p>
6055 <p>For the JPEG and MPEG image formats, quality is 1 (lowest image quality and
6056 highest compression) to 100 (best quality but least effective compression).
6057 The default is to use the estimated quality of your input image if it can
6058 be determined, otherwise 92. When the quality is greater than 90, then the
6059 chroma channels are not downsampled.
6060 Use the <a href="command-line-options.html#sampling-factor">-sampling-factor</a> option to specify the
6061 factors for chroma downsampling.</p>
6063 <p>For the JPEG-2000 image format, quality is mapped using a non-linear
6064 equation to the compression ratio required by the Jasper library. This
6065 non-linear equation is intended to loosely approximate the quality provided by
6066 the JPEG v1 format. The default quality value 100, a request for non-lossy
6067 compression. A quality of 75 results in a request for 16:1 compression.</p>
6069 <p>For the MNG and PNG image formats, the quality value sets the zlib
6070 compression level (quality / 10) and filter-type (quality % 10). The default
6071 PNG "quality" is 75, which means compression level 7 with adaptive PNG
6072 filtering, unless the image has a color map, in which case it means
6073 compression level 7 with no PNG filtering.</p>
6075 <p>For compression level 0 (quality value less than 10), the Huffman-only
6076 strategy is used, which is fastest but not necessarily the worst
6079 <p>If filter-type is 4 or less, the specified PNG filter-type is used for
6082 <dl class="dl-horizontal">
6083 <dt>0</dt><dd>none</dd>
6084 <dt>1</dt><dd>sub</dd>
6085 <dt>2</dt><dd>up</dd>
6086 <dt>3</dt><dd>average</dd>
6087 <dt>4</dt><dd>Paeth</dd>
6090 <p>If filter-type is 5, adaptive filtering is used when quality is greater
6091 than 50 and the image does not have a color map, otherwise no filtering is
6094 <p>If filter-type is 6, adaptive filtering
6095 with <var>minimum-sum-of-absolute-values</var> is used.</p>
6097 <p>Only if the output is MNG, if filter-type is 7, the LOCO color
6098 transformation (intrapixel differencing) and adaptive filtering
6099 with <var>minimum-sum-of-absolute-values</var> are used.</p>
6101 <p>If the filter-type is 8 the zlib Z_RLE compression strategy (or the
6102 Z_HUFFMAN_ONLY strategy, when compression level is 0) is used with
6103 adaptive PNG filtering.</p>
6105 <p>If the filter-type is 9 the zlib Z_RLE compression strategy (or the
6106 Z_HUFFMAN_ONLY strategy, when compression level is 0) is used with
6107 no PNG filtering.</p>
6109 <p>The quality setting has no effect on the appearance or signature of PNG
6110 and MNG images, since the compression is always lossless.</p>
6112 <p>Not all combinations of compression level, strategy, and PNG filter type
6113 can be obtained using the -quality option. For more precise control,
6114 you can use the PNG:compression-level=N, PNG:compression-strategy=N, and
6115 PNG:compression-filter=N defines, respectively, instead.
6116 See <a href="command-line-options.html#define">-define</a>. Values from the defines take precedence
6117 over values from the -quality option.</p>
6119 <p>For further information, see
6120 the <a href="http://www.w3.org/pub/WWW/TR">PNG</a> specification.</p>
6122 <p>For the MIFF and TIFF image formats, quality/10 is the <a href="command-line-options.html#compress">Zip/BZip</a> 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>
6124 <p>For the BPG image format, quality/2 is the actual BPG compression level (range from 0 to 51).</p>
6126 <div style="margin: auto;">
6127 <h3 class="magick-header"><a id="quantize"></a>-quantize <var>colorspace</var></h3>
6130 <p class="magick-description">reduce colors using this colorspace.</p>
6132 <p>This setting defines the colorspace used to sort out and reduce the number
6133 of colors needed by an image (for later dithering) by operators such as <a href="command-line-options.html#colors">-colors</a>, Note that color reduction also happens
6134 automatically when saving images to color-limited image file formats, such as
6138 <div style="margin: auto;">
6139 <h3 class="magick-header"><a id="quiet"></a>-quiet</h3>
6142 <p class="magick-description">suppress all warning messages. Error messages are still reported.</p>
6144 <div style="margin: auto;">
6145 <h3 class="magick-header"><a id="radial-blur"></a>-radial-blur <var>angle</var></h3>
6148 <p class="magick-description">Blur around the center of the image.</p>
6150 <p>Note that this is actually a rotational blur rather than a radial and as
6151 such actually mis-named. </p>
6153 <p>The <a href="command-line-options.html#virtual-pixel">-virtual-pixel</a> setting will determine how
6154 pixels which are outside the image proper are blurred into the final result.
6158 <div style="margin: auto;">
6159 <h3 class="magick-header"><a id="raise"></a>-raise <var>thickness</var></h3>
6162 <p class="magick-description">Lighten or darken image edges.</p>
6164 <p>This will create a 3-D effect. Use <a href="command-line-options.html#raise">-raise</a> to create
6165 a raised effect, otherwise use <a href="command-line-options.html#raise">+raise</a>. </p>
6167 <p>Unlike the similar <a href="command-line-options.html#frame">-frame</a> option, <a href="command-line-options.html#raise">-raise</a> does not alter the dimensions of the image.</p>
6169 <div style="margin: auto;">
6170 <h3 class="magick-header"><a id="random-threshold"></a>-random-threshold <var>low</var>x<var>high</var></h3>
6173 <p class="magick-description">Apply a random threshold to the image.</p>
6175 <div style="margin: auto;">
6176 <h3 class="magick-header"><a id="read-mask"></a>-read-mask <var>filename</var></h3>
6179 <p class="magick-description">Prevent updates to image pixels specified by the mask.</p>
6181 <p>This the same as using a mask used for composite masking operations, with
6182 grayscale values causing blended updates of the image the mask is attached to.
6185 <p>Use <a href="command-line-options.html#read-mask">+read-mask</a> to remove the mask from images.</p>
6187 <p>Also see <a href="command-line-options.html#clip-mask">-clip-mask</a> which work in the same way,
6188 but with strict boolean masking. </p>
6190 <div style="margin: auto;">
6191 <h3 class="magick-header"><a id="red-primary"></a>-red-primary <var>x,y</var></h3>
6194 <p class="magick-description">Set the red chromaticity primary point.</p>
6196 <div style="margin: auto;">
6197 <h3 class="magick-header"><a id="regard-warnings"></a>-regard-warnings</h3>
6200 <p class="magick-description">Pay attention to warning messages.</p>
6202 <p>This option causes some warnings in some image formats to be treated
6205 <div style="margin: auto;">
6206 <h3 class="magick-header"><a id="remap"></a>-remap <var>filename</var></h3>
6209 <p class="magick-description">Reduce the number of colors in an image to the colors used by this image.</p>
6211 <p>If the <a href="command-line-options.html#dither">-dither</a> setting is enabled (the default) then
6212 the given colors are dithered over the image as necessary, otherwise the closest
6213 color (in RGB colorspace) is selected to replace that pixel in the image. </p>
6215 <p>As a side effect of applying a <a href="command-line-options.html#remap">-remap</a> of colors across all
6216 images in the current image sequence, all the images will have the same color
6217 table. That means that when saved to a file format such as GIF, it will use
6218 that color table as a single common or global color table, for all the images,
6219 without requiring extra local color tables. </p>
6221 <p>Use <a href="command-line-options.html#remap">+remap</a> to reduce all images in the current image
6222 sequence to use a common color map over all the images. This equivalent to
6223 appending all the images together (without extra background colors) and color
6224 reducing those images using <a href="command-line-options.html#colors">-colors</a> with a 256 color
6225 limit, then <a href="command-line-options.html#remap">-remap</a> those colors over the original list of
6226 images. This ensures all the images follow a single color map. </p>
6228 <p>If the number of colors over all the images is less than 256, then <a href="command-line-options.html#remap">+remap</a> should not perform any color reduction or dithering, as
6229 no color changes are needed. In that case, its only effect is to force the use
6230 of a global color table. This recommended after using either <a href="command-line-options.html#colors">-colors</a> or <a href="command-line-options.html#ordered-dither">-ordered-dither</a> to
6231 reduce the number of colors in an animated image sequence. </p>
6233 <p>Note, the remap image colormap has at most 8-bits of precision. Deeper color maps are automagically coalesced with other colors to meet this requirement.</p>
6235 <div style="margin: auto;">
6236 <h3 class="magick-header"><a id="region"></a>-region <var>geometry</var></h3>
6239 <p class="magick-description">Set a region in which subsequent operations apply.</p>
6241 <p>The <var>x</var> and <var>y</var> offsets are treated
6242 in the same manner as in <a href="command-line-options.html#crop">-crop</a>.</p>
6244 <p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
6246 <div style="margin: auto;">
6247 <h3 class="magick-header"><a id="remote"></a>-remote</h3>
6250 <p class="magick-description">perform a remote operation.</p>
6252 <p>The only command recognized is the name of an image file to load.</p>
6254 <p>If you have more than one <a href="display.html">display</a> application
6255 running simultaneously, use the <a href="command-line-options.html#window"> window</a> option to
6256 specify which application to control.</p>
6258 <div style="margin: auto;">
6259 <h3 class="magick-header"><a id="render"></a>-render</h3>
6262 <p class="magick-description">render vector operations.</p>
6264 <p>Use <a href="command-line-options.html#render">+render</a> to turn off rendering vector operations.
