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60 <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#alpha-color">‑alpha‑color</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 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61 <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>
63 <div style="margin: auto;">
64 <h3 class="magick-header"><a id="adaptive-blur"></a>-adaptive-blur <var>radius</var>[x<var>sigma</var>]</h3>
67 <p class="magick-description">Adaptively blur pixels, with decreasing effect near edges.</p>
69 <p>A Gaussian operator of the given radius and standard deviation (<var>sigma</var>) is used. If <var>sigma</var> is not given it
72 <div style="margin: auto;">
73 <h3 class="magick-header"><a id="adaptive-resize"></a>-adaptive-resize <var>geometry</var></h3>
76 <p class="magick-description">Resize the image using data-dependent triangulation.</p>
78 <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>
79 option defaults to data-dependent triangulation. Use the <a
80 href="command-line-options.html#filter">-filter</a> to choose a different resampling algorithm.
81 Offsets, if present in the geometry string, are ignored, and the <a
82 href="command-line-options.html#gravity">-gravity</a> option has no effect.</p>
84 <div style="margin: auto;">
85 <h3 class="magick-header"><a id="adaptive-sharpen"></a>-adaptive-sharpen <var>radius</var>[x<var>sigma</var>]</h3>
88 <p class="magick-description">Adaptively sharpen pixels, with increasing effect near edges.</p>
90 <p>A Gaussian operator of the given radius and standard deviation
91 (<var>sigma</var>) is used. If <var>sigma</var> is not given it
94 <div style="margin: auto;">
95 <h3 class="magick-header"><a id="adjoin"></a>-adjoin</h3>
98 <p class="magick-description">Join images into a single multi-image file.</p>
100 <p>This option is enabled by default. An attempt is made to save all images of
101 an image sequence into the given output file. However, some formats, such as
102 JPEG and PNG, do not support more than one image per file, and in that case
103 ImageMagick is forced to write each image as a separate file. As such, if
104 more than one image needs to be written, the filename given is modified by
105 adding a <a href="command-line-options.html#scene">-scene</a> number before the suffix, in order to
106 make distinct names for each image. </p>
108 <p>Use <a href="command-line-options.html#adjoin">+adjoin</a> to force each image to be written to
109 separate files, whether or not the file format allows multiple images per file
110 (for example, GIF, MIFF, and TIFF). </p>
112 <p>Including a C-style integer format string in the output filename will
113 automagically enable <a href="command-line-options.html#adjoin">+adjoin</a> and are used to specify
114 where the <a href="command-line-options.html#scene">-scene</a> number is placed in the filenames. These
115 strings, such as '<code>%d</code>' or '<code>%03d</code>', are familiar to those
116 who have used the standard <code>printf()</code>' C-library function. As an
117 example, the command</p>
120 convert logo: rose: -morph 15 my%02dmorph.jpg
123 <p>will create a sequence of 17 images (the two given plus 15 more created by
124 <a href="command-line-options.html#morph">-morph</a>), named: my00morph.jpg, my01morph.jpg,
125 my02morph.jpg, ..., my16morph.jpg. </p>
127 <p>In summary, ImageMagick tries to write all images to one file, but will
128 save to multiple files, if any of the following conditions exist...</p>
130 <li>the output image's file format does not allow multi-image files,</li>
131 <li>the <a href="command-line-options.html#adjoin">+adjoin</a> option is given, or</li>
132 <li>a printf() integer format string (eg: "%d") is present in the output
137 <div style="margin: auto;">
138 <h3 class="magick-header"><a id="affine"></a>-affine
139 <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>
142 <p class="magick-description">Set the drawing transformation matrix for combined rotating and scaling.</p>
144 <p>This option sets a transformation matrix, for use by subsequent <a
145 href="command-line-options.html#draw">-draw</a> or <a href="command-line-options.html#transform">-transform</a> options. </p>
147 <p>The matrix entries are entered as comma-separated numeric values either in
148 quotes or without spaces. </p>
150 <p>Internally, the transformation matrix has 3x3 elements, but three of them
151 are omitted from the input because they are constant. The new (transformed)
152 coordinates (<var>x'</var>, <var>y'</var>) of a pixel at
153 position (<var>x</var>, <var>y</var>) in the original
154 image are calculated using the following matrix equation.</p>
156 <p class="text-center"><img class="img-thumbnail" alt="affine transformation" src="../images/affine.png"/> </p>
158 <p> The size of the resulting image is that of the smallest rectangle that
159 contains the transformed source image. The parameters
160 <var>t<sub>x</sub></var> and <var>t<sub>y</sub></var>
161 subsequently shift the image pixels so that those that are moved out of the
162 image area are cut off.</p>
164 <p>The transformation matrix complies with the left-handed pixel coordinate
165 system: positive <var>x</var> and <var>y</var> directions
166 are rightward and downward, resp.; positive rotation is clockwise.</p>
168 <p> If the translation coefficients <var>t<sub>x</sub></var> and
169 <var>t<sub>y</sub></var> are omitted they default to 0,0. Therefore,
170 four parameters suffice for rotation and scaling without translation.</p>
172 <p>Scaling by the factors <var>s<sub>x</sub></var> and
173 <var>s<sub>y</sub></var> in the <var>x</var> and <var>y</var> directions,
174 respectively, is accomplished with the following.</p>
176 <p>See <a href="command-line-options.html#transform">-transform</a>, and the <a
177 href="command-line-options.html#distort">-distort</a> method '<code>Affineprojection</code> for more
182 -affine <var>s<sub>x</sub></var>,0,0,<var>s<sub>y</sub></var>
185 <p>Translation by a displacement (<var>t<sub>x</sub></var>, <var>t<sub>y</sub></var>) is accomplished like so:</p>
188 -affine 1,0,0,1,<var>t<sub>x</sub></var>,<var>t<sub>y</sub></var>
191 <p>Rotate clockwise about the origin (the upper left-hand corner) by an angle
192 <var>a</var> by letting <var>c</var> = cos(<var>a</var>), <var>s</var>
193 = sin(<var>a</var>), and using the following.</p>
196 -affine <var>c</var>,<var>s</var>,-<var>s</var>,<var>c</var>
199 <p>The cumulative effect of a sequence of <a href="command-line-options.html#affine" >-affine</a>
200 transformations can be accomplished by instead by a single <a href="command-line-options.html#affine"
201 >-affine</a> operation using the matrix equal to the product of the matrices
202 of the individual transformations.</p>
204 <p>An attempt is made to detect near-singular transformation matrices. If the
205 matrix determinant has a sufficiently small absolute value it is rejected.</p>
207 <div style="margin: auto;">
208 <h3 class="magick-header"><a id="alpha"></a>-alpha <var>type</var></h3>
211 <p class="magick-description">Gives control of the alpha/matte channel of an image.</p>
213 <p>Used to set a flag on an image indicating whether or not to use existing alpha
214 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>
216 <dl class="dl-horizontal">
219 Enable the image's transparency channel. Note normally Set
220 should be used instead of this, unless you specifically need to
221 preserve existing (but specifically turned Off) transparency
226 associate the alpha channel with the image.</dd>
230 Disables the image's transparency channel. Does not delete or change the
231 existing data, just turns off the use of that data.</dd>
233 <dt>Disassociate</dt>
235 disassociate the alpha channel from the image.</dd>
239 Activates the alpha/matte channel. If it was previously turned off
240 then it also resets the channel to opaque. If the image already had
241 the alpha channel turned on, it will have no effect.</dd>
245 Enables the alpha/matte channel and forces it to be fully opaque.
250 Activates the alpha/matte channel and forces it to be fully
251 transparent. This effectively creates a fully transparent image the
252 same size as the original and with all its original RGB data still
253 intact, but fully transparent. </dd>
257 Copies the alpha channel values into all the color channels and turns
258 'Off' the the image's transparency, so as to generate
259 a grayscale mask of the image's shape. The alpha channel data is left
260 intact just deactivated. This is the inverse of 'Copy'.
265 Turns 'On' the alpha/matte channel, then copies the
266 grayscale intensity of the image, into the alpha channel, converting
267 a grayscale mask into a transparent shaped mask ready to be colored
268 appropriately. The color channels are not modified. </dd>
272 As per 'Copy' but also colors the resulting shape mask with
273 the current background color. That is the RGB color channels is
274 replaced, with appropriate alpha shape.
279 Composite the image over the background color.
284 Set any fully-transparent pixel to the background color, while leaving
285 it fully-transparent. This can make some image file formats, such as
286 PNG, smaller as the RGB values of transparent pixels are more uniform,
287 and thus can compress better.
291 <p>Note that while the obsolete <code>+matte</code> operation was the
292 same as "<code><a href="command-line-options.html#alpha" >-alpha</a> Off</code>", the <code>
293 >-matte</code> operation was the same as "<code><a href="command-line-options.html#alpha" >-alpha</a>
294 Set</code>" and not "<code><a href="command-line-options.html#alpha" >-alpha</a> On</code>". </p>
296 <div style="margin: auto;">
297 <h3 class="magick-header"><a id="alpha-color"></a>-alpha-color <var>color</var></h3>
300 <p class="magick-description">Specify the color to be used with the <a href="command-line-options.html#frame">-frame</a> option.</p>
302 <p>The color is specified using the format described under the <a href="command-line-options.html#fill">-fill</a> option.</p>
304 <p>The default matte color is <code>#BDBDBD</code>, <span
305 style="background-color: #bdbdbd;">this shade of gray</span>.</p>
307 <p>This is an IMv7 option, use <a href="command-line-options.html#mattecolor">mattecolor</a> with IMv6.</p>
310 <div style="margin: auto;">
311 <h3 class="magick-header"><a id="annotate"></a>
312 -annotate <var>degrees</var> <var>text</var><br />
313 -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>
316 <p class="magick-description">Annotate an image with text</p>
318 <p>This is a convenience for annotating an image with text. For more precise
319 control over text annotations, use <a href="command-line-options.html#draw">-draw</a>.</p>
322 <p>The values <var>Xdegrees</var> and <var>Ydegrees</var>
323 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>
325 <p>Using <a href="command-line-options.html#annotate">-annotate</a> <var>degrees</var>
326 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
327 direction of the rotation is positive, which means a clockwise rotation if <var>degrees</var> is positive. (This conforms to the usual mathematical
328 convention once it is realized that the positive <var>y</var>–direction is
329 conventionally considered to be <var>downward</var> for images.)</p>
331 <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
334 <p class="text-center"><img class="img-thumbnail" alt="annotate transformation" src="../images/annotate.png"/></p>
336 <p>If <var>t<sub>x</sub></var> and <var>t<sub>y</sub></var> are omitted, they default to 0. This makes the
337 bottom-left of the text becomes the upper-left corner of the image, which is
338 probably undesirable. Adding a <a href="command-line-options.html#gravity" >-gravity</a> option in this
339 case leads to nice results.</p>
341 <p>Text is any UTF-8 encoded character sequence. If <var>text</var>
342 is of the form '@mytext.txt', the text is read from the file
343 <code>mytext.txt</code>. Text in a file is taken literally; no embedded
344 formatting characters are recognized.</p>
346 <div style="margin: auto;">
347 <h3 class="magick-header"><a id="antialias"></a>-antialias</h3>
350 <p class="magick-description">Enable/Disable of the rendering of anti-aliasing pixels when drawing fonts and lines.</p>
352 <p>By default, objects (e.g. text, lines, polygons, etc.) are antialiased when
353 drawn. Use <a href="command-line-options.html#antialias">+antialias</a> to disable the addition of
354 antialiasing edge pixels. This will then reduce the number of colors added to
355 an image to just the colors being directly drawn. That is, no mixed colors
356 are added when drawing such objects. </p>
358 <div style="margin: auto;">
359 <h3 class="magick-header"><a id="append"></a>-append</h3>
362 <p class="magick-description">Join current images vertically or horizontally.</p>
364 <p>This option creates a single longer image, by joining all the current
365 images in sequence top-to-bottom. Use <a href="command-line-options.html#append">+append</a> to
366 stack images left-to-right. </p>
368 <p>If they are not of the same width, narrower images are padded with the
369 current <a href="command-line-options.html#background">-background</a> color setting, and their
370 position relative to each other can be controlled by the current <a
371 href="command-line-options.html#gravity">-gravity</a> setting. </p>
374 <div style="margin: auto;">
375 <h3 class="magick-header"><a id="attenuate"></a>-attenuate <var>value</var></h3>
378 <p class="magick-description">Lessen (or intensify) when adding noise to an image.</p>
380 <p>If unset the value is equivalent to 1.0, or a maximum noise addition</p>
382 <div style="margin: auto;">
383 <h3 class="magick-header"><a id="authenticate"></a>-authenticate <var>password</var></h3>
386 <p class="magick-description">Decrypt a PDF with a password.</p>
388 <p>Use this option to supply a <var>password</var> for decrypting
389 a PDF that has been encrypted using Microsoft Crypto API (MSC API). The
390 encrypting using the MSC API is not supported.</p>
392 <p>For a different encryption method, see <a href="command-line-options.html#encipher">-encipher</a>
393 and <a href="command-line-options.html#decipher">-decipher</a>. </p>
396 <div style="margin: auto;">
397 <h3 class="magick-header"><a id="auto-gamma"></a>-auto-gamma</h3>
400 <p class="magick-description">Automagically adjust gamma level of image.</p>
402 <p>This calculates the mean values of an image, then applies a calculated <a
403 href="command-line-options.html#gamma" >-gamma</a> adjustment so that is the mean color exists in the
404 image it will get a have a value of 50%. </p>
406 <p>This means that any solid 'gray' image becomes 50% gray. </p>
408 <p>This works well for real-life images with little or no extreme dark and
409 light areas, but tend to fail for images with large amounts of bright sky or
410 dark shadows. It also does not work well for diagrams or cartoon like images.
413 <p>It uses the <a href="command-line-options.html#channel" >-channel</a> setting, (including the
414 '<var>sync</var>' flag for channel synchronization), to determine which color
415 values is used and modified. As the default <a href="command-line-options.html#channel"
416 >-channel</a> setting is '<var>RGB,sync</var>', channels are modified
417 together by the same gamma value, preserving colors. </p>
421 <div style="margin: auto;">
422 <h3 class="magick-header"><a id="auto-level"></a>-auto-level</h3>
425 <p class="magick-description">Automagically adjust color levels of image.</p>
427 <p>This is a 'perfect' image normalization operator. It finds the exact
428 minimum and maximum color values in the image and then applies a <a
429 href="command-line-options.html#level" >-level</a> operator to stretch the values to the full range of
432 <p>The operator is not typically used for real-life images, image scans, or
433 JPEG format images, as a single 'out-rider' pixel can set a bad min/max values
434 for the <a href="command-line-options.html#level" >-level</a> operation. On the other hand it is the
435 right operator to use for color stretching gradient images being used to
436 generate Color lookup tables, distortion maps, or other 'mathematically'
439 <p>The operator is very similar to the <a href="command-line-options.html#normalize">-normalize</a>, <a
440 href="command-line-options.html#contrast-stretch" >-contrast-stretch</a>, and <a href="command-line-options.html#linear-stretch"
441 >-linear-stretch</a> operators, but without 'histogram binning' or 'clipping'
442 problems that these operators may have. That is <a href="command-line-options.html#auto-level"
443 >-auto-level</a> is the perfect or ideal version these operators. </p>
445 <p>It uses the <a href="command-line-options.html#channel" >-channel</a> setting, (including the
446 special '<var>sync</var>' flag for channel synchronization), to determine
447 which color values are used and modified. As the default <a
448 href="command-line-options.html#channel" >+channel</a> setting is '<var>RGB,sync</var>', the
449 '<var>sync</var>' ensures that the color channels will are modified
450 together by the same gamma value, preserving colors, and ignoring
454 <div style="margin: auto;">
455 <h3 class="magick-header"><a id="auto-orient"></a>-auto-orient</h3>
458 <p class="magick-description">adjusts an image so that its orientation is suitable for viewing (i.e. top-left orientation).</p>
460 <p>This operator reads and resets the EXIF image profile setting 'Orientation'
461 and then performs the appropriate 90 degree rotation on the image to orient
462 the image, for correct viewing. </p>
464 <p>This EXIF profile setting is usually set using a gravity sensor in digital
465 camera, however photos taken directly downward or upward may not have an
466 appropriate value. Also images that have been orientation 'corrected' without
467 reseting this setting, may be 'corrected' again resulting in a incorrect
468 result. If the EXIF profile was previously stripped, the <a
469 href="command-line-options.html#auto-orient" >-auto-orient</a> operator will do nothing. </p>
472 <div style="margin: auto;">
473 <h3 class="magick-header"><a id="average"></a>-average</h3>
476 <p class="magick-description">Average a set of images.</p>
478 <p>An error results if the images are not identically sized.</p>
481 <div style="margin: auto;">
482 <h3 class="magick-header"><a id="backdrop"></a>-backdrop</h3>
485 <p class="magick-description">Display the image centered on a backdrop.</p>
487 <p>This backdrop covers the entire workstation screen and is useful for hiding
488 other X window activity while viewing the image. The color of the backdrop is
489 specified as the background color. The color is specified using the format
490 described under the <a href="command-line-options.html#fill">-fill</a> option.</p>
492 <div style="margin: auto;">
493 <h3 class="magick-header"><a id="background"></a>-background <var>color</var></h3>
496 <p class="magick-description">Set the background color.</p>
498 <p>The color is specified using the format described under the <a
499 href="command-line-options.html#fill">-fill</a> option. The default background color (if none is
500 specified or found in the image) is white.</p>
502 <div style="margin: auto;">
503 <h3 class="magick-header"><a id="bench"></a>-bench <var>iterations</var></h3>
506 <p class="magick-description">Measure performance.</p>
508 <p>Repeat the entire command for the given number of <var>iterations</var> and report the user-time and elapsed time. For instance,
509 consider the following command and its output. Modify the benchmark with the
510 -duration to run the benchmark for a fixed number of seconds and -concurrent
511 to run the benchmark in parallel (requires the OpenMP feature).</p>
514 -> convert logo: -resize 200% -bench 5 logo.png
515 Performance[1]: 5i 1.344ips 1.000e 3.710u 0:03.720
516 Performance[2]: 5i 1.634ips 0.549e 3.890u 0:03.060
517 Performance[3]: 5i 2.174ips 0.618e 3.190u 0:02.300
518 Performance[4]: 5i 1.678ips 0.555e 3.810u 0:02.980
519 Performance[4]: 5i 0.875657ips 6.880u 0:05.710
522 <p>In this example, 5 iterations were completed at 2.174 iterations per
523 second, using 3 threads and 3.190 seconds of the user allotted time, for
524 a total elapsed time of 2.300 seconds.</p>
526 <div style="margin: auto;">
527 <h3 class="magick-header"><a id="bias"></a>-bias <var>value</var>{<var>%</var>}</h3>
530 <p class="magick-description">Add bias when convolving an image.</p>
532 <p>This option shifts the output of <a href="command-line-options.html#convolve">‑convolve</a> so that
533 positive and negative results are relative to the specified bias value. </p>
535 <p>This is important for non-HDRI compilations of ImageMagick when dealing
536 with convolutions that contain negative as well as positive values. This is
537 especially the case with convolutions involving high pass filters or edge
538 detection. Without an output bias, the negative values are clipped at
541 <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
542 negative results without clipping to the color value range
543 (0..QuantumRange).</p>
545 <p>See the discussion on HDRI implementations of ImageMagick on the page <a
546 href="high-dynamic-range.html" >High Dynamic-Range Images</a>. For more
547 about HDRI go the ImageMagick <a
548 href="https://www.imagemagick.org/Usage/basics/#hdri" >Usage</a> pages or this
550 href="http://en.wikipedia.org/wiki/High_dynamic_range_imaging">Wikipedia</a>
553 <div style="margin: auto;">
554 <h3 class="magick-header"><a id="black-point-compensation"></a>-black-point-compensation</h3>
557 <p class="magick-description">Use black point compensation.</p>
559 <div style="margin: auto;">
560 <h3 class="magick-header"><a id="black-threshold"></a>-black-threshold <var>value</var>{<var>%</var>}</h3>
563 <p class="magick-description">Force to black all pixels below the threshold while leaving all pixels at or above the threshold unchanged.</p>
565 <p> The threshold value can be given as a percentage or as an absolute integer
566 value within [0, <var>QuantumRange</var>] corresponding to the
567 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>
570 <div style="margin: auto;">
571 <h3 class="magick-header"><a id="blend"></a>-blend <var>geometry</var></h3>
574 <p class="magick-description">blend an image into another by the given absolute value or percent.</p>
576 <p>Blend will average the images together ('plus') according to the
577 percentages given and each pixels transparency. If only a single percentage
578 value is given it sets the weight of the composite or 'source' image, while
579 the background image is weighted by the exact opposite amount. That is a
580 <code>-blend 30%</code> merges 30% of the 'source' image with 70% of the
581 'destination' image. Thus it is equivalent to <code>-blend 30x70%</code>.</p>
584 <div style="margin: auto;">
585 <h3 class="magick-header"><a id="blue-primary"></a>-blue-primary <var>x</var>,<var>y</var></h3>
588 <p class="magick-description">Set the blue chromaticity primary point.</p>
590 <div style="margin: auto;">
591 <h3 class="magick-header"><a id="blue-shift"></a>-blue-shift <var>factor</var></h3>
594 <p class="magick-description">simulate a scene at nighttime in the moonlight. Start with a factor of 1.5</p>
596 <div style="margin: auto;">
598 <div style="margin: auto;">
599 <h3 class="magick-header"><a id="blur"></a>-blur <var>radius</var><br />-blur <var>radius</var>x<var>sigma</var></h3>
602 <p class="magick-description">Reduce image noise and reduce detail levels.</p>
604 <p>Convolve the image with a Gaussian or normal distribution using the given
605 <var >Sigma</var> value. The formula is:</p>
607 <p class="text-center"><img class="img-thumbnail" alt="gaussian distribution" width="243px" height="42px" src="../images/gaussian-blur.png"/></p>
609 <p>The <var >Sigma</var> value is the important argument, and
610 determines the actual amount of blurring that will take place. </p>
612 <p>The <var >Radius</var> is only used to determine the size of the
613 array which will hold the calculated Gaussian distribution. It should be an
614 integer. If not given, or set to zero, IM will calculate the largest possible
615 radius that will provide meaningful results for the Gaussian distribution.
618 <p>The larger the <var >Radius</var> the slower the
619 operation is. However too small a <var >Radius</var>, and sever
620 aliasing effects may result. As a guideline, <var >Radius</var>
621 should be at least twice the <var >Sigma</var> value, though three
622 times will produce a more accurate result. </p>
624 <p>This option differs from <a href="command-line-options.html#gaussian-blur">-gaussian-blur</a> simply
625 by taking advantage of the separability properties of the distribution. Here
626 we apply a single-dimensional Gaussian matrix in the horizontal direction,
627 then repeat the process in the vertical direction.</p>
629 <p>The <a href="command-line-options.html#virtual-pixel">-virtual-pixel</a> setting will determine how
630 pixels which are outside the image proper are blurred into the final result.
634 <div style="margin: auto;">
635 <h3 class="magick-header"><a id="border"></a>-border <var>geometry</var></h3>
638 <p class="magick-description">Surround the image with a border of color. </p>
640 <p>Set the width and height using the <var>size</var> portion of the
641 <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
644 <p>As of IM 6.7.8-8, the <var>geometry</var> arguments behave as follows:</p>
646 <dl class="dl-horizontal">
647 <dt><var>value</var></dt>
648 <dd>value is added to both left/right and top/bottom</dd>
649 <dt><var>value-x</var><kbd>x</kbd></dt>
650 <dd>value-x is added only to left/right and top/bottom are unchanged</dd>
651 <dt><kbd>x</kbd><var>value-y</var></dt>
652 <dd>value-y is added only to top/bottom and left/right are unchanged</dd>
653 <dt><var>value-x</var><kbd>x</kbd><var>value-y</var></dt>
654 <dd>value-x is added to left/right and value-y added to top/bottom</dd>
655 <dt><var>value-x</var><kbd>x</kbd>0</dt>
656 <dd>value-x is added only to left/right and top/bottom are unchanged</dd>
657 <dt>0<kbd>x</kbd><var>value-y</var></dt>
658 <dd>value-y is added only to top/bottom and left/right are unchanged</dd>
659 <dt><var>value</var>%</dt>
660 <dd>value % of width is added to left/right and value % of height is added to top/bottom</dd>
661 <dt><var>value-x</var><kbd>x</kbd>%</dt>
662 <dd>value-x % of width is added to left/right and to top/bottom</dd>
663 <dt>x<var>value-y</var>%</dt>
664 <dd>value-y % of height is added to top/bottom and to left/right</dd>
665 <dt><var>value-x</var>%<kbd>x</kbd><var>value-y</var>%</dt>
666 <dd>value-x % of width is added to left/right and value-y % of height is added to top/bottom</dd>
667 <dt><var>value-x</var>%<kbd>x</kbd>0%</dt>
668 <dd>value-x % of width is added to left/right and top/bottom are unchanged</dd>
669 <dt>0%<kbd>x</kbd><var>value-y</var>%</dt>
670 <dd>value-y % of height is added to top/bottom and left/right are unchanged</dd>
673 <p>Set the border color by preceding with the <a
674 href="command-line-options.html#bordercolor">-bordercolor</a> setting.</p>
676 <p>The <a href="command-line-options.html#border">-border</a> operation is affected by the current <a
677 href="command-line-options.html#compose">-compose</a> setting and assumes that this is using the default
678 '<code>Over</code>' composition method. It generates an image of the appropriate
679 size colors by the current <a href="command-line-options.html#bordercolor">-bordercolor</a> before
680 overlaying the original image in the center of this net image. This means that
681 with the default compose method of '<code>Over</code>' any transparent parts may
682 be replaced by the current <a href="command-line-options.html#bordercolor">-bordercolor</a> setting.</p>
683 <p>See also the <a href="command-line-options.html#frame">-frame</a> option, which has more
686 <div style="margin: auto;">
687 <h3 class="magick-header"><a id="bordercolor"></a>-bordercolor <var>color</var></h3>
690 <p class="magick-description">Set the border color.</p>
692 <p>The color is specified using the format described under the <a href="command-line-options.html#fill">-fill</a> option.</p>
694 <p>The default border color is <code>#DFDFDF</code>, <span style="background-color: #dfdfdf;">this shade of gray</span>.</p>
696 <div style="margin: auto;">
697 <h3 class="magick-header"><a id="borderwidth"></a>-borderwidth <var>geometry</var> </h3>
700 <p class="magick-description">Set the border width.</p>
702 <div style="margin: auto;">
703 <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>
706 <p class="magick-description">Adjust the brightness and/or contrast of the image.</p>
708 <p>Brightness and Contrast values apply changes to the input image. They are
709 not absolute settings. A brightness or contrast value of zero means no change.
710 The range of values is -100 to +100 on each. Positive values increase the
711 brightness or contrast and negative values decrease the brightness or contrast.
712 To control only contrast, set the brightness=0. To control only brightness,
713 set contrast=0 or just leave it off.</p>
715 <p>You may also use <a href="command-line-options.html#fill">-channel</a> to control which channels to
716 apply the brightness and/or contrast change. The default is to apply the same
717 transformation to all channels.</p>
719 <p>Brightness and Contrast arguments are converted to offset and slope of a
720 linear transform and applied
721 using <a href="command-line-options.html#fill">-function polynomial "slope,offset"</a>.</p>
723 <p>The slope varies from 0 at contrast=-100 to almost vertical at
724 contrast=+100. For brightness=0 and contrast=-100, the result are totally
725 midgray. For brightness=0 and contrast=+100, the result will approach but
726 not quite reach a threshold at midgray; that is the linear transformation
727 is a very steep vertical line at mid gray.</p>
729 <p>Negative slopes, i.e. negating the image, are not possible with this
730 function. All achievable slopes are zero or positive.</p>
732 <p>The offset varies from -0.5 at brightness=-100 to 0 at brightness=0 to +0.5
733 at brightness=+100. Thus, when contrast=0 and brightness=100, the result is
734 totally white. Similarly, when contrast=0 and brightness=-100, the result is
737 <p>As the range of values for the arguments are -100 to +100, adding the '%'
738 symbol is no different than leaving it off.</p>
740 <div style="margin: auto;">
741 <h3 class="magick-header"><a id="cache"></a>-cache <var>threshold</var></h3>
744 <p class="magick-description">(This option has been replaced by the <a href='command-line-options.html#limit'>-limit</a> option).</p>
746 <div style="margin: auto;">
747 <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>
750 <p class="magick-description">Canny edge detector uses a multi-stage algorithm to detect a wide range of edges in the image.</p>
752 <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>
754 <div style="margin: auto;">
755 <h3 class="magick-header"><a id="caption"></a>-caption <var>string</var></h3>
758 <p class="magick-description">Assign a caption to an image.</p>
760 <p>This option sets the caption meta-data of an image read in after this
761 option has been given. To modify a caption of images already in memory use
762 "<code><a href="command-line-options.html#set">-set</a> caption</code>". </p>
764 <p>The caption can contain special format characters listed in the <a
765 href="escape.html">Format and
766 Print Image Properties</a>. These attributes are expanded when the caption
767 is finally assigned to the individual images. </p>
769 <p>If the first character of <var>string</var> is <var>@</var>, the image caption is read from a file titled by the
770 remaining characters in the string. Comments read in from a file are literal;
771 no embedded formatting characters are recognized.</p>
773 <p>Caption meta-data is not visible on the image itself. To do that use the
774 <a href="command-line-options.html#annotate">-annotate</a> or <a href="command-line-options.html#draw">-draw</a> options
780 -caption "%m:%f %wx%h" bird.miff
783 <p>produces an image caption of <code>MIFF:bird.miff 512x480</code> (assuming
784 that the image <code>bird.miff</code> has a width of 512 and a height of
788 <div style="margin: auto;">
789 <h3 class="magick-header"><a id="cdl"></a>-cdl <var>filename</var></h3>
792 <p class="magick-description">color correct with a color decision list.</p>
794 <p>Here is an example color correction collection:</p>
797 <?xml version="1.0" encoding="UTF-8"?>
798 <ColorCorrectionCollection xmlns="urn:ASC:CDL:v1.2">
799 <ColorCorrection id="cc06668">
801 <Slope> 0.9 1.2 0.5 </Slope>
802 <Offset> 0.4 -0.5 0.6 </Offset>
803 <Power> 1.0 0.8 1.5 </Power>
806 <Saturation> 0.85 </Saturation>
808 </ColorCorrection>
809 </ColorCorrectionCollection>
812 <div style="margin: auto;">
813 <h3 class="magick-header"><a id="channel"></a>-channel <var>type</var></h3>
816 <p class="magick-description">Specify those image color channels to which subsequent operators are limited.</p>
818 <p>Choose from: <code>Red</code>, <code>Green</code>, <code>Blue</code>,
819 <code>Alpha</code>, <code>Gray</code>, <code>Cyan</code>, <code>Magenta</code>,
820 <code>Yellow</code>, <code>Black</code>, <code>Opacity</code>,
821 <code>Index</code>, <code>RGB</code>, <code>RGBA</code>, <code>CMYK</code>, or
822 <code>CMYKA</code>.</p>
824 <p>The channels above can also be specified as a comma-separated list or can be
825 abbreviated as a concatenation of the letters '<code>R</code>', '<code>G</code>',
826 '<code>B</code>', '<code>A</code>', '<code>O</code>', '<code>C</code>',
827 '<code>M</code>', '<code>Y</code>', '<code>K</code>'.