6265 This useful when saving the result to vector formats such as MVG or SVG.</p>
6267 <div style="margin: auto;">
6268 <h3 class="magick-header"><a id="repage"></a>-repage <var>geometry</var></h3>
6271 <p class="magick-description">Adjust the canvas and offset information of the image.</p>
6273 <p>This option is like <a href="command-line-options.html#page">-page</a> but acts as an image operator
6274 rather than a setting. You can separately set the canvas size or the offset
6275 of the image on that canvas by only providing those components. </p>
6277 <p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
6279 <p>If a <code>!</code> flag is given the offset given is added to the existing
6280 offset to move the image relative to its previous position. This useful for
6281 animation sequences. </p>
6283 <p>A given a canvas size of zero such as '<code>0x0</code>' forces it to
6284 recalculate the canvas size so the image (at its current offset) will appear
6285 completely on that canvas (unless it has a negative offset).</p>
6287 <p>Use <a href="command-line-options.html#repage">+repage</a> to completely remove/reset the virtual
6288 canvas meta-data from the images. </p>
6290 <p>The <a href="command-line-options.html#set">-set</a> '<code>page</code>' option can be used to
6291 directly assign virtual canvas meta-data. </p>
6294 <div style="margin: auto;">
6295 <h3 class="magick-header"><a id="resample"></a>-resample <var>horizontal</var>x<var>vertical</var></h3>
6298 <p class="magick-description">Resample image to specified horizontal and vertical resolution.</p>
6300 <p>Resize the image so that its rendered size remains the same as the original
6301 at the specified target resolution. For example, if a 300 DPI image renders at
6302 3 inches by 2 inches on a 300 DPI device, when the image has been resampled to
6303 72 DPI, it will render at 3 inches by 2 inches on a 72 DPI device. Note that
6304 only a small number of image formats (e.g. JPEG, PNG, and TIFF) are capable of
6305 storing the image resolution. For formats which do not support an image
6306 resolution, the original resolution of the image must be specified via <a href="command-line-options.html#density">-density</a> on the command line prior to specifying the
6307 resample resolution.</p>
6309 <p>Note that Photoshop stores and obtains image resolution from a proprietary
6310 embedded profile. If this profile exists in the image, then Photoshop will
6311 continue to treat the image using its former resolution, ignoring the image
6312 resolution specified in the standard file header.</p>
6314 <div style="margin: auto;">
6315 <h3 class="magick-header"><a id="resize"></a>-resize <var>geometry</var></h3>
6318 <p class="magick-description">Resize an image.</p>
6320 <p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument. Offsets, if present in the geometry string, are
6321 ignored, and the <a href="command-line-options.html#gravity">-gravity</a> option has no effect.</p>
6323 <p>If the <a href="command-line-options.html#filter">-filter</a> option
6324 or <code>-define filter:option=value</code> precedes the <a href="command-line-options.html#resize">-resize</a> option, the image is resized with the specified
6327 <p>Many image processing algorithms assume your image is in a linear-light
6328 coding. If your image is gamma-corrected, you can remove the nonlinear gamma
6329 correction, apply the transform, then restore it like this:</p>
6332 convert portrait.jpg -gamma .45455 -resize 25% -gamma 2.2 \
6333 -quality 92 passport.jpg
6336 <div style="margin: auto;">
6337 <h3 class="magick-header"><a id="respect-parentheses"></a>-respect-parentheses</h3>
6340 <p class="magick-description">settings remain in effect until parenthesis boundary.</p>
6342 <div style="margin: auto;">
6343 <h3 class="magick-header"><a id="reverse"></a>-reverse</h3>
6346 <p class="magick-description">Reverse the order of images in the current image list.</p>
6349 <div style="margin: auto;">
6350 <h3 class="magick-header"><a id="roll"></a>-roll {<var>+-</var>}<var>x</var>{<var>+-</var>}<var>y</var></h3>
6353 <p class="magick-description">roll an image vertically or horizontally by the amount given.</p>
6355 <p>A negative <var>x</var> offset rolls the image right-to-left.
6356 A negative <var>y</var> offset rolls the image bottom-to-top.</p>
6359 <div style="margin: auto;">
6360 <h3 class="magick-header"><a id="rotate"></a>-rotate <var>degrees</var>{<var><</var>}{<var>></var>}</h3>
6363 <p class="magick-description">Apply Paeth image rotation (using shear operations) to the image.</p>
6365 <p>Use <code>></code> to rotate the image only if its width exceeds the
6366 height. <code><</code> rotates the image <var>only</var> if its width is less
6367 than the height. For example, if you specify <code>-rotate "-90>"</code> and
6368 the image size is 480x640, the image is not rotated. However, if the image is
6369 640x480, it is rotated by -90 degrees. If you use <code>></code> or
6370 <code><</code>, enclose it in quotation marks to prevent it from being
6371 misinterpreted as a file redirection.</p>
6373 <p>Empty triangles in the corners, left over from rotating the image, are
6374 filled with the <code>background</code> color. </p>
6376 <p>See also the <a href="command-line-options.html#distort">-distort</a> operator and specifically the
6377 '<code>ScaleRotateTranslate</code>' distort method. </p>
6380 <div style="margin: auto;">
6381 <h3 class="magick-header"><a id="sample"></a>-sample <var>geometry</var></h3>
6384 <p class="magick-description">minify / magnify the image with pixel subsampling and pixel replication, respectively.</p>
6386 <p>Change the image size simply by directly sampling the pixels original
6387 from the image. When magnifying, pixels are replicated in blocks. When
6388 minifying, pixels are sub-sampled (i.e., some rows and columns are skipped
6391 <p>The results are thus equivalent to using <a href="command-line-options.html#resize">-resize</a> with
6392 a <a href="command-line-options.html#filter">-filter</a> setting of <code>point</code> (nearest
6393 neighbour), though <a href="command-line-options.html#sample">-sample</a> is a lot faster, as it
6394 avoids all the filter processing of the image. As such it completely ignores
6395 the current <a href="command-line-options.html#filter">-filter</a> setting. </p>
6397 <p>The key feature of the <a href="command-line-options.html#sample">-sample</a> is that no new colors
6398 will be added to the resulting image, though some colors may disappear. </p>
6400 <p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument. Offsets, if present in the geometry string, are
6401 ignored, unlike <a href="command-line-options.html#resize">-resize</a>. </p>
6404 <p>The actual sampling point is the middle of the sub-region being sampled.
6405 As such a single pixel sampling of an image will take the middle pixel, (or
6406 top-left-middle if image has even dimensions). However the <a href="command-line-options.html#define">-define</a> '<code>sample:offset</code>' can be set to modify
6407 this position some other location within each sub-region being sampled, as
6408 a percentage offset.</p>
6410 <p>By default this value is '<code>50</code>' for the midpoint, but could be set
6411 to '<code>0</code>' for top-left, '<code>100</code>' for bottom-right, or with
6412 separate X and Y offsets such as '<code>0x50</code>' for left-middle edge of
6413 sampling sub-region.</p>
6416 <div style="margin: auto;">
6417 <h3 class="magick-header"><a id="sampling-factor"></a>-sampling-factor <var>horizontal-factor</var>x<var>vertical-factor</var></h3>
6420 <p class="magick-description">sampling factors used by JPEG or MPEG-2 encoder and YUV decoder/encoder.</p>
6422 <p>This option specifies the sampling factors to be used by the JPEG encoder
6423 for chroma downsampling. If this option is omitted, the JPEG library will use
6424 its own default values. When reading or writing the YUV format and when
6425 writing the M2V (MPEG-2) format, use <a href="command-line-options.html#sampling-factor">-sampling-factor 2x1</a> or <a href="command-line-options.html#sampling-factor">-sampling-factor 4:2:2</a> to specify the 4:2:2
6426 downsampling method.</p>
6428 <div style="margin: auto;">
6429 <h3 class="magick-header"><a id="scale"></a>-scale <var>geometry</var></h3>
6432 <p class="magick-description">minify / magnify the image with pixel block averaging and pixel replication, respectively.</p>
6434 <p>Change the image size simply by replacing pixels by averaging pixels
6435 together when minifying, or replacing pixels when magnifying. </p>
6437 <p>The results are thus equivalent to using <a href="command-line-options.html#resize">-resize</a> with
6438 a <a href="command-line-options.html#filter">-filter</a> setting of <code>box</code>. Though it is a lot
6439 faster, as it avoids all the filter processing of the image. As such it
6440 completely ignores the current <a href="command-line-options.html#filter">-filter</a> setting. </p>
6442 <p>If when shrinking (minifying) images the original image is some integer
6443 multiple of the new image size, the number of pixels averaged together to
6444 produce the new pixel color is the same across the whole image. This is
6445 a special case known as 'binning' and is often used as a method of reducing
6446 noise in image such as those generated by digital cameras, especially in low
6447 light conditions. </p>
6450 <div style="margin: auto;">
6451 <h3 class="magick-header"><a id="scene"></a>-scene <var>value</var></h3>
6454 <p class="magick-description">set scene number.</p>
6456 <p>This option sets the scene number of an image or the first image in an image sequence.</p>
6458 <div style="margin: auto;">
6459 <h3 class="magick-header"><a id="screen"></a>-screen</h3>
6462 <p class="magick-description">specify the screen to capture.</p>
6464 <p>This option indicates that the GetImage request used to obtain the image
6465 should be done on the root window, rather than directly on the specified
6466 window. In this way, you can obtain pieces of other windows that overlap the
6467 specified window, and more importantly, you can capture menus or other popups
6468 that are independent windows but appear over the specified window.</p>
6470 <div style="margin: auto;">
6471 <h3 class="magick-header"><a id="seed"></a>-seed</h3>
6474 <p class="magick-description">seed a new sequence of pseudo-random numbers</p>
6476 <div style="margin: auto;">
6477 <h3 class="magick-header"><a id="segment"></a>-segment <var>cluster-threshold</var>x<var>smoothing-threshold</var></h3>
6480 <p class="magick-description">segment the colors of an image.</p>
6482 <p>Segment an image by analyzing the histograms of the color components and
6483 identifying units that are homogeneous with the fuzzy c-means technique. This
6484 is part of the ImageMagick color quantization routines. </p>
6486 <p>Specify <var>cluster threshold</var> as the number of pixels in
6487 each cluster that must exceed the cluster threshold to be considered valid.
6488 <var>Smoothing threshold</var> eliminates noise in the second
6489 derivative of the histogram. As the value is increased, you can expect
6490 a smoother second derivative. The default is 1.5.</p>
6492 <p>If the <a href="command-line-options.html#verbose">-verbose</a> setting is defined, a detailed report
6493 of the color clusters is returned.</p>
6496 <div style="margin: auto;">
6497 <h3 class="magick-header"><a id="selective-blur"></a>-selective-blur <var>radius</var><br>-selective-blur <var>radius</var>x<var>sigma</var>{<var>+threshold</var>}</h3>
6500 <p class="magick-description">Selectively blur pixels within a contrast threshold.</p>
6502 <p>Blurs those pixels that are less than or equal to the threshold in
6503 contrast. The threshold may be expressed as a fraction of <var>QuantumRange</var> or as a percentage.</p>
6505 <div style="margin: auto;">
6506 <h3 class="magick-header"><a id="separate"></a>-separate</h3>
6509 <p class="magick-description">separate an image channel into a grayscale image. Specify the channel with <a href="command-line-options.html#channel">-channel</a>.</p>
6511 <div style="margin: auto;">
6512 <h3 class="magick-header"><a id="sepia-tone"></a>-sepia-tone <var>threshold</var></h3>
6515 <p class="magick-description">simulate a sepia-toned photo.</p>
6517 <p>Specify <var>threshold</var> as the percent threshold of the intensity (0 - 99.9%).</p>
6519 <p>This option applies a special effect to the image, similar to the effect
6520 achieved in a photo darkroom by sepia toning. Threshold ranges from 0 to <var>QuantumRange</var> and is a measure of the extent of the sepia
6521 toning. A threshold of 80% is a good starting point for a reasonable
6526 <div style="margin: auto;">
6527 <h3 class="magick-header"><a id="set"></a>-set <var>key value</var></h3>
6528 <h3 class="magick-header">+set <var>key</var></h3>
6531 <p class="magick-description">sets image attributes and properties for images in the current image sequence.</p>
6533 <p>This will assign (or modify) specific settings attached to all the images
6534 in the current image sequence. Using the <a href="command-line-options.html#set">+set</a> form of the
6535 option will either remove, or reset that setting to a default state, as
6538 <p>For example, it will modify specific well known image meta-data
6539 'attributes' such as those normally overridden by: the options <a href="command-line-options.html#delay">-delay</a>, <a href="command-line-options.html#dispose">-dispose</a>, and <a href="command-line-options.html#page">-page</a>, <a href="command-line-options.html#colorspace">-colorspace</a>; generally
6540 assigned before the image is read in, by using a <var>key</var> of
6543 <p>If the given <var>key</var> does not match a specific known
6544 'attribute ', such as shown above, the setting is stored as a a free form
6545 'property' string. Such settings are listed in <a href="command-line-options.html#verbose">-verbose</a> information ("<code>info:</code>" output format) as "Properties".
6548 <p>This includes string 'properties' that are set by and assigned to images
6549 using the options <a href="command-line-options.html#comment">-comment</a>, <a href="command-line-options.html#label">-label</a>, <a href="command-line-options.html#caption">-caption</a>. These options actually assign
6550 a global 'artifact' which are automatically assigned (and any <a href="escape.html">Format Percent
6551 Escapes</a> expanded) to images as they are read in. For example:</p>
6554 -> convert rose: -set comment 'Rose is a rose is a rose is a rose' rose.png
6555 identify -format %c rose.png
6556 Rose is a rose is a rose is a rose
6559 <p>The set value can also make use of <a href="escape.html">Format and Print Image
6560 Properties</a> in the defined value. For example:</p>
6563 -> convert rose: -set origsize '%wx%h' -resize 50% \
6564 -format 'Old size = %[origsize] New size = %wx%h' info:
6565 Old size = 70x46 New size = 35x23
6568 <p>Other well known 'properties' that are availible include:
6569 '<code>date:create</code>' and '<code>date:modify</code>' and
6570 '<code>signature</code>'. </p>
6572 <p>The <a href="command-line-options.html#repage">-repage</a> operator will also allow you to modify
6573 the '<code>page</code>' attribute of an image for images already in memory (also
6574 see <a href="command-line-options.html#repage">-page</a>). However it is designed to provide a finer
6575 control of the sub-parts of this 'attribute'. The <a href="command-line-options.html#set">-set page</a>
6576 option will only provide a direct, unmodified assignment of '<code>page</code>'
6579 <p>This option can also associate a colorspace or profile with your image.
6583 convert image.psd -set profile ISOcoated_v2_eci.icc image-icc.psd
6586 <p>Some 'properties' must be defined in a specific way to be used. For
6587 example only 'properties' prefixed with "<code>filename:</code>" can be used to
6588 modify the output filename of an image. For example</p>
6591 convert rose: -set filename:mysize '%wx%h' 'rose_%[filename:mysize].png'
6594 <p>If the setting value is prefixed with "<code>option:</code>" the setting will
6595 be saved as a global "Artifact" exactly as if it was set using the <a href="command-line-options.html#define">-define</a> option. As such settings are global in scope, they
6596 can be used to pass 'attributes' and 'properties' of one specific image,
6597 in a way that allows you to use them in a completely different image, even if
6598 the original image has long since been modified or destroyed. For example: </p>
6601 convert rose: -set option:rosesize '%wx%h' -delete 0 \
6602 label:'%[rosesize]' label_size_of_rose.gif"
6605 <p>Note that <a href="escape.html">Format Percent Escapes</a> will only match
6606 a 'artifact' if the given <var>key</var> does not match an existing
6607 'attribute' or 'property'. </p>
6609 <p>You can set the attributes of the image registry by prefixing the value
6610 with <code>registry:</code>.</p>
6612 <p>The <a href="command-line-options.html#set">-set profile</a> option can also be used to inject
6613 previously-formatted ancillary chunks into the output PNG file, using
6614 the commandline option as shown below or by setting the profile via a
6615 programming interface:</p>
6618 convert in.png -set profile PNG-chunk-x:<filename> out.png
6621 <p>where <var>x</var> is a location flag and
6622 <var>filename</var> is a file containing the chunk
6623 name in the first 4 bytes, then a colon (":"), followed by the chunk data.