829 For example, to only select the <code>Red</code> and <code>Blue</code> channels
830 you can either use </p>
834 <p>or you can use the short hand form</p>
839 <p>All the channels that are present in an image can be specified using the
840 special channel type <code>All</code>. Not all operators are 'channel capable',
841 but generally any operators that are generally 'grey-scale' image operators,
842 will understand this setting. See individual operator documentation. </p>
846 <p>On top of the normal channel selection an extra flag can be specified,
847 '<code>Sync</code>'. This is turned on by default and if set means that
848 operators that understand this flag should perform: cross-channel
849 synchronization of the channels. If not specified, then most grey-scale
850 operators will apply their image processing operations to each individual
851 channel (as specified by the rest of the <a href="command-line-options.html#channel">-channel</a>
852 setting) completely independently from each other. </p>
854 <p>For example for operators such as <a href="command-line-options.html#auto-level">-auto-level</a> and
855 <a href="command-line-options.html#auto-gamma">-auto-gamma</a> the color channels are modified
856 together in exactly the same way so that colors will remain in-sync. Without
857 it being set, then each channel is modified separately and
858 independently, which may produce color distortion. </p>
860 <p>The <a href="command-line-options.html#morphology">-morphology</a> '<code>Convolve</code>' method
861 and the <a href="command-line-options.html#compose">-compose</a> mathematical methods, also understands
862 the '<code>Sync</code>' flag to modify the behavior of pixel colors according
863 to the alpha channel (if present). That is to say it will modify the image
864 processing with the understanding that fully-transparent colors should not
865 contribute to the final result. </p>
867 <p>Basically, by default, operators work with color channels in synchronous, and
868 treats transparency as special, unless the <a href="command-line-options.html#channel">-channel</a>
869 setting is modified so as to remove the effect of the '<code>Sync</code>' flag.
870 How each operator does this depends on that operators current implementation.
871 Not all operators understands this flag at this time, but that is changing.
874 <p>To print a complete list of channel types, use <a href="command-line-options.html#list">-list
877 <p>By default, ImageMagick sets <a href="command-line-options.html#channel">-channel</a> to the value
878 '<code>RGBK,sync</code>', which specifies that operators act on all color
879 channels except the transparency channel, and that all the color channels are
880 to be modified in exactly the same way, with an understanding of transparency
881 (depending on the operation being applied). The 'plus' form <a
882 href="command-line-options.html#channel" >+channel</a> will reset the value back to this default. </p>
884 <p>Options that are affected by the <a href="command-line-options.html#channel" >-channel</a> setting
885 include the following.
887 <a href="command-line-options.html#auto-gamma">-auto-gamma</a>,
888 <a href="command-line-options.html#auto-level">-auto-level</a>,
889 <a href="command-line-options.html#black-threshold">-black-threshold</a>,
890 <a href="command-line-options.html#blur">-blur</a>,
891 <a href="command-line-options.html#clamp">-clamp</a>,
892 <a href="command-line-options.html#clut">-clut</a>,
893 <a href="command-line-options.html#combine">-combine</a>,
894 <a href="command-line-options.html#composite">-composite</a> (Mathematical compose methods only),
895 <a href="command-line-options.html#convolve">-convolve</a>,
896 <a href="command-line-options.html#contrast-stretch">-contrast-stretch</a>,
897 <a href="command-line-options.html#evaluate">-evaluate</a>,
898 <a href="command-line-options.html#function">-function</a>,
899 <a href="command-line-options.html#fx">-fx</a>,
900 <a href="command-line-options.html#gaussian-blur">-gaussian-blur</a>,
901 <a href="command-line-options.html#hald-clut">-hald-clut</a>,
902 <a href="command-line-options.html#motion-blur">-motion-blur</a>,
903 <a href="command-line-options.html#morphology">-morphology</a>,
904 <a href="command-line-options.html#negate">-negate</a>,
905 <a href="command-line-options.html#normalize">-normalize</a>,
906 <a href="command-line-options.html#ordered-dither">-ordered-dither</a>,
907 <a href="command-line-options.html#radial-blur">-radial-blur</a>,
908 <a href="command-line-options.html#random-threshold">-random-threshold</a>,
909 <a href="command-line-options.html#separate">-separate</a>,
910 <a href="command-line-options.html#threshold">-threshold</a>, and
911 <a href="command-line-options.html#white-threshold">-white-threshold</a>.
914 <p>Warning, some operators behave differently when the <a href="command-line-options.html#channel"
915 >+channel</a> default setting is in effect, verses ANY user defined <a
916 href="command-line-options.html#channel" >-channel</a> setting (including the equivalent of the
917 default). These operators have yet to be made to understand the newer 'Sync'
920 <p>For example <a href="command-line-options.html#threshold">-threshold</a> will by default grayscale
921 the image before thresholding, if no <a href="command-line-options.html#channel" >-channel</a> setting
922 has been defined. This is not 'Sync flag controlled, yet. </p>
924 <p>Also some operators such as <a href="command-line-options.html#blur">-blur</a>, <a
925 href="command-line-options.html#gaussian-blur">-gaussian-blur</a>, will modify their handling of the
926 color channels if the '<code>alpha</code>' channel is also enabled by <a
927 href="command-line-options.html#channel" >-channel</a>. Generally this done to ensure that
928 fully-transparent colors are treated as being fully-transparent, and thus any
929 underlying 'hidden' color has no effect on the final results. Typically
930 resulting in 'halo' effects. The newer <a href="command-line-options.html#morphology">-morphology</a>
931 convolution equivalents however does have a understanding of the 'Sync' flag
932 and will thus handle transparency correctly by default. </p>
934 <p>As a alpha channel is optional within images, some operators will read the
935 color channels of an image as a greyscale alpha mask, when the image has no
936 alpha channel present, and the <a href="command-line-options.html#channel" >-channel</a> setting tells
937 the operator to apply the operation using alpha channels. The <a
938 href="command-line-options.html#clut">-clut</a> operator is a good example of this. </p>
940 <div style="margin: auto;">
941 <h3 class="magick-header"><a id="channel-fx"></a>-channel-fx <var>expression</var></h3>
944 <p class="magick-description">exchange, extract, or copy one or more image channels.</p>
946 <p>The expression consists of one or more channels, either mnemonic or numeric (e.g. red or 0, green or 1, etc.), separated by certain operation symbols as follows:</p>
949 <=> exchange two channels (e.g. red<=>blue)
950 => copy one channel to another channel (e.g. red=>green)
951 = assign a constant value to a channel (e.g. red=50%)
952 , write new image with channels in the specified order (e.g. red, green)
953 ; add a new output image for the next set of channel operations (e.g. red; green; blue)
954 | move to the next input image for the source of channel data (e.g. | gray=>alpha)
957 <p>For example, to create 3 grayscale images from the red, green, and blue channels of an image, use:</p>
960 -channel-fx "red; green; blue"
963 <p>A channel without an operation symbol implies separate (i.e, semicolon).</p>
965 <p>Here we take an sRGB image and a grayscale image and inject the grayscale image into the alpha channel:</p>
967 convert wizard.png mask.pgm -channel-fx '| gray=>alpha' wizard-alpha.png
969 <p>Use a similar command to define a read mask:</p>
971 convert wizard.png mask.pgm -channel-fx '| gray=>read-mask' wizard-mask.png
974 <p>Add <code>-debug pixel</code> prior to the <code>-channel-fx</code> option to track the channel morphology.</p>
976 <div style="margin: auto;">
977 <h3 class="magick-header"><a id="charcoal"></a>-charcoal <var>factor</var></h3>
980 <p class="magick-description">Simulate a charcoal drawing.</p>
983 <div style="margin: auto;">
984 <h3 class="magick-header"><a id="chop"></a>-chop <var>geometry</var></h3>
987 <p class="magick-description">Remove pixels from the interior of an image.</p>
989 <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>
990 and <var>height</var> given in the of the <var>size</var>
991 portion of the <var>geometry</var> argument give the number of
992 columns and rows to remove. The <var>offset</var> portion of
993 the <var>geometry</var> argument is influenced by
994 a <a href="command-line-options.html#gravity">-gravity</a> setting, if present.</p>
996 <p>The <a href="command-line-options.html#chop">-chop</a> option removes entire rows and columns,
997 and moves the remaining corner blocks leftward and upward to close the gaps.</p>
999 <p>While it can remove internal rows and columns of pixels, it is more
1000 typically used with as <a href="command-line-options.html#gravity">-gravity</a> setting and zero
1001 offsets so as to remove a single edge from an image. Compare this to <a
1002 href="command-line-options.html#shave" >-shave</a> which removes equal numbers of pixels from opposite
1003 sides of the image. </p>
1005 <p>Using <a href="command-line-options.html#chop">-chop</a> effectively undoes the results of a <a
1006 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>
1008 <div style="margin: auto;">
1009 <h3 class="magick-header"><a id="clamp"></a>-clamp</h3>
1012 <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>
1014 <div style="margin: auto;">
1015 <h3 class="magick-header"><a id="clip"></a>-clip</h3>
1018 <p class="magick-description">Apply the clipping path if one is present.</p>
1020 <p>If a clipping path is present, it is applied to subsequent operations.</p>
1022 <p>For example, in the command</p>
1025 convert cockatoo.tif -clip -negate negated.tif
1028 <p>only the pixels within the clipping path are negated.</p>
1030 <p>The <a href="command-line-options.html#clip">-clip</a> feature requires SVG support. If the SVG
1031 delegate library is not present, the option is ignored.</p>
1033 <p>Use <a href="command-line-options.html#clip">+clip</a> to disable clipping for subsequent operations.</p>
1035 <div style="margin: auto;">
1036 <h3 class="magick-header"><a id="clip-mask"></a>-clip-mask</h3>
1039 <p class="magick-description">Clip the image as defined by this mask.</p>
1041 <p>Use the alpha channel of the current image as a mask. Any areas that is
1042 white is not modified by any of the 'image processing operators' that follow,
1043 until the mask is removed. Pixels in the black areas of the clip mask are
1044 modified per the requirements of the operator. </p>
1046 <p>In some ways this is similar to (though not the same) as defining
1047 a rectangular <a href="command-line-options.html#region" >-region</a>, or using the negative of the
1048 mask (third) image in a three image <a href="command-line-options.html#composite" >-composite</a>,
1051 <p>Use <a href="command-line-options.html#clip-mask">+clip-mask</a> to disable clipping for subsequent operations.</p>
1053 <div style="margin: auto;">
1054 <h3 class="magick-header"><a id="clip-path"></a>-clip-path <var>id</var></h3>
1057 <p class="magick-description">Clip along a named path from the 8BIM profile.</p>
1059 <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>
1061 <p>Use <a href="command-line-options.html#clip-path">+clip-path</a> to disable clipping for subsequent operations.</p>
1063 <div style="margin: auto;">
1064 <h3 class="magick-header"><a id="clone"></a>-clone <var>index(s)</var></h3>
1067 <p class="magick-description">make a clone of an image (or images).</p>
1069 <p>Inside parenthesis (where the operator is normally used) it will make a
1070 clone of the images from the last 'pushed' image sequence, and adds them to
1071 the end of the current image sequence. Outside parenthesis
1072 (not recommended) it clones the images from the current image sequence. </p>
1074 <p>Specify the image by its index in the sequence. The first image is index
1075 0. Negative indexes are relative to the end of the sequence; for
1076 example, <code>−1</code>
1077 represents the last image of the sequence. Specify a range of images with a
1078 dash (e.g. <code>0−4</code>). Separate multiple indexes with commas but no
1079 spaces (e.g. <code>0,2,5</code>). A value of '<code>0−−1</code> will
1080 effectively clone all the images. </p>
1082 <p>The <a href="command-line-options.html#clone">+clone</a> will simply make a copy of the last image
1083 in the image sequence, and is thus equivalent to using a argument of
1084 '<code>−1</code>'. </p>
1086 <div style="margin: auto;">
1087 <h3 class="magick-header"><a id="clut"></a>-clut</h3>
1090 <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>
1092 <p>The second (LUT) image is ordinarily a gradient image containing the
1093 histogram mapping of how each channel should be modified. Typically it is a
1094 either a single row or column image of replacement color values. If larger
1095 than a single row or column, values are taken from a diagonal line from
1096 top-left to bottom-right corners.</p>
1098 <p>The lookup is further controlled by the <a
1099 href="command-line-options.html#interpolate">-interpolate</a> setting, which is especially handy for an
1100 LUT which is not the full length needed by the ImageMagick installed Quality
1101 (Q) level. Good settings for this are the '<code>bilinear</code>' and
1102 '<code>bicubic</code>' interpolation settings, which give smooth color
1103 gradients, and the '<code>integer</code>' setting for a direct, unsmoothed
1104 lookup of color values. </p>
1106 <p>This operator is especially suited to replacing a grayscale image with a
1107 specific color gradient from the CLUT image. </p>
1109 <p>Only the channel values defined by the <a href="command-line-options.html#channel">-channel</a>
1110 setting will have their values replaced. In particular, since the default <a
1111 href="command-line-options.html#channel">-channel</a> setting is <code>RGB</code>, this means that
1112 transparency (alpha/matte channel) is not affected, unless the <a
1113 href="command-line-options.html#channel">-channel</a> setting is modified. When the alpha channel is
1114 set, it is treated by the <a href="command-line-options.html#clut" >-clut</a> operator in the same way
1115 as the other channels, implying that alpha/matte values are replaced using the
1116 alpha/matte values of the original image. </p>
1118 <p>If either the image being modified, or the lookup image, contains no
1119 transparency (i.e. <a href="command-line-options.html#alpha" >-alpha</a> is turned 'off') but the <a
1120 href="command-line-options.html#channel">-channel</a> setting includes alpha replacement, then it is
1121 assumed that image represents a grayscale gradient which is used for the
1122 replacement alpha values. That is you can use a grayscale CLUT image to
1123 adjust a existing images alpha channel, or you can color a grayscale image
1124 using colors form CLUT containing the desired colors, including transparency.
1127 <p>See also <a href="command-line-options.html#hald-clut" >-hald-clut</a> which replaces colors
1128 according to the lookup of the full color RGB value from a 2D representation
1129 of a 3D color cube. </p>
1132 <div style="margin: auto;">
1133 <h3 class="magick-header"><a id="coalesce"></a>-coalesce</h3>
1136 <p class="magick-description">Fully define the look of each frame of an GIF animation sequence, to form a 'film strip' animation.</p>
1138 <p>Overlay each image in an image sequence according to
1139 its <a href="command-line-options.html#dispose">-dispose</a> meta-data, to reproduce the look of
1140 an animation at each point in the animation sequence. All images should be
1141 the same size, and are assigned appropriate GIF disposal settings for the
1142 animation to continue working as expected as a GIF animation. Such frames
1143 are more easily viewed and processed than the highly optimized GIF overlay
1146 <p>The animation can be re-optimized after processing using
1147 the <a href="command-line-options.html#layers">-layers</a> method '<code>optimize</code>', although
1148 there is no guarantee that the restored GIF animation optimization is
1149 better than the original. </p>
1152 <div style="margin: auto;">
1153 <h3 class="magick-header"><a id="colorize"></a>-colorize <var>value</var></h3>
1156 <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>
1158 <p>Specify the amount of colorization as a percentage. Separate colorization
1159 values can be applied to the red, green, and blue channels of the image with
1160 a comma-delimited list of colorization
1161 values (e.g., <code>-colorize 0,0,50</code>).</p>
1163 <div style="margin: auto;">
1164 <h3 class="magick-header"><a id="colormap"></a>-colormap <var>type</var></h3>
1167 <p class="magick-description">Define the colormap type.</p>
1169 <p>The <var>type</var> can be <code>shared</code> or <code>private</code>.</p>
1171 <p>This option only applies when the default X server visual
1172 is <code>PseudoColor</code> or <code>GrayScale</code>. Refer
1173 to <a href="command-line-options.html#visual">-visual</a> for more details. By default,
1174 a shared colormap is allocated. The image shares colors with
1175 other X clients. Some image colors could be approximated,
1176 therefore your image may look very different than intended.
1177 If <code>private</code> is chosen, the image colors appear exactly
1178 as they are defined. However, other clients may go <var>technicolor</var>
1179 when the image colormap is installed.</p>
1181 <div style="margin: auto;">
1182 <h3 class="magick-header"><a id="colors"></a>-colors <var>value</var></h3>
1185 <p class="magick-description">Set the preferred number of colors in the image.</p>
1187 <p>The actual number of colors in the image may be less than your request,
1188 but never more. Note that this a color reduction option. Images with fewer
1189 unique colors than specified by <var>value</var> will have any
1190 duplicate or unused colors removed. The ordering of an existing color
1191 palette may be altered. When converting an image from color to grayscale,
1192 it is more efficient to convert the image to the gray colorspace before
1193 reducing the number of colors. Refer to
1194 the <a href="http://www.imagemagick.org/www/quantize.html">
1195 color reduction algorithm</a> for more details.</p>
1197 <div style="margin: auto;">
1198 <h3 class="magick-header"><a id="color-matrix"></a>-color-matrix <var>matrix</var></h3>
1201 <p class="magick-description">apply color correction to the image.</p>
1203 <p>This option permits saturation changes, hue rotation, luminance to alpha,
1204 and various other effects. Although variable-sized transformation matrices
1205 can be used, typically one uses a 5x5 matrix for an RGBA image and a 6x6
1206 for CMYKA (or RGBA with offsets). The matrix is similar to those used by
1207 Adobe Flash except offsets are in column 6 rather than 5 (in support of
1208 CMYKA images) and offsets are normalized (divide Flash offset by 255).</p>
1210 <p>As an example, to add contrast to an image with offsets, try this command:</p>
1213 convert kittens.jpg -color-matrix \
1214 " 1.5 0.0 0.0 0.0, 0.0, -0.157 \
1215 0.0 1.5 0.0 0.0, 0.0, -0.157 \
1216 0.0 0.0 1.5 0.0, 0.0, -0.157 \
1217 0.0 0.0 0.0 1.0, 0.0, 0.0 \
1218 0.0 0.0 0.0 0.0, 1.0, 0.0 \
1219 0.0 0.0 0.0 0.0, 0.0, 1.0" kittens.png
1221 <div style="margin: auto;">
1222 <h3 class="magick-header"><a id="colorspace"></a>-colorspace <var>value</var></h3>
1225 <p class="magick-description">Set the image colorspace.</p>
1234 OHTA Rec601YCbCr Rec709YCbCr RGB
1235 scRGB sRGB Transparent xyY
1237 YIQ YPbPr YUV Undefined
1240 <p>To print a complete list of colorspaces, use <a href="command-line-options.html#list">-list colorspace</a>.</p>
1242 <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>
1244 <table class="table table-condensed table-striped">
1245 <caption>Conversion of RGB to Other Color Spaces</caption>
1246 <tr><th valign="middle">CMY</th></tr>
1247 <tr><td valign="middle">C=<var>QuantumRange</var>−R</td></tr>
1248 <tr><td valign="middle">M=<var>QuantumRange</var>−G</td></tr>
1249 <tr><td valign="middle">Y=<var>QuantumRange</var>−B</td></tr>
1250 <tr><th valign="middle">CMYK — starts with CMY from above</th></tr>
1251 <tr><td valign="middle">K=min(C,Y,M)</td></tr>
1252 <tr><td valign="middle">C=<var>QuantumRange</var>*(C−K)/(<var>QuantumRange</var>−K)</td></tr>
1253 <tr><td valign="middle">M=<var>QuantumRange</var>*(M−K)/(<var>QuantumRange</var>−K)</td></tr>
1254 <tr><td valign="middle">Y=<var>QuantumRange</var>*(Y−K)/(<var>QuantumRange</var>−K)</td></tr>
1256 <tr><th valign="middle">Gray</th></tr>
1257 <tr><td valign="middle">Gray = 0.298839*R+0.586811*G+0.114350*B</td></tr>
1259 <tr><th valign="middle">HSB — Hue, Saturation, Brightness; like a cone peak downward</th></tr>
1260 <tr><td valign="middle">H=angle around perimeter (0 to 360 deg); H=0 is red; increasing angles toward green</td></tr>
1261 <tr><td valign="middle">S=distance from axis outward</td></tr>
1262 <tr><td valign="middle">B=distance along axis from bottom upward; B=max(R,G,B); <var>intensity-like</var></td></tr>
1264 <tr><th valign="middle">HSL — Hue, Saturation, Lightness; like a double cone end-to-end with peaks at very top and bottom</th></tr>
1265 <tr><td valign="middle">H=angle around perimeter (0 to 360 deg); H=0 is red; increasing angles toward green</td></tr>
1266 <tr><td valign="middle">S=distance from axis outward</td></tr>
1267 <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>
1269 <tr><th valign="middle">HWB — Hue, Whiteness, Blackness</th></tr>
1270 <tr><td valign="middle">Hue (complicated equation)</td></tr>
1271 <tr><td valign="middle">Whiteness (complicated equation)</td></tr>
1272 <tr><td valign="middle">Blackness (complicated equation)</td></tr>
1274 <tr><th valign="middle">LAB</th></tr>
1275 <tr><td valign="middle">L (complicated equation relating X,Y,Z)</td></tr>
1276 <tr><td valign="middle">A (complicated equation relating X,Y,Z)</td></tr>
1277 <tr><td valign="middle">B (complicated equation relating X,Y,Z)</td></tr>
1279 <tr><th valign="middle">LOG</th></tr>
1280 <tr><td valign="middle">I1 (complicated equation involving logarithm of R)</td></tr>
1281 <tr><td valign="middle">I2 (complicated equation involving logarithm of G)</td></tr>
1282 <tr><td valign="middle">I3 (complicated equation involving logarithm of B)</td></tr>
1284 <tr><th valign="middle">OHTA — approximates principal components transformation</th></tr>
1285 <tr><td valign="middle">I1=0.33333*R+0.33334*G+0.33333*B; <var>intensity-like</var></td></tr>
1286 <tr><td valign="middle">I2=(0.50000*R+0.00000*G−0.50000*B)*(<var>QuantumRange</var>+1)/2</td></tr>
1287 <tr><td valign="middle">I3=(−0.25000*R+0.50000*G−0.25000*B)*(<var>QuantumRange</var>+1)/2</td></tr>
1289 <tr><th valign="middle">Rec601Luma</th></tr>
1290 <tr><td valign="middle">Gray = 0.298839*R+0.586811*G+0.114350*B</td></tr>
1292 <tr><th valign="middle">Rec601YCbCr</th></tr>
1293 <tr><td valign="middle">Y=0.2988390*R+0.5868110*G+0.1143500*B; <var>intensity-like</var></td></tr>
1294 <tr><td valign="middle">Cb=(−0.168736*R-0.331264*G+0.500000*B)*(<var>QuantumRange</var>+1)/2</td></tr>
1295 <tr><td valign="middle">Cr=(0.500000*R−0.418688*G−0.081312*B)*(<var>QuantumRange</var>+1)/2</td></tr>
1297 <tr><th valign="middle">Rec709Luma</th></tr>
1298 <tr><td valign="middle">Gray=0.212656*R+0.715158*G+0.072186*B</td></tr>
1300 <tr><th valign="middle">Rec709YCbCr</th></tr>
1301 <tr><td valign="middle">Y=0.212656*R+0.715158*G+0.072186*B; <var>intensity-like</var></td></tr>
1302 <tr><td valign="middle">Cb=(−0.114572*R−0.385428*G+0.500000*B)+(<var>QuantumRange</var>+1)/2</td></tr>
1303 <tr><td valign="middle">Cr=(0.500000*R−0.454153*G−0.045847*B)+(<var>QuantumRange</var>+1)/2</td></tr>
1305 <tr><th valign="middle">sRGB</th></tr>
1306 <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>
1307 <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>
1308 <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>
1310 <tr><th valign="middle">XYZ</th></tr>
1311 <tr><td valign="middle">X=0.4124564*R+0.3575761*G+0.1804375*B</td></tr>
1312 <tr><td valign="middle">Y=0.2126729*R+0.7151522*G+0.0721750*B</td></tr>
1313 <tr><td valign="middle">Z=0.0193339*R+0.1191920*G+0.9503041*B</td></tr>
1315 <tr><th valign="middle">YCC</th></tr>
1316 <tr><td valign="middle">Y=(0.298839*R+0.586811*G+0.114350*B) (with complicated scaling); <var>intensity-like</var></td></tr>
1317 <tr><td valign="middle">C1=(−0.298839*R−0.586811*G+0.88600*B) (with complicated scaling)</td></tr>
1318 <tr><td valign="middle">C2=(0.70100*R−0.586811*G−0.114350*B) (with complicated scaling)</td></tr>
1320 <tr><th valign="middle">YCbCr</th></tr>
1321 <tr><td valign="middle">Y=0.2988390*R+0.5868110*G+0.1143500*B; <var>intensity-like</var></td></tr>
1322 <tr><td valign="middle">Cb=(−0.168736*R−0.331264*G+0.500000*B)*(<var>QuantumRange</var>+1)/2</td></tr>
1323 <tr><td valign="middle">Cr=(0.500000*R−0.418688*G−0.081312*B)*(<var>QuantumRange</var>+1)/2</td></tr>
1325 <tr><th valign="middle">YIQ</th></tr>
1326 <tr><td valign="middle">Y=0.298839*R+0.586811*G+0.114350*B; <var>intensity-like</var></td></tr>
1327 <tr><td valign="middle">I=(0.59600*R−0.27400*G−0.32200*B)*(<var>QuantumRange</var>+1)/2</td></tr>
1328 <tr><td valign="middle">Q=(0.21100*R−0.52300*G+0.31200*B)*(<var>QuantumRange</var>+1)/2</td></tr>
1330 <tr><th valign="middle">YPbPr</th></tr>
1331 <tr><td valign="middle">Y=0.2988390*R+0.5868110*G+0.1143500*B; <var>intensity-like</var></td></tr>
1332 <tr><td valign="middle">Pb=(−0.168736*R−0.331264*G+0.500000*B)*(<var>QuantumRange</var>+1)/2</td></tr>
1333 <tr><td valign="middle">Pr=(0.500000*R−0.418688*G−0.081312*B)*(<var>QuantumRange</var>+1)/2</td></tr>
1335 <tr><th valign="middle">YUV</th></tr>
1336 <tr><td valign="middle">Y=0.298839*R+0.586811*G+0.114350*B; <var>intensity-like</var></td></tr>
1337 <tr><td valign="middle">U=(−0.14740*R−0.28950*G+0.43690*B)*(<var>QuantumRange</var>+1)/2</td></tr>
1338 <tr><td valign="middle">V=(0.61500*R−0.51500*G−0.10000*B)*(<var>QuantumRange</var>+1)/2</td></tr>
1341 <p>Note the scRGB colorspace requires HDRI support otherwise it behaves just like linear RGB.</p>
1343 <p>Use the <code>Undefined</code> colorspace to identify multi-spectral images.</p>
1345 <div style="margin: auto;">
1346 <h3 class="magick-header"><a id="combine"></a>-combine</h3>
1349 <p class="magick-description">Combine one or more images into a single image.</p>
1351 <p>The channels (previously set by <a href="command-line-options.html#channel">-channel</a>) of the
1352 combined image are taken from the grayscale values of each image in the
1353 sequence, in order. For the default -channel setting of <code>RGB</code>, this
1354 means the first image is assigned to the <code>Red</code> channel, the second
1355 to the <code>Green</code> channel, the third to the <code>Blue</code>.</p>
1357 <p>This option can be thought of as the inverse to <a
1358 href="command-line-options.html#separate">-separate</a>, so long as the channel settings are the same.
1359 Thus, in the following example, the final image should be a copy of the
1363 convert original.png -channel RGB -separate sepimage.png
1364 convert sepimage-0.png sepimage-1.png sepimage-2.png -channel RGB \
1365 -combine imagecopy.png
1368 <div style="margin: auto;">
1369 <h3 class="magick-header"><a id="comment"></a>-comment <var>string</var></h3>
1372 <p class="magick-description">Embed a comment in an image.</p>
1374 <p>This option sets the comment meta-data of an image read in after this
1375 option has been given. To modify a comment of images already in memory use
1376 "<code><a href="command-line-options.html#set">-set</a> comment</code>". </p>
1378 <p>The comment can contain special format characters listed in the <a
1379 href="escape.html">Format and
1380 Print Image Properties</a>. These attributes are expanded when the comment
1381 is finally assigned to the individual images. </p>
1383 <p>If the first character of <var>string</var> is <var>@</var>, the image comment is read from a file titled by the
1384 remaining characters in the string. Comments read in from a file are literal;
1385 no embedded formatting characters are recognized.</p>
1387 <p>Comment meta-data are not visible on the image itself. To do that use the
1388 <a href="command-line-options.html#annotate">-annotate</a> or <a href="command-line-options.html#draw">-draw</a> options
1394 -comment "%m:%f %wx%h" bird.miff
1397 <p>produces an image comment of <code>MIFF:bird.miff 512x480</code> (assuming
1398 that the image <code>bird.miff</code> has a width of 512 and a height of
1401 <div style="margin: auto;">
1402 <h3 class="magick-header"><a id="compare"></a>-compare</h3>
1405 <p class="magick-description">mathematically and visually annotate the difference between an image and its reconstruction</p>
1407 <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>
1410 convert image.png reference.png -metric RMSE -compare \ <br/> difference.png
1413 <p>To get the metric value use the string format "%[distortion]".</p>
1416 convert image.png reference.png -metric RMSE -compare -format \
1417 "%[distortion]" info:
1420 <div style="margin: auto;">
1421 <h3 class="magick-header"><a id="complex"></a>-complex <var>operator</var></h3>
1424 <p class="magick-description">perform complex mathematics on an image sequence</p>
1426 Choose from these operators:
1438 <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>
1440 <div style="margin: auto;">
1441 <h3 class="magick-header"><a id="compose"></a>-compose <var>operator</var></h3>
1444 <p class="magick-description">Set the type of image composition.</p>
1446 <p>See <a href="http://www.imagemagick.org/www/compose.html">Alpha Compositing</a> for
1447 a detailed discussion of alpha compositing.</p>
1449 <p>This setting effects image processing operators that merge two (or more)
1450 images together in some way. This includes the operators,
1451 <a href="command-line-options.html#composite">-compare</a>,
1452 <a href="command-line-options.html#composite">-composite</a>,
1453 <a href="command-line-options.html#layers">-layers</a> composite,
1454 <a href="command-line-options.html#flatten">-flatten</a>,
1455 <a href="command-line-options.html#mosaic">-mosaic</a>,
1456 <a href="command-line-options.html#layers">-layers</a> merge,
1457 <a href="command-line-options.html#border">-border</a>,
1458 <a href="command-line-options.html#frame">-frame</a>,
1459 and <a href="command-line-options.html#extent">-extent</a>. </p>
1461 <p>It is also one of the primary options for the "<code>composite</code>"
1465 <div style="margin: auto;">
1466 <h3 class="magick-header"><a id="composite"></a>-composite</h3>
1469 <p class="magick-description">Perform alpha composition on two images and an optional mask</p>
1471 <p>Take the first image 'destination' and overlay the second 'source' image
1472 according to the current <a href="command-line-options.html#compose">-compose</a> setting. The location
1473 of the 'source' or 'overlay' image is controlled according to <a
1474 href="command-line-options.html#gravity" >-gravity</a>, and <a href="command-line-options.html#geometry" >-geometry</a>
1477 <p>If a third image is given this is treated as a grayscale blending 'mask' image
1478 relative to the first 'destination' image. This mask is blended with the
1479 source image. However for the '<code>displace</code>' compose method, the
1480 mask is used to provide a separate Y-displacement image instead. </p>
1482 <p>If a <a href="command-line-options.html#compose">-compose</a> method requires extra numerical
1483 arguments or flags these can be provided by setting the <a
1484 href="command-line-options.html#set">-set</a> '<code>option:compose:args</code>'
1485 appropriately for the compose method. </p>
1487 <p>Some <a href="command-line-options.html#compose">-compose</a> methods can modify the 'destination'
1488 image outside the overlay area. You can disable this by setting the special <a
1489 href="command-line-options.html#set">-set</a> '<code>option:compose:outside-overlay</code>'
1490 to '<code>false</code>'. </p>
1492 <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>
1495 <div style="margin: auto;">
1496 <h3 class="magick-header"><a id="compress"></a>-compress <var>type</var></h3>
1499 <p class="magick-description">Use pixel compression specified by <var>type</var> when writing the image.</p>
1501 <p>Choices are: <code>None</code>, <code>BZip</code>, <code
1502 >Fax</code>, <code>Group4</code>, <code
1503 >JPEG</code>, <code>JPEG2000</code>, <code
1504 >Lossless</code>, <code>LZW</code>, <code
1505 >RLE</code> or <code>Zip</code>.</p>
1507 <p>To print a complete list of compression types, use <a href="command-line-options.html#list">-list
1510 <p>Specify <a href="command-line-options.html#compress">+compress</a> to store the binary image in an
1511 uncompressed format. The default is the compression type of the specified
1514 <p>If <code>LZW</code> compression is specified but LZW compression has not been
1515 enabled, the image data is written in an uncompressed LZW format that can be
1516 read by LZW decoders. This may result in larger-than-expected GIF files.</p>
1518 <p><code>Lossless</code> refers to lossless JPEG, which is only available if the
1519 JPEG library has been patched to support it. Use of lossless JPEG is generally
1520 not recommended.</p>
1523 When writing an ICO file, you may request that the images be encoded in
1524 PNG format, by specifying <code>Zip</code> compression.</p>
1527 When writing a JNG file, specify <code>Zip</code> compression to request that
1528 the alpha channel be encoded in PNG "IDAT" format, or <code>JPEG</code>
1529 to request that it be encoded in JPG "JDAA" format.</p>
1531 <p>Use the <a href="command-line-options.html#quality">-quality</a> option to set the compression level
1532 to be used by JPEG, PNG, MIFF, and MPEG encoders.