6624 This encoder will compute the chunk length and CRC, so those must not
6625 be included in the file.</p>
6627 <p>"x" can be "b" (before PLTE), "m" (middle, i.e., between PLTE and IDAT),
6628 or "e" (end, i.e., after IDAT). If you want to write multiple chunks
6629 of the same type, then add a short unique string after the "x" to prevent
6630 subsequent profiles from overwriting the preceding ones, e.g.,</p>
6634 convert in.png -set profile PNG-chunk-b01:file01 \
6635 -profile PNG-chunk-b02:file02 out.png
6638 <div style="margin: auto;">
6639 <h3 class="magick-header"><a id="shade"></a>-shade <var>azimuth</var>x<var>elevation</var></h3>
6642 <p class="magick-description">shade the image using a distant light source.</p>
6644 <p>Specify <var>azimuth</var> and <var>elevation</var> as
6645 the position of the light source. Use <a href="command-line-options.html#shade">+shade</a> to return
6646 the shading results as a grayscale image.</p>
6648 <div style="margin: auto;">
6649 <h3 class="magick-header"><a id="shadow"></a>-shadow <var>percent-opacity</var>{x<var>sigma</var>}{<var>+-</var>}<var>x</var>{<var>+-</var>}<var>y</var>{<var>%</var>}</h3>
6652 <p class="magick-description">simulate an image shadow.</p>
6654 <div style="margin: auto;">
6655 <h3 class="magick-header"><a id="shared-memory"></a>-shared-memory</h3>
6658 <p class="magick-description">use shared memory.</p>
6660 <p>This option specifies whether the utility should attempt to use shared
6661 memory for pixmaps. ImageMagick must be compiled with shared memory support,
6662 and the display must support the <var>MIT-SHM</var> extension.
6663 Otherwise, this option is ignored. The default is <code>True</code>.</p>
6665 <div style="margin: auto;">
6666 <h3 class="magick-header"><a id="sharpen"></a>-sharpen <var>radius</var><br>-sharpen <var>radius</var>x<var>sigma</var></h3>
6669 <p class="magick-description">sharpen the image.</p>
6671 <p>Use a Gaussian operator of the given radius and standard deviation (sigma).</p>
6673 <div style="margin: auto;">
6674 <h3 class="magick-header"><a id="shave"></a>-shave <var>geometry</var></h3>
6677 <p class="magick-description">Shave pixels from the image edges.</p>
6679 <p>The <var>size</var> portion of the <var>geometry</var>
6680 argument specifies the width of the region to be removed from both sides of
6681 the image and the height of the regions to be removed from top and bottom.
6682 Offsets are ignored.</p>
6684 <p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
6686 <div style="margin: auto;">
6687 <h3 class="magick-header"><a id="shear"></a>-shear <var>Xdegrees</var>[x<var>Ydegrees</var>]</h3>
6690 <p class="magick-description">Shear the image along the x-axis and/or y-axis.</p>
6692 <p>The shear angles may be positive, negative, or zero. When <var>Ydegrees</var> is omitted it defaults to 0. When both angles are
6693 given, the horizontal component of the shear is performed before the vertical
6696 <p>Shearing slides one edge of an image along the x-axis or y-axis (i.e.,
6697 horizontally or vertically, respectively),creating a parallelogram. The amount
6698 of each is controlled by the respective shear angle. For horizontal shears,
6699 <var>Xdegrees</var> is measured clockwise relative to "up" (the
6700 negative y-axis), sliding the top edge to the right when 0°<<var>Xdegrees</var><90° and to the left when 90°<<var>Xdegrees</var><180°. For vertical shears <var>Ydegrees</var> is measured clockwise relative to "right" (the
6701 positive x-axis), sliding the right edge down when 0°<<var>Ydegrees</var><90° and up when 90°<<var>Ydegrees</var><180°.</p>
6703 <p>Empty triangles left over from shearing the image are filled with the color
6704 defined by the <a href="command-line-options.html#fill">-background</a> option. The color is specified
6705 using the format described under the <a href="command-line-options.html#fill">-fill</a> option.</p>
6707 <p>The horizontal shear is performed before the vertical part. This is
6708 important to note, since horizontal and vertical shears do not
6709 <var>commute</var>, i.e., the order matters in a sequence of shears. For
6710 example, the following two commands are not equivalent.</p>
6713 convert logo: -shear 20x0 -shear 0x60 logo-sheared.png
6714 convert logo: -shear 0x60 -shear 20x0 logo-sheared.png
6717 <p>The first of the two commands above is equivalent to the following, except
6718 for the amount of empty space created; the command that follows generates
6719 a smaller image, and so is a better choice in terms of time and space.</p>
6722 convert logo: -shear 20x60 logo-sheared.png
6725 <div style="margin: auto;">
6726 <h3 class="magick-header"><a id="sigmoidal-contrast"></a>-sigmoidal-contrast <var>contrast</var>x<var>mid-point</var></h3>
6729 <p class="magick-description">increase the contrast without saturating highlights or shadows.</p>
6731 <p>Increase the contrast of the image using a sigmoidal transfer function
6732 without saturating highlights or shadows. <var>Contrast</var>
6733 indicates how much to increase the contrast. For example, 0 is none, 3 is
6734 typical and 20 is a lot.
6737 <p>The <var>mid-point</var> indicates where the maximum change
6738 'slope' in contrast should fall in the resultant image (0 is white; 50% is
6739 middle-gray; 100% is black). </p>
6741 <p>By default the image contrast is increased, use <var>+sigmoidal-contrast</var> to decrease the contrast.</p>
6743 <p>To achieve the equivalent of a sigmoidal brightness change (similar to
6744 a gamma adjustment), you would use <var>-sigmoidal-contrast
6745 {brightness}x0%</var> to increase brightness and <var>+sigmoidal-contrast {brightness}x0%</var> to decrease brightness.
6746 Note the use of '0' fo rthe mid-point of the sigmoidal curve. </p>
6748 <p>Using a very high <var>contrast</var> will produce a sort of
6749 'smoothed thresholding' of the image. Not as sharp (with high aliasing
6750 effects) of a true threshold, but with tapered gray-levels around the threshold
6751 <var>mid-point</var>. </p>
6753 <div style="margin: auto;">
6754 <h3 class="magick-header"><a id="silent"></a>-silent</h3>
6757 <p class="magick-description">operate silently.</p>
6759 <div style="margin: auto;">
6760 <h3 class="magick-header"><a id="similarity-threshold"></a>-similarity-threshold <var>value</var></h3>
6763 <p class="magick-description">minimum RMSE for subimage match.</p>
6765 <p>If this setting is used, then the search will stop as soon as it finds a match whose metric is less than or equal to the value. A partially filled second output image will result. Using a value of zero, will cause the search to stop at the first perfect match it finds. If this setting is left off, then the search will proceed to completion or as limited by <var>-dissimilarity-threshold</var>.</p>
6767 <div style="margin: auto;">
6768 <h3 class="magick-header"><a id="size"></a>-size <var>width</var>[x<var>height</var>][<var>+offset</var>]</h3>
6771 <p class="magick-description">set the width and height of the image.</p>
6773 <p>Use this option to specify the width and height of raw images whose
6774 dimensions are unknown such as <code>GRAY</code>, <code>RGB</code>, or
6775 <code>CMYK</code>. In addition to width and height, use <a href="command-line-options.html#size">-size</a> with an offset to skip any header information in the
6776 image or tell the number of colors in a <code>MAP</code> image file, (e.g. -size
6779 <p>For Photo CD images, choose from these sizes:</p>
6789 <div style="margin: auto;">
6790 <h3 class="magick-header"><a id="sketch"></a>-sketch <var>radius</var><br>-sketch <var>radius</var>x<var>sigma</var>+<var>angle</var></h3>
6793 <p class="magick-description">simulate a pencil sketch.</p>
6795 <p>Sketch with the given radius, standard deviation (sigma), and angle. The
6796 angle given is the angle toward which the image is sketched. That is the
6797 direction people would consider the object is coming from. </p>
6799 <div style="margin: auto;">
6800 <h3 class="magick-header"><a id="smush"></a>-smush <var>offset</var></h3>
6803 <p class="magick-description">smush an image sequence together.</p>
6805 <div style="margin: auto;">
6806 <h3 class="magick-header"><a id="snaps"></a>-snaps <var>value</var></h3>
6809 <p class="magick-description">Set the number of screen snapshots.</p>
6811 <p>Use this option to grab more than one image from the X server screen, to create an animation sequence.</p>
6813 <div style="margin: auto;">
6814 <h3 class="magick-header"><a id="solarize"></a>-solarize <var>threshold</var></h3>
6817 <p class="magick-description">negate all pixels above the threshold level.</p>
6819 <p>Specify <var>factor</var> as the percent threshold of the intensity (0 - 99.9%).</p>
6821 <p>This option produces a <var>solarization</var> effect seen when
6822 exposing a photographic film to light during the development process.</p>
6824 <div style="margin: auto;">
6825 <h3 class="magick-header"><a id="sparse-color"></a>-sparse-color <var>method</var> '<var>x</var>,<var>y</var> <var>color</var> ...'</h3>
6828 <p class="magick-description"> color the given image using the specified points of color, and filling the other intervening colors using the given methods. </p>
6831 <dl class="dl-horizontal">
6832 <dt>barycentric</dt>
6833 <dd>three point triangle of color given 3 points.
6834 Giving only 2 points will form a linear gradient between those points.
6835 The gradient generated extends beyond the triangle created by those
6838 <dd>Like barycentric but for 4 points. Less than 4 points
6839 fall back to barycentric. </dd>
6841 <dd>Simply map each pixel to the to nearest color point
6842 given. The result are polygonal 'cells' of solid color. </dd>
6844 <dd>Colors points biased on the ratio of inverse distance
6845 squared. Generating spots of color in a sea of the average of
6848 <dd>Colors points biased on the ratio of inverse distance.
6849 This generates sharper points of color rather than rounded spots of
6850 '<code>shepards</code>' Generating spots of color in a sea of the
6851 average of colors. </dd>
6854 <p>The points are placed according to the images location on the virtual
6855 canvas (<a href="command-line-options.html#page">-page</a> or <a href="command-line-options.html#repage">-repage</a>
6856 offset), and do not actually have to exist on the given image, but may be
6857 some point beyond the edge of the image. All points are floating point values.
6860 <p>Only the color channels defined by the <a href="command-line-options.html#channel">-channel</a> are
6861 modified, which means that by default matte/alpha transparency channel is not
6862 effected. Typically transparency channel is turned off either before or after
6865 <p>Of course if some color points are transparent to generate a transparent
6866 gradient, then the image also requires transparency enabled to store the
6869 <p>All the above methods when given a single point of color will replace all
6870 the colors in the image with the color given, regardless of the point. This is
6871 logical, and provides an alternative technique to recolor an image to some
6875 <div style="margin: auto;">
6876 <h3 class="magick-header"><a id="splice"></a>-splice <var>geometry</var></h3>
6879 <p class="magick-description">Splice the current background color into the image.</p>
6881 <p>This will add rows and columns of the current <a href="command-line-options.html#background">-background</a> color into the given image according to the
6882 given <a href="command-line-options.html#gravity">-gravity</a> geometry setting. See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument. Essentially <a href="command-line-options.html#splice">-splice</a> will divide the
6883 image into four quadrants, separating them by the inserted rows and columns.
6886 <p>If a dimension of geometry is zero no rows or columns will be added for that
6887 dimension. Similarly using a zero offset with the appropriate <a href="command-line-options.html#gravity">-gravity</a> setting will add rows and columns to the edges of
6888 the image, padding the image only along that one edge. Edge padding is what <a href="command-line-options.html#splice">-splice</a> is most commonly used for. </p>
6890 <p>If the exact same <var>geometry</var> and <a href="command-line-options.html#gravity">-gravity</a> is later used with <a href="command-line-options.html#chop">-chop</a> the
6891 added added all splices removed. </p>
6893 <div style="margin: auto;">
6894 <h3 class="magick-header"><a id="spread"></a>-spread <var>amount</var></h3>
6897 <p class="magick-description">displace image pixels by a random amount.</p>
6899 <p>The argument <var>amount</var> defines the size of the
6900 neighborhood around each pixel from which to choose a candidate pixel to
6903 <div style="margin: auto;">
6904 <h3 class="magick-header"><a id="statistic"></a>-statistic <var>type</var> <var>geometry</var></h3>
6907 <p class="magick-description">replace each pixel with corresponding statistic from the neighborhood.</p>
6909 <p>Choose from these statistic types:</p>
6910 <dl class="dl-horizontal">
6911 <dt>Gradient</dt><dd>maximum difference (max - min) value in neighborhood</dd>
6912 <dt>Maximum</dt><dd>maximum value per channel in neighborhood</dd>
6913 <dt>Minimum</dt><dd>minimum value per channel in neighborhood</dd>
6914 <dt>Mean</dt><dd>average value per channel in neighborhood</dd>
6915 <dt>Median</dt><dd>median value per channel in neighborhood</dd>
6916 <dt>Mode</dt><dd>mode (most frequent) value per channel in neighborhood</dd>
6917 <dt>Nonpeak</dt><dd>value just before or after the median value per channel in neighborhood</dd>
6918 <dt>RMS</dt><dd>root mean square value per channel in neighborhood</dd>
6919 <dt>StandardDeviation</dt><dd> standard deviation value per channel in neighborhood</dd>
6922 <div style="margin: auto;">
6923 <h3 class="magick-header"><a id="stegano"></a>-stegano <var>offset</var></h3>
6926 <p class="magick-description">hide watermark within an image.</p>
6928 <p>Use an offset to start the image hiding some number of pixels from the
6929 beginning of the image. Note this offset and the image size. You will need
6930 this information to recover the steganographic image (e.g. display -size
6931 320x256+35 stegano:image.png).</p>
6933 <div style="margin: auto;">
6934 <h3 class="magick-header"><a id="stereo"></a>-stereo <var>+x</var>{<var>+y</var>}</h3>
6937 <p class="magick-description">composite two images to create a red / cyan stereo anaglyph.</p>
6939 <p>The left side of the stereo pair (second image) is saved as the red channel of the output image. The right side (first image) is saved as the green and blue channels. Red-green stereo glasses are required to properly view the stereo image.</p>
6941 <div style="margin: auto;">
6942 <h3 class="magick-header"><a id="storage-type"></a>-storage-type <var>type</var></h3>
6945 <p class="magick-description">pixel storage type. Here are the valid types:</p>
6947 <dl class="dl-horizontal">
6948 <dt>char</dt><dd>unsigned characters</dd>
6949 <dt>double</dt><dd>doubles</dd>
6950 <dt>float</dt><dd>floats</dd>
6951 <dt>integer</dt><dd>integers</dd>
6952 <dt>long</dt><dd>longs</dd>
6953 <dt>quantum</dt><dd>pixels in the native depth of your ImageMagick distribution</dd>
6954 <dt>short</dt><dd>unsigned shorts</dd>
6957 <p>Float and double types are normalized from 0.0 to 1.0 otherwise the pixels
6958 values range from 0 to the maximum value the storage type can support.</p>
6960 <div style="margin: auto;">
6961 <h3 class="magick-header"><a id="stretch"></a>-stretch <var>fontStretch</var></h3>
6964 <p class="magick-description">Set a type of stretch style for fonts.</p>
6966 <p>This setting suggests a type of stretch that ImageMagick should try to
6967 apply to the currently selected font family. Select <var>fontStretch</var> from the following.</p>
6982 <p>To print a complete list of stretch types, use <a href="command-line-options.html#list">-list
6985 <p>For other settings that affect fonts, see the options <a href="command-line-options.html#font">-font</a>, <a href="command-line-options.html#family">-family</a>, <a href="command-line-options.html#style">-style</a>, and <a href="command-line-options.html#weight">-weight</a>. </p>
6987 <div style="margin: auto;">
6988 <h3 class="magick-header"><a id="strip"></a>-strip</h3>
6991 <p class="magick-description">strip the image of any profiles or comments.</p>
6993 <div style="margin: auto;">
6994 <h3 class="magick-header"><a id="stroke"></a>-stroke <var>color</var></h3>
6997 <p class="magick-description">color to use when stroking a graphic primitive.</p>
6999 <p>The color is specified using the format described under the <a href="command-line-options.html#fill">-fill</a> option.</p>
7001 <p>See <a href="command-line-options.html#draw">-draw</a> for further details.</p>
7003 <div style="margin: auto;">
7004 <h3 class="magick-header"><a id="strokewidth"></a>-strokewidth <var>value</var></h3>
7007 <p class="magick-description">set the stroke width.</p>
7009 <p>See <a href="command-line-options.html#draw">-draw</a> for further details.</p>
7011 <div style="margin: auto;">
7012 <h3 class="magick-header"><a id="style"></a>-style <var>fontStyle</var></h3>
7015 <p class="magick-description">Set a font style for text.</p>
7017 <p>This setting suggests a font style that ImageMagick should try to apply to
7018 the currently selected font family. Select <var>fontStyle</var> from
7028 <p>For other settings that affect fonts, see the options <a href="command-line-options.html#font">-font</a>, <a href="command-line-options.html#family">-family</a>, <a href="command-line-options.html#stretch">-stretch</a>, and <a href="command-line-options.html#weight">-weight</a>. </p>
7030 <div style="margin: auto;">
7031 <h3 class="magick-header"><a id="subimage-search"></a>-subimage-search</h3>
7034 <p class="magick-description">search for subimage.</p>
7036 <p>This option is required to have compare search for the best match location
7037 of a small image within a larger image. This search will produce two images
7038 (or two frames). The first is the "difference" image and the second will
7039 be the "match score" image.</p>
7041 <p>The "match-score" image is smaller containing a pixel for ever possible
7042 position of the top-left corner of the given sub-image. that is its size will
7043 be the size of the larger_image - sub_image + 1. The brightest location in
7044 this image is the location s the locate on the best match that is also