1533 Use the <a href="command-line-options.html#sampling-factor">-sampling-factor</a> option to set the
1534 sampling factor to be used by JPEG, MPEG, and YUV encoders for down-sampling
1535 the chroma channels.</p>
1537 <div style="margin: auto;">
1538 <h3 class="magick-header"><a id="connected-components"></a>-connected-components <var>connectivity</var></h3>
1541 <p class="magick-description"><a href="connected-components.html">connected-components</a> labeling detects connected regions in an image, choose from 4 or 8 way connectivity.</p>
1543 <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>
1545 <div style="margin: auto;">
1546 <h3 class="magick-header"><a id="contrast"></a>-contrast</h3>
1549 <p class="magick-description">Enhance or reduce the image contrast.</p>
1551 <p>This option enhances the intensity differences between the lighter and
1552 darker elements of the image. Use <a href="command-line-options.html#contrast">-contrast</a> to enhance
1553 the image or <a href="command-line-options.html#contrast">+contrast</a> to reduce the image
1556 <p>For a more pronounced effect you can repeat the option:</p>
1559 convert rose: -contrast -contrast rose_c2.png
1562 <div style="margin: auto;">
1563 <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>
1566 <p class="magick-description">Increase the contrast in an image by <var>stretching</var> the range of intensity values.</p>
1568 <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
1569 <var >black-point %</var> pixels and white-out at most <var>white-point %</var> pixels.</p>
1571 <p>Prior to ImageMagick 6.4.7-0, <a href="command-line-options.html#contrast-stretch"
1572 >-contrast-stretch</a> will black-out at most <var>black-point</var> pixels and white-out at most <var >total pixels
1573 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>
1575 <p>Note that <code>-contrast-stretch 0</code> will modify the image such that
1576 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
1577 clipping at either end. This is not the same as <a href="command-line-options.html#normalize"
1578 >-normalize</a>, which is equivalent to <code>-contrast-stretch 0.15x0.05%</code> (or
1579 prior to ImageMagick 6.4.7-0, <code>-contrast-stretch 2%x99%</code>).</p>
1581 <p>Internally operator works by creating a histogram bin, and then uses that
1582 bin to modify the image. As such some colors may be merged together when they
1583 originally fell into the same 'bin'. </p>
1585 <p>All the channels are normalized in concert by the same amount so as to
1586 preserve color integrity, when the default <a href="command-line-options.html#channel" >+channel</a>
1587 setting is in use. Specifying any other <a href="command-line-options.html#channel" >-channel</a>
1588 setting will normalize the RGB channels independently.</p>
1590 <p>See also <a href="command-line-options.html#auto-level" >-auto-level</a> for a 'perfect'
1591 normalization of mathematical images. </p>
1593 <p>This operator is under review for re-development. </p>
1596 <div style="margin: auto;">
1597 <h3 class="magick-header"><a id="convolve"></a>-convolve <var>kernel</var></h3>
1600 <p class="magick-description">Convolve an image with a user-supplied convolution kernel.</p>
1602 <p>The <var>kernel</var> is a matrix specified as
1603 a comma-separated list of integers (with no spaces), ordered left-to right,
1604 starting with the top row. Presently, only odd-dimensioned kernels are
1605 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,
1606 7<sup>2</sup>=49, etc. </p>
1608 <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
1609 positive and negative results are relative to a user-specified bias value.
1610 This is important for non-HDRI compilations of ImageMagick when dealing with
1611 convolutions that contain negative as well as positive values. This is
1612 especially the case with convolutions involving high pass filters or edge
1613 detection. Without an output bias, the negative values is clipped at zero.
1616 <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
1617 negative results without clipping to the color value range (0..QuantumRange).
1618 See the discussion on HDRI implementations of ImageMagick on the page <a
1619 href="high-dynamic-range.html">High
1620 Dynamic-Range Images</a>. For more about HDRI go the ImageMagick <a
1621 href="https://www.imagemagick.org/Usage/basics/#hdri">Usage</a> pages or this
1622 <a href="http://en.wikipedia.org/wiki/High_dynamic_range_imaging">Wikipedia</a>
1626 <div style="margin: auto;">
1627 <h3 class="magick-header"><a id="copy"></a>-copy <var>geometry</var> <var>offset</var></h3>
1630 <p class="magick-description">copy pixels from one area of an image to another.</p>
1632 <div style="margin: auto;">
1633 <h3 class="magick-header"><a id="crop"></a>-crop <var>geometry</var>{<var>@</var>}{<var>!</var>}</h3>
1636 <p class="magick-description">Cut out one or more rectangular regions of the image.</p>
1638 <p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
1640 <p>The <var>width</var> and <var>height</var> of the <var>geometry</var> argument give the size of the image that remains
1641 after cropping, and <var>x</var> and <var>y</var> in the
1642 <var>offset</var> (if present) gives the location of the top left
1643 corner of the cropped image with respect to the original image. To specify the
1644 amount to be removed, use <a href="command-line-options.html#shave">-shave</a> instead.</p>
1646 <p>If the <var>x</var> and <var>y</var> offsets are
1647 present, a single image is generated, consisting of the pixels from the
1648 cropping region. The offsets specify the location of the upper left corner of
1649 the cropping region measured downward and rightward with respect to the upper
1650 left corner of the image. If the <a href="command-line-options.html#gravity">-gravity</a> option is
1651 present with <code>NorthEast</code>, <code>East</code>, or <code>SouthEast</code>
1652 gravity, it gives the distance leftward from the right edge of the image to
1653 the right edge of the cropping region. Similarly, if the <a
1654 href="command-line-options.html#gravity">-gravity</a> option is present with <code>SouthWest</code>,
1655 <code>South</code>, or <code>SouthEast</code> gravity, the distance is measured
1656 upward between the bottom edges.</p>
1658 <p>If the <var>x</var> and <var>y</var> offsets are
1659 omitted, a set of tiles of the specified geometry, covering the entire input
1660 image, is generated. The rightmost tiles and the bottom tiles are smaller if
1661 the specified geometry extends beyond the dimensions of the input image.</p>
1663 <p>You can add the <var>@</var> to the geometry argument to equally divide the image into the number of tiles generated.</p>
1665 <p>By adding a exclamation character flag to the geometry argument, the
1666 cropped images virtual canvas page size and offset is set as if the
1667 geometry argument was a viewport or window. This means the canvas page size
1668 is set to exactly the same size you specified, the image offset set
1669 relative top left corner of the region cropped. </p>
1671 <p>If the cropped image 'missed' the actual image on its virtual canvas, a
1672 special single pixel transparent 'missed' image is returned, and a 'crop
1673 missed' warning given. </p>
1675 <p>It might be necessary to <a href="command-line-options.html#repage" >+repage</a> the image prior to
1676 cropping the image to ensure the crop coordinate frame is relocated to the
1677 upper-left corner of the visible image.
1679 Similarly you may want to use <a href="command-line-options.html#repage" >+repage</a> after cropping to
1680 remove the page offset that will be left behind. This is especially true when
1681 you are going to write to an image format such as PNG that supports an image
1684 <div style="margin: auto;">
1685 <h3 class="magick-header"><a id="cycle"></a>-cycle <var>amount</var></h3>
1688 <p class="magick-description">displace image colormap by amount.</p>
1690 <p><var>Amount</var> defines the number of positions each
1691 colormap entry is shifted.</p>
1694 <div style="margin: auto;">
1695 <h3 class="magick-header"><a id="debug"></a>-debug <var>events</var></h3>
1698 <p class="magick-description">enable debug printout.</p>
1700 <p>The <code>events</code> parameter specifies which events are to be logged. It
1701 can be either <code>None</code>, <code>All</code>, <code>Trace</code>, or
1702 a comma-separated list consisting of one or more of the following domains:
1703 <code>Accelerate</code>, <code>Annotate</code>, <code>Blob</code>, <code>Cache</code>,
1704 <code>Coder</code>, <code>Configure</code>, <code>Deprecate</code>,
1705 <code>Exception</code>, <code>Locale</code>, <code>Render</code>,
1706 <code>Resource</code>, <code>Security</code>, <code>TemporaryFile</code>,
1707 <code>Transform</code>, <code>X11</code>, or <code>User</code>. </p>
1710 <p>For example, to log cache and blob events, use.</p>
1713 convert -debug "Cache,Blob" rose: rose.png
1716 <p>The <code>User</code> domain is normally empty, but developers can log user
1717 events in their private copy of ImageMagick.</p>
1719 <p>To print the complete list of debug methods, use <a href="command-line-options.html#list">-list
1722 <p>Use the <a href="command-line-options.html#log">-log</a> option to specify the format for debugging
1725 <p>Use <a href="command-line-options.html#debug">+debug</a> to turn off all logging.</p>
1727 <p>Debugging may also be set using the <code>MAGICK_DEBUG</code> <a href="resources.html#environment"
1728 >environment variable</a>. The allowed values for the <code>MAGICK_DEBUG</code>
1729 environment variable are the same as for the <a href="command-line-options.html#debug">-debug</a>
1733 <div style="margin: auto;">
1734 <h3 class="magick-header"><a id="decipher"></a>-decipher <var>filename</var></h3>
1737 <p class="magick-description">Decipher and restore pixels that were previously transformed by <a href="command-line-options.html#encipher">-encipher</a>.</p>
1739 <p>Get the passphrase from the file specified by <var>filename</var>.</p>
1741 <p>For more information, see the webpage, <a
1742 href="https://www.imagemagick.org/script/cipher.html">ImageMagick: Encipher or
1743 Decipher an Image</a>.</p>
1746 <div style="margin: auto;">
1747 <h3 class="magick-header"><a id="deconstruct"></a>-deconstruct</h3>
1750 <p class="magick-description">find areas that has changed between images </p>
1752 <p>Given a sequence of images all the same size, such as produced by <a
1753 href="command-line-options.html#coalesce">-coalesce</a>, replace the second and later images, with
1754 a smaller image of just the area that changed relative to the previous image.
1757 <p>The resulting sequence of images can be used to optimize an animation
1758 sequence, though will not work correctly for GIF animations when parts of the
1759 animation can go from opaque to transparent. </p>
1761 <p>This option is actually equivalent to the <a href="command-line-options.html#layers">-layers</a>
1762 method '<code>compare-any</code>'. </p>
1765 <div style="margin: auto;">
1766 <h3 class="magick-header"><a id="define"></a>-define <var>key</var>{<var>=value</var>}<var>...</var></h3>
1769 <p class="magick-description">add specific global settings generally used to control coders and image processing operations.</p>
1771 <p>This option creates one or more definitions for coders and decoders to use
1772 while reading and writing image data. Definitions are generally used to
1773 control image file format coder modules, and image processing operations,
1774 beyond what is provided by normal means. Defined settings are listed in <a
1775 href="command-line-options.html#verbose" >-verbose</a> information ("<code>info:</code>" output format)
1776 as "Artifacts". </p>
1778 <p>If <var>value</var> is missing for a definition, an empty-valued
1779 definition of a flag is created with that name. This used to control on/off
1780 options. Use <a href="command-line-options.html#define">+define key</a> to remove definitions
1781 previously created. Use <a href="command-line-options.html#define">+define "*"</a> to remove all
1782 existing definitions.</p>
1784 <p>The same 'artifact' settings can also be defined using the <a
1785 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
1786 Properties</a> in the defined value. </p>
1788 <p>The <var>option</var> and <var>key</var> are case-independent (they are
1789 converted to lowercase for use within the decoders) while the <var>value</var>
1790 is case-dependent.</p>
1792 <p>Such settings are global in scope, and affect all images and operations. </p>
1794 <p>The following definitions are just some of the artifacts that are
1797 <table class="table table-condensed table-striped">
1799 <td>bmp:alpha=<var>true|false</var></td>
1800 <td>include any alpha channel when writing in the BMP image format.</td>
1804 <td>bmp:format=<var>value</var></td>
1805 <td> valid values are <var>bmp2</var>, <var>bmp3</var>,
1806 and <var>bmp4</var>. This option can be useful when the
1807 method of prepending "BMP2:" to the output filename is inconvenient or
1808 is not available, such as when using the <a href="mogrify.html">mogrify</a> utility.</td>
1812 <td>colorspace:auto-grayscale=<var>on|off</var></td>
1813 <td>prevent automatic conversion to grayscale inside coders that support
1814 grayscale. This should be accompanied by -type truecolor. PNG and TIF do
1815 not need this define. With PNG, just use PNG24:image. With TIF, just use
1816 -type truecolor. JPG and PSD will need this define.</td>
1820 <td>complex:snr=<var>value</var></td>
1821 <td>Set the divide SNR constant<a href="command-line-options.html#complex">-complex</a></td>
1825 <td>compose:args=<var>arguments</var></td>
1826 <td>Sets certain compose argument values when using convert ... -compose ...
1827 -composite. See <a href="compose.html"
1828 >Image Composition</a></td>
1832 <td>compose:clamp=<var>on|off</var></td>
1833 <td>set each pixel whose value is below zero to zero and any the pixel
1834 whose value is above the quantum range to the quantum range (e.g. 65535)
1835 otherwise the pixel value remains unchanged. Define supported in
1836 ImageMagick 6.9.1-3 and above.</td>
1840 <td>connected-components:area-threshold=<var>value</var></td>
1841 <td>Merges any region with area smaller than <var>value</var> into its surrounding region or largest neighbor.</td>
1845 <td>connected-components:keep=<var>list-of-ids</var></td>
1846 <td>Comma and/or hyphenated list of id values to keep in the output.
1847 Supported in Imagemagick 6.9.3-0.</td>
1851 <td>connected-components:mean-color=<var>true</var></td>
1852 <td>Changes the output image from id values to mean color values. Supported
1853 in Imagemagick 6.9.2-8.</td>
1857 <td>connected-components:remove=<var>list-of-ids</var></td>
1858 <td>Comma and/or hyphenated list of id values to remove from the output.
1859 Supported in Imagemagick 6.9.2-9.</td>
1863 <td>connected-components:verbose=<var>true</var></td>
1864 <td>Lists id, bounding box, centroid, area, mean color for each region.</td>
1868 <td>convolve:scale=<var>{kernel_scale}[!^] [,{origin_addition}] [%]</var></td>
1869 <td>Defines the kernel scaling. The special flag ! automatically scales to
1870 full dynamic range. The ! flag can be used in combination with a factor or
1871 percent. The factor or percent is then applied after the automatic scaling.
1872 An example is 50%!. This produces a result 50% darker than full dynamic
1873 range scaling. The ^ flag assures the kernel is 'zero-summing', for
1874 example when some values are positive and some are negative as in edge
1875 detection kernels. The origin addition adds that value to the center
1876 pixel of the kernel. This produces and effect that is like adding the image
1877 that many times to the result of the filtered image. The typical value
1878 is 1 so that the original image is added to the result of the convolution.
1879 The default is 0.</td>
1883 <td>convolve:showkernel=<var>1</var></td>
1884 <td>Outputs (to 'standard error') all the information about a specified <a
1885 href="command-line-options.html#morphology" >-morphology convolve</a> kernel.</td>
1889 <td>dcm:display-range=<var>reset</var></td>
1890 <td>Sets the display range to the minimum and maximum pixel values for the
1891 DCM image format.</td>
1895 <td>dds:cluster-fit=<var>true|false</var></td>
1896 <td>Enables the dds cluster-fit.</td>
1900 <td>dds:compression=<var>dxt1|dxt5|none</var></td>
1901 <td>Sets the dds compression.</td>
1905 <td>dds:mipmaps=<var>value</var></td>
1906 <td>Sets the dds number of mipmaps.</td>
1910 <td>dds:weight-by-alpha=<var>true|false</var></td>
1911 <td>Enables the dds alpha weighting.</td>
1915 <td>deskew:auto-crop=<var>true</var></td>
1916 <td>auto crop the image after deskewing.</td>
1920 <td>delegate:bimodal=<var>true</var></td>
1921 <td>Specifies direct conversion from Postscript to PDF.</td>
1925 <td>distort:scale=<var>value</var></td>
1926 <td>Sets the output scaling factor for use with <a href="command-line-options.html#distort"
1931 <td>distort:viewport=<var>WxH+X+Y</var></td>
1932 <td>Sets the viewport for use with <a href="command-line-options.html#distort">-distort</a></td>
1936 <td>dot:layout-engine=<var>value</var></td>
1937 <td>Specifies the layout engine for the DOT image format (e.g.
1938 <code>neato</code>).</td>
1942 <td>filter:option=<var>value</var></td>
1943 <td>Set a filter option for use with <a href="command-line-options.html#resize">-resize</a>.
1944 See <a href="command-line-options.html#filter">-filter</a> for details.</td>
1948 <td>fourier:normalize=<var>inverse</var></td>
1949 <td>Sets the location for the FFT/IFT normalization as use by
1950 <a href="command-line-options.html#fft">+-fft</a> and <a href="command-line-options.html#ift">+-ift</a>. The default is
1951 <var>forward</var>.</td>
1955 <td>h:format=<var>value</var></td>
1956 <td>Set the image encoding format use when writing a C-style header.
1957 <var>format</var> can be any output format supported by ImageMagick
1958 except for <var>h</var> and <var>magick</var>. If this
1959 option is omitted, the default is <var>GIF</var> for PseudoClass
1960 images and <var>PNM</var> for DirectClass images.
1965 <td>icon:auto-resize</td>
1966 <td>Automatically stores multiple sizes when writing an ico image
1967 (requires a 256x256 input image).</td>
1971 <td>jp2:layer-number=<var>value</var></td>
1972 <td>Sets the maximum number of quality layers to decode. Same for JPT, JC2,
1977 <td>jp2:number-resolutions=<var>value</var></td>
1978 <td>Sets the number of resolutions to encode.Same for JPT, JC2, and
1983 <td>jp2:progression-order=<var>value</var></td>
1984 <td>choose from LRCP, RLCP, RPCL, PCRL or CPRL. Same for JPT, JC2, and
1989 <td>jp2:quality=<var>value,value...</var></td>
1990 <td>Sets the quality layer PSNR, given in dB. The order is from left to
1991 right in ascending order. The default is a single lossless quality layer.
1992 Same for JPT, JC2, and J2K</td>
1996 <td>jp2:rate=<var>value</var></td>
1997 <td>Specify the compression factor to use while writing JPEG-2000 files.
1998 The compression factor is the reciprocal of the compression ratio. The
1999 valid range is 0.0 to 1.0, with 1.0 indicating lossless compression. If
2000 defined, this value overrides the -quality setting. A quality setting
2001 of 75 results in a rate value of 0.06641. Same for JPT, JC2, and J2K</td>
2005 <td>jp2:reduce-factor=<var>value</var></td>
2006 <td>Sets the number of highest resolution levels to be discarded.Same for
2007 JPT, JC2, and J2K</td>
2011 <td>jpeg:block-smoothing=<var>on|off</var></td>
2016 <td>jpeg:colors=<var>value</var></td>
2017 <td>Set the desired number of colors and let the JPEG encoder do the
2022 <td>jpeg:dct-method=<var>value</var></td>
2023 <td>Choose from <code>default</code>, <code>fastest</code>,
2024 <code>float</code>, <code>ifast</code>, and <code>islow</code>.</td>
2028 <td>jpeg:extent=<var>value</var></td>
2029 <td>Restrict the maximum JPEG file size, for example <code>-define
2030 jpeg:extent=400KB</code>. The JPEG encoder will search for the highest
2031 compression quality level that results in an output file that does not
2032 exceed the value. The <code>-quality</code> option also will be respected
2033 starting with version 6.9.2-5. Between 6.9.1-0 and 6.9.2-4, add -quality
2034 100 in order for the jpeg:extent to work properly. Prior to 6.9.1-0, the
2035 -quality setting was ignored.</td>
2039 <td>jpeg:fancy-upsampling=<var>on|off</var></td>
2044 <td>jpeg:optimize-coding=<var>on|off</var></td>
2049 <td>jpeg:q-table=<var>table</var></td>
2054 <td>jpeg:sampling-factor=<var>sampling-factor-string</var></td>
2059 <td>jpeg:size=<var>geometry</var></td>
2060 <td>Set the size hint of a JPEG image, for
2061 example, <code>-define jpeg:size=128x128</code>.
2062 It is most useful for increasing performance and reducing the memory
2063 requirements when reducing the size of a large JPEG image.</td>
2067 <td>json:features</td>
2068 <td>includes features in verbose information</td>
2077 <td>json:locate</td>
2082 <td>json:moments</td>
2083 <td>includes image moments in verbose information</td>
2087 <td>magick:format=<var>value</var></td>
2088 <td>Set the image encoding format use when writing a C-style header.
2089 This is the same as "h:format=format" described above.</td>
2093 <td>mng:need-cacheoff</td>
2094 <td>turn playback caching off for streaming MNG.</td>
2098 <td>morphology:compose=<var>compose-method</var></td>
2099 <td>Specifies how to merge results generated by multiple<a
2100 href="command-line-options.html#morphology" >-morphology</a> kernel. The default is none. One
2101 typical value is 'lighten' as used, for example, with the sobel edge
2106 <td>morphology:showkernel=<var>1</var></td>
2107 <td>Outputs (to 'standard error') all the information about a generated <a
2108 href="command-line-options.html#morphology" >-morphology</a> kernel.</td>
2112 <td>pcl:fit-to-page=<var>true</var></td>
2116 <td>pdf:fit-page=<var>geometry</var></td>
2117 <td> geometry specifies the scaling dimensions for resizing when the PDF is
2118 being read. The geometry is either WxH{%} or page size. No offsets are
2119 allowed. (introduced in IM 6.8.8-8)</td>
2123 <td>pdf:fit-to-page=<var>true</var></td>
2128 <td>pdf:use-cropbox=<var>true</var></td>
2133 <td>pdf:use-trimbox=<var>true</var></td>
2138 <td>phash:colorspaces=<var>colorspace,colorspace,...</var></td>
2139 <td>the perceptual hash defaults to the sRGB and HCLp colorspaces. When
2140 using this define, you can specify up to six alternative colorspaces. (as
2145 <td>phash:normalize=<var>true</var></td>
2146 <td>normalizes the phash metric by dividing by the number of channels
2147 specified by <code>-define phash:colorspaces</code> when using compare
2148 -metric phash. (as of IM 7.0.3-8)</td>
2152 <td>png:bit-depth=<var>value</var></td>
2157 <td>png:color-type=<var>value</var></td>
2158 <td>desired bit-depth and color-type for PNG output. You can force the PNG
2159 encoder to use a different bit-depth and color-type than it would have
2160 normally selected, but only if this does not cause any loss of image
2161 quality. Any attempt to reduce image quality is treated as an error and no
2162 PNG file is written. E.g., if you have a 1-bit black-and-white image, you
2163 can use these "defines" to cause it to be written as an 8-bit grayscale,
2164 indexed, or even a 64-bit RGBA. But if you have a 16-million color image,
2165 you cannot force it to be written as a grayscale or indexed PNG. If you
2166 wish to do this, you must use the appropriate <a href="command-line-options.html#depth">-depth</a>,
2167 <a href="command-line-options.html#colors">-colors</a>, or <a href="command-line-options.html#type">-type</a> directives to
2168 reduce the image quality prior to using the PNG encoder. Note that in
2169 indexed PNG files, "bit-depth" refers to the number of bits per index,
2170 which can be 1, 2, 4, or 8. In such files, the color samples always have
2175 <td>png:compression-filter=<var>value</var></td>
2176 <td> valid values are 0 through 9. 0-4 are the corresponding PNG filters,
2177 5 means adaptive filtering except for images with a colormap, 6 means
2178 adaptive filtering for all images, 7 means MNG "loco" compression, 8 means
2179 Z_RLE strategy with adaptive filtering, and 9 means Z_RLE strategy with no
2184 <td>png:compression-level=<var>value</var></td>
2185 <td> valid values are 0 through 9, with 0 providing the least but fastest
2186 compression and 9 usually providing the best and always the slowest.</td>
2190 <td>png:compression-strategy=<var>value</var></td>
2191 <td> valid values are 0 through 4, meaning default, filtered, huffman_only,
2192 rle, and fixed ZLIB compression strategy. If you are using an old zlib
2193 that does not support Z_RLE (before 1.2.0) or Z_FIXED (before 1.2.2.2),
2194 values 3 and 4, respectively, will use the zlib default strategy
2199 <td>png:format=<var>value</var></td>
2200 <td> valid values are <var>png8</var>, <var>png24</var>,
2201 <var>png32</var>, <var>png48</var>,
2202 <var>png64</var>, and <var>png00</var>.
2203 This property can be useful for specifying
2204 the specific PNG format to be used, when the usual method of prepending the
2205 format name to the output filename is inconvenient, such as when writing
2206 a PNG-encoded ICO file or when using <a href="mogrify.html">mogrify</a>.
2207 Value = <var>png8</var> reduces the number of colors to 256,
2208 only one of which may be fully transparent, if necessary. The other
2209 values do not force any reduction of quality; it is an error to request
2210 a format that cannot represent the image data without loss (except that
2211 it is allowed to reduce the bit-depth from 16 to 8 for all formats).
2212 Value = <var>png24</var> and <var>png48</var>
2213 allow transparency, only if a single color is fully transparent and that
2214 color does not also appear in an opaque pixel; such transparency is
2215 written in a PNG <code>tRNS</code> chunk.
2216 Value = <var>png00</var> causes the image to inherit its
2217 color-type and bit-depth from the input image, if the input was also
2222 <td>png:exclude-chunk=<var>value</var></td>
2225 <td>png:include-chunk=<var>value</var></td>
2226 <td>ancillary chunks to be excluded from or included in PNG output.
2228 <p>The <var>value</var> can be the name of a PNG chunk-type such
2229 as <var>bKGD</var>, a comma-separated list of chunk-names
2230 (which can include the word <var>date</var>, the word
2231 <var>all</var>, or the word <var>none</var>).
2232 Although PNG chunk-names are case-dependent, you can use all lowercase
2233 names if you prefer.</p>
2235 <p>The "include-chunk" and "exclude-chunk" lists only affect the behavior
2236 of the PNG encoder and have no effect on the PNG decoder.</p>
2238 <p>As a special case, if the <code>sRGB</code> chunk is excluded and
2239 the <code>gAMA</code> chunk is included, the <code>gAMA</code> chunk will
2240 only be written if gamma is not 1/2.2, since most decoders assume
2241 sRGB and gamma=1/2.2 when no colorspace information is included in
2242 the PNG file. Because the list is processed from left to right, you
2243 can achieve this with a single define:</p>
2246 -define png:include-chunk=none,gAMA
2249 <p>As a special case, if the <code>sRGB</code> chunk is not excluded and
2250 the PNG encoder recognizes that the image contains the sRGB ICC profile,
2251 the PNG encoder will write the <code>sRGB</code> chunk instead of the
2252 entire ICC profile. To force the PNG encoder to write the sRGB
2253 profile as an <code>iCCP</code> chunk in the output PNG instead of the
2254 <code>sRGB</code> chunk, exclude the <code>sRGB</code> chunk.</p>
2256 <p>The critical PNG chunks <code>IHDR</code>, <code>PLTE</code>,
2257 <code>IDAT</code>, and <code>IEND</code> cannot be excluded. Any such
2258 entries appearing in the list will be ignored.</p>
2260 <p>If the ancillary PNG <code>tRNS</code> chunk is excluded and the
2261 image has transparency, the PNG colortype is forced to be 4 or 6
2262 (GRAY_ALPHA or RGBA). If the image is not transparent, then the
2263 <code>tRNS</code> chunk isn't written anyhow, and there is no effect
2264 on the PNG colortype of the output image.</p>
2266 <p>The <a href="command-line-options.html#strip">-strip</a> option does the equivalent of the
2267 following for PNG output:</p>
2270 -define png:exclude-chunk=EXIF,iCCP,iTXt,sRGB,tEXt,zCCP,zTXt,date
2273 <p>The default behavior is to include all known PNG ancillary chunks
2274 plus ImageMagick's private <code>vpAg</code> ("virtual page") chunk,
2275 and to exclude all PNG chunks that are unknown to ImageMagick,
2276 regardless of their PNG "copy-safe" status as described in the
2277 PNG specification.</p>
2279 <p>Any chunk names that are not known to ImageMagick are ignored
2280 if they appear in either the "include-chunk" or "exclude-chunk" list.
2281 The ancillary chunks currently known to ImageMagick are
2282 <code>bKGD</code>, <code>cHRM</code>, <code>gAMA</code>, <code>iCCP</code>,
2283 <code>oFFs</code>, <code>pHYs</code>, <code>sRGB</code>, <code>tEXt</code>,
2284 <code>tRNS</code>, <code>vpAg</code>, and <code>zTXt</code>.</p>
2286 <p>You can also put <code>date</code> in the list to include or exclude
2287 the "Date:create" and "Date:modify" text chunks that ImageMagick normally
2288 inserts in the output PNG.</p></td>
2292 <td>png:preserve-colormap[=<var>true</var>]</td>
2293 <td>Use the existing image->colormap. Normally the PNG encoder will
2294 try to optimize the palette, eliminating unused entries and putting
2295 the transparent colors first. If this flag is set, that behavior
2300 <td>png:preserve-iCCP[=<var>true</var>]</td>
2301 <td>By default, the PNG decoder and encoder examine any ICC profile
2302 that is present, either from an <code>iCCP</code> chunk in the PNG
2303 input or supplied via an option, and if the profile is recognized
2304 to be the sRGB profile, converts it to the <code>sRGB</code> chunk.
2305 You can use <code>-define png:preserve-iCCP</code> to prevent
2306 this from happening; in such cases the <code>iCCP</code> chunk
2307 will be read or written and no <code>sRGB</code> chunk will be
2308 written. There are some ICC profiles that claim to be sRGB but
2309 have various errors that cause them to be rejected by libpng16; such
2310 profiles are recognized anyhow and converted to the <code>sRGB</code>
2311 chunk, but are rejected if the <code>-define png:preserve-iCCP</code>
2312 is present. Note that not all "sRGB" ICC profiles are recognized
2313 yet; we will add them to the list as we encounter them.</td>
2317 <td>png:swap-bytes[=<var>true</var>]</td>
2318 <td>The PNG specification requires that any multi-byte integers be stored in
2319 network byte order (MSB-LSB endian). This option allows you to
2320 fix any invalid PNG files that have 16-bit samples stored incorrectly
2321 in little-endian order (LSB-MSB). The "-define png:swap-bytes" option
2322 must appear before the input filename on the commandline. The swapping
2323 is done during the libpng decoding operation.</td>
2327 <td>profile:skip=<var>name1,name2,...</var></td>
2328 <td>Skip the named profile[s] when reading the image. Use skip="*" to
2329 skip all named profiles in the image. Many named profiles exist,
2330 including ICC, EXIF, APP1, IPTC, XMP, and others.</td>
2334 <td>ps:imagemask</td>
2335 <td>If the ps:imagemask flag is defined, the PS3 and EPS3 coders will
2336 create Postscript files that render bilevel images with the Postscript
2337 imagemask operator instead of the image operator.</td>
2341 <td>psd:additional-info=all|selective</td>
2342 <td>This option should only be used when converting from a PSD file to
2343 another PSD file. This should be placed after the image is read. The two
2344 options are 'all' and 'selective'. The 'selective' option will preserve
2345 all additional information that is not related to the geometry of the
2346 image. The 'all' option should only be used when the geometry of the
2347 image has not been changed. This option is helpful when transferring
2348 non-simple layers, such as adjustment layers from the input PSD file to
2349 the output PSD file. If this option is not used, the additional
2350 information will not be preserved. This define is available as of
2351 Imagemagick version 6.9.5-8.
2356 <td>psd:alpha-unblend=off</td>
2357 <td>Disables new automatic un-blending of transparency with the base image
2358 for the flattened layer 0 before adding the alpha channel to the output
2359 image. This define must be placed before the input psd image. (Available
2360 as of IM 6.9.2.5). The automatic un-blending is new to IM 6.9.2.5 and
2361 prevents the transparency from being applied twice in the output
2362 image. This option should be set before reading the image.</td>
2366 <td>psd:preserve-opacity-mask=true</td>
2367 <td>This option should only be used when converting from a PSD file to
2368 another PSD file. It will preserve the opacity mask of a layer and add it
2369 back to the layer when the image is saved. Setting this to 'true' will
2370 enable this feature. This define is available as of Imagemagick version
2376 <td>preserve-timestamp=<var>{True, False}</var></td>
2377 <td>Preserve file timestamp (<code>mogrify</code> only).</td>
2381 <td>quantum:format=<var>type</var></td>
2382 <td>Set the type to <code>floating-point</code> to specify a floating-point
2383 format for raw files (e.g. GRAY:) or for MIFF and TIFF images in HDRI mode
2384 to preserve negative values. If <a href="command-line-options.html#depth">-depth</a> 16 is
2385 included, the result is a single precision floating point format.
2386 If <a href="command-line-options.html#depth">-depth</a> 32 is included, the result is
2387 double precision floating point format.</td>
2391 <td>quantum:polarity=<var>photometric-interpretation</var></td>
2392 <td>Set the photometric-interpretation of an image (typically for TIFF
2393 image file format) to either <code>min-is-black</code> (default) or
2394 <code>min-is-white</code>.</td>
2398 <td>sample:offset=<var>geometry</var></td>
2399 <td>Location of the sampling point within the sub-region being sampled,
2400 expressed as percentages (see <a href="command-line-options.html#sample" >-sample</a>).</td>
2404 <td>showkernel=<var>1</var></td>
2405 <td>Outputs (to 'standard error') all the information about a generated <a
2406 href="command-line-options.html#morphology" >-morphology</a> kernel.</td>
2410 <td>stream:buffer-size=<var>value</var></td>
2411 <td>Set the stream buffer size. Select 0 for unbuffered I/O.</td>
2415 <td>tiff:alpha=<var>associated|unassociated|unspecified</var></td>
2416 <td>Specify the alpha extra samples as associated, unassociated or
2421 <td>tiff:endian=<var>msb|lsb</var></td>
2426 <td>tiff:exif-properties=<var>false</var></td>
2427 <td>Skips reading the EXIF properties.</td>
2431 <td>tiff:fill-order=<var>msb|lsb</var></td>
2436 <td>tiff:ignore-layers=<var>true</var></td>
2437 <td>Ignores the photoshop layers.</td>
2441 <td>tiff:ignore-tags=<var>comma-separate-list-of-tag-IDs</var></td>
2442 <td>Allows one or more tag ID values to be ignored.</td>
2446 <td>tiff:rows-per-strip=<var>value</var></td>
2447 <td>Sets the number of rows per strip</td>
2451 <td>tiff:tile-geometry=<var>WxH</var></td>
2452 <td>Sets the tile size for pyramid tiffs. Requires the suffix
2453 PTIF: before the outputname</td>
2457 <td>type:features=<var>string</var></td>
2462 <td>type:hinting=<var>off</var></td>
2467 <p>For example, to create a postscript file that will render only the black
2468 pixels of a bilevel image, use:</p>
2471 convert bilevel.tif -define ps:imagemask eps3:stencil.ps
2474 <p>Set attributes of the image registry by prefixing the value with
2475 <code>registry:</code>. For example, to set a temporary path to put work files,
2479 -define registry:temporary-path=/data/tmp
2482 <div style="margin: auto;">
2483 <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>
2486 <p class="magick-description">display the next image after pausing.</p>
2488 <p>This option is useful for regulating the animation of image sequences
2489 <var>ticks/ticks-per-second</var> seconds must expire before the display of the
2490 next image. The default is no delay between each showing of the image
2491 sequence. The default ticks-per-second is 100.</p>
2493 <p>Use <code>></code> to change the image delay <var>only</var> if its current
2494 value exceeds the given delay. <code><</code> changes the image delay
2495 <var>only</var> if current value is less than the given delay. For example, if
2496 you specify <code>30></code> and the image delay is 20, the image delay does
2497 not change. However, if the image delay is 40 or 50, the delay it is changed
2498 to 30. Enclose the given delay in quotation marks to prevent the
2499 <code><</code> or <code>></code> from being interpreted by your shell as
2500 a file redirection.</p>
2503 <div style="margin: auto;">
2504 <h3 class="magick-header"><a id="delete"></a>-delete <var>indexes</var></h3>
2507 <p class="magick-description">delete the images specified by index, from the image sequence.</p>
2509 <p>Specify the image by its index in the sequence. The first image is index
2510 0. Negative indexes are relative to the end of the sequence, for example, -1
2511 represents the last image of the sequence. Specify a range of images with
2512 a dash (e.g. 0-4). Separate indexes with a comma (e.g. 0,2). Use
2513 <code>+delete</code> to delete the last image in the current image sequence. Use <code>-delete 0--1</code> to delete the entire image sequence.</p>
2516 <div style="margin: auto;">
2517 <h3 class="magick-header"><a id="density"></a>-density <var>width</var><br />-density <var>width</var>x<var>height</var></h3>
2520 <p class="magick-description">Set the horizontal and vertical resolution of an image for rendering to devices.</p>
2522 <p>This option specifies the image resolution to store while encoding a raster
2523 image or the canvas resolution while rendering (reading) vector formats such
2524 as Postscript, PDF, WMF, and SVG into a raster image. Image resolution
2525 provides the unit of measure to apply when rendering to an output device or
2526 raster image. The default unit of measure is in dots per inch (DPI). The <a
2527 href="command-line-options.html#units">-units</a> option may be used to select dots per centimeter
2530 <p>The default resolution is 72 dots per inch, which is equivalent to one
2531 point per pixel (Macintosh and Postscript standard). Computer screens are
2532 normally 72 or 96 dots per inch, while printers typically support 150, 300,
2533 600, or 1200 dots per inch. To determine the resolution of your display, use
2534 a ruler to measure the width of your screen in inches, and divide by the
2535 number of horizontal pixels (1024 on a 1024x768 display).</p>
2537 <p>If the file format supports it, this option may be used to update the
2538 stored image resolution. Note that Photoshop stores and obtains image
2539 resolution from a proprietary embedded profile. If this profile is not
2540 stripped from the image, then Photoshop will continue to treat the image using
2541 its former resolution, ignoring the image resolution specified in the standard
2544 <p>The <a href="command-line-options.html#density">-density</a> option sets an <var>attribute</var> and
2545 does not alter the underlying raster image. It may be used to adjust the
2546 rendered size for desktop publishing purposes by adjusting the scale applied
2547 to the pixels. To resize the image so that it is the same size at a different
2548 resolution, use the <a href="command-line-options.html#resample">-resample</a> option.</p>
2550 <div style="margin: auto;">
2551 <h3 class="magick-header"><a id="depth"></a>-depth <var>value</var></h3>
2554 <p class="magick-description">depth of the image.</p>
2556 <p>This the number of bits in a color sample within a pixel. Use this option
2557 to specify the depth of raw images whose depth is unknown such as GRAY, RGB,
2558 or CMYK, or to change the depth of any image after it has been read.</p>
2560 <div style="margin: auto;">
2561 <h3 class="magick-header"><a id="descend"></a>-descend</h3>
2564 <p class="magick-description">obtain image by descending window hierarchy.</p>
2566 <div style="margin: auto;">
2567 <h3 class="magick-header"><a id="deskew"></a>-deskew <var>threshold{%}</var></h3>
2570 <p class="magick-description">straighten an image. A threshold of 40% works for most images.</p>
2572 <p>Use <a href="command-line-options.html#set">-set</a> <code>option:deskew:auto-crop
2573 <var>true | false</var></code> to auto crop the image.</p>
2575 <div style="margin: auto;">
2576 <h3 class="magick-header"><a id="despeckle"></a>-despeckle</h3>
2579 <p class="magick-description">reduce the speckles within an image.</p>
2581 <div style="margin: auto;">
2582 <h3 class="magick-header"><a id="direction"></a>-direction <var>type</var></h3>
2585 <p class="magick-description">render text right-to-left or left-to-right.</p>
2587 <div style="margin: auto;">
2588 <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>
2591 <p class="magick-description">shift image pixels as defined by a displacement map.</p>
2593 <p>With this option, the 'overlay' image, and optionally the 'mask' image,
2594 is used as a displacement map, which is used to displace the lookup of
2595 what part of the 'background' image is seen at each point of the overlaid
2596 area. Much like the displacement map is a 'lens' that redirects light shining
2597 through it so as to present a distorted view the original 'background' image
2600 <p>Any perfect grey areas of the displacement map produce a zero
2601 displacement of the image. Black areas produce the given maximum negative
2602 displacement of the lookup point, while white produce a maximum positive
2603 displacement of the lookup. </p>
2605 <p>Note that it is the lookup of the 'background' that is displaced, not a
2606 displacement of the image itself. As such an area of the displacement map
2607 containing 'white' will have the lookup point 'shifted' by a positive amount,
2608 and thus generating a copy of the destination image to the right/downward from
2609 the correct position. That is the image will look like it may have been
2610 'shifted' in a negative left/upward direction. Understanding this is a very
2611 important in understanding how displacement maps work. </p>
2613 <p>The given arguments define the maximum amount of displacement in pixels
2614 that a particular map can produce. If the displacement scale is large enough
2615 it is also possible to lookup parts of the 'background' image that lie well
2616 outside the bounds of the displacement map itself. That is you could very
2617 easily copy a section of the original image from outside the overlay area
2618 into the overlay area. </p>
2620 <p>The '%' flag makes the displacement scale relative to the size of the
2621 overlay image (100% = half width/height of image). Using '!' switches
2622 percentage arguments to refer to the destination image size instead.
2623 these flags were added as of IM v6.5.3-5.</p>
2625 <p>Normally a single grayscale displacement map is provided, which with the
2626 given scaling values will determine a single direction (vector) in which
2627 displacements can occur (positively or negatively). However, if you also
2628 specify a third image which is normally used as a <var>mask</var>,
2629 the <var>composite image</var> is used for horizontal X
2630 displacement, while the <var>mask image</var> is used for vertical Y
2631 displacement. This allows you to define completely different displacement
2632 values for the X and Y directions, and allowing you to lookup any point within
2633 the <var>scale</var> bounds. In other words each pixel can lookup
2634 any other nearby pixel, producing complex 2 dimensional displacements, rather
2635 than a simple 1 dimensional vector displacements. </p>
2637 <p>Alternatively rather than supplying two separate images, as of IM v6.4.4-0,
2638 you can use the 'red' channel of the overlay image to specify the horizontal
2639 or X displacement, and the 'green' channel for the vertical or Y displacement.
2642 <p>As of IM v6.5.3-5 any alpha channel in the overlay image is used as a
2643 mask the transparency of the destination image. However areas outside the
2644 overlaid areas will not be effected. </p>
2647 <div style="margin: auto;">
2648 <h3 class="magick-header"><a id="display"></a>-display <var>host:display[.screen]</var></h3>
2651 <p class="magick-description">Specifies the X server to contact.</p>
2653 <p>This option is used with convert for obtaining image or font from this
2654 X server. See <var>X(1)</var>.</p>
2656 <div style="margin: auto;">
2657 <h3 class="magick-header"><a id="dispose"></a>-dispose <var>method</var></h3>
2660 <p class="magick-description">define the GIF disposal image setting for images that are being created or read in. </p>
2662 <p>The layer disposal method defines the way each the displayed image is to be
2663 modified after the current 'frame' of an animation has finished being
2664 displayed (after its 'delay' period), but before the next frame on an
2665 animation is to be overlaid onto the display. </p>
2667 <p>Here are the valid methods:</p>
2669 <dl class="dl-horizontal">
2670 <dt>Undefined</dt><dd>0: No disposal specified (equivalent to '<code>none</code>').</dd>
2671 <dt>None</dt><dd>1: Do not dispose, just overlay next frame image.</dd>
2672 <dt>Background</dt><dd>2: Clear the frame area with the background color.</dd>
2673 <dt>Previous</dt><dd>3: Clear to the image prior to this frames overlay.</dd>
2676 <p>You can also use the numbers given above, which is what the GIF format
2677 uses internally to represent the above settings. </p>
2679 <p>To print a complete list of dispose methods, use <a href="command-line-options.html#list">-list dispose</a>.</p>
2681 <p>Use <a href="command-line-options.html#dispose" >+dispose</a>, turn off the setting and prevent
2682 resetting the layer disposal methods of images being read in. </p>
2684 <p>Use <a href="command-line-options.html#set">-set</a> '<code>dispose</code>' method to set the image
2685 disposal method for images already in memory.</p>
2687 <div style="margin: auto;">
2688 <h3 class="magick-header"><a id="dissimilarity-threshold"></a>-dissimilarity-threshold <var>value</var></h3>
2691 <p class="magick-description">maximum RMSE for subimage match (default 0.2).</p>
2694 <div style="margin: auto;">
2695 <h3 class="magick-header"><a id="dissolve"></a>-dissolve <var>src_percent</var>[x<var>dst_percent</var>]</h3>
2698 <p class="magick-description">dissolve an image into another by the given percent.</p>
2700 <p>The opacity of the composite image is multiplied by the given percent, then
2701 it is composited 'over' the main image. If <var>src_percent</var>
2702 is greater than 100, start dissolving the main image so it becomes
2703 transparent at a value of '<code>200</code>'. If both percentages
2704 are given, each image are dissolved to the percentages given. </p>
2706 <p>Note that dissolve percentages do not add, two opaque images dissolved
2707 '50,50', produce a 75% transparency. For a 50% + 50% blending of the two
2708 images, you would need to use dissolve values of '50,100'. </p>
2710 <div style="margin: auto;">
2711 <h3 class="magick-header"><a id="distort"></a>-distort <var>method arguments</var></h3>
2714 <p class="magick-description">distort an image, using the given <var>method</var> and its required <var>arguments</var>.</p>
2716 <p>The <var>arguments</var> is a single string containing a list
2717 of floating point numbers separated by commas or spaces. The number of
2718 and meaning of the floating point values depends on the distortion <var>method</var> being used. </p>
2720 <p>Choose from these distortion types:</p>
2722 <table class="table table-condensed table-striped">
2724 <th style="width: 8%">Method</th>
2725 <th>Description</th>
2729 <td>ScaleRotateTranslate <br/> SRT</td>
2731 Distort image by first scaling and rotating about a given 'center',
2732 before translating that 'center' to the new location, in that order. It
2733 is an alternative method of specifying a 'Affine' type of
2734 distortion, but without shearing effects. It also provides a good way
2735 of rotating and displacing a smaller image for tiling onto a larger
2736 background (IE 2-dimensional animations). <br/>
2738 The number of arguments determine the specific meaning of each
2739 argument for the scales, rotation, and translation operations. <br/>
2741 <dl class="dl-horizontal">
2742 <dt>2:</dt><dd><var>Scale Angle</var></dd>
2743 <dt>3:</dt><dd><var>X,Y Angle</var></dd>
2744 <dt>4:</dt><dd><var>X,Y Scale Angle</var></dd>
2745 <dt>5:</dt> <dd><var>X,Y ScaleX,ScaleY Angle</var></dd>
2746 <dt>6:</dt> <dd><var>X,Y Scale Angle NewX,NewY</var></dd>
2747 <dt>7:</dt> <dd><var>X,Y ScaleX,ScaleY Angle NewX,NewY</var></dd>
2750 This is actually an alternative way of specifying a 2 dimensional linear
2751 'Affine' or 'AffineProjection' distortion. </td> </tr>
2756 Distort the image linearly by moving a list of at least 3 or more sets
2757 of control points (as defined below). Ideally 3 sets or 12 floating
2758 point values are given allowing the image to be linearly scaled,
2759 rotated, sheared, and translated, according to those three points. See
2760 also the related 'AffineProjection' and 'SRT'
2763 More than 3 sets given control point pairs (12 numbers) is least
2764 squares fitted to best match a linear affine distortion. If only 2
2765 control point pairs (8 numbers) are given a two point image translation
2766 rotation and scaling is performed, without any possible shearing,
2767 flipping or changes in aspect ratio to the resulting image. If only one
2768 control point pair is provides the image is only translated, (which may
2769 be a floating point non-integer translation). <br/>
2771 This distortion does not include any form of perspective distortion.
2777 <td>AffineProjection</td>
2779 Linearly distort an image using the given Affine Matrix of 6
2780 pre-calculated coefficients forming a set of Affine Equations to map
2781 the source image to the destination image.
2783 <p class="text-center"><var>
2784 s<sub>x</sub>, r<sub>x</sub>,
2785 r<sub>y</sub>, s<sub>y</sub>,
2786 t<sub>x</sub>, t<sub>y</sub>
2789 See <a href="command-line-options.html#affine" >-affine</a> setting for more detail, and
2790 meanings of these coefficients. <br/>
2792 The distortions 'Affine' and 'SRT' provide
2793 alternative methods of defining this distortion, with ImageMagick doing
2794 the calculations needed to generate the required coefficients. You can
2795 see the internally generated coefficients, by using a <a
2796 href="command-line-options.html#verbose" >-verbose</a> setting with those other variants. </td>
2801 <td>BilinearForward<br/>
2802 BilinearReverse</td>
2804 Bilinear Distortion, given a minimum of 4 sets of coordinate pairs, or
2805 16 values (see below). Not that lines may not appear straight after
2806 distortion, though the distance between coordinates will remain
2809 The 'BilinearForward' is used to map rectangles to any
2810 quadrilateral, while the 'BilinearReverse' form maps any
2811 quadrilateral to a rectangle, while preserving the straight line edges
2814 Note that 'BilinearForward' can generate invalid pixels
2815 which will be colored using the <a href="command-line-options.html#alpha-color" >-alpha-color</a>
2816 color setting. Also if the quadrilateral becomes 'flipped' the image
2817 may disappear. <br/>
2819 There are future plans to produce a true Bilinear distortion that will
2820 attempt to map any quadrilateral to any other quadrilateral, while
2821 preserving edges (and edge distance ratios).
2827 <td>Perspective</td>
2829 Perspective distort the images, using a list of 4 or more sets of
2830 control points (as defined below). More that 4 sets (16 numbers) of
2831 control points provide least squares fitting for more accurate
2832 distortions (for the purposes of image registration and panorama
2833 effects). Less than 4 sets will fall back to a 'Affine'
2834 linear distortion. <br/>
2836 Perspective Distorted images ensures that straight lines remain
2837 straight, but the scale of the distorted image will vary. The horizon
2838 is anti-aliased, and the 'sky' color may be set using the
2839 <a href="command-line-options.html#alpha-color" >-alpha-color</a> setting. </td>
2843 <td>PerspectiveProjection </td>
2845 Do a 'Perspective' distortion biased on a set of 8
2846 pre-calculated coefficients. You can get these coefficients by looking
2847 at the <a href="command-line-options.html#verbose" >-verbose</a> output of a
2848 'Perspective' distortion, or by calculating them yourself.
2849 If the last two perspective scaling coefficients are zero, the
2850 remaining 6 represents a transposed 'Affine Matrix'. </td>
2857 Arc the image (variation of polar mapping) over the angle given around
2860 <dl class="dl-horizontal">
2862 <dd>The angle over which to arc the image side-to-side</dd>
2863 <dt>rotate_angle</dt>
2864 <dd>Angle to rotate resulting image from vertical center</dd>
2866 <dd>Set top edge of source image at this radius</dd>
2867 <dt>bottom_radius </dt>
2868 <dd>Set bottom edge to this radius (radial scaling)</dd>
2871 The resulting image is always resized to best fit the resulting image,
2872 (as if using <a href="command-line-options.html#distort" >+distort</a>) while attempting to
2873 preserve scale and aspect ratio of the original image as much as
2874 possible with the arguments given by the user. All four arguments will
2875 be needed to change the overall aspect ratio of an 'Arc'ed image. <br/>
2877 This a variation of a polar distortion designed to try to preserve the
2878 aspect ratio of the image rather than direct Cartesian to Polar
2885 Like 'Arc' but do a complete Cartesian to Polar mapping of
2886 the image. that is the height of the input image is mapped to the
2887 radius limits, while the width is wrapped around between the
2890 Arguments: <var>Rmax,Rmin CenterX,CenterY, start,end_angle</var> <br/>
2892 All arguments are optional. With <var>Rmin</var> defaulting to zero, the
2893 center to the center of the image, and the angles going from -180 (top)
2894 to +180 (top). If <var>Rmax</var> is given the special value of
2895 '0', the the distance from the center to the nearest edge
2896 is used for the radius of the output image, which will ensure the whole
2897 image is visible (though scaled smaller). However a special value of
2898 '-1' will use the distance from the center to the furthest
2899 corner, This may 'clip' the corners from the input rectangular image,
2900 but will generate the exact reverse of a 'DePolar' with
2901 the same arguments. <br/>
2903 If the plus form of distort (<a href="command-line-options.html#distort" >+distort</a>) is used
2904 output image center will default to 0,0 of the virtual
2905 canvas, and the image size adjusted to ensure the whole input image is
2906 made visible in the output image on the virtual canvas. </td>
2913 Uses the same arguments and meanings as a 'Polar' distortion
2914 but generates the reverse Polar to Cartesian distortion. <br/>
2916 The special <var>Rmax</var> setting of '0' may however clip
2917 the corners of the input image. However using the special
2918 <var>Rmax</var> setting of '-1' (maximum center to corner
2919 distance) will ensure the whole distorted image is preserved in the
2920 generated result, so that the same argument to 'Polar' will
2921 reverse the distortion re-producing the original.
2923 Note that as this distortion requires the area resampling of a circular
2924 arc, which can not be handled by the builtin EWA resampling function.
2925 As such the normal EWA filters are turned off. It is recommended some
2926 form of 'super-sampling' image processing technique be used to produce
2927 a high quality result. </td>
2934 Given the four coefficients (A,B,C,D) as defined by <a
2935 href="http://wiki.panotools.org/Lens_correction_model" >Helmut
2936 Dersch</a>, perform a barrel or pin-cushion distortion appropriate to
2937 correct radial lens distortions. That is in photographs, make straight
2938 lines straight again. <br/>
2940 <p class="text-center">Arguments: <var>A B C</var> [ <var>D</var> [
2941 <var>X</var> , <var>Y</var> ] ] <br/>
2942 or <var>A<sub>x</sub> B<sub>x</sub> C<sub>x</sub> D<sub>x</sub>
2943 A<sub>y</sub> B<sub>y</sub> C<sub>y</sub> D<sub>y</sub></var>
2944 [ <var>X</var> , <var>Y</var> ] </p>
2945 So that it forms the function
2946 <p class="text-center">Rsrc = r * ( <var>A</var>*r<sup>3</sup> + <var>B</var>*r<sup>2</sup> +
2947 <var>C</var>*r + <var>D</var> )</p>
2949 Where <var>X</var>,<var>Y</var> is the optional center of the distortion
2950 (defaulting to the center of the image). <br/>
2951 The second form is typically used to distort images, rather than
2952 correct lens distortions. <br/>
2958 <td>BarrelInverse</td>
2960 This is very similar to 'Barrel' with the same set of
2961 arguments, and argument handling. However it uses the inverse
2962 of the radial polynomial,
2963 so that it forms the function
2964 <p class="text-center">Rsrc = r / ( <var>A</var>*r<sup>3</sup> + <var>B</var>*r<sup>2</sup> +
2965 <var>C</var>*r + <var>D</var> )</p>
2966 Note that this is not the reverse of the 'Barrel'
2967 distortion, just a different barrel-like radial distortion method.
2975 Distort the given list control points (any number) using an Inverse
2976 Squared Distance Interpolation Method (<a
2977 href="http://en.wikipedia.org/wiki/Shepard%27s_method" >Shepards
2978 Method</a>). The control points in effect do 'localized' displacement
2979 of the image around the given control point (preserving the look and
2980 the rotation of the area near the control points. For best results
2981 extra control points should be added to 'lock' the positions of the
2982 corners, edges and other unchanging parts of the image, to prevent
2983 their movement. <br/>
2985 The distortion has been likened to 'taffy pulling' using nails, or
2986 pins' stuck in a block of 'jelly' which is then moved to the new
2987 position, distorting the surface of the jelly. <br/>
2989 Internally it is equivalent to generating a displacement map (see <a
2990 href="command-line-options.html#displace" >-displace</a>) for source image color look-up using
2991 the <a href="command-line-options.html#sparse-color" >-sparse-color</a> method of the same name.
2998 <p>To print a complete list of distortion methods, use <a href="command-line-options.html#list">-list
3001 <p>Many of the above distortion methods such as '<code>Affine</code>',
3002 '<code>Perspective</code>', and '<code>Shepards</code>' use a list control points
3003 defining how these points in the given image should be distorted in the
3004 destination image. Each set of four floating point values represent a source
3005 image coordinate, followed immediately by the destination image coordinate.
3006 This produces a list of values such as...</p>
3007 <p class="text-center"><var>
3008 U<sub>1</sub>,V<sub>1</sub> X<sub>1</sub>,Y<sub>1</sub>
3009 U<sub>2</sub>,V<sub>2</sub> X<sub>2</sub>,Y<sub>2</sub>
3010 U<sub>3</sub>,V<sub>3</sub> X<sub>3</sub>,Y<sub>3</sub>
3012 U<sub>n</sub>,V<sub>n</sub> X<sub>n</sub>,Y<sub>n</sub>
3014 <p>where <var>U,V</var> on the source image is mapped to <var>X,Y</var> on the
3015 destination image. </p>
3017 <p>For example, to warp an image using '<code>perspective</code>' distortion,
3018 needs a list of at least 4 sets of coordinates, or 16 numbers. Here is the
3019 perspective distortion of the built-in "rose:" image. Note how spaces were
3020 used to group the 4 sets of coordinate pairs, to make it easier to read and
3024 convert rose: -virtual-pixel black \
3025 -distort Perspective '0,0,0,0 0,45,0,45 69,0,60,10 69,45,60,35' \
3026 rose_3d_rotated.gif"
3029 <p>If more that the required number of coordinate pairs are given for
3030 a distortion, the distortion method is 'least squares' fitted to produce the
3031 best result for all the coordinate pairs given. If less than the ideal number
3032 of points are given, the distort will generally fall back to a simpler form of
3033 distortion that can handles the smaller number of coordinates (usually a linear
3034 '<code>Affine</code>' distortion). </p>
3036 <p>By using more coordinates you can make use of image registration tool to
3037 find matching coordinate pairs in overlapping images, so as to improve the
3038 'fit' of the distortion. Of course a bad coordinate pair can also make the
3039 'fit' worse. Caution is always advised. </p>
3041 <p>Colors are acquired from the source image according to a cylindrical
3042 resampling <a href="command-line-options.html#filter" >-filter</a>, using a special technique known as
3043 EWA resampling. This produces very high quality results, especially when
3044 images become smaller (minified) in the output, which is very common when
3045 using '<code>perspective</code>' distortion. For example here we view
3046 a infinitely tiled 'plane' all the way to the horizon. </p>
3049 convert -size 90x90 pattern:checkerboard -normalize -virtual-pixel tile \
3050 -distort perspective '0,0,5,45 89,0,45,46 0,89,0,89 89,89,89,89' \
3054 <p>Note that a infinitely tiled perspective images involving the horizon can
3055 be very slow, because of the number of pixels that are compressed to generate
3056 each individual pixel close to the 'horizon'. You can turn off EWA
3057 resampling, by specifying the special <a href="command-line-options.html#filter" >-filter</a> setting of
3058 '<code>point</code>' (recommended if you plan to use super-sampling instead).