7045 reported. Note that this may or may not be a perfect match, and the actual
7046 brightness will reflect this. Other bright 'peaks' can be used to locate other
7047 possible matching locations. </p>
7049 <p>Note that the search will try to compare the sub-image at every possible
7050 location in the larger image, as such it can be very slow. The smaller the
7051 sub-image the faster this search is. </p>
7054 <div style="margin: auto;">
7055 <h3 class="magick-header"><a id="swap"></a>-swap <var>index,index</var></h3>
7058 <p class="magick-description">Swap the positions of two images in the image sequence.</p>
7060 <p>For example, <a href="command-line-options.html#swap">-swap 0,2</a> swaps the first and the third
7061 images in the current image sequence. Use <a href="command-line-options.html#swap">+swap</a> to switch
7062 the last two images in the sequence.</p>
7064 <div style="margin: auto;">
7065 <h3 class="magick-header"><a id="swirl"></a>-swirl <var>degrees</var></h3>
7068 <p class="magick-description">swirl image pixels about the center.</p>
7070 <p><var>Degrees</var> defines the tightness of the swirl.</p>
7072 <div style="margin: auto;">
7073 <h3 class="magick-header"><a id="synchronize"></a>-synchronize</h3>
7076 <p class="magick-description">synchronize image to storage device.</p>
7078 <p>Set to "true" to ensure all image data is fully flushed and synchronized
7079 to disk. There is a performance penalty, but the benefits include ensuring a
7080 valid image file in the event of a system crash and early reporting if there
7081 is not enough disk space for the image pixel cache.</p>
7083 <div style="margin: auto;">
7084 <h3 class="magick-header"><a id="taint"></a>-taint</h3>
7087 <p class="magick-description">Mark the image as modified.</p>
7089 <div style="margin: auto;">
7090 <h3 class="magick-header"><a id="text-font"></a>-text-font <var>name</var></h3>
7093 <p class="magick-description">font for writing fixed-width text.</p>
7095 <p>Specifies the name of the preferred font to use in fixed (typewriter style)
7096 formatted text. The default is 14 point <var>Courier</var>.</p>
7098 <p>You can tag a font to specify whether it is a PostScript, TrueType, or
7099 OPTION1 font. For example, <code>Courier.ttf</code> is a TrueType font and
7100 <code>x:fixed</code> is OPTION1.</p>
7102 <div style="margin: auto;">
7103 <h3 class="magick-header"><a id="texture"></a>-texture <var>filename</var></h3>
7106 <p class="magick-description">name of texture to tile onto the image background.</p>
7108 <div style="margin: auto;">
7109 <h3 class="magick-header"><a id="threshold"></a>-threshold <var>value</var>{<var>%</var>}</h3>
7112 <!-- {<var>green,blue,opacity</var>}
7113 <p>If the green or blue value is omitted, these channels use the same value as
7114 the first one provided. If all three color values are the same, the result is
7115 a bi-level image. If the opacity threshold is omitted, OpaqueOpacity is used
7116 and any partially transparent pixel becomes fully transparent.</p>
7119 <p class="magick-description">Apply simultaneous black/white threshold to the image.</p>
7121 <p>Any pixel values (more specifically, those channels set using <a href="command-line-options.html#channel">‑channel</a>) that exceed the specified threshold are reassigned the
7122 maximum channel value, while all other values are assigned the minimum.</p>
7124 <p> The threshold value can be given as a percentage or as an absolute integer
7125 value corresponding to the desired channel value. When given as an integer,
7126 the minimum attainable value is 0 (corresponding to black when all channels
7127 are affected), but the maximum value (corresponding to white) is that of the
7128 <code>quantum depth</code> of the particular build of ImageMagick, and is
7129 therefore dependent on the installation. For that reason, a reasonable
7130 recommendation for most applications is to specify the threshold values as
7133 <p> The following would force pixels with red values above 50% to have 100%
7134 red values, while those at or below 50% red would be set to 0 in the red
7135 channel. The green, blue, and alpha channels (if present) would be unchanged.
7139 convert in.png -channel red -threshold 50% out.png
7142 <p>As (possibly) impractical but instructive examples, the following would
7143 generate an all-black and an all-white image with the same dimensions as the
7148 convert in.png -threshold 100% black.png
7149 convert in.png -threshold -1 white.png
7152 <p>Note that the values of the transparency channel is treated as 'matte'
7153 values (0 is opaque) and not as 'alpha' values (0 is transparent).</p>
7155 <p> See also <a href="command-line-options.html#black-threshold">‑black‑threshold</a> and <a href="command-line-options.html#white-threshold">‑white‑threshold</a>.
7158 <div style="margin: auto;">
7159 <h3 class="magick-header"><a id="thumbnail"></a>-thumbnail <var>geometry</var></h3>
7162 <p class="magick-description">Create a thumbnail of the image.</p>
7164 <p>This is similar to <a href="command-line-options.html#resize">-resize</a>, except it is optimized
7165 for speed and any image profile, other than a color profile, is removed to
7166 reduce the thumbnail size. To strip the color profiles as well, add <a href="command-line-options.html#strip">-strip</a> just before of after this option.</p>
7168 <p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
7170 <div style="margin: auto;">
7171 <h3 class="magick-header"><a id="tile"></a>-tile <var>filename</var></h3>
7174 <p class="magick-description">Set the tile image used for filling a subsequent graphic primitive.</p>
7176 <div style="margin: auto;">
7177 <h3 class="magick-header">-tile <var>geometry</var></h3>
7180 <p class="magick-description">Specify the layout of images.</p>
7182 <p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
7184 <div style="margin: auto;">
7185 <h3 class="magick-header">-tile</h3>
7188 <p class="magick-description">Specifies that a subsequent composite operation is repeated across and down image.</p>
7190 <div style="margin: auto;">
7191 <h3 class="magick-header"><a id="tile-offset"></a>-tile-offset {<var>+-</var>}<var>x</var>{<var>+-</var>}<var>y</var></h3>
7194 <p class="magick-description">Specify the offset for tile images, relative to the background image it is tiled on.</p>
7196 <p>This should be set before the tiling image is set by <a href="command-line-options.html#tile">-tile</a> or <a href="command-line-options.html#texture">-texture</a>, or directly applied for
7197 creating a tiled canvas using <code>TILE:</code> or <code>PATTERN:</code> input
7200 <p>Internally ImageMagick does a <a href="command-line-options.html#roll">-roll</a> of the tile image
7201 by the arguments given when the tile image is set. </p>
7203 <div style="margin: auto;">
7204 <h3 class="magick-header"><a id="tint"></a>-tint <var>value</var></h3>
7207 <p class="magick-description">Tint the image with the fill color.</p>
7209 <p>Tint the image with the fill color.</p>
7211 <p>Specify the amount of tinting as a percentage. Pure colors like black,
7212 white red, yellow, will not be affected by -tint. Only mid-range colors such
7213 as the various shades of grey.</p>
7215 <div style="margin: auto;">
7216 <h3 class="magick-header"><a id="title"></a>-title <var>string</var></h3>
7219 <p class="magick-description">Assign a title to displayed image.", "animate", "display", "montage</p>
7221 <p>Use this option to assign a specific title to the image. This assigned to
7222 the image window and is typically displayed in the window title bar.
7223 Optionally you can include the image filename, type, width, height, Exif data,
7224 or other image attribute by embedding special format characters described
7225 under the <a href="command-line-options.html#format">-format</a> option.</p>
7230 -title "%m:%f %wx%h"
7233 <p>produces an image title of <code>MIFF:bird.miff 512x480</code> for an image
7234 titled <code>bird.miff</code> and whose width is 512 and height is 480.</p>
7237 <div style="margin: auto;">
7238 <h3 class="magick-header"><a id="transform"></a>-transform</h3>
7241 <p class="magick-description">transform the image.</p>
7243 <p>This option applies the transformation matrix from a previous <a href="command-line-options.html#affine">-affine</a> option.</p>
7246 convert -affine 2,2,-2,2,0,0 -transform bird.ppm bird.jpg
7250 <p>This operator has been now been superseded by the <a href="command-line-options.html#distort">-distort</a> '<code>AffineProjection</code>' method. </p>
7253 <div style="margin: auto;">
7254 <h3 class="magick-header"><a id="transparent"></a>-transparent <var>color</var></h3>
7257 <p class="magick-description">Make this color transparent within the image.</p>
7259 <p>The <var>color</var> argument is defined using the format
7260 described under the <a href="command-line-options.html#fill">-fill</a> option. The <a href="command-line-options.html#fuzz">-fuzz</a> setting can be used to match and replace colors similar to the one
7263 <p>Use <a href="command-line-options.html#transparent">+transparent</a> to invert the pixels matched.