3061 <p>If an image generates <i>invalid pixels</i>, such as the 'sky' in the last
3062 example, <a href="command-line-options.html#distort" >-distort</a> will use the current <a
3063 href="command-line-options.html#alpha-color" >-alpha-color</a> setting for these pixels. If you do not
3064 what these pixels to be visible, set the color to match the rest of the
3067 <p>The output image size will by default be the same as the input image. This
3068 means that if the part of the distorted image falls outside the viewed area of
3069 the 'distorted space', those parts is clipped and lost. However if you use
3070 the plus form of the operator (<a href="command-line-options.html#distort" >+distort</a>) the operator
3071 will attempt (if possible) to show the whole of the distorted image, while
3072 retaining a correct 'virtual canvas' offset, for image layering. This offset
3073 may need to be removed using <a href="command-line-options.html#repage" >+repage</a>, to remove if it
3076 <p>Setting <a href="command-line-options.html#verbose" >-verbose</a> setting, will cause <a
3077 href="command-line-options.html#distort" >-distort</a> to attempt to output the internal coefficients,
3078 and the <a href="command-line-options.html#fx" >-fx</a> equivalent to the distortion, for expert study,
3079 and debugging purposes. This many not be available for all distorts. </p>
3081 <p>You can alternatively specify a special "<code><a href="command-line-options.html#define"
3082 >-define</a> distort:viewport={geometry_string}</code>" setting which will
3083 specify the size and the offset of the generated 'viewport' image of the
3084 distorted image space.</p>
3086 <p>Setting a "<code><a href="command-line-options.html#define" >-define</a>
3087 distort:scale=<var>scale_factor</var></code>" will scale the output image (viewport or
3088 otherwise) by that factor without changing the viewed contents of the
3089 distorted image. This can be used either for 'super-sampling' the image for
3090 a higher quality result, or for panning and zooming around the image (with
3091 appropriate viewport changes, or post-distort cropping and resizing). </p>
3093 <p>Setting "<code><a href="command-line-options.html#define" >-define</a> resample:verbose=1</code>"
3094 will output the cylindrical filter lookup table created by the EWA (Elliptical
3095 Weighted Average) resampling algorithm. Note this table uses a squared radius
3096 lookup value. This is typically only used for debugging EWA resampling. </p>
3099 <div style="margin: auto;">
3100 <h3 class="magick-header"><a id="distribute-cache"></a>-distribute-cache <var>port</var></h3>
3103 <p class="magick-description">launch a distributed pixel cache server. </p>
3105 <div style="margin: auto;">
3106 <h3 class="magick-header"><a id="dither"></a>-dither <var>method</var></h3>
3109 <p class="magick-description">Apply a Riemersma or Floyd-Steinberg error diffusion dither to
3110 images when general color reduction is applied via an option, or automagically
3111 when saving to specific formats. This enabled by default.</p>
3113 <p>Dithering places two or more colors in neighboring pixels so that to the
3114 eye a closer approximation of the images original color is reproduced. This
3115 reduces the number of colors needed to reproduce the image but at the cost of
3116 a lower level pattern of colors. Error diffusion dithers can use any set of
3117 colors (generated or user defined) to an image. </p>
3119 <p>Dithering is turned on by default, to turn it off use the plus form of the
3120 setting, <a href="command-line-options.html#dither">+dither</a>. This will also also render PostScript
3121 without text or graphic aliasing. Disabling dithering often (but not always)
3122 leads to faster process, a smaller number of colors, but more cartoon like
3123 image coloring. Generally resulting in 'color banding' effects in areas with
3124 color gradients. </p>
3126 <p>The color reduction operators <a href="command-line-options.html#colors">-colors</a>, <a
3127 href="command-line-options.html#monochrome">-monochrome</a>, <a href="command-line-options.html#remap ">-remap</a>, and <a
3128 href="command-line-options.html#posterize">-posterize</a>, apply dithering to images using the reduced
3129 color set they created. These operators are also used as part of automatic
3130 color reduction when saving images to formats with limited color support, such
3131 as <code>GIF:</code>, <code>XBM:</code>, and others, so dithering may also be used
3132 in these cases. </p>
3134 <p>Alternatively you can use <a href="command-line-options.html#random-threshold">-random-threshold</a>
3135 to generate purely random dither. Or use <a
3136 href="command-line-options.html#ordered-dither">-ordered-dither</a> to apply threshold mapped dither
3137 patterns, using uniform color maps, rather than specific color maps. </p>
3140 <div style="margin: auto;">
3141 <h3 class="magick-header"><a id="draw"></a>-draw <var>string</var></h3>
3144 <p class="magick-description">Annotate an image with one or more graphic primitives.</p>
3146 <p>Use this option to annotate or decorate an image with one or more graphic
3147 primitives. The primitives include shapes, text, transformations, and pixel
3150 <p>The shape primitives:</p>
3152 <dl class="dl-horizontal">
3153 <dt>point</dt><dd> x,y</dd>
3154 <dt>line</dt><dd> x0,y0 x1,y1</dd>
3155 <dt>rectangle</dt><dd> x0,y0 x1,y1</dd>
3156 <dt>roundRectangle</dt><dd> x0,y0 x1,y1 wc,hc</dd>
3157 <dt>arc</dt><dd> x0,y0 x1,y1 a0,a1</dd>
3158 <dt>ellipse</dt><dd> x0,y0 rx,ry a0,a1</dd>
3159 <dt>circle</dt><dd> x0,y0 x1,y1</dd>
3160 <dt>polyline</dt><dd> x0,y0 ... xn,yn</dd>
3161 <dt>polygon</dt><dd> x0,y0 ... xn,yn</dd>
3162 <dt>bezier</dt><dd> x0,y0 ... xn,yn</dd>
3163 <dt>path</dt><dd>specification </dd>
3164 <dt>image</dt><dd> operator x0,y0 w,h filename</dd>
3167 <p>The text primitive:</p>
3169 <dl class="dl-horizontal">
3170 <dt>text</dt><dd>x0,y0 string</dd>
3172 <p>The text gravity primitive:</p>
3174 <dl class="dl-horizontal">
3175 <dt>gravity</dt><dd>NorthWest, North, NorthEast, West, Center, East, SouthWest, South, or SouthEast</dd>
3178 <p>The text gravity primitive only affects the placement of text and does not
3179 interact with the other primitives. It is equivalent to using the <a
3180 href="command-line-options.html#gravity">-gravity</a> command-line option, except that it is limited in
3181 scope to the <a href="command-line-options.html#draw">-draw</a> option in which it appears.</p>
3183 <p>The transformation primitives:</p>
3185 <dl class="dl-horizontal">
3186 <dt>rotate</dt><dd>degrees</dd>
3187 <dt>translate</dt><dd>dx,dy</dd>
3188 <dt>scale</dt><dd>sx,sy</dd>
3189 <dt>skewX</dt><dd>degrees</dd>
3190 <dt>skewY</dt><dd>degrees</dd>
3193 <p>The pixel operation primitives:</p>
3195 <dl class="dl-horizontal">
3196 <dt>color</dt><dd>x0,y0 method</dd>
3197 <dt>matte</dt><dd>x0,y0 method</dd>
3200 <p>The shape primitives are drawn in the color specified by the preceding <a
3201 href="command-line-options.html#fill">-fill</a> setting. For unfilled shapes, use <a
3202 href="command-line-options.html#fill">-fill none</a>. You can optionally control the stroke (the
3203 "outline" of a shape) with the <a href="command-line-options.html#stroke">-stroke</a> and <a
3204 href="command-line-options.html#strokewidth">-strokewidth</a> settings.</p>
3206 <p>A <code>point</code> primitive is specified by a single <var>point</var> in the
3207 pixel plane, that is, by an ordered pair of integer coordinates,
3208 <var>x</var>,<var>y</var>. (As it involves only a single pixel, a <code>point</code>
3209 primitive is not affected by <a href="command-line-options.html#stroke">-stroke</a> or <a
3210 href="command-line-options.html#strokewidth">-strokewidth</a>.)</p>
3212 <p>A <code>line</code> primitive requires a start point and end point.</p>
3214 <p>A <code>rectangle</code> primitive is specified by the pair of points at the
3215 upper left and lower right corners.</p>
3217 <p>A <code>roundRectangle</code> primitive takes the same corner points as
3218 a <code>rectangle</code> followed by the width and height of the rounded corners
3221 <p>The <code>circle</code> primitive makes a disk (filled) or circle (unfilled).
3222 Give the center and any point on the perimeter (boundary).</p>
3224 <p>The <code>arc</code> primitive is used to inscribe an elliptical segment in
3225 to a given rectangle. An <code>arc</code> requires the two corners used for
3226 <code>rectangle</code> (see above) followed by the start and end angles of the
3227 arc of the segment segment (e.g. 130,30 200,100 45,90). The start and end
3228 points produced are then joined with a line segment and the resulting segment
3229 of an ellipse is filled.</p>
3231 <p>Use <code>ellipse</code> to draw a partial (or whole) ellipse. Give the
3232 center point, the horizontal and vertical "radii" (the <var>semi-axes</var> of
3233 the ellipse) and start and end angles in degrees (e.g. 100,100 100,150
3236 <p>The <code>polyline</code> and <code>polygon</code> primitives require three or
3237 more points to define their perimeters. A <code>polyline</code> is simply
3238 a <code>polygon</code> in which the final point is not stroked to the start
3239 point. When unfilled, this is a <var>polygonal line</var>. If the <a
3240 href="command-line-options.html#stroke">-stroke</a> setting is <code>none</code> (the default), then
3241 a <code>polyline</code> is identical to a <code>polygon</code>. </p>
3243 <p>A <var>coordinate</var> is a pair of integers separated by a space or
3244 optional comma. </p>
3246 <p>As an example, to define a circle centered at 100,100 that extends to
3250 -draw 'circle 100,100 150,150'
3253 <p>The <code>Bezier</code> primitive creates a spline curve and requires three
3254 or points to define its shape. The first and last points are the
3255 <var>knots</var> and these points are attained by the curve, while any
3256 intermediate coordinates are <var>control points</var>. If two control points
3257 are specified, the line between each end knot and its sequentially respective
3258 control point determines the tangent direction of the curve at that end. If
3259 one control point is specified, the lines from the end knots to the one
3260 control point determines the tangent directions of the curve at each end. If
3261 more than two control points are specified, then the additional control points
3262 act in combination to determine the intermediate shape of the curve. In order
3263 to draw complex curves, it is highly recommended either to use the
3264 <code>path</code> primitive or to draw multiple four-point bezier segments with
3265 the start and end knots of each successive segment repeated. For example:</p>
3268 -draw 'bezier 20,50 45,100 45,0 70,50'
3269 -draw 'bezier 70,50 95,100 95,0 120,50'
3272 <p>A <code>path</code> represents an outline of an object, defined in terms of
3273 moveto (set a new current point), lineto (draw a straight line), curveto (draw
3274 a Bezier curve), arc (elliptical or circular arc) and closepath (close the
3275 current shape by drawing a line to the last moveto) elements. Compound paths
3276 (i.e., a path with subpaths, each consisting of a single moveto followed by
3277 one or more line or curve operations) are possible to allow effects such as
3278 <var>donut holes</var> in objects. (See <a
3279 href="http://www.w3.org/TR/SVG/paths.html">Paths</a>.)</p>
3281 <p>Use <code>image</code> to composite an image with another image. Follow the
3282 image keyword with the composite operator, image location, image size, and
3286 -draw 'image SrcOver 100,100 225,225 image.jpg'
3289 <p>You can use 0,0 for the image size, which means to use the actual
3290 dimensions found in the image header. Otherwise, it is scaled to the given
3291 dimensions. See <a href="http://www.imagemagick.org/www/compose.html">Alpha Compositing</a> for
3292 a detailed discussion of alpha composition methods that are available. </p>
3294 <p>The "special augmented compose operators" such as "dissolve" that require
3295 arguments cannot be used at present with the <code>-draw image</code> option.
3298 <p>Use <code>text</code> to annotate an image with text. Follow the text
3299 coordinates with a string. If the string has embedded spaces, enclose it in
3300 single or double quotes.</p>
3302 <p>For example, the following annotates the image with <code>Works like
3303 magick!</code> for an image titled <code>bird.miff</code>. </p>
3306 -draw "text 100,100 'Works like magick!' "
3309 <p>See the <a href="command-line-options.html#annotate">-annotate</a> option for another convenient way
3310 to annotate an image with text.</p>
3312 <p>The <code>rotate</code> primitive rotates subsequent shape primitives and
3313 text primitives about the origin of the main image. If the <a
3314 href="command-line-options.html#region">-region</a> option precedes the <a href="command-line-options.html#draw">-draw</a>
3315 option, the origin for transformations is the upper left corner of the
3318 <p>The <code>translate</code> primitive translates subsequent shape and text
3321 <p>The <code>scale</code> primitive scales them.</p>
3323 <p>The <code>skewX</code> and <code>skewY</code> primitives skew them with respect
3324 to the origin of the main image or the region.</p>
3326 <p>The transformations modify the current affine matrix, which is initialized
3327 from the initial affine matrix defined by the <a href="command-line-options.html#affine">-affine</a>
3328 option. Transformations are cumulative within the <a href="command-line-options.html#draw">-draw</a>
3329 option. The initial affine matrix is not affected; that matrix is only changed
3330 by the appearance of another <a href="command-line-options.html#affine">-affine</a> option. If another
3331 <a href="command-line-options.html#draw">-draw</a> option appears, the current affine matrix is
3332 reinitialized from the initial affine matrix.</p>
3334 <p>Use the <code>color</code> primitive to change the color of a pixel to the
3335 fill color (see <a href="command-line-options.html#fill">-fill</a>). Follow the pixel coordinate with
3346 <p>Consider the target pixel as that specified by your coordinate. The
3347 <code>point</code> method recolors the target pixel. The <code>replace</code>
3348 method recolors any pixel that matches the color of the target pixel.
3349 <code>Floodfill</code> recolors any pixel that matches the color of the target
3350 pixel and is a neighbor, whereas <code>filltoborder</code> recolors any neighbor
3351 pixel that is not the border color. Finally, <code>reset</code> recolors all
3354 <p>Use <code>matte</code> to the change the pixel matte value to transparent.
3355 Follow the pixel coordinate with a method (see the <code>color</code> primitive
3356 for a description of methods). The <code>point</code> method changes the matte
3357 value of the target pixel. The <code>replace</code> method changes the matte
3358 value of any pixel that matches the color of the target pixel.
3359 <code>Floodfill</code> changes the matte value of any pixel that matches the
3360 color of the target pixel and is a neighbor, whereas <code>filltoborder</code>
3361 changes the matte value of any neighbor pixel that is not the border color (<a
3362 href="command-line-options.html#bordercolor">-bordercolor</a>). Finally <code>reset</code> changes the
3363 matte value of all pixels.</p>
3365 <p>You can set the primitive color, font, and font bounding box color with <a
3366 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>
3367 respectively. Options are processed in command line order so be sure to use
3368 these options <var>before</var> the <a href="command-line-options.html#draw">-draw</a> option.</p>
3370 <p>Strings that begin with a number must be quoted (e.g. use '1.png' rather
3373 <p>Drawing primitives conform to the <a href="magick-vector-graphics.html" >Magick
3374 Vector Graphics</a> format.</p>
3377 <div style="margin: auto;">
3378 <h3 class="magick-header"><a id="duplicate"></a>-duplicate <var>count,indexes</var></h3>
3381 <p class="magick-description">duplicate an image one or more times.</p>
3383 <p>Specify the count and the image to duplicate by its index in the sequence.
3384 The first image is index 0. Negative indexes are relative to the end of the
3385 sequence, for example, -1 represents the last image of the sequence. Specify
3386 a range of images with a dash (e.g. 0-4). Separate indexes with a comma (e.g.
3387 0,2). Use <code>+duplicate</code> to duplicate the last image in the current
3390 <div style="margin: auto;">
3391 <h3 class="magick-header"><a id="edge"></a>-edge <var>radius</var></h3>
3394 <p class="magick-description">detect edges within an image.</p>
3396 <div style="margin: auto;">
3397 <h3 class="magick-header"><a id="emboss"></a>-emboss <var>radius</var></h3>
3400 <p class="magick-description">emboss an image.</p>
3402 <div style="margin: auto;">
3403 <h3 class="magick-header"><a id="encipher"></a>-encipher <var>filename</var></h3>
3406 <p class="magick-description">Encipher pixels for later deciphering by <a href="command-line-options.html#decipher">-decipher</a>.</p>
3408 <p>Get the passphrase from the file specified by <var>filename</var>.</p>
3410 <p>For more information, see the webpage, <a
3411 href="https://www.imagemagick.org/script/cipher.html">ImageMagick: Encipher or
3412 Decipher an Image</a>.</p>
3416 <div style="margin: auto;">
3417 <h3 class="magick-header"><a id="encoding"></a>-encoding <var>type</var></h3>
3420 <p class="magick-description">specify the text encoding.</p>
3425 AdobeCustom AdobeExpert
3426 AdobeStandard AppleRoman
3433 <div style="margin: auto;">
3434 <h3 class="magick-header"><a id="endian"></a>-endian <var>type</var></h3>
3437 <p class="magick-description">Specify endianness (<code>MSB</code> or <code>LSB</code>) of the image.</p>
3439 <p>To print a complete list of endian types, use the <a href="command-line-options.html#list">-list endian</a> option.</p>
3441 <p>Use <a href="command-line-options.html#endian">+endian</a> to revert to unspecified endianness.</p>
3444 <div style="margin: auto;">
3445 <h3 class="magick-header"><a id="enhance"></a>-enhance</h3>
3448 <p class="magick-description">Apply a digital filter to enhance a noisy image.</p>
3451 <div style="margin: auto;">
3452 <h3 class="magick-header"><a id="equalize"></a>-equalize</h3>
3455 <p class="magick-description">perform histogram equalization on the image channel-by-channel.</p>
3457 <p>To perform histogram equalization on all channels in concert, transform the
3458 image into some other color space, such as HSL, OHTA, YIQ or YUV, then
3459 equalize the appropriate intensity-like channel, then convert back to RGB.</p>
3461 <p>For example using HSL, we have: ... <code>-colorspace HSL -channel lightness
3462 -equalize -colorspace RGB</code> ...</p>
3464 <p>For YIQ, YUV and OHTA use the red channel. For example, OHTA is a principal
3465 components transformation that puts most of the information in the first
3466 channel. Here we have ... <code>-colorspace OHTA -channel red -equalize
3467 -colorspace RGB</code> ...</p>
3469 <div style="margin: auto;">
3470 <h3 class="magick-header"><a id="evaluate"></a>-evaluate <var>operator value</var></h3>
3473 <p class="magick-description">Alter channel pixels by evaluating an arithmetic, relational, or logical expression.</p>
3475 <p>(See the <a href="command-line-options.html#function" >-function</a> operator for some
3476 multi-parameter functions. See the <a href="command-line-options.html#fx" >-fx</a> operator if more
3477 elaborate calculations are needed.)</p>
3479 <p>The behaviors of each <var>operator</var> are summarized in the
3480 following list. For brevity, the numerical value of a "pixel" referred to
3481 below is the value of the corresponding channel of that pixel, while
3482 a "normalized pixel" is that number divided by the maximum
3483 (installation-dependent) value <var>QuantumRange</var>. (If
3484 normalized pixels are used, they are restored, following the other
3485 calculations, to the full range by multiplying by <var>QuantumRange</var>.)</p>
3487 <table class="table table-condensed table-striped">
3492 <th><var>operator</var></th>
3493 <th>Summary (see further below for details)</th>
3498 <tr><td>Abs </td> <td>Add <var>value</var> to pixels and return absolute value. </td></tr>
3499 <tr><td>Add </td> <td>Add <var>value</var> to pixels. </td></tr>
3500 <tr><td>AddModulus </td> <td>Add <var>value</var> to pixels modulo <var>QuantumRange</var>.</td></tr>
3501 <tr><td>And </td> <td>Binary AND of pixels with <var>value</var>.</td></tr>
3502 <tr><td>Cos, Cosine </td> <td>Apply cosine to pixels with frequency <var>value</var> with 50% bias added.</td></tr>
3503 <tr><td>Divide </td> <td>Divide pixels by <var>value</var>.</td></tr>
3504 <tr><td>Exp </td> <td>base-e exponential function</td></tr>
3505 <tr><td>Exponential </td> <td>base-e exponential function</td></tr>
3506 <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>
3507 <tr><td>Log </td> <td>Apply scaled logarithm to normalized pixels.</td></tr>
3508 <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>
3509 <tr><td>Mean </td> <td>Add the <var>value</var> and divide by 2.</td></tr>
3510 <tr><td>Median </td> <td>Choose the median value from an image sequence.</td></tr>
3511 <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>
3512 <tr><td>Multiply </td> <td>Multiply pixels by <var>value</var>.</td></tr>
3513 <tr><td>Or </td> <td>Binary OR of pixels with <var>value</var>.</td></tr>
3514 <tr><td>Pow </td> <td>Raise normalized pixels to the power <var>value</var>.</td></tr>
3515 <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>
3516 <tr><td>RMS</td> <td>Square the pixel and add the <var>value</var>.</td></tr>
3517 <tr><td>RootMeanSquare</td> <td>Square the pixel and add the <var>value</var>.</td></tr>
3518 <tr><td>Set </td> <td>Set pixel equal to <var>value</var>.</td></tr>
3519 <tr><td>Sin, Sine </td> <td>Apply sine to pixels with frequency <var>value</var> with 50% bias added.</td></tr>
3520 <tr><td>Subtract </td> <td>Subtract <var>value</var> from pixels.</td></tr>
3521 <tr><td>Xor </td> <td>Binary XOR of pixels with <var>value.</var></td></tr>
3523 <tr><td> </td><td> </td></tr>
3525 <tr><td>Gaussian-noise</td><td> </td></tr>
3526 <tr><td>Impulse-noise</td><td> </td></tr>
3527 <tr><td>Laplacian-noise</td><td> </td></tr>
3528 <tr><td>Multiplicative-noise</td> <td>(These are equivalent to the corresponding <a href="command-line-options.html#noise" >-noise</a> operators.)</td></tr>
3529 <tr><td>PoissonNoise</td><td> </td></tr>
3530 <tr><td>Uniform-noise</td><td> </td></tr>
3532 <tr><td> </td><td> </td></tr>
3534 <tr><td>Threshold </td> <td>Threshold pixels larger than <var>value</var>.</td></tr>
3535 <tr><td>ThresholdBlack </td> <td>Threshold pixels to zero values equal to or below <var>value</var>.</td></tr>
3536 <tr><td>ThresholdWhite </td> <td>Threshold pixels to maximum values above <var>value</var>. </td></tr>
3540 <p>The specified functions are applied only to each previously set <a
3541 href="command-line-options.html#channel" >-channel</a> in the image. If necessary, the results of the
3542 calculations are truncated (clipped) to fit in the interval [0, <var>QuantumRange</var>]. The transparency channel of the image is
3543 represented as a 'alpha' values (0 = fully transparent), so, for example, a
3544 <code>Divide</code> by 2 of the alpha channel will make the image
3545 semi-transparent. Append the percent symbol '<code>%</code>' to specify a value
3546 as a percentage of the <var>QuantumRange</var>.</p>
3548 <p>To print a complete list of <a href="command-line-options.html#evaluate">-evaluate</a> operators, use
3549 <a href="command-line-options.html#list">-list evaluate</a>.</p>
3551 <p>The results of the <code>Add</code>, <code>Subtract</code> and
3552 <code>Multiply</code> methods can also be achieved using either the <a
3553 href="command-line-options.html#level" >-level</a> or the <a href="command-line-options.html#level" >+level</a> operator, with
3554 appropriate argument, to linearly modify the overall range of color values.
3555 Please note, however, that <a href="command-line-options.html#level" >-level</a> treats transparency as
3556 'matte' values (0 = opaque), while <a href="command-line-options.html#level" >-evaluate</a> works with
3559 <p><code>AddModulus</code> has been added as of ImageMagick 6.4.8-4 and provides
3560 addition modulo the <var>QuantumRange</var>. It is therefore
3561 equivalent to <code>Add</code> unless the resulting pixel value is outside the
3562 interval [0, <var>QuantumRange</var>]. </p>
3564 <p><code>Exp or Exponential</code> has been added as of ImageMagick 6.6.5-1 and
3565 works on normalized pixel values. The <var>value</var> used with
3566 <code>Exp</code> should be negative so as to produce a decaying exponential
3567 function. Non-negative values will always produce results larger unity and
3568 thus outside the interval [0, <var>QuantumRange</var>]. The
3569 formula is expressed below. </p>
3571 <p class="text-center">
3572 exp(<var>value</var> × <b><var>u</var></b>)
3575 <p> If the input image is squared, for example, using <a href="command-line-options.html#-function"
3576 >-function polynomial "2 0 0"</a>, then a decaying Gaussian function will be
3579 <p><code>Log</code> has been added as of ImageMagick 6.4.2-1 and works on
3580 normalized pixel values. This a <var>scaled</var> log function. The <var>value</var> used with <code>Log</code> provides a <var>scaling
3581 factor</var> that adjusts the curvature in the graph of the log function. The
3582 formula applied to a normalized value <b><var>u</var></b> is below. </p>
3584 <p class="text-center">
3585 log(<var>value</var> × <b><var>u</var></b> + 1) / log(<var>value</var> + 1)
3588 <p><code>Pow</code> has been added as of ImageMagick 6.4.1-9, and works on
3589 normalized pixel values. Note that <code>Pow</code> is related to the <a
3590 href="command-line-options.html#gamma" >-gamma</a> operator. For example, <b>-gamma 2</b> is equivalent
3591 to <b>-evaluate pow 0.5</b>, i.e., a 'square root' function. The value used
3592 with <a href="command-line-options.html#gamma" >-gamma</a> is simply the reciprocal of the value used
3593 with <code>Pow</code>.</p>
3595 <p><code>Cosine</code> and <code>Sine</code> was added as of IM v6.4.8-8 and
3596 converts the image values into a value according to a (co)sine wave function.
3597 The synonyms <code>Cos</code> and <code>Sin</code> may also be used. The output
3598 is biased 50% and normalized by 50% so as to fit in the respective color value
3599 range. The <var>value</var> scaling of the <var>period</var> of the
3600 function (its frequency), and thus determines the number of 'waves' that will
3601 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,
3602 then the effective period is the <var>half</var> the <var>QuantumRange</var>.</p>
3604 <p class="text-center">
3605 0.5 + 0.5 × cos(2 π <b><var>u</var></b> × <var>value</var>).
3608 <p>See also the <a href="command-line-options.html#function" >-function</a> operator, which is a
3609 multi-value version of evaluate. </p>
3611 <div style="margin: auto;">
3612 <h3 class="magick-header"><a id="evaluate-sequence"></a>-evaluate-sequence <var>operator</var></h3>
3615 <p class="magick-description">Alter channel pixels by evaluating an arithmetic, relational, or
3616 logical expression over a sequence of images.</p>
3618 <p>To print a complete list of <a
3619 href="command-line-options.html#evaluate-sequence">-evaluate-sequence</a> operators, use <a
3620 href="command-line-options.html#list">-list evaluate</a>.</p>
3622 <div style="margin: auto;">
3623 <h3 class="magick-header"><a id="extent"></a>-extent <var>geometry</var></h3>
3626 <p class="magick-description">Set the image size and offset.</p>
3628 <p>If the image is enlarged, unfilled areas are set to the background color.
3629 To position the image, use offsets in the <var>geometry</var>
3630 specification or precede with a <a href="command-line-options.html#gravity">-gravity</a> setting. To
3631 specify how to compose the image with the background, use <a href="command-line-options.html#compose"
3634 <p>This command reduces or expands a JPEG image to fit on an 800x600
3635 display. If the aspect ratio of the input image isn't exactly 4:3, then the
3636 image is centered on an 800x600 black canvas: </p>
3639 convert input.jpg -resize 800x600 -background black -compose Copy \
3640 -gravity center -extent 800x600 -quality 92 output.jpg
3643 <p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
3645 <div style="margin: auto;">
3646 <h3 class="magick-header"><a id="extract"></a>-extract <var>geometry</var></h3>
3649 <p class="magick-description">Extract the specified area from image.</p>
3651 <p>This option is most useful for extracting a subregion of a very large raw
3652 image. Note that these two commands are equivalent:</p>
3655 convert -size 16000x16000 -depth 8 -extract 640x480+1280+960 \
3656 image.rgb image.png",
3657 convert -size 16000x16000 -depth 8 'image.rgb[640x480+1280+960]' \
3658 image.rgb image.png"
3661 <p>If you omit the offsets, as in</p>
3664 convert -size 16000x16000 -depth 8 -extract 640x480 \
3668 <p>the image is <var>resized</var> to the specified dimensions instead,
3672 convert -size 16000x16000 -depth 8 -resize 640x480 image.rgb image.png
3675 <p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
3677 <div style="margin: auto;">
3678 <h3 class="magick-header"><a id="family"></a>-family <var>fontFamily</var></h3>
3681 <p class="magick-description">Set a font family for text.</p>
3683 <p>This setting suggests a font family that ImageMagick should try to use for
3684 rendering text. If the family can be found it is used; if not, a default font
3685 (e.g., "Arial") or a family known to be similar is substituted (e.g.,
3686 "Courier" might be used if "System" is requested but not found). </p>
3688 <p>For other settings that affect fonts, see the options <a
3689 href="command-line-options.html#font">-font</a>, <a href="command-line-options.html#stretch">-stretch</a>, <a
3690 href="command-line-options.html#style">-style</a>, and <a href="command-line-options.html#weight">-weight</a>. </p>
3692 <div style="margin: auto;">
3693 <h3 class="magick-header"><a id="features"></a>-features <var>distance</var></h3>
3696 <p class="magick-description">display (co-occurrence 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>
3699 Angular Second Moment Sum Entropy
3701 Correlation Difference Variance
3702 Sum of Squares Variance Difference Entropy
3703 Inverse Difference Moment Information Measure of Correlation 1
3704 Sum Average Information Measure of Correlation 2
3705 Sum Variance Maximum Correlation Coefficient
3708 <div style="margin: auto;">
3709 <h3 class="magick-header"><a id="fft"></a>-fft</h3>
3712 <p class="magick-description">implements the forward discrete Fourier transform (DFT).</p>
3714 <p>This option is new as of ImageMagick 6.5.4-3 (and now working for Windows
3715 users in ImageMagick 6.6.0-9). It transforms an image from the normal
3716 (spatial) domain to the frequency domain. In the frequency domain, an image is
3717 represented as a superposition of complex sinusoidal waves of varying
3718 amplitudes. The image x and y coordinates are the possible frequencies along
3719 the x and y directions, respectively, and the pixel intensity values are
3720 complex numbers that correspond to the sinusoidal wave amplitudes. See for
3721 example, <a href="http://en.wikipedia.org/wiki/Fourier_transform">Fourier
3722 Transform</a>, <a href="http://en.wikipedia.org/wiki/DFT">Discrete Fourier
3723 Transform</a> and <a href="http://en.wikipedia.org/wiki/FFT">Fast Fourier
3726 <p>A single image name is provided as output for this option. However, the
3727 output result will have two components. It is either a two-frame image or two
3728 separate images, depending upon whether the image format specified supports
3729 multi-frame images. The reason that we get a dual output result is because the
3730 frequency domain represents an image using complex numbers, which cannot be
3731 visualized directly. Therefore, the complex values are automagically separated
3732 into a two-component image representation. The first component is the
3733 magnitude of the complex number and the second is the phase of the complex
3734 number. See for example, <a
3735 href="http://en.wikipedia.org/wiki/Complex_numbers">Complex Numbers</a>.</p>
3737 <p>The magnitude and phase component images must be specified using image
3738 formats that do not limit the color or compress the image. Thus, MIFF, TIF,
3739 PFM, EXR and PNG are the recommended image formats to use. All of these
3740 formats, except PNG support multi-frame images. So for example,</p>
3743 convert image.png -fft fft_image.miff
3746 <p>generates a magnitude image as <code>fft_image.miff[0]</code> and a phase
3747 image as <code>fft_image.miff[1]</code>. Similarly,</p>
3750 convert image.png -fft fft_image.png
3753 <p>generates a magnitude image as <code>fft_image-0.png</code> and a phase image
3754 as <code>fft_image-1.png</code>. If you prefer this representation, then you can
3755 force any of the other formats to produce two output images by including <a
3756 href="command-line-options.html#adjoin">+adjoin</a> following -fft in the command line.</p>
3758 <p>The input image can be any size, but if not square and even-dimensioned, it
3759 is padded automagically to the larger of the width or height of the input
3760 image and to an even number of pixels. The padding will occur at the bottom
3761 and/or right sides of the input image. The resulting output magnitude and
3762 phase images is square at this size. The kind of padding relies on the <a
3763 href="command-line-options.html#virtual-pixel">-virtual-pixel</a> setting.</p>
3765 <p>Both output components will have dynamic ranges that fit within
3766 [0, <var>QuantumRange</var>], so that HDRI need not be enabled.
3767 Phase values nominally range from 0 to 2*π, but is scaled to span the full
3768 dynamic range. (The first few releases had non-HDRI scaled but HDRI not
3769 scaled). The magnitude image is not scaled and thus generally will contain
3770 very small values. As such, the image normally will appear totally black. In
3771 order to view any detail, the magnitude image typically is enhanced with a log
3772 function into what is usually called the spectrum. A log function is used to
3773 enhance the darker values more in comparison to the lighter values. This can
3774 be done, for example, as follows:</p>
3777 convert fft_image.miff[0] -contrast-stretch 0 \
3778 -evaluate log 1000 fft_image_spectrum.png"
3781 <p>where either <a href="command-line-options.html#contrast-stretch">-contrast-stretch</a> 0 or <a
3782 href="command-line-options.html#auto-level">-auto-level</a> is used to scale the image to full dynamic
3783 range, first. The argument to the <a href="command-line-options.html#evaluate">-evaluate</a> log
3784 typically is specified between 100 and 10,000, depending upon the amount of
3785 detail that one wants to bring out in the spectrum. Larger values produce more
3786 visible detail. Too much detail, however, may hide the important features.</p>
3788 <p>The <a href="http://www.fftw.org/">FFTW</a> delegate library is required to
3789 use <a href="command-line-options.html#fft">-fft</a>.</p>
3791 <p>Use <a href="command-line-options.html#fft">+fft</a> to produce two output images that are the real
3792 and imaginary components of the complex valued Fourier transform.</p>
3794 <p>However, as the real and imaginary components can contain negative values,
3795 this requires that IM be configured with HDRI enabled. In this case, you must
3796 use either MIFF, TIF, PFM or MPC formats for the real and imaginary component
3797 results, since they are formats that preserve both negative and fractional
3798 values without clipping them or truncating the fractional part. With either
3799 MIFF or TIF, one should add -define quantum:format=32, to allow those image
3800 types to work properly in HDRI mode without clipping.</p>
3802 <p>The real and imaginary component images resulting from <a
3803 href="command-line-options.html#fft">+fft</a> are also square, even dimensioned images due to the same
3804 padding that was discussed above for the magnitude and phase component
3807 <p>See the discussion on HDRI implementations of ImageMagick on the page <a
3808 href="high-dynamic-range.html" >High Dynamic-Range Images</a>. For more
3809 about HDRI go the ImageMagick <a
3810 href="https://www.imagemagick.org/Usage/basics/#hdri" >Usage</a> pages, <a
3811 href="http://www.fmwconcepts.com/imagemagick/fourier_transforms/fourier.html"
3812 >Fred's Fourier Processing With ImageMagick page</a> or this <a
3813 href="http://en.wikipedia.org/wiki/High_dynamic_range_imaging" >Wikipedia</a>
3816 <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 explicitly normalize the FFT and unnormalize the IFT.</p>
3819 <div style="margin: auto;">
3820 <h3 class="magick-header"><a id="fill"></a>-fill <var>color</var></h3>
3823 <p class="magick-description">color to use when filling a graphic primitive.</p>
3825 <p>This option accepts a color name, a hex color, or a numerical RGB, RGBA,
3826 HSL, HSLA, CMYK, or CMYKA specification. See <a href="color.html" >Color Names</a> for
3827 a description of how to properly specify the color argument.</p>
3829 <p>Enclose the color specification in quotation marks to prevent the "#" or
3830 the parentheses from being interpreted by your shell.</p>
3837 -fill "rgb(255,255,255)"
3840 <p>See <a href="command-line-options.html#draw">-draw</a> for further details.</p>
3842 <p>To print a complete list of color names, use the <a href="command-line-options.html#list">-list color</a> option.</p>
3844 <div style="margin: auto;">
3845 <h3 class="magick-header"><a id="filter"></a>-filter <var>type</var></h3>
3848 <p class="magick-description">Use this <var>type</var> of filter when resizing or distorting an image.</p>
3850 <p>Use this option to affect the resizing operation of an image during
3851 operations such as <a href="command-line-options.html#resize">-resize</a> and <a href="command-line-options.html#distort"
3852 >-distort</a>. For example you can use a simple resize filter such as:</p>
3857 Triangle Quadratic Mitchell
3860 <p>The <code>Bessel</code> and <code>Sinc</code> filter is also provided (as well
3861 as a faster <code>SincFast</code> equivalent form). However these filters are
3862 generally useless on their own as they are infinite filters that are being
3863 clipped to the filters support size. Their direct use is not recommended
3864 except via expert settings (see below). </p>
3866 <p>Instead these special filter functions are typically windowed by a windowing
3867 function that the <a href="command-line-options.html#filter" >-filter</a> setting defines. That is
3868 using these functions will define a 'Windowed' filter, appropriate to the
3869 operator involved. Windowed filters include: </p>
3872 Lanczos Hamming Parzen
3873 Blackman Kaiser Welsh
3874 Hanning Bartlett Bohman
3877 <p>Also one special self-windowing filter is also provided
3878 <code>Lagrange</code>, which will automagically re-adjust its function depending
3879 on the current 'support' or 'lobes' expert settings (see below).</p>
3881 <p>If you do not select a filter with this option, the filter defaults to
3882 <code>Mitchell</code> for a colormapped image, an image with a matte channel, or
3883 if the image is enlarged. Otherwise the filter default to
3884 <code>Lanczos</code>.</p>
3886 <p>To print a complete list of resize filters, use the <a href="command-line-options.html#list">-list
3887 filter</a> option.</p>
3889 <p>You can modify how the filter behaves as it scales your image through the
3890 use of these expert settings (see also <a href="command-line-options.html#define" >-define</a> and <a
3891 href="command-line-options.html#set" >-set</a>):-</p>
3893 <table class="table table-condensed table-striped">
3895 <td>-define filter:blur=<var>factor</var></td>
3896 <td>Scale the X axis of the filter (and its window). Use > 1.0 for
3897 blurry or < 1.0 for sharp. This should only be used with Gaussian and
3898 Gaussian-like filters simple filters, or you may not get the expected
3903 <td>-define filter:support=<var>radius</var></td>
3904 <td>Set the filter support radius. Defines how large the filter should be and
3905 thus directly defines how slow the filtered resampling process is. All
3906 filters have a default 'preferred' support size. Some filters like
3907 <code>Lagrange</code> and windowed filters adjust themselves depending on
3908 this value. With simple filters this value either does nothing (but slow
3909 the resampling), or will clip the filter function in a detrimental way.
3914 <td>-define filter:lobes=<var>count</var></td>
3915 <td>Set the number of lobes to use for the Sinc/Bessel filter. This an
3916 alternative way of specifying the 'support' range of the filter, that is
3917 designed to be more suited to windowed filters, especially when used for
3918 image distorts.</td>
3922 <td>-define filter:sigma=<var>value</var></td>
3923 <td>The 'sigma' value used to define the <code>Gaussian</code> filter. Default
3924 sigma value is '<code>0.5</code>'. It only effects <code>Gaussian</code> but
3925 does not shrink (but may enlarge) the filter's 'support'. It can be used
3926 to generate very small blurs but without the filter 'missing' pixels due
3927 to using a small support setting. A larger value of '<code>0.707</code>'
3928 (a value of '1/sqrt(2)') is another common setting. </td>
3932 <td>-define filter:b=<var>b-spline_factor</var></td>
3936 <td>-define filter:c=<var>keys_alpha_factor</var></td>
3937 <td>Redefine the values used for cubic filters such as <code>Cubic</code>,
3938 <code>Catrom</code>, <code>Mitchel</code>, and <code>Hermite</code>, as well as
3939 the <code>Parzen</code> cubic windowing function. If only one of the values
3940 are defined, the other is set so as to generate a 'Cubic-Keys' filter.
3941 The values meaning was defined by a research paper by
3942 Mitchell-Netravali.</td>
3946 <td>-define filter:kaiser-beta=<var>value</var></td>
3947 <td>The 'alpha' value used to as part of the Kaiser Windowing function.
3948 Default value is '6.5'. It only effects Kaiser windowing function, and
3949 does not effect any other attributes.
3950 Before ImageMagick v6.7.6-10, this option was known as "filter:alpha", (an
3951 inheritance from the very old "zoom" program). It was changed to bring the
3952 function in line with more modern academic research usage, and better
3953 assign it be more definitive. </td>
3957 <td>-define filter:kaiser-alpha=<var>value</var></td>
3958 <td>This value when multiplied by 'PI' is equivalent to "kaiser-beta", and
3959 will override that setting. It only effects Kaiser windowing function,
3960 and does not effect any other attributes. </td>
3964 <td>-define filter:filter=<var>filter_function</var></td>
3965 <td>Use this function directly as the weighting filter. This will allow
3966 you to directly use a windowing function such as <code>Blackman</code>,
3967 as a resampling filter, rather than as its normal usage as a windowing
3968 function. If defined, no windowing function also defined, the window function is set
3969 to <code>Box</code>). Directly specifying <code>Sinc</code> or <code>Jinc</code>
3970 as a filter will also do this. </td>
3974 <td>-define filter:window=<var>filter_function</var></td>
3975 <td>The IIR (infinite impulse response) filters <code>Sinc</code> and
3976 <code>Jinc</code> are windowed (brought down to zero over the defined
3977 support range) with the given filter. This allows you to specify a filter
3978 function to be used as a windowing function for these IIR filters.
3979 Many of the defined filters are actually windowing functions for these IIR
3980 filters. A typical choices is <code>Box</code>, (which effectively turns
3981 off the windowing function). </td>
3985 <td>-define filter:win-support=<var>radius</var></td>
3986 <td>Scale windowing function to this size instead. This causes the windowing
3987 (or self-windowing Lagrange filter) to act is if the support window is
3988 larger than what is actually supplied to the calling operator. The filter
3989 however is still clipped to the real support size given. If unset this
3990 will equal the normal filter support size. </td>
3994 <td>-define filter:verbose=<var>1</var></td>
3995 <td>This causes IM to print information on the final internal filter
3996 selection to standard output. This includes a commented header on the
3997 filter settings being used, and data allowing the filter weights to be
3998 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
3999 a <code>SincFast</code> windowed <code>SincFast</code> filter, while
4000 <code>Mitchell</code> is defined as a general <code>Cubic</code> family filter
4001 with specific 'B' and 'C' settings. </td>
4006 <p>For example, to get a 8 lobe jinc windowed sinc filter (Genseng filter?):</p>
4011 -set filter:window=jinc \
4012 -set filter:lobes=8 \
4013 -resize 150% image.jpg"
4016 <p>Or a raw un-windowed Sinc filter with 4 lobes:</p>
4020 -set filter:filter=sinc \
4021 -set filter:lobes=4 \
4022 -resize 150% image.jpg"
4025 <p>To extract the data for a raw windowing function, combine it with
4026 a '<code>Box</code>' filter. For example the '<code>Welch</code> parabolic
4027 windowing function. </p>
4030 convert null: -define filter:filter=Box \
4031 -define filter:window=Welch \
4032 -define filter:support=1.0 \
4033 -define filter:verbose=1 \
4034 -resize 2 null: > window_welch.dat
4037 plot \"window_welch.dat\" with lines
4040 <p>Note that the use of expert options is provided for image processing experts
4041 who have studied and understand how resize filters work. Without this
4042 knowledge, and an understanding of the definition of the actual filters
4043 involved, using expert settings are more likely to be detrimental to your image
4047 <div style="margin: auto;">
4048 <h3 class="magick-header"><a id="flatten"></a>-flatten</h3>
4051 <p class="magick-description">This is a simple alias for the <a href="command-line-options.html#layers" >-layers</a> method "flatten".</p>
4054 <div style="margin: auto;">
4055 <h3 class="magick-header"><a id="flip"></a>-flip</h3>
4058 <p class="magick-description">create a <var>mirror image</var></p>
4060 <p>reflect the scanlines in the vertical direction. The image will be mirrored
4064 <div style="margin: auto;">
4065 <h3 class="magick-header"><a id="floodfill"></a>-floodfill {<var>+-</var>}<var>x</var>{<var>+-</var>}<var>y</var> <var>color</var></h3>
4068 <p class="magick-description">floodfill the image with color at the specified offset.</p>
4070 <p>Flood fill starts from the given 'seed point' which is not gravity effected.
4071 Any color that matches within <a href="command-line-options.html#fuzz" >-fuzz</a> color distance of the
4072 given <var>color</var> argument, connected to that 'seed point'
4073 will be replaced with the current <a href="command-line-options.html#fill" >-fill</a> color. </p>
4075 <p>Note that if the pixel at the 'seed point' does not itself match the given
4076 <var>color</var> (according to <a href="command-line-options.html#fuzz" >-fuzz</a>), then no
4077 action will be taken. </p>
4079 <p>This operator works more like the <a href="command-line-options.html#opaque" >-opaque</a> option, than
4080 a more general flood fill that reads the matching color directly at the 'seed
4081 point'. For this form of flood fill, look at <a href="command-line-options.html#draw" >-draw</a> and
4082 its 'color floodfill' drawing method. </p>
4085 <div style="margin: auto;">
4086 <h3 class="magick-header"><a id="flop"></a>-flop</h3>
4089 <p class="magick-description">create a <var>mirror image</var>.</p>
4091 <p>Reflect the scanlines in the horizontal direction, just like the image in
4092 a vertical mirror. </p>
4095 <div style="margin: auto;">
4096 <h3 class="magick-header"><a id="font"></a>-font <var>name</var></h3>
4099 <p class="magick-description">set the font to use when annotating images with text, or creating labels.</p>
4101 <p>To print a complete list of fonts, use the <a href="command-line-options.html#list">-list font</a>
4102 option (for versions prior to 6.3.6, use 'type' instead of 'font').</p>
4104 <p>In addition to the fonts specified by the above pre-defined list, you can
4105 also specify a font from a specific source. For example <code>Arial.ttf</code>
4106 is a TrueType font file, <code>ps:helvetica</code> is PostScript font, and
4107 <code>x:fixed</code> is X11 font.</p>
4109 <p>For other settings that affect fonts, see the options <a
4110 href="command-line-options.html#family">-family</a>, <a href="command-line-options.html#stretch">-stretch</a>, <a
4111 href="command-line-options.html#style">-style</a>, and <a href="command-line-options.html#weight">-weight</a>. </p>
4114 <div style="margin: auto;">
4115 <h3 class="magick-header"><a id="foreground"></a>-foreground <var>color</var></h3>
4118 <p class="magick-description">Define the foreground color for menus.", "display</p>
4120 <p>The color is specified using the format described under the <a
4121 href="command-line-options.html#fill">-fill</a> option.</p>
4123 <p>The default foreground color is black.</p>
4125 <div style="margin: auto;">
4126 <h3 class="magick-header"><a id="format"></a>-format <var>type</var></h3>
4129 <p class="magick-description">the image format type.</p>
4131 <p>When used with the <code>mogrify</code> utility, this option converts any
4132 image to the image <a href="formats.html">format</a> you specify.
4133 For a list of image format types supported by ImageMagick, use <a
4134 href="command-line-options.html#list">-list format</a>.</p>
4136 <p>By default the file is written to its original name. However, if the
4137 filename extension matches a supported format, the extension is replaced with
4138 the image format type specified with <a href="command-line-options.html#format">-format</a>. For
4139 example, if you specify <var>tiff</var> as the format type and the
4140 input image filename is <var>image.gif</var>, the output image
4141 filename becomes <var>image.tiff</var>.</p>
4143 <div style="margin: auto;">
4144 <h3 class="magick-header"><a id="format_identify_"></a>-format <var>string</var></h3>
4147 <p class="magick-description">output formatted image characteristics.</p>
4149 <p>See <a href="escape.html">Format and Print Image
4150 Properties</a> for an explanation on how to specify the argument to this
4153 <div style="margin: auto;">
4154 <h3 class="magick-header"><a id="frame"></a>-frame <var>geometry</var></h3>
4157 <p class="magick-description">Surround the image with a border or beveled frame.</p>
4159 <p>The color of the border is specified with the <a href="command-line-options.html#alpha-color"
4160 >-alpha-color</a> command line option. </p>
4162 <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
4163 height that is added to the dimensions of the image. If no offsets are given
4164 in the <var>geometry</var> argument, then the border added is
4165 a solid color. Offsets <var>x</var> and <var>y</var>, if present, specify that
4166 the width and height of the border is partitioned to form an outer bevel of
4167 thickness <var>x</var> pixels and an inner bevel of thickness
4168 <var>y</var> pixels. Negative offsets make no sense as frame arguments.
4171 <p>The <a href="command-line-options.html#frame">-frame</a> option is affected by the current <a
4172 href="command-line-options.html#compose">-compose</a> setting and assumes that this is using the default
4173 '<code>Over</code>' composition method. It generates an image of the appropriate
4174 size with the current <a href="command-line-options.html#bordercolor">-bordercolor</a> setting, and then
4175 draws the frame of four distinct colors close to the current <a
4176 href="command-line-options.html#alpha-color">-alpha-color</a>. The original image is then overlaid onto
4177 center of this image. This means that with the default compose method of
4178 '<code>Over</code>' any transparent parts may be replaced by the current <a
4179 href="command-line-options.html#bordercolor">-bordercolor</a> setting.</p>
4181 <p>The image composition is not
4182 affected by the <a href="command-line-options.html#gravity">-gravity</a> option.</p>
4185 <div style="margin: auto;">
4186 <h3 class="magick-header"><a id="frame_import_"></a>-frame</h3>
4189 <p class="magick-description">include the X window frame in the imported image. </p>
4190 <div style="margin: auto;">
4191 <h3 class="magick-header"><a id="function"></a>-function <var>function</var> <var>parameters</var></h3>
4194 <p class="magick-description">Apply a function to channel values.</p>
4196 <p>This operator performs calculations based on the given arguments to modify
4197 each of the color values for each previously set <a
4198 href="command-line-options.html#channel">-channel</a> in the image. See <a
4199 href="command-line-options.html#evaluate">-evaluate</a> for details concerning how the results of the
4200 calculations are handled.</p>
4202 <p>This is can be considered a multi-argument version of the <a
4203 href="command-line-options.html#evaluate">-evaluate</a> operator. (Added in
4204 ImageMagick 6.4.8−8.)</p>
4206 <p>Here, <var>parameters</var> is a comma-separated list of
4207 numerical values. The number of values varies depending on which <var>function</var> is selected. Choose the <var>function</var> from:</p>
4216 <p>To print a complete list of <a href="command-line-options.html#function">-function</a> operators,
4217 use <a href="command-line-options.html#list">-list function</a>. Descriptions follow.</p>
4219 <dl class="dl-horizontal">
4221 <dd><p>The <code>Polynomial</code> function takes an arbitrary number of parameters,
4222 these being the coefficients of a polynomial, in decreasing order of degree.
4223 That is, entering</p>
4226 -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>
4229 <p>will invoke a polynomial function given by</p>
4232 <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>,
4235 <p>where <b><var>u</var></b> is pixel's original normalized channel value.</p>
4237 <p>The <code>Polynomial</code> function can be used in place of <code>Set</code>
4238 (the <var>constant</var> polynomial) and <code>Add</code>, <code>Divide</code>,
4239 <code>Multiply</code>, and <code>Subtract</code> (some <var>linear</var>
4240 polynomials) of the <a href="command-line-options.html#evaluate">-evaluate</a> operator. The <a
4241 href="command-line-options.html#level">-level</a> operator also affects channels linearly. Some
4242 correspondences follow.</p>
4244 <table class="table table-condensed table-striped">
4246 <td>-evaluate Set <var>value</var> </td>
4247 <td>-function Polynomial <var>value</var></td>
4248 <td>(Constant functions; set <var>value</var>×100% gray when channels are RGB.)</td>
4251 <td>-evaluate Add <var>value</var> </td>
4252 <td>-function Polynomial 1,<var>value</var></td>
4255 <td>-evaluate Subtract <var>value</var> </td>
4256 <td>-function Polynomial 1,−<var>value</var></td>
4259 <td>-evaluate Multiply <var>value</var> </td>
4260 <td>-function Polynomial <var>value</var>,0</td>
4263 <td>+level black% x white%</td>
4264 <td>-function Polynomial A,B</td>
4265 <td>(Reduce contrast. Here, A=(white-black)/100 and B=black/100.)</td>
4269 <p>The <code>Polynomial</code> function gives great versatility, since
4270 polynomials can be used to fit any continuous curve to any degree of accuracy
4276 <p>The <code>Sinusoid</code> function can be used to vary the channel values
4277 sinusoidally by setting frequency, phase shift, amplitude, and a bias. These
4278 values are given as one to four parameters, as follows,</p>
4281 -function <code>Sinusoid</code> <var>freq</var>,[<var>phase</var>,[<var>amp</var>,[<var>bias</var>]]]
4284 <p>where <var>phase</var> is in degrees. (The domain [0,1] of the function
4285 corresponds to 0 through <var>freq</var>×360 degrees.)
4286 The result is that if a pixel's normalized channel value is originally
4287 <b><var>u</var></b>, its resulting normalized value is given by </p>
4290 <var>amp</var> * sin(2*π* (<var>freq</var> * <b><var>u</var></b> + <var>phase</var> / 360)) + <var>bias</var>
4293 <p> For example, the following generates a curve that starts and ends at 0.9
4294 (when <b><var>u</var></b>=0 and 1, resp.), oscillating three times between
4295 .7−.2=.5 and .7+.2=.9. </p>
4298 -function Sinusoid 3,-90,.2,.7
4301 <p>The default values of <var>amp</var> and <var>bias</var> are both .5. The default for <var>phase</var>
4304 <p>The <code>Sinusoid</code> function generalizes <code>Sin</code> and
4305 <code>Cos</code> of the <a href="command-line-options.html#evaluate">-evaluate</a> operator by allowing
4306 varying amplitude, phase and bias. The correspondence is as follows.</p>
4308 <table class="table table-condensed table-striped">
4310 <td>-evaluate Sin <var>freq</var> </td>
4311 <td>-function Sinusoid <var>freq</var>,0 </td>
4314 <td>-evaluate Cos <var>freq</var> </td>
4315 <td>-function Sinusoid <var>freq</var>,90 </td>
4321 <p>The <code>ArcSin</code> function generates the inverse curve of a Sinusoid,
4322 and can be used to generate cylindrical distortion and displacement maps.
4323 The curve can be adjusted relative to both the input values and output range
4327 -function <code>ArcSin</code> <var>width</var>,[<var>center</var>,[<var>range</var>,[<var>bias</var>]]]
4330 <p>with all values given in terms of normalized color values (0.0 for black,
4331 1.0 for white). Defaulting to values covering the full range from 0.0 to 1.0
4332 for bout input (<var>width</var>), and output (<var>width</var>) values. '<code>1.0,0.5,1.0,0.5</code>' </p>
4335 <var>range</var>/π * asin( 2/<var>width</var> * ( <b><var>u</var></b> - <var>center</var> ) ) + <var>bias</var>
4341 <p>The <code>ArcTan</code> function generates a curve that smooth crosses from
4342 limit values at infinities, though a center using the given slope value.
4343 All these values can be adjusted via the arguments.</p>
4346 -function <code>ArcTan</code> <var>slope</var>,[<var>center</var>,[<var>range</var>,[<var>bias</var>]]]
4349 <p>Defaulting to '<code>1.0,0.5,1.0,0.5</code>'.
4353 <var>range</var>/π * atan( <var>slope</var>*π * ( <b><var>u</var></b> - <var>center</var> ) ) + <var>bias</var>
4360 <div style="margin: auto;">
4361 <h3 class="magick-header"><a id="fuzz"></a>-fuzz <var>distance</var>{<var>%</var>}</h3>
4364 <p class="magick-description">Colors within this <var>distance</var> are considered equal.</p>
4366 <p>A number of algorithms search for a target color. By default the color must
4367 be exact. Use this option to match colors that are close to the target color
4368 in RGB space. For example, if you want to automagically trim the edges of an
4369 image with <a href="command-line-options.html#trim">-trim</a> but the image was scanned and the target
4370 background color may differ by a small amount. This option can account for
4371 these differences.</p>
4373 <p>The <var>distance</var> can be in absolute intensity units or, by
4374 appending <code>%</code> as a percentage of the maximum possible intensity (255,
4375 65535, or 4294967295).</p>
4377 <p>Use <a href="command-line-options.html#fuzz" >+fuzz</a> to reset the fuzz value to 0.</p>
4380 <div style="margin: auto;">
4381 <h3 class="magick-header"><a id="fx"></a>-fx <var>expression</var></h3>
4384 <p class="magick-description">apply a mathematical expression to an image or image channels.</p>
4386 <p>If the first character of <var>expression</var> is <code>@</code>,
4387 the expression is read from a file titled by the remaining characters in the
4390 <p>See <a href="fx.html">FX,
4391 The Special Effects Image Operator</a> for a detailed discussion of this
4395 <div style="margin: auto;">
4396 <h3 class="magick-header"><a id="gamma"></a>-gamma <var>value</var></h3>
4399 <p class="magick-description">level of gamma correction.</p>
4401 <p>The same color image displayed on two different workstations may look
4402 different due to differences in the display monitor. Use gamma correction to
4403 adjust for this color difference. Reasonable values extend from
4404 <code>0.8</code> to <code>2.3</code>. Gamma less than 1.0 darkens the image and
4405 gamma greater than 1.0 lightens it. Large adjustments to image gamma may
4406 result in the loss of some image information if the pixel quantum size is only
4407 eight bits (quantum range 0 to 255).</p>
4409 <p>Gamma adjusts the image's channel values pixel-by-pixel according to
4410 a power law, namely, pow(pixel,1/gamma) or pixel^(1/gamma), where pixel is the
4411 normalized or 0 to 1 color value. For example, using a value of gamma=2 is the
4412 same as taking the square root of the image.</p>
4414 <p>You can apply separate gamma values to the red, green, and blue channels of
4415 the image with a gamma value list delimited with commas (e.g.,
4416 <code>1.7,2.3,1.2</code>).</p>
4418 <p>Use <a href="command-line-options.html#gamma">+gamma <var>value</var></a> to set the
4419 image gamma level without actually adjusting the image pixels. This option
4420 is useful if the image is of a known gamma but not set as an image attribute
4421 (e.g. PNG images). Write the "file gamma" which is the reciprocal of the
4422 display gamma; e.g., if your image is sRGB and you want to write a PNG gAMA
4426 convert input.png +gamma .45455 output.png
4429 <p>(0.45455 is 1/2.2)</p>
4431 <p>Note that gamma adjustments are also available via the <a href="command-line-options.html#level">-level</a> operator.</p>
4433 <div style="margin: auto;">
4434 <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>
4437 <p class="magick-description">Blur the image with a Gaussian operator.</p>
4439 <p>Convolve the image with a Gaussian or normal distribution using the given
4440 <var >Sigma</var> value. The formula is:</p>
4442 <p class="text-center"><img class="img-thumbnail" alt="gaussian distribution" width="243px" height="42px" src="../images/gaussian-blur.png"/> </p>
4444 <p>The <var >Sigma</var> value is the important argument, and
4445 determines the actual amount of blurring that will take place. </p>
4447 <p>The <var >Radius</var> is only used to determine the size of the
4448 array which will hold the calculated Gaussian distribution. It should be an
4449 integer. If not given, or set to zero, IM will calculate the largest possible
4450 radius that will provide meaningful results for the Gaussian distribution.
4453 <p>The larger the <var >Radius</var> the radius the slower the
4454 operation is. However too small a <var >Radius</var>, and sever
4455 aliasing effects may result. As a guideline, <var >Radius</var>
4456 should be at least twice the <var >Sigma</var> value, though three
4457 times will produce a more accurate result. </p>
4459 <p>This differs from the faster <a href="command-line-options.html#blur">-blur</a> operator in that a
4460 full 2-dimensional convolution is used to generate the weighted average of the
4461 neighboring pixels. </p>
4463 <p>The <a href="command-line-options.html#virtual-pixel">-virtual-pixel</a> setting will determine how
4464 pixels which are outside the image proper are blurred into the final result.