7264 that is make all non-matching colors transparent. </p>
7266 <p>The <a href="command-line-options.html#opaque">-opaque</a> operator is exactly the same as <a href="command-line-options.html#transparent">-transparent</a> but replaces the matching color with the
7267 current <a href="command-line-options.html#fill">-fill</a> color setting, rather than transparent.
7268 However the <a href="command-line-options.html#transparent">-transparent</a> operator also ensures
7269 that the image has an alpha channel enabled, as per "<code><a href="command-line-options.html#alpha">-alpha</a> set</code>", and does not require you to modify the <a href="command-line-options.html#channel">-channel</a> to enable alpha channel handling. </p>
7271 <p>Note that this does not define the color as being the 'transparency color'
7272 used for color-mapped image formats, such as GIF. For that use <a href="command-line-options.html#transparent-color">-transparent-color</a> </p>
7275 <div style="margin: auto;">
7276 <h3 class="magick-header"><a id="transparent-color"></a>-transparent-color <var>color</var></h3>
7279 <p class="magick-description">Set the transparent color.</p>
7281 <p>Sometimes this is used for saving to image formats such as
7282 GIF and PNG8 which uses this color to represent boolean transparency. This
7283 does not make a color transparent, it only defines what color the transparent
7284 color is in the color palette of the saved image. Use <a href="command-line-options.html#transparent">-transparent</a> to make an opaque color transparent.</p>
7286 <p>This option allows you to have both an opaque visible color, as well as a
7287 transparent color of the same color value without conflict. That is, you can
7288 use the same color for both the transparent and opaque color areas within an
7289 image. This, in turn, frees to you to select a transparent color that is
7290 appropriate when an image is displayed by an application that does not handle a
7291 transparent color index, while allowing ImageMagick to correctly handle images of this
7294 <p>The default transparent color is <code>#00000000</code>, which is fully transparent black.</p>
7296 <div style="margin: auto;">
7297 <h3 class="magick-header"><a id="transpose"></a>-transpose</h3>
7300 <p class="magick-description">Mirror the image along the top-left to bottom-right diagonal.</p>
7302 <p> This option mathematically transposes the pixel array. It is equivalent to the sequence <code>-flip -rotate 90</code>.
7305 <div style="margin: auto;">
7306 <h3 class="magick-header"><a id="transverse"></a>-transverse</h3>
7309 <p class="magick-description">Mirror the image along the images bottom-left top-right diagonal. Equivalent to the operations <code>-flop -rotate 90</code>.</p>
7312 <div style="margin: auto;">
7313 <h3 class="magick-header"><a id="treedepth"></a>-treedepth <var>value</var></h3>
7316 <p class="magick-description">tree depth for the color reduction algorithm.</p>
7318 <p>Normally, this integer value is zero or one. A value of zero or one causes
7319 the use of an optimal tree depth for the color reduction algorithm.</p>
7321 <p>An optimal depth generally allows the best representation of the source
7322 image with the fastest computational speed and the least amount of memory.
7323 However, the default depth is inappropriate for some images. To assure the
7324 best representation, try values between 2 and 8 for this parameter. Refer to
7325 the <a href="quantize.html">color reduction algorithm</a> for more details.</p>
7327 <p>The <a href="command-line-options.html#colors">-colors</a> or <a href="command-line-options.html#monochrome">-monochrome</a>
7328 option, or writing to an image format which requires color reduction, is
7329 required for this option to take effect.</p>
7331 <div style="margin: auto;">
7332 <h3 class="magick-header"><a id="trim"></a>-trim</h3>
7335 <p class="magick-description">trim an image.</p>
7337 <p>This option removes any edges that are exactly the same color as the corner
7338 pixels. Use <a href="command-line-options.html#fuzz">-fuzz</a> to make <a href="command-line-options.html#trim">-trim</a> remove
7339 edges that are nearly the same color as the corner pixels.</p>
7341 <p>The page or virtual canvas information of the image is preserved allowing
7342 you to extract the result of the <a href="command-line-options.html#trim">-trim</a> operation from the
7343 image. Use a <a href="command-line-options.html#repage">+repage</a> to remove the virtual canvas page
7344 information if it is unwanted.</p>
7346 <p>If the trimmed image 'disappears' an warning is produced, and a special
7347 single pixel transparent 'missed' image is returned, in the same way as when a
7348 <a href="command-line-options.html#crop">-crop</a> operation 'misses' the image proper. </p>
7351 <div style="margin: auto;">
7352 <h3 class="magick-header"><a id="type"></a>-type <var>type</var></h3>
7355 <p class="magick-description">the image type.</p> <p>Choose from: <code>Bilevel</code>,
7356 <code>Grayscale</code>, <code>GrayscaleMatte</code>, <code>Palette</code>,
7357 <code>PaletteMatte</code>, <code>TrueColor</code>, <code>TrueColorMatte</code>,
7358 <code>ColorSeparation</code>, or <code>ColorSeparationMatte</code>.</p>
7360 <p>Normally, when a format supports different subformats such as grayscale and
7361 truecolor, the encoder will try to choose an efficient subformat. The <a href="command-line-options.html#type">-type</a> option can be used to override this behavior. For
7362 example, to prevent a JPEG from being written in grayscale format even though
7363 only gray pixels are present, use.</p>
7366 convert bird.png -type TrueColor bird.jpg
7369 <p>Similarly, use <a href="command-line-options.html#type">-type TrueColorMatte</a> to force the
7370 encoder to write an alpha channel even though the image is opaque, if the
7371 output format supports transparency.</p>
7373 <p>Use <a href="command-line-options.html#type">-type optimize</a> to ensure the image is written in the smallest possible file size.</p>
7375 <div style="margin: auto;">
7376 <h3 class="magick-header"><a id="undercolor"></a>-undercolor <var>color</var></h3>
7379 <p class="magick-description">set the color of the annotation bounding box.</p>
7381 <p>The color is specified using the format described under the <a href="command-line-options.html#fill">-fill</a> option.</p>
7383 <p>See <a href="command-line-options.html#draw">-draw</a> for further details.</p>
7386 <div style="margin: auto;">
7387 <h3 class="magick-header"><a id="update"></a>-update <var>seconds</var></h3>
7390 <p class="magick-description">detect when image file is modified and redisplay.</p>
7392 <p>Suppose that while you are displaying an image the file that is currently
7393 displayed is over-written. <code>display</code> will automagically detect that
7394 the input file has been changed and update the displayed image
7398 <div style="margin: auto;">
7399 <h3 class="magick-header"><a id="unique-colors"></a>-unique-colors</h3>
7402 <p class="magick-description">discard all but one of any pixel color.</p>
7405 <div style="margin: auto;">
7406 <h3 class="magick-header"><a id="units"></a>-units <var>type</var></h3>
7409 <p class="magick-description">the units of image resolution.</p>
7411 <p>Choose from: <code>Undefined</code>, <code>PixelsPerInch</code>, or
7412 <code>PixelsPerCentimeter</code>. This option is normally used in conjunction
7413 with the <a href="command-line-options.html#density">-density</a> option.</p>
7416 <div style="margin: auto;">
7417 <h3 class="magick-header"><a id="unsharp"></a>-unsharp <var>radius</var><br>-unsharp <var>radius</var>x<var>sigma</var>{<var>+gain</var>}{<var>+threshold</var>}</h3>
7420 <p class="magick-description">sharpen the image with an unsharp mask operator.</p>
7422 <p>The <a href="command-line-options.html#unsharp">-unsharp</a> option sharpens an image. The image is
7423 convolved with a Gaussian operator of the given radius and standard deviation
7424 (sigma). For reasonable results, radius should be larger than sigma. Use
7425 a radius of 0 to have the method select a suitable radius.</p>
7427 <p>The parameters are:</p>
7429 <dl class="dl-horizontal">
7431 <dd>The radius of the Gaussian, in pixels, not counting the center pixel (default 0).</dd>
7433 <dd>The standard deviation of the Gaussian, in pixels (default 1.0).</dd>
7435 <dd>The fraction of the difference between the original and the blur image that is added back into the original (default 1.0).</dd>
7437 <dd>The threshold, as a fraction of <var>QuantumRange</var>, needed to apply the difference amount (default 0.05).</dd>
7440 <div style="margin: auto;">
7441 <h3 class="magick-header"><a id="verbose"></a>-verbose</h3>
7444 <p class="magick-description">print detailed information about the image when this option precedes the <a href="command-line-options.html#identify">-identify</a> option or <code>info:</code>.</p>
7447 <div style="margin: auto;">
7448 <h3 class="magick-header"><a id="version"></a>-version</h3>