4468 <div style="margin: auto;">
4469 <h3 class="magick-header"><a id="geometry"></a>-geometry <var>geometry</var></h3>
4472 <p class="magick-description">Set the preferred size and location of the image.</p>
4474 <p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
4476 <div style="margin: auto;">
4477 <h3 class="magick-header"><a id="gravity"></a>-gravity <var>type</var></h3>
4480 <p class="magick-description">Sets the current gravity suggestion for various other settings and options.</p>
4482 <p>Choices include: <code>NorthWest</code>, <code>North</code>,
4483 <code>NorthEast</code>, <code>West</code>, <code>Center</code>, <code>East</code>,
4484 <code>SouthWest</code>, <code>South</code>, <code>SouthEast</code>. Use <a
4485 href="command-line-options.html#list">-list gravity</a> to get a complete list of <a
4486 href="command-line-options.html#gravity">-gravity</a> settings available in your ImageMagick
4489 <p>The direction you choose specifies where to position text or subimages. For
4490 example, a gravity of <code>Center</code> forces the text to be centered within
4491 the image. By default, the image gravity is <code>undefined</code>. See <a
4492 href="command-line-options.html#draw">-draw</a> for more details about graphic primitives. Only the
4493 text primitive of <a href="command-line-options.html#draw">-draw</a> is affected by the <a
4494 href="command-line-options.html#gravity">-gravity</a> option.</p>
4496 <p>The <a href="command-line-options.html#gravity">-gravity</a> option is also used in concert with the
4497 <a href="command-line-options.html#geometry">-geometry</a> setting and other settings or options that
4498 take <var>geometry</var> as an argument, such as the <a
4499 href="command-line-options.html#crop">-crop</a> option. </p>
4501 <p>If a <a href="command-line-options.html#gravity">-gravity</a> setting occurs before another option
4502 or setting having a <var>geometry</var> argument that specifies an
4503 offset, the offset is usually applied to the point within the image suggested
4504 by the <a href="command-line-options.html#gravity">-gravity</a> argument. Thus, in the following
4505 command, for example, suppose the file <code>image.png</code> has dimensions
4506 200x100. The offset specified by the argument to <a href="command-line-options.html#region">-region</a>
4507 is (−40,+20). The argument to <a href="command-line-options.html#gravity">-gravity</a> is
4508 <code>Center</code>, which suggests the midpoint of the image, at the point
4509 (100,50). The offset (−40,20) is applied to that point, giving
4510 (100−40,50+20)=(60,70), so the specified 10x10 region is located at
4511 that point. (In addition, the <a href="command-line-options.html#gravity">-gravity</a> affects the
4512 region itself, which is <var>centered</var> at the pixel
4513 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>
4516 convert image.png -gravity Center -region 10x10-40+20 \
4520 <p>When used as an option to <a href="composite.html">composite</a>, <a
4521 href="command-line-options.html#gravity">-gravity</a> gives the direction that the image gravitates
4522 within the composite.</p>
4524 <p>When used as an option to <a href="montage.html">montage</a>, <a
4525 href="command-line-options.html#gravity">-gravity</a> gives the direction that an image gravitates
4526 within a tile. The default gravity is <code>Center</code> for this purpose.</p>
4529 <div style="margin: auto;">
4530 <h3 class="magick-header"><a id="grayscale"></a>-grayscale <var>method</var></h3>
4533 <p class="magick-description">convert image to grayscale.</p>
4535 <p>This will use one of the <a href="command-line-options.html#intensity" >-intensity</a> methods to
4536 convert the given image into a linear-grayscale image. </p>
4538 <p>For example, to convert an image to (linear) Rec709Luminance grayscale, type:</p>
4541 convert in.png -grayscale Rec709Luminance out.png
4544 <p>which is equivalent to:</p>
4547 convert in.png -colorspace gray out.png
4550 <p>Similarly, to convert an image to (non-linear) Rec709Luma grayscale, type:</p>
4553 convert in.png -grayscale Rec709Luma out.png
4556 <p>which is equivalent to:</p>
4559 convert in.png -set colorspace RGB -colorspace gray out.png
4562 <p>Note that a 'colorspace' intensity method will produce the same result
4563 regardless of the current colorpsace of the image. But a 'mathematical'
4564 intensity method will depend on the current colorspace the image is currently
4567 <p>While this operation uses an <a href="command-line-options.html#intensity" >-intensity</a> method,
4568 it does not use or set the <a href="command-line-options.html#intensity" >-intensity</a> setting, so
4569 will not effect other operations that may use that setting.</p>
4572 <div style="margin: auto;">
4573 <h3 class="magick-header"><a id="green-primary"></a>-green-primary <var>x,y</var></h3>
4576 <p class="magick-description">green chromaticity primary point.</p>
4579 <div style="margin: auto;">
4580 <h3 class="magick-header"><a id="hald-clut"></a>-hald-clut</h3>
4583 <p class="magick-description">apply a Hald color lookup table to the image.</p>
4585 <p>A Hald color lookup table is a 3-dimensional color cube mapped to 2
4586 dimensions. Create it with the <code>HALD:</code> prefix (e.g. HALD:8). You
4587 can apply any color transformation to the Hald image and then use this option
4588 to apply the transform to the image. </p>
4591 convert image.png hald.png -hald-clut transform.png
4594 <p>This option provides a convenient method for you to use Gimp or Photoshop
4595 to make color corrections to the Hald CLUT image and subsequently apply them
4596 to multiple images using an ImageMagick script. </p>
4598 <p>Note that the representation is only of the normal RGB color space and that
4599 the whole color value triplet is used for the interpolated lookup of the
4600 represented Hald color cube image. Because of this the operation is not <a
4601 href="command-line-options.html#channel" >-channel</a> setting effected, nor can it adjust or modify an
4602 images transparency or alpha/matte channel.</p>
4604 <p>See also <a href="command-line-options.html#clut" >-clut</a> which provides color value replacement
4605 of the individual color channels, usually involving a simpler grayscale
4606 image. E.g: grayscale to color replacement, or modification by a histogram
4610 <div style="margin: auto;">
4611 <h3 class="magick-header"><a id="help"></a>-help</h3>
4614 <p class="magick-description">print usage instructions.</p>
4616 <div style="margin: auto;">
4617 <h3 class="magick-header"><a id="highlight-color"></a>-highlight-color <var>color</var></h3>
4620 <p class="magick-description">when comparing images, emphasize pixel differences with this color.</p>
4622 <div style="margin: auto;">
4623 <h3 class="magick-header"><a id="hough-lines"></a>-hough-lines <var>width</var>x<var>height</var>{<var>+threshold</var>}</h3>
4626 <p class="magick-description">identify straight lines in the image (e.g. -hough-lines 9x9+195).</p>
4628 <p>Use the Hough line detector with any binary edge extracted image to locate and draw any straight lines that it finds.</p>
4630 <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>.
4632 <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>
4634 <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>
4636 <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>
4638 <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>
4640 <p>A text file listing the endpoints and counts may be created by using the suffix, .mvg, for the output image.</p>
4642 <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>
4644 <div style="margin: auto;">
4645 <h3 class="magick-header"><a id="iconGeometry"></a>-iconGeometry <var>geometry</var></h3>
4648 <p class="magick-description">specify the icon geometry.</p>
4650 <p>Offsets, if present in the geometry specification, are handled in the same
4651 manner as the <a href="command-line-options.html#geometry">-geometry</a> option, using X11 style to
4652 handle negative offsets.</p>
4654 <p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
4656 <div style="margin: auto;">
4657 <h3 class="magick-header"><a id="iconic"></a>-iconic</h3>
4660 <p class="magick-description">start in icon mode in X Windows", 'animate', 'display</p>
4662 <div style="margin: auto;">
4663 <h3 class="magick-header"><a id="identify"></a>-identify</h3>
4666 <p class="magick-description">identify the format and characteristics of the image.</p>
4668 <p>This information is printed: image scene number; image name; image size;
4669 the image class (<var>DirectClass</var> or <var>PseudoClass</var>); the total number of unique colors; and the
4670 number of seconds to read and transform the image. Refer to <a href="miff.html">MIFF</a> for
4671 a description of the image class.</p>
4673 <p>If <a href="command-line-options.html#colors">-colors</a> is also specified, the total unique colors
4674 in the image and color reduction error values are printed. Refer to <a
4675 href="http://www.imagemagick.org/www/quantize.html">color
4676 reduction algorithm</a> for a description of these values.</p>
4678 <p>If <a href="command-line-options.html#verbose">-verbose</a> precedes this option, copious
4679 amounts of image properties are displayed including image statistics, profiles,
4680 image histogram, and others.</p>
4682 <div style="margin: auto;">
4683 <h3 class="magick-header"><a id="ift"></a>-ift</h3>
4686 <p class="magick-description">implements the inverse discrete Fourier transform (DFT).</p>
4688 <p>This option is new as of ImageMagick 6.5.4-3 (and now working for Windows
4689 users in ImageMagick 6.6.0-9). It transforms a pair of magnitude and phase
4690 images from the frequency domain to a single image in the normal or spatial
4691 domain. See for example, <a
4692 href="http://en.wikipedia.org/wiki/Fourier_transform">Fourier Transform</a>,
4693 <a href="http://en.wikipedia.org/wiki/DFT">Discrete Fourier Transform</a> and
4694 <a href="http://en.wikipedia.org/wiki/FFT">Fast Fourier Transform</a>.</p>
4696 <p>For example, depending upon the image format used to store the result of
4697 the <a href="command-line-options.html#fft">-fft</a>, one would use either</p>
4700 convert fft_image.miff -ift fft_image_ift.png
4706 convert fft_image-0.png fft_image-1.png -ift fft_image_ift.png
4709 <p>The resulting image may need to be cropped due to padding introduced when
4710 the original image, prior to the <a href="command-line-options.html#fft">-fft</a> or <a
4711 href="command-line-options.html#fft">+fft</a>, was not square or even dimensioned. Any padding is at
4712 the right and/or bottom sides of the image.</p>
4714 <p>The <a href="http://www.fftw.org/">FFTW</a> delegate library is required to
4715 use <a href="command-line-options.html#ift">-ift</a>.</p>
4717 <p>Use <a href="command-line-options.html#ift">+ift</a> (with HDRI enabled) to transform a pair of real
4718 and imaginary images from the frequency domain to a single image in the normal
4719 (spatial) domain.</p>
4721 <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 explicitly normalize the IFT and unnormalize the FFT.</p>
4723 <div style="margin: auto;">
4724 <h3 class="magick-header"><a id="immutable"></a>-immutable</h3>
4727 <p class="magick-description">make image immutable.</p>
4729 <div style="margin: auto;">
4730 <h3 class="magick-header"><a id="implode"></a>-implode <var>factor</var></h3>
4733 <p class="magick-description">implode image pixels about the center.</p>
4735 <div style="margin: auto;">
4736 <h3 class="magick-header"><a id="insert"></a>-insert <var>index</var></h3>
4739 <p class="magick-description">insert the last image into the image sequence.</p>
4741 <p>This option takes last image in the current image sequence and inserts it
4742 at the given index. If a negative index is used, the insert position is
4743 calculated before the last image is removed from the sequence. As such
4744 <code>-insert -1</code> will result in no change to the image sequence.</p>
4746 <p>The <code>+insert</code> option is equivalent to <code>-insert -1</code>. In
4747 other words, insert the last image, at the end of the current image sequence.
4748 Consequently this has no effect on the image sequence order.</p>
4750 <div style="margin: auto;">
4751 <h3 class="magick-header"><a id="intensity"></a>-intensity <var>method</var></h3>
4754 <p class="magick-description">method to generate intensity value from pixel.</p>
4756 <p>ImageMagick provides a number of methods used in situations where an
4757 operator needs to determine a single grayscale value for some purpose, from
4758 an image with red, green, and blue pixel components. Typically the linear
4759 <code>Rec709Luminance</code> formula is used, which is the same formula used when
4760 converting images to <code>-colorspace gray</code>. </p>
4762 <p>The following formulas are currently provided, and will first convert
4763 the pixel values to linear-RGB or non-linear sRGB colorspace before
4764 being applied to calculate the final greyscale value. </p>
4766 <dl class="dl-horizontal">
4767 <dt>Rec601Luma</dt><dd> 0.298839R' + 0.586811G'+ 0.114350B'</dd>
4768 <dt>Rec601Luminance</dt><dd> 0.298839R + 0.586811G + 0.114350B</dd>
4769 <dt>Rec709Luma</dt><dd> 0.212656R' + 0.715158G' + 0.072186B'</dd>
4770 <dt>Rec709Luminance</dt><dd> 0.212656R + 0.715158G + 0.072186B</dd>
4771 <dt>Brightness</dt><dd> max(R', G', B')</dd>
4772 <dt>Lightness</dt><dd> (min(R', G', B') + max(R', G', B')) / 2.0</dd>
4775 <p>Note that the above R,G,B values is the image's linear-RGB values, while
4776 R',G',B' are sRGB non-linear values. </p>
4778 <p>These intensity methods are mathematical in nature and will use the
4779 current value in the images respective R,G,B channel regardless of
4780 what that is, or what colorspace the image is currently using.</p>
4782 <dl class="dl-horizontal">
4783 <dt>Average</dt><dd>(R + G + B) / 3.0</dd>
4784 <dt>MS</dt><dd>(R^2 + G^2 + B^2) / 3.0</dd>
4785 <dt>RMS</dt><dd>sqrt( (R^2 + G^2 + B^2) / 3.0 )</dd>
4788 <p>These methods are often used for other purposes, such as generating a
4789 grayscale difference image between two color images (using <a href="command-line-options.html#compose"
4790 >-compose</a> '<code>Difference</code>' composition. </p>
4792 <p> For example The 'MS' (Mean Squared) setting is good for minimizing color
4793 error comparisions. While... The method 'RMS' (Root Mean Squared) for
4794 example is appropriate for calculating color vector distance, from a color
4795 difference image. This is equivalent to the color only component of the <a
4796 href="command-line-options.html#fuzz" >-fuzz</a> factor color compare setting. </p>
4798 <p>See also <a href="command-line-options.html#grayscale" >-grayscale</a> which applies one of the above
4799 grayscaling formula directly to an image without setting the <a
4800 href="command-line-options.html#intensity" >-intensity</a> setting.</p>
4802 <p>The <a href="command-line-options.html#colorspace" >-colorspace gray</a> image conversion also uses
4803 the current intensity setting, but will always convert the image to the
4804 appropriate sRGB or linear-RGB colorspace before appling the above
4807 <p>To print a complete list of possible pixel intensity setting methods, use <a href="command-line-options.html#list">-list intensity</a>.</p>
4809 <p>Operators affected by the <a href="command-line-options.html#intensity" >-intensity</a> setting include:</p>
4815 -clut (when mapping greyscale CLUT image to alpha channel if set by -channels)
4816 -colors for gray colorspace
4817 -compose {LightenIntensity, DarkenIntensity, CopyOpacity, CopyBlack}
4819 -distort {ErodeIntensity, DilateIntensity}
4829 <div style="margin: auto;">
4830 <h3 class="magick-header"><a id="intent"></a>-intent <var>type</var></h3>
4833 <p class="magick-description">use this type of rendering intent when managing the image color.</p>
4835 <p>Use this option to affect the color management operation of an image (see
4836 <a href="command-line-options.html#profile">-profile</a>). Choose from these intents: <code>Absolute,
4837 Perceptual, Relative, Saturation</code>.</p>
4839 <p>The default intent is Perceptual for the sRGB colorspace and undefined for the RGB and gray colorspaces.</p>
4841 <p>To print a complete list of rendering intents, use <a href="command-line-options.html#list">-list intent</a>.</p>
4843 <div style="margin: auto;">
4844 <h3 class="magick-header"><a id="interlace"></a>-interlace <var>type</var></h3>
4847 <p class="magick-description">the type of interlacing scheme.</p>
4861 <p>This option is used to specify the type of interlacing scheme for raw image
4862 formats such as <code>RGB</code> or <code>YUV</code>.</p>
4864 <p><code>None</code> means do not interlace (RGBRGBRGBRGBRGBRGB...),</p>
4866 <p><code>Line</code> uses scanline interlacing (RRR...GGG...BBB...RRR...GGG...BBB...), and.</p>
4868 <p><code>Plane</code> uses plane interlacing (RRRRRR...GGGGGG...BBBBBB...).</p>
4870 <p><code>Partition</code> is like plane except the different planes are saved to
4871 individual files (e.g. image.R, image.G, and image.B).</p>
4873 <p>Use <code>Line</code> or <code>Plane</code> to create an <code>interlaced
4874 PNG</code> or <code>GIF</code> or <code>progressive JPEG</code> image.</p>
4876 <p>To print a complete list of interlacing schemes, use <a href="command-line-options.html#list">-list
4879 <div style="margin: auto;">
4880 <h3 class="magick-header"><a id="interpolate"></a>-interpolate <var>type</var></h3>
4883 <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>
4885 <p>When looking up the color of a pixel using a non-integer floating point
4886 value, you typically fall in between the pixel colors defined by the source
4887 image. This setting determines how the color is determined from the colors of
4888 the pixels surrounding that point. That is how to determine the color of a
4889 point that falls between two, or even four different colored pixels. </p>
4891 <dl class="dl-horizontal">
4893 <dd>The color of the top-left pixel (floor function)</dd>
4894 <dt>nearest-neighbor</dt>
4895 <dd>The nearest pixel to the lookup point (rounded function)</dd>
4897 <dd>The average color of the surrounding four pixels</dd>
4899 <dd>A double linear interpolation of pixels (the default)</dd>
4901 <dd>Divide area into two flat triangular interpolations</dd>
4903 <dd>Fitted bicubic-spines of surrounding 16 pixels</dd>
4905 <dd>Direct spline curves (colors are blurred)</dd>
4907 <dd>Use resize <a href="command-line-options.html#filter">-filter</a> settings</dd>
4910 <p>This most important for distortion operators such as <a href="command-line-options.html#distort"
4911 >-distort</a>, <a href="command-line-options.html#implode" >-implode</a>, <a href="command-line-options.html#transform"
4912 >-transform</a> and <a href="command-line-options.html#fx" >-fx</a>. </p>
4914 <p>To print a complete list of interpolation methods, use <a href="command-line-options.html#list">-list interpolate</a>.</p>
4916 <p>See also <a href="command-line-options.html#virtual-pixel" >-virtual-pixel</a>, for control of the
4917 lookup for positions outside the boundaries of the image. </p>
4920 <div style="margin: auto;">
4921 <h3 class="magick-header"><a id="interline-spacing"></a>-interline-spacing <var>value</var></h3>
4924 <p class="magick-description">the space between two text lines.</p>
4926 <div style="margin: auto;">
4927 <h3 class="magick-header"><a id="interword-spacing"></a>-interword-spacing <var>value</var></h3>
4930 <p class="magick-description">the space between two words.</p>
4932 <div style="margin: auto;">
4933 <h3 class="magick-header"><a id="kerning"></a>-kerning <var>value</var></h3>
4936 <p class="magick-description">the space between two letters.</p>
4938 <div style="margin: auto;">
4939 <h3 class="magick-header"><a id="kuwahara"></a>-kuwahara <var>radius</var><br />-kuwahara <var>radius</var>x<var>sigma</var></h3>
4942 <p class="magick-description">edge preserving noise reduction filter.</p>
4944 <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>
4947 <div style="margin: auto;">
4948 <h3 class="magick-header"><a id="label"></a>-label <var>name</var></h3>
4951 <p class="magick-description">assign a label to an image.</p>
4953 <p>Use this option to assign a specific label to the image, as it is read in
4954 or created. You can use the <a href="command-line-options.html#set" >-set</a> operation to re-assign
4955 a the labels of images already read in. Image formats such as TIFF, PNG,
4956 MIFF, supports saving the label information with the image.</p>
4958 <p>When saving an image to a <var>PostScript</var> file, any label
4959 assigned to an image is used as a header string to print above the postscript
4962 <p>You can include the image filename, type, width, height, or other image
4963 attribute by embedding special format character. See <a href="escape.html">Format and Print Image
4964 Properties</a> for details of the percent escape codes.</p>
4969 -label "%m:%f %wx%h" bird.miff
4972 <p>assigns an image label of <code>MIFF:bird.miff 512x480</code> to the
4973 "<code>bird.miff</code>" image and whose width is 512 and height is 480, as it
4974 is read in. If a <a href="command-line-options.html#label">+label</a> option was used instead, any
4975 existing label present in the image would be used. You can remove all labels
4976 from an image by assigning the empty string. </p>
4978 <p>A label is not drawn on the image, but is embedded in the image datastream
4979 via <var>Label</var> tag or similar mechanism. If you want the label to be
4980 visible on the image itself, use the <a href="command-line-options.html#draw">-draw</a> option, or
4981 during the final processing in the creation of an image montage.</p>
4983 <p>If the first character of <var>string</var> is <var>@</var>, the image label is read from a file titled by the
4984 remaining characters in the string. Labels in a file are literal, no embedded
4985 formatting characters are recognized.</p>
4988 <div style="margin: auto;">
4989 <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>
4992 <p class="magick-description">perform local adaptive threshold.</p>
4994 <p>Adaptively threshold each pixel based on the value of pixels in a
4995 surrounding window. If the current pixel is lighter than this average plus
4996 the optional <code>offset</code>, then it is made white, otherwise it is made
4997 black. Small variations in pixel values such as found in scanned documents
4998 can be ignored if offset is positive. A negative offset will make it more
4999 sensitive to those small variations. </p>
5001 <p>This is commonly used to threshold images with an uneven background. It is
5002 based on the assumption that average color of the small window is the
5003 the local background color, from which to separate the foreground color. </p>
5006 <div style="margin: auto;">
5007 <h3 class="magick-header"><a id="layers"></a>-layers <var>method</var></h3>
5010 <p class="magick-description">handle multiple images forming a set of image layers or animation frames.</p>
5012 <p>Perform various image operation methods to a ordered sequence of images
5013 which may represent either a set of overlaid 'image layers', a GIF disposal
5014 animation, or a fully-'coalesced' animation sequence. </p>
5016 <table class="table table-condensed table-striped">
5019 <th style="width: 8%">Method</th>
5020 <th>Description</th>
5024 <td>compare-any</td>
5025 <td>Crop the second and later frames to the smallest rectangle
5026 that contains all the differences between the two images. No GIF <a
5027 href="command-line-options.html#dispose" >-dispose</a> methods are taken into account. </td>
5030 <tr><td></td><td>This exactly the same as the <a href="command-line-options.html#deconstruct"
5031 >-deconstruct</a> operator, and does not preserve animations normal
5032 working, especially when animation used layer disposal methods such as
5033 '<code>Previous</code>' or '<code>Background</code>'. </td>
5037 <td>compare-clear</td>
5038 <td>As '<code>compare-any</code>' but crop to the bounds of any
5039 opaque pixels which become transparent in the second frame. That is the
5040 smallest image needed to mask or erase pixels for the next frame. </td>
5044 <td>compare-overlay</td>
5045 <td>As '<code>compare-any</code>' but crop to pixels that add
5046 extra color to the next image, as a result of overlaying color pixels.
5047 That is the smallest single overlaid image to add or change colors. </td>
5050 <tr><td></td><td>This can be used with the <a href="command-line-options.html#compose" >-compose</a> alpha
5051 composition method '<code>change-mask</code>', to reduce the image to
5052 just the pixels that need to be overlaid. </td>
5057 <td>Equivalent to a call to the <a href="command-line-options.html#coalesce"
5058 >-coalesce</a> operator. Apply the layer disposal methods set in the
5059 current image sequence to form a fully defined animation sequence, as
5060 it should be displayed. Effectively converting a GIF animation into a
5061 'film strip'-like animation. </td>
5066 <td>Alpha Composition of two image lists, separated by a
5067 "<code>null:</code>" image, with the destination image list first, and
5068 the source images last. An image from each list are composited
5069 together until one list is finished. The separator image and source
5070 image lists are removed. </td>
5075 <td>The <a href="command-line-options.html#geometry" >-geometry</a> offset is adjusted according
5076 to <a href="command-line-options.html#gravity" >-gravity</a> in accordance of the virtual
5077 canvas size of the first image in each list. Unlike a normal <a
5078 href="command-line-options.html#composite" >-composite</a> operation, the canvas offset is also
5079 added to the final composite positioning of each image. </td> </tr>
5082 <td>If one of the image lists only contains one image, that image is
5083 applied to all the images in the other image list, regardless of which
5084 list it is. In this case it is the image meta-data of the list which
5091 <td>This like '<code>coalesce</code>' but shows the look of
5092 the animation after the layer disposal method has been applied, before
5093 the next sub-frame image is overlaid. That is the 'dispose' image that
5094 results from the application of the GIF <a href="command-line-options.html#dispose"
5095 >-dispose</a> method. This allows you to check what
5096 is going wrong with a particular animation you may be developing.
5102 <td>Create a canvas the size of the first images virtual
5103 canvas using the current <a href="command-line-options.html#background" >-background</a> color,
5104 and <a href="command-line-options.html#compose" >-compose</a> each image in turn onto that
5105 canvas. Images falling outside that canvas is clipped. Final
5106 image will have a zero virtual canvas offset. </td>
5110 <td>This usually used as one of the final 'image layering' operations
5111 overlaying all the prepared image layers into a final image. </td>
5115 <td>For a single image this method can also be used to fillout a virtual
5116 canvas with real pixels, or to underlay an opaque color to remove
5117 transparency from an image.</td>
5123 <td>As 'flatten' method but merging all the given image
5124 layers to create a new layer image just large enough to hold all the
5125 image without clipping or extra space. The new images virtual offset
5126 will preserve the position of the new layer, even if this offset is
5127 negative. The virtual canvas size of the first image is preserved.
5131 <tr><td></td><td>Caution is advised when handling image layers with
5132 negative offsets as few image file formats handle them correctly.
5133 Following this operation method with <a href="command-line-options.html#repage" >+repage</a>
5134 will remove the layer offset, and create an image in which all the
5135 overlaid image positions relative to each other is preserved, though
5136 not necessarily exactly where you specified them.
5140 <tr><td></td><td>See also 'trim-bounds' below which is closely related but
5141 without doing the'flatten' to merge the images together. </td>
5146 <td>As 'flatten' method but expanding the initial canvas size
5147 of the first image in a positive direction only so as to hold all the
5148 image layers. However as a virtual canvas is 'locked' to the origin,
5149 by its own definition, image layers with a negative offsets will still
5150 become clipped by the top and left edges. See 'merge' or 'trim-bounds'
5151 if this could be a problem. </td>
5155 <tr><td></td><td>This method is commonly used to layout individual image
5156 using various offset but without knowing the final canvas size. The
5157 resulting image will, like 'flatten' not have any virtual offset, so
5158 can be saved to any image file format. </td>
5164 <td>Optimize a coalesced animation, into GIF animation using
5165 a number of general techniques. This currently a short cut to
5166 apply both the '<code>optimize-frame</code>', and
5167 '<code>optimize-transparency</code>' methods but may be expanded to
5168 include other optimization methods as they are developed. </td>
5172 <td>optimize-frame</td>
5173 <td>Optimize a coalesced animation, into GIF animation by
5174 reducing the number of pixels per frame as much as possible by
5175 attempting to pick the best layer disposal method to use, while ensuring
5176 the result will continue to animate properly. </td>
5179 <tr><td></td><td> There is no guarantee that the best optimization is found.
5180 But then no reasonably fast GIF optimization algorithm can do this.
5181 However this does seem to do better than most other GIF frame
5182 optimizers seen. </td>
5186 <td>optimize-plus</td>
5187 <td>As '<code>optimize-frame</code>' but attempt to improve the
5188 overall optimization by adding extra frames to the animation, without
5189 changing the final look or timing of the animation. The frames are
5190 added to attempt to separate the clearing of pixels from the
5191 overlaying of new additional pixels from one animation frame to the
5192 next. If this does not improve the optimization (for the next frame
5193 only), it will fall back to the results of the previous normal
5194 '<code>optimize-frame</code>' technique. </td>
5197 <tr><td></td><td>There is the possibility that the change in the disposal
5198 style will result in a worsening in the optimization of later frames,
5199 though this is unlikely. In other words there no guarantee that it is
5200 better than the normal '<code>optimize-frame</code>' technique. For some
5201 animations however you can get a vast improvement in the final
5202 animation size. </td>
5206 <td>optimize-transparency</td>
5207 <td>Given a GIF animation, replace any pixel in the sub-frame
5208 overlay images with transparency, if it does not change the resulting
5209 animation by more than the current <a href="command-line-options.html#fuzz" >-fuzz</a> factor.
5213 <tr><td></td><td>This should allow a existing frame optimized GIF animation
5214 to compress into a smaller file size due to larger areas of one
5215 (transparent) color rather than a pattern of multiple colors repeating
5216 the current disposed image of the last frame. </td>
5220 <td>remove-dups</td>
5221 <td>Remove (and merge time delays) of duplicate consecutive
5222 images, so as to simplify layer overlays of coalesced animations.
5226 <tr><td></td><td>Usually this a result of using a constant time delay
5227 across the whole animation, or after a larger animation was split into
5228 smaller sub-animations. The duplicate frames could also have been
5229 used as part of some frame optimization methods. </td>
5233 <td>remove-zero</td>
5234 <td>Remove any image with a zero time delay, unless ALL the
5235 images have a zero time delay (and is not a proper timed animation, a
5236 warning is then issued). </td>
5239 <tr><td></td><td>In a GIF animation, such images are usually frames which
5240 provide partial intermediary updates between the frames that are
5241 actually displayed to users. These frames are usually added for
5242 improved frame optimization in GIF animations. </td>
5246 <td>trim-bounds</td>
5247 <td>Find the bounds of all the images in the current
5248 image sequence, then adjust the offsets so all images are contained on
5249 a minimal positive canvas. None of the image data is modified or
5250 merged, only the individual image virtual canvas size and offset.
5251 All the images is given the same canvas size, and and will have
5252 a positive offset, but will remain in the same position relative to
5253 each other. As a result of the minimal canvas size at least one image
5254 will touch every edge of that canvas. The image data touching those
5255 edges however may be transparent. </td>
5258 <tr><td></td><td>The result is much like if you used 'merge' followed by a
5259 <a href="command-line-options.html#repage" >+repage</a> option, except that all the images
5260 have been kept separate. If 'flatten' is used after using
5261 'trim-bounds' you will get the same result. </td>
5267 <p>To print a complete list of layer types, use <a href="command-line-options.html#list">-list layers</a>.</p>
5269 <p>The operators <a href="command-line-options.html#coalesce" >-coalesce</a>, <a href="command-line-options.html#deconstruct"
5270 >-deconstruct</a>, <a href="command-line-options.html#flatten" >-flatten</a>, and <a href="command-line-options.html#mosaic"
5271 >-mosaic</a> are only aliases for the above methods and may be depreciated in
5272 the future. Also see <a href="command-line-options.html#page" >-page</a>, <a href="command-line-options.html#repage"
5273 >-repage</a> operators, the <a href="command-line-options.html#compose" >-compose</a> setting, and the
5274 GIF <a href="command-line-options.html#dispose" >-dispose</a> and <a href="command-line-options.html#delay" >-delay</a>
5278 <div style="margin: auto;">
5279 <h3 class="magick-header"><a id="level"></a>-level <var>black_point</var>{,<var>white_point</var>}{<var>%</var>}{,<var>gamma</var>}</h3>
5282 <p class="magick-description">adjust the level of image channels.</p>
5284 <p>Given one, two or three values delimited with commas: black-point,
5285 white-point, gamma (for example: 10,250,1.0 or 2%,98%,0.5). The black and
5286 white points range from 0 to <var>QuantumRange</var>, or from 0 to
5287 100%; if the white point is omitted it is set to (<var>QuantumRange</var> - black_point), so as to center contrast changes.