7451 <p class="magick-description">print ImageMagick version string and exit.</p>
7454 <div style="margin: auto;">
7455 <h3 class="magick-header"><a id="view"></a>-view <var>string</var></h3>
7458 <p class="magick-description">FlashPix viewing parameters.</p>
7461 <div style="margin: auto;">
7462 <h3 class="magick-header"><a id="vignette"></a>-vignette <var>radius</var>{x<var>sigma</var>}{<var>+-</var>}<var>x</var>{<var>+-</var>}<var>y</var>{<var>%</var>}</h3>
7465 <p class="magick-description">soften the edges of the image in vignette style.</p>
7467 <p>The vignette effect rolloff is controlled by radiusxsigma. For nominal rolloff, this would be set to 0xsigma. A value of 0x0 will produce a circle/ellipse with no rolloff. The arguments x and y control the size of the circle. Larger values decrease the radii and smaller values increase the radii. Values of +0+0 will generate a circle/ellipse the same size as the image. The default values for x and y are 10% of the corresponding image dimension. Thus, the radii will be decreased by 10%, i.e., the diameters of the circle/ellipse will be 80% of the corresponding image dimension.</p>
7469 <div style="margin: auto;">
7470 <h3 class="magick-header"><a id="virtual-pixel"></a>-virtual-pixel <var>method</var></h3>
7473 <p class="magick-description">Specify contents of <var>virtual pixels</var>.</p>
7475 <p>This option defines what color source should be used if and when a color
7476 lookup completely 'misses' the source image. The color(s) that appear to
7477 surround the source image. Generally this color is derived from the source
7478 image, but could also be set to a specify background color. </p>
7480 <p>Choose from these methods:</p>
7482 <dl class="dl-horizontal">
7483 <dt>background</dt><dd>the area surrounding the image is the background color</dd>
7484 <dt>black</dt><dd>the area surrounding the image is black</dd>
7485 <dt>checker-tile</dt><dd>alternate squares with image and background color</dd>
7486 <dt>dither</dt><dd>non-random 32x32 dithered pattern</dd>
7487 <dt>edge</dt><dd>extend the edge pixel toward infinity</dd>
7488 <dt>gray</dt><dd>the area surrounding the image is gray</dd>
7489 <dt>horizontal-tile</dt><dd>horizontally tile the image, background color above/below</dd>
7490 <dt>horizontal-tile-edge</dt><dd>horizontally tile the image and replicate the side edge pixels</dd>
7491 <dt>mirror</dt><dd>mirror tile the image</dd>
7492 <dt>random</dt><dd>choose a random pixel from the image</dd>
7493 <dt>tile</dt><dd>tile the image (default)</dd>
7494 <dt>transparent</dt><dd>the area surrounding the image is transparent blackness</dd>
7495 <dt>vertical-tile</dt><dd>vertically tile the image, sides are background color</dd>
7496 <dt>vertical-tile-edge</dt><dd>vertically tile the image and replicate the side edge pixels</dd>
7497 <dt>white</dt><dd>the area surrounding the image is white</dd>
7500 <p>The default value is "edge".</p>
7502 <p>This most important for distortion operators such as <a href="command-line-options.html#distort">-distort</a>, <a href="command-line-options.html#implode">-implode</a>, and <a href="command-line-options.html#fx">-fx</a>.
7503 However it also effects operations that may access pixels just outside the
7504 image proper, such as <a href="command-line-options.html#convolve">-convolve</a>, <a href="command-line-options.html#blur">-blur</a>, and <a href="command-line-options.html#sharpen">-sharpen</a>. </p>
7506 <p>To print a complete list of virtual pixel types, use the <a href="command-line-options.html#list">-list virtual-pixel</a> option.</p>
7509 <div style="margin: auto;">
7510 <h3 class="magick-header"><a id="visual"></a>-visual <var>type</var></h3>
7513 <p class="magick-description">Animate images using this X visual type.", 'animate', 'display'</p>
7515 <p>Choose from these visual classes:</p>
7518 StaticGray TrueColor
7519 GrayScale DirectColor
7521 PseudoColor visual id
7524 <p>The X server must support the visual you choose, otherwise an error occurs.
7525 If a visual is not specified, the visual class that can display the most
7526 simultaneous colors on the default screen is chosen.</p>
7529 <div style="margin: auto;">
7530 <h3 class="magick-header"><a id="watermark"></a>-watermark <var>brightness</var>x<var>saturation</var></h3>
7533 <p class="magick-description">Watermark an image using the given percentages of brightness and saturation.</p>
7535 <p>Take a grayscale image (with alpha mask) and modify the destination image's
7536 brightness according to watermark image's grayscale value and the
7537 <var>brightness</var> percentage. The destinations color saturation
7538 attribute is just direct modified by the <var>saturation</var>
7539 percentage, which defaults to 100 percent (no color change). </p>
7542 <div style="margin: auto;">
7543 <h3 class="magick-header"><a id="wave"></a>-wave <var>amplitude</var><br>-wave <var>amplitude</var>x<var>wavelength</var></h3>
7546 <p class="magick-description">Shear the columns of an image into a sine wave.</p>
7548 <p>Specify <var>amplitude</var> and <var>wavelength</var>
7551 <div style="margin: auto;">
7552 <h3 class="magick-header"><a id="weight"></a>-weight <var>fontWeight</var></h3>
7555 <p class="magick-description">Set a font weight for text.</p>
7557 <p>This setting suggests a font weight that ImageMagick should try to apply to
7558 the currently selected font family. Use a positive integer for
7559 <var>fontWeight</var> or select from the following.</p>
7561 <dl class="dl-horizontal">
7563 <dd>No effect. </dd>
7565 <dd>Same as <var>fontWeight</var> = 700.</dd>
7567 <dd>Add 100 to font weight if currently ≤ 800.</dd>
7569 <dd>Subtract 100 to font weight if currently ≤ 100.</dd>
7571 <dd>Same as <var>fontWeight</var> = 400.</dd>
7575 <p>To print a complete list of weight types, use <a href="command-line-options.html#list">-list weight</a>.</p>
7577 <p>For other settings that affect fonts, see the options <a href="command-line-options.html#font">-font</a>, <a href="command-line-options.html#family">-family</a>, <a href="command-line-options.html#stretch">-stretch</a>, and <a href="command-line-options.html#style">-style</a>. </p>
7579 <div style="margin: auto;">
7580 <h3 class="magick-header"><a id="white-point"></a>-white-point <var>x,y</var></h3>
7583 <p class="magick-description">chromaticity white point.</p>
7585 <div style="margin: auto;">
7586 <h3 class="magick-header"><a id="white-threshold"></a>-white-threshold <var>value</var>{<var>%</var>}</h3>
7589 <p class="magick-description">Force to white all pixels above the threshold while leaving all pixels at or below the threshold unchanged.</p>
7591 <p> The threshold value can be given as a percentage or as an absolute integer
7592 value within [0, <var>QuantumRange</var>] corresponding to the
7593 desired <a href="command-line-options.html#channel">‑channel</a> value. See <a href="command-line-options.html#threshold">‑threshold</a>for more details on thresholds and resulting values. </p>
7595 <div style="margin: auto;">
7596 <h3 class="magick-header"><a id="window"></a>-window <var>id</var></h3>
7599 <p class="magick-description">Make the image the background of a window.", 'animate', 'display'</p>
7601 <p><var>id</var> can be a window id or name. Specify <code>root</code>
7602 to select X's root window as the target window.</p>
7604 <p>By default the image is tiled onto the background of the target window. If
7605 <code>backdrop</code> or <a href="command-line-options.html#geometry">-resize</a> are specified, the
7606 image is surrounded by the background color. Refer to <code>X RESOURCES</code>
7609 <p>The image will not display on the root window if the image has more unique
7610 colors than the target window colormap allows. Use <a href="command-line-options.html#colors">-colors</a> to reduce the number of colors.</p>
7612 <div style="margin: auto;">
7613 <h3 class="magick-header"><a id="window-group"></a>-window-group</h3>
7616 <p class="magick-description">specify the window group.</p>
7618 <div style="margin: auto;">
7619 <h3 class="magick-header"><a id="write"></a>-write <var>filename</var></h3>
7622 <p class="magick-description">write an image sequence.</p>
7624 <p>The image sequence preceding the <a href="command-line-options.html#write">-write</a> <var>filename</var> option is written out, and processing continues with the same image in its current state if there are additional options. To restore the image to its original state after writing it, use the <a href="command-line-options.html#write">+write</a> <var>filename</var> option.</p>
7626 <p>Use <a href="command-line-options.html#compress">-compress</a> to specify the type of image compression.</p>
7628 <div style="margin: auto;">
7629 <h3 class="magick-header"><a id="write-mask"></a>-write-mask <var>filename</var></h3>
7632 <p class="magick-description">prevent pixels from being written.</p>
7634 <p>Use <a href="command-line-options.html#read-mask">+write-mask</a> to remove the mask from images.</p>
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