5288 If a <code>%</code> sign is present anywhere in the string, both black and white
5289 points are percentages of the full color range. Gamma will do a <a
5290 href="command-line-options.html#gamma">-gamma</a> adjustment of the values. If it is omitted, the
5291 default of 1.0 (no gamma correction) is assumed.</p>
5293 <p>In normal usage (<code>-level</code>) the image values are stretched so that
5294 the given '<code>black_point</code>' value in the original image is set to zero
5295 (or black), while the given '<code>white_point</code>' value is set to <var>QuantumRange</var> (or white). This provides you with direct
5296 contrast adjustments to the image. The '<code>gamma</code>' of the resulting
5297 image will then be adjusted. </p>
5299 <p>From ImageMagick v6.4.1-9 using the plus form of the operator
5300 (<code>+level</code>) or adding the special '!' flag anywhere in the argument
5301 list, will cause the operator to do the reverse of the level adjustment. That
5302 is a zero, or <var>QuantumRange</var> value (black, and white, resp.)
5303 in the original image, is adjusted to the given level values, allowing you to
5304 de-contrast, or compress the channel values within the image. The
5305 '<code>gamma</code>' is adjusted before the level adjustment to de-contrast the
5308 <p>Only the channels defined by the current <a href="command-line-options.html#channel">-channel</a>
5309 setting are adjusted (defaults to RGB color channels only), allowing you to
5310 limit the effect of this operator. </p>
5312 <p>Please note that the transparency channel is treated as 'matte'
5313 values (0 is opaque) and not as 'alpha' values (0 is transparent).</p>
5316 <div style="margin: auto;">
5317 <h3 class="magick-header"><a id="level-colors"></a>-level-colors {<var>black_color</var>}{,}{<var>white_color</var>}</h3>
5320 <p class="magick-description">adjust the level of an image using the provided dash separated colors.</p>
5322 <p>This function is exactly like <a href="command-line-options.html#level">-level</a>, except that the
5323 value value for each color channel is determined by the
5324 '<code>black_color</code>' and '<code>white_color</code>' colors given (as
5325 described under the <a href="command-line-options.html#fill">-fill</a> option). </p>
5327 <p>This effectually means the colors provided to <code>-level-colors</code>
5328 is mapped to become 'black' and 'white' respectively, with all the other
5329 colors linearly adjusted (or clipped) to match that change. Each channel is
5330 adjusted separately using the channel values of the colors specified. </p>
5332 <p>On the other hand the plus form of the operator (<code>+level-colors</code>)
5333 will map the image color 'black' and 'white' to the given colors
5334 respectively, resulting in a gradient (de-contrasting) tint of the image to
5335 those colors. This can also be used to convert a plain grayscale image into a
5336 one using the gradient of colors specified. </p>
5338 <p>By supplying a single color with a comma separator either before or after
5339 that color, will just replace the respective 'black' or 'white' point
5340 respectively. But if no comma separator is provided, the given color is
5341 used for both the black and white color points, making the operator either
5342 threshold the images around that color (- form) or set all colors to that
5343 color (+ form). </p>
5346 <div style="margin: auto;">
5347 <h3 class="magick-header"><a id="limit"></a>-limit <var>type value</var></h3>
5350 <p class="magick-description">Set the pixel cache resource limit.</p>
5352 <p>Choose from: <code>width</code>, <code>height</code>, <code>area</code>, <code>memory</code>, <code>map</code>, <code>disk</code>, <code>file</code>, <code>thread</code>, <code>throttle</code>, or <code>time</code>.</p>
5354 <p>The value for <code>file</code> is in number of files. The other limits are
5355 in bytes. Define arguments for the memory, map, area, and disk resource limits
5356 with SI prefixes (.e.g 100MB).</p>
5358 <p>By default the limits are 768 files, 3GB of image area, 1.5GiB memory, 3GiB
5359 memory map, and 18.45EB of disk. These limits are adjusted relative to the
5360 available resources on your computer if this information is available. When
5361 any limit is reached, ImageMagick fails in some fashion but attempts to take
5362 compensating actions, if possible. For example, the following limits
5366 -limit memory 32MiB -limit map 64MiB
5369 <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>
5372 -> identify -list resource
5386 <p>Requests for pixel storage to keep intermediate images are satisfied by one
5387 of three resource categories: in-memory pool, memory-mapped files pool, and
5388 disk pool (in that order) depending on the <a href="command-line-options.html#limit">‑limit</a> settings
5389 and whether the system honors a resource request. If the total size of
5390 allocated pixel storage in the given pool reaches the corresponding limit, the
5391 request is passed to the next pool. Additionally, requests that exceed the
5392 <code>area</code> limit automagically are allocated on disk.</p>
5394 <p>To illustrate how ImageMagick utilizes resource limits, consider a typical
5395 image resource request. First, ImageMagick tries to allocate the pixels in
5396 memory. The request might be denied if the resource request exceeds the
5397 <code>memory</code> limit or if the system does not honor the request. If
5398 a memory request is not honored, the pixels are allocated to disk and the file
5399 is memory-mapped. However, if the allocation request exceeds the
5400 <code>map</code> limit, the resource allocation goes to disk. In all cases, if
5401 the resource request exceeds the <code>area</code> limit, the pixels are
5402 automagically cached to disk. If the disk has a hard limit, the program
5405 <p>In most cases you simply do not need to concern yourself with resource
5406 limits. ImageMagick chooses reasonable defaults and most images do not tax
5407 your computer resources. Where limits do come in handy is when you process
5408 images that are large or on shared systems where ImageMagick can consume all
5409 or most of the available memory. In this case, the ImageMagick workflow slows
5410 other processes or, in extreme cases, brings the system to a halt. Under
5411 these circumstances, setting limits give some assurances that the ImageMagick
5412 workflow will not interfere with other concurrent uses of the computer. For
5413 example, assume you have a web interface that processes images uploaded from
5414 the Internet. To assure ImageMagick does not exceed 10MiB of memory you can
5415 simply set the area limit to 10MiB:</p>
5421 <p>Now whenever a large image is processed, the pixels are automagically
5422 cached to disk instead of memory. This of course implies that large images
5423 typically process very slowly, simply because pixel processing in memory can
5424 be an order of magnitude faster than on disk. Because your web site users
5425 might inadvertently upload a huge image to process, you should set a disk
5429 -limit area 10MB -limit disk 500MB
5432 <p>Here ImageMagick stops processing if an image requires more than 500MB of disk storage.</p>
5434 <p>In addition to command-line resource limit option, resources can be set
5435 with <a href="resources.html#environment" >environment variables</a>. Set the
5436 environment variables <code>MAGICK_AREA_LIMIT</code>,
5437 <code>MAGICK_DISK_LIMIT</code>, <code>MAGICK_FILE_LIMIT</code>,
5438 <code>MAGICK_MEMORY_LIMIT</code>, <code>MAGICK_MAP_LIMIT</code>,
5439 <code>MAGICK_THREAD_LIMIT</code>, <code>MAGICK_TIME_LIMIT</code> for limits of
5440 image area, disk space, open files, heap memory, memory map, number of threads
5441 of execution, and maximum elapsed time in seconds respectively.</p>
5443 <p> Inquisitive users can try adding <a href="command-line-options.html#debug">-debug cache</a> to
5444 their commands and then scouring the generated output for references to the
5445 pixel cache, in order to determine how the pixel cache was allocated and how
5446 resources were consumed. Advanced Unix/Linux users can pipe that output
5447 through <code>grep memory|open|destroy|disk</code> for more readable sifting.
5450 <p>For more about ImageMagick's use of resources, see the section <b>Cache
5451 Storage and Resource Requirements</b> on the <a href="architecture.html#cache
5452 ">Architecture</a> page. </p>
5454 <div style="margin: auto;">
5455 <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>
5458 <p class="magick-description">Linear with saturation stretch.</p>
5460 <p>This is very similar to <a href="command-line-options.html#contrast-stretch" >-contrast-stretch</a>,
5461 and uses a 'histogram bin' to determine the range of color values that needs to
5462 be stretched. However it then stretches those colors using the <a
5463 href="command-line-options.html#level" >-level</a> operator.</p>
5465 <p>As such while the initial determination may have 'binning' round off
5466 effects, the image colors are stretched mathematically, rather than using the
5467 histogram bins. This makes the operator more accurate. </p>
5469 <p>note however that a <a href="command-line-options.html#linear-stretch" >-linear-stretch</a> of
5470 '<code>0</code>' does nothing, while a value of '<code>1</code>' does a near
5471 perfect stretch of the color range. </p>
5473 <p>See also <a href="command-line-options.html#auto-level" >-auto-level</a> for a 'perfect'
5474 normalization of mathematical images. </p>
5476 <p>This operator is under review for re-development. </p>
5479 <div style="margin: auto;">
5480 <h3 class="magick-header"><a id="linewidth"></a>-linewidth</h3>
5483 <p class="magick-description">the line width for subsequent draw operations.</p>
5485 <div style="margin: auto;">
5486 <h3 class="magick-header"><a id="liquid-rescale"></a>-liquid-rescale <var>geometry</var></h3>
5489 <p class="magick-description">rescale image with seam-carving.</p>
5491 <p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
5493 <div style="margin: auto;">
5494 <h3 class="magick-header"><a id="list"></a>-list <var>type</var></h3>
5497 <p class="magick-description">Print a list of supported arguments for various options or settings. Choose from these list types:</p>
5499 <pre class="pre-scrollable">
5572 <p>These lists vary depending on your version of ImageMagick. Use "<code>-list
5573 list</code>" to get a complete listing of all the "<code>-list</code>" arguments
5580 <div style="margin: auto;">
5581 <h3 class="magick-header"><a id="log"></a>-log <var>string</var></h3>
5584 <p class="magick-description">Specify format for debug log.</p>
5586 <p>This option specifies the format for the log printed when the <a
5587 href="command-line-options.html#debug">-debug</a> option is active.</p>
5589 <p>You can display the following components by embedding special format
5592 <dl class="dl-horizontal">
5593 <dt>%d</dt><dd>domain</dd>
5594 <dt>%e</dt><dd>event</dd>
5595 <dt>%f</dt><dd>function</dd>
5596 <dt>%l</dt><dd>line</dd>
5597 <dt>%m</dt><dd>module</dd>
5598 <dt>%p</dt><dd>process ID</dd>
5599 <dt>%r</dt><dd>real CPU time</dd>
5600 <dt>%t</dt><dd>wall clock time</dd>
5601 <dt>%u</dt><dd>user CPU time</dd>
5602 <dt>%%</dt><dd>percent sign</dd>
5603 <dt>\n</dt><dd>newline</dd>
5604 <dt>\r</dt><dd>carriage return</dd>
5610 convert -debug coders -log "%u %m:%l %e" in.gif out.png
5613 <p>The default behavior is to print all of the components.</p>
5615 <div style="margin: auto;">
5616 <h3 class="magick-header"><a id="loop"></a>-loop <var>iterations</var></h3>
5619 <p class="magick-description">add Netscape loop extension to your GIF animation.</p>
5621 <p>Set iterations to zero to repeat the animation an infinite number of times,
5622 otherwise the animation repeats itself up to <var>iterations</var>
5625 <div style="margin: auto;">
5626 <h3 class="magick-header"><a id="lowlight-color"></a>-lowlight-color <var>color</var></h3>
5629 <p class="magick-description">when comparing images, de-emphasize pixel differences with this color.</p>
5631 <div style="margin: auto;">
5632 <h3 class="magick-header"><a id="magnify"></a>-magnify</h3>
5635 <p class="magick-description">double the size of the image with pixel art scaling.</p>
5638 <div style="margin: auto;">
5639 <h3 class="magick-header"><a id="map"></a>-map <var>type</var></h3>
5642 <p class="magick-description">Display image using this <var>type</var>.</p>
5644 <p>Choose from these <var>Standard Colormap</var> types:</p>
5655 <p>The <var>X server</var> must support the <var>Standard
5656 Colormap</var> you choose, otherwise an error occurs. Use <code>list</code> as
5657 the type and <code>display</code> searches the list of colormap types in
5658 <code>top-to-bottom</code> order until one is located. See <var>xstdcmap(1)</var> for one way of creating Standard Colormaps.</p>
5661 <div style="margin: auto;">
5662 <h3 class="magick-header"><a id="map_stream_"></a>-map <var>components</var></h3>
5665 <p class="magick-description">pixel map.</p>
5667 <p>Here are the valid components of a map:</p>
5669 <dl class="dl-horizontal">
5670 <dt>r</dt><dd> red pixel component</dd>
5671 <dt>g</dt><dd> green pixel component</dd>
5672 <dt>b</dt><dd> blue pixel component</dd>
5673 <dt>a</dt><dd> alpha pixel component (0 is transparent)</dd>
5674 <dt>o</dt><dd> opacity pixel component (0 is opaque)</dd>
5675 <dt>i</dt><dd> grayscale intensity pixel component</dd>
5676 <dt>c</dt><dd> cyan pixel component</dd>
5677 <dt>m</dt><dd> magenta pixel component</dd>
5678 <dt>y</dt><dd> yellow pixel component</dd>
5679 <dt>k</dt><dd> black pixel component</dd>
5680 <dt>p</dt><dd> pad component (always 0)</dd>
5683 <p>You can specify as many of these components as needed in any order (e.g.
5684 bgr). The components can repeat as well (e.g. rgbr).</p>
5687 <div style="margin: auto;">
5688 <h3 class="magick-header"><a id="mattecolor"></a>-mattecolor <var>color</var></h3>
5691 <p class="magick-description">Specify the color to be used with the <a href="command-line-options.html#frame">-frame</a> option.</p>
5693 <p>The color is specified using the format described under the <a href="command-line-options.html#fill">-fill</a> option.</p>
5695 <p>The default matte color is <code>#BDBDBD</code>, <span
5696 style="background-color: #bdbdbd;">this shade of gray</span>.</p>
5698 <p>This is an IMv6 option, use <a href="command-line-options.html#alpha-color">-alpha-color</a> with IMv7.</p>
5700 <div style="margin: auto;">
5701 <h3 class="magick-header"><a id="maximum"></a>-maximum</h3>
5704 <p class="magick-description">return the maximum intensity of an image sequence.</p>
5706 <p>Select the 'maximum' value from all the surrounding pixels. </p>
5708 <p>This is legacy option from the <a href="command-line-options.html#statistic" >method</a> of the same
5711 <div style="margin: auto;">
5712 <h3 class="magick-header"><a id="median"></a>-median <var>geometry</var></h3>
5715 <p class="magick-description">apply a median filter to the image.</p>
5717 <p>Select the 'middle' value from all the surrounding pixels. </p>
5719 <p>This is legacy option from the <a href="command-line-options.html#statistic" >method</a> of the same
5722 <div style="margin: auto;">
5723 <h3 class="magick-header"><a id="mean-shift"></a>-mean-shift <var>width</var>x<var>height</var>{<var>+distance</var>{%}</h3>
5726 <p class="magick-description">image noise removal and color reduction/segmentation (e.g. -mean-shift 7x7+10%).</p>
5728 <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>
5730 <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>
5732 <div style="margin: auto;">
5733 <h3 class="magick-header"><a id="metric"></a>-metric <var>type</var></h3>
5736 <p class="magick-description">Output to STDERR a measure of the differences between images according to the <var>type</var> given metric.</p>
5740 <dl class="dl-horizontal">
5741 <dt>AE</dt><dd> absolute error count, number of different pixels (-fuzz effected)</dd>
5742 <dt>FUZZ</dt><dd> mean color distance</dd>
5743 <dt>MAE</dt><dd> mean absolute error (normalized), average channel error distance</dd>
5744 <dt>MEPP</dt><dd> mean error per pixel (normalized mean error, normalized peak error)</dd>
5745 <dt>MSE</dt><dd> mean error squared, average of the channel error squared</dd>
5746 <dt>NCC</dt><dd> normalized cross correlation</dd>
5747 <dt>PAE</dt><dd> peak absolute (normalized peak absolute)</dd>
5748 <dt>PHASH</dt><dd> perceptual hash for the sRGB and HCLp colorspaces. Specify an alternative colorspace with <code>-define phash:colorspaces=<var>colorspace,colorspace,...</var></code></dd>
5749 <dt>PSNR</dt><dd> peak signal to noise ratio</dd>
5750 <dt>RMSE</dt><dd> root mean squared (normalized root mean squared)</dd>
5753 <p>Control the '<code>AE</code>', or absolute count of pixels that are different,
5754 with the <a href="command-line-options.html#fuzz" >-fuzz</a> factor (ignore pixels which
5755 only changed by a small amount). Use '<code>PAE</code>' to find the
5756 size of the <a href="command-line-options.html#fuzz" >-fuzz</a> factor needed to make all pixels
5757 'similar', while '<code>MAE</code>' determines the factor needed
5758 for about half the pixels to be similar. </p>
5760 <p>The '<code>MEPP</code>' metric returns three different metrics
5761 ('<code>MAE</code>', '<code>MAE</code>' normalized, and '<code>PAE</code>'
5762 normalized) from a single comparison run. </p>
5764 <p>To print a complete list of metrics, use the <a href="command-line-options.html#list">-list
5765 metric</a> option.</p>
5768 <div style="margin: auto;">
5769 <h3 class="magick-header"><a id="minimum"></a>-minimum</h3>
5772 <p class="magick-description">return the minimum intensity of an image sequence.</p>
5774 <p>Select the 'minimal' value from all the surrounding pixels. </p>
5776 <p>This is legacy option from the <a href="command-line-options.html#statistic" >method</a> of the same
5781 <div style="margin: auto;">
5782 <h3 class="magick-header"><a id="mode"></a>-mode <var>geometry</var></h3>
5785 <p class="magick-description">make each pixel the \'predominant color\' of the neighborhood.'</p>
5787 <div style="margin: auto;">
5788 <h3 class="magick-header">-mode <var>value</var></h3>
5791 <p class="magick-description">Mode of operation.</p>
5793 <p>Choose the <var>value</var> from these styles: <code>Frame,
5794 Unframe, or Concatenate</code></p>
5796 <p>Use the <a href="command-line-options.html#list" >-list</a> option with a '<code>Mode</code>' argument
5797 for a list of <a href="command-line-options.html#mode" >-mode</a> arguments available in your
5798 ImageMagick installation.</p>
5801 <div style="margin: auto;">
5802 <h3 class="magick-header"><a id="modulate"></a>-modulate <var>brightness</var>[,<var>saturation</var>,<var>hue</var>]</h3>
5805 <p class="magick-description">Vary the <var>brightness</var>, <var>saturation</var>, and <var>hue</var> of an image.</p>
5807 <p>The arguments are given as a percentages of variation. A value of 100 means
5808 no change, and any missing values are taken to mean 100.</p>
5810 <p>The <var>brightness</var> is a multiplier of the overall
5811 brightness of the image, so 0 means pure black, 50 is half as bright, 200 is
5812 twice as bright. To invert its meaning <a href="command-line-options.html#negate">-negate</a> the image
5813 before and after. </p>
5815 <p>The <var>saturation</var> controls the amount of color in an
5816 image. For example, 0 produce a grayscale image, while a large value such as
5817 200 produce a very colorful, 'cartoonish' color.</p>
5819 <p>The <var>hue</var> argument causes a "rotation" of the colors
5820 within the image by the amount specified. For example, 50 results in
5821 a counter-clockwise rotation of 90, mapping red shades to purple, and so on.
5822 A value of either 0 or 200 results in a complete 180 degree rotation of the
5823 image. Using a value of 300 is a 360 degree rotation resulting in no change to
5824 the original image. </p>
5826 <p>For example, to increase the color brightness by 20% and decrease the color
5827 saturation by 10% and leave the hue unchanged, use <a
5828 href="command-line-options.html#modulate">-modulate 120,90</a>.</p>
5830 <p>Use <a href="command-line-options.html#set">-set</a> attribute of '<code
5831 >option:modulate:colorspace</code>' to specify which colorspace to
5832 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>
5835 convert image.png -set option:modulate:colorspace hsb -modulate 120,90 modulate.png
5838 <div style="margin: auto;">
5839 <h3 class="magick-header"><a id="moments"></a>-moments</h3>
5842 <p class="magick-description">report image moments and perceptual hash.</p>
5845 <div style="margin: auto;">
5846 <h3 class="magick-header"><a id="monitor"></a>-monitor</h3>
5849 <p class="magick-description">monitor progress.</p>
5852 <div style="margin: auto;">
5853 <h3 class="magick-header"><a id="monochrome"></a>-monochrome</h3>
5856 <p class="magick-description">transform the image to black and white.</p>
5858 <div style="margin: auto;">
5859 <h3 class="magick-header"><a id="morph"></a>-morph <var>frames</var></h3>
5862 <p class="magick-description">morphs an image sequence.</p>
5864 <p>Both the image pixels and size are linearly interpolated to give the
5865 appearance of a metamorphosis from one image to the next, over all the images
5866 in the current image list. The added images are the equivalent of a <a
5867 href="command-line-options.html#blend">-blend</a> composition. The <var>frames</var>
5868 argument determine how many images to interpolate between each image. </p>
5871 <div style="margin: auto;">
5872 <h3 class="magick-header"><a id="morphology"></a>-morphology</h3>
5873 <h3 class="magick-header">-morphology <var>method</var> <var>kernel</var></h3>
5876 <p class="magick-description">apply a morphology method to the image.</p>
5878 <p>Until I get around to writing an option summary for this, see <a
5879 href="https://www.imagemagick.org/Usage/morphology/" >IM Usage Examples,
5880 Morphology</a>. </p>
5883 <div style="margin: auto;">
5884 <h3 class="magick-header"><a id="mosaic"></a>-mosaic</h3>
5887 <p class="magick-description">an simple alias for the <a href="command-line-options.html#layers" >-layers</a> method "mosaic"</p>
5890 <div style="margin: auto;">
5891 <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>
5894 <p class="magick-description">simulate motion blur.</p>
5896 <p>Blur with the given radius, standard deviation (sigma), and angle. The
5897 angle given is the angle toward which the image is blurred. That is the
5898 direction people would consider the object is coming from. </p>
5900 <p>Note that the blur is not uniform distribution, giving the motion a
5901 definite sense of direction of movement. </p>
5903 <p>The <a href="command-line-options.html#virtual-pixel">-virtual-pixel</a> setting will determine how
5904 pixels which are outside the image proper are blurred into the final result.
5907 <div style="margin: auto;">
5908 <h3 class="magick-header"><a id="name"></a>-name</h3>
5911 <p class="magick-description">name an image.</p>
5912 <div style="margin: auto;">
5913 <h3 class="magick-header"><a id="negate"></a>-negate</h3>
5916 <p class="magick-description">replace each pixel with its complementary color.</p>
5918 <p>The red, green, and blue intensities of an image are negated. White becomes
5919 black, yellow becomes blue, etc. Use <a href="command-line-options.html#negate">+negate</a> to only
5920 negate the grayscale pixels of the image.</p>
5922 <div style="margin: auto;">
5923 <h3 class="magick-header"><a id="noise"></a>-noise <var>geometry</var><br/>
5924 +noise <var>type</var></h3>
5927 <p class="magick-description">Add or reduce noise in an image.</p>
5929 <p>The principal function of noise peak elimination filter is to smooth the
5930 objects within an image without losing edge information and without creating
5931 undesired structures. The central idea of the algorithm is to replace a pixel
5932 with its next neighbor in value within a pixel window, if this pixel has been
5933 found to be noise. A pixel is defined as noise if and only if this pixel is
5934 a maximum or minimum within the pixel window.</p>
5936 <p>Use <code><a href="command-line-options.html#noise">-noise</a> <var>radius</var></code> to
5937 specify the width of the neighborhood when reducing noise. This is equivalent
5938 to using a <code><a href="command-line-options.html#statistic" >-statistic</a> NonPeak</code> operation,
5939 which should be used in preference.</p>
5941 <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
5954 <p>The amount of noise added can be controlled by the <code><a
5955 href="command-line-options.html#attenuate" >-attenuate</a></code> setting. If unset the value is
5956 equivalent to 1.0, or a maximum noise addition.</p>
5958 <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>
5960 <p>To print a complete list of noises, use the <a href="command-line-options.html#list">-list noise</a> option.</p>
5962 <p>Also see the <a href="command-line-options.html#evaluate">-evaluate</a> noise functions that allows
5963 the use of a controlling value to specify the amount of noise that should be
5964 added to an image. </p>
5967 <div style="margin: auto;">
5968 <h3 class="magick-header"><a id="normalize"></a>-normalize</h3>
5971 <p class="magick-description">Increase the contrast in an image by <var>stretching</var> the range of intensity values.</p>
5973 <p>The intensity values are stretched to cover the entire range of possible
5974 values. While doing so, black-out at most <var>2%</var> of the pixels and
5975 white-out at most <var>1%</var> of the pixels.</p>
5977 <p>Note that as of ImageMagick 6.4.7-0, <a href="command-line-options.html#normalize" >-normalize</a>
5978 is equivalent to <a href="command-line-options.html#contrast-stretch" >-contrast-stretch 2%x1%</a>.
5979 (Before this version, it was equivalent to <a href="command-line-options.html#contrast-stretch"
5980 >-contrast-stretch 2%x99%</a>).</p>
5982 <p>All the channels are normalized in concert by the same amount so as to
5983 preserve color integrity, when the default <a href="command-line-options.html#channel" >+channel</a>
5984 setting is in use. Specifying any other <a href="command-line-options.html#channel" >-channel</a>
5985 setting will normalize the RGB channels independently.</p>
5987 <p>See <a href="command-line-options.html#contrast-stretch" >-contrast-stretch</a> for more details.
5988 Also see <a href="command-line-options.html#auto-level" >-auto-level</a> for a 'perfect' normalization
5989 that is better suited to mathematically generated images. </p>
5991 <p>This operator is under review for re-development. </p>
5994 <div style="margin: auto;">
5995 <h3 class="magick-header"><a id="opaque"></a>-opaque <var>color</var></h3>
5998 <p class="magick-description">change this color to the fill color within the image.</p>
6000 <p>The <var>color</var> argument is defined using the format
6001 described under the <a href="command-line-options.html#fill" >-fill</a> option. The <a href="command-line-options.html#fuzz"
6002 >-fuzz</a> setting can be used to match and replace colors similar to the one
6005 <p>Use <a href="command-line-options.html#opaque">+opaque</a> to paint any pixel that does not match
6006 the target color. </p>
6008 <p>The <a href="command-line-options.html#transparent">-transparent</a> operator is exactly the same
6009 as <a href="command-line-options.html#opaque" >-opaque</a> but replaces the matching color with
6010 transparency rather than the current <a href="command-line-options.html#fill">-fill</a> color setting.
6011 To ensure that it can do this it also ensures that the image has an alpha
6012 channel enabled, as per "<code><a href="command-line-options.html#alpha" >-alpha</a> set</code>", for
6013 the new transparent colors, and does not require you to modify the <a
6014 href="command-line-options.html#channel">-channel</a> to enable alpha channel handling. </p>
6017 <div style="margin: auto;">
6018 <h3 class="magick-header"><a id="ordered-dither"></a>-ordered-dither <var>threshold_map</var>{,<var>level</var>...}</h3>
6021 <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
6022 given number of <var>levels</var> per color channel.</p>
6024 <p>You can choose from these standard threshold maps:</p>
6026 <pre class="pre-scrollable">
6027 threshold 1x1 Threshold 1x1 (non-dither)
6028 checks 2x1 Checkerboard 2x1 (dither)
6029 o2x2 2x2 Ordered 2x2 (dispersed)
6030 o3x3 3x3 Ordered 3x3 (dispersed)
6031 o4x4 4x4 Ordered 4x4 (dispersed)
6032 o8x8 8x8 Ordered 8x8 (dispersed)
6033 h3x4a 4x1 Halftone 4x4 (angled)
6034 h6x6a 6x1 Halftone 6x6 (angled)
6035 h8x8a 8x1 Halftone 8x8 (angled)
6036 h3x4o Halftone 4x4 (orthogonal)
6037 h6x6o Halftone 6x6 (orthogonal)
6038 h8x8o Halftone 8x8 (orthogonal)
6039 h36x16o Halftone 16x16 (orthogonal)
6040 c5x5b c5x5 Circles 5x5 (black)
6041 c5x5w Circles 5x5 (white)
6042 c6x6b c6x6 Circles 6x6 (black)
6043 c6x6w Circles 6x6 (white)
6044 c7x7b c7x7 Circles 7x7 (black)
6045 c7x7w Circles 7x7 (white)
6048 <p> The <code>threshold</code> generated a simple 50% threshold of the image.
6049 This could be used with <var >level</var> to do the equivalent of <a
6050 href="command-line-options.html#posterize" >-posterize</a> to reduce an image to basic primary colors.
6053 <p>The <code>checks</code> pattern produces a 3 level checkerboard dither
6054 pattern. That is a grayscale will become a pattern of solid black, solid
6055 white, and mid-tone colors into a checkerboard pattern of black and white.
6058 <p>You can define your own <var >threshold map</var> for ordered
6059 dithering and halftoning your images, in either personal or system
6060 <code>thresholds.xml</code> XML file. See <a href="resources.html" >Resources</a>
6061 for more details of configuration files. </p>
6063 <p>To print a complete list of the thresholds that have been defined, use the
6064 <a href="command-line-options.html#list" >-list threshold</a> option.</p>
6066 <p>Note that at this time the same threshold dithering map is used for all
6067 color channels, no attempt is made to offset or rotate the map for different
6068 channels is made, to create an offset printing effect. Also as the maps are
6069 simple threshold levels, the halftone and circle maps will create incomplete
6070 circles along the edges of a colored area. Also all the effects are purely
6071 on/off boolean effects, without anti-aliasing to make the circles smooth
6072 looking. Large dots can be made to look better with a small amount of blurring
6073 after being created. </p>
6076 <div style="margin: auto;">
6077 <h3 class="magick-header"><a id="orient"></a>-orient <var>image orientation</var></h3>
6080 <p class="magick-description">specify orientation of a digital camera image.</p>
6082 <p>Choose from these orientations:</p>
6085 bottom-left right-top
6086 bottom-right top-left
6087 left-bottom top-right
6092 <p>To print a complete list of orientations, use the <a href="command-line-options.html#list" >-list
6093 orientation</a> option.</p>
6096 <div style="margin: auto;">
6097 <h3 class="magick-header"><a id="page"></a>-page <var>geometry</var><br/>
6098 -page <var>media</var>[<var>offset</var>][{<var>^!<></var>}]<br/>
6103 <p class="magick-description">Set the size and location of an image on the larger virtual canvas.</p>
6105 <p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
6107 <p>For convenience you can specify the page size using <var>media</var> (see below). Offsets can then be added as with other
6108 <var>geometry</var> arguments (e.g. <a
6109 href="command-line-options.html#page">-page</a> <code>Letter+43+43</code>).</p>
6111 <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.
6112 The choices for a PostScript page are:</p>
6114 <dl class="dl-horizontal">
6115 <dt> 11x17 </dt> <dd> 792 x 1224</dd>
6116 <dt> Ledger </dt> <dd> 1224 x 792</dd>
6117 <dt> Legal </dt> <dd> 612 x 1008</dd>
6118 <dt> Letter </dt> <dd> 612 x 792</dd>
6119 <dt> LetterSmall</dt> <dd> 612 x 792</dd>
6120 <dt> ArchE </dt> <dd> 2592 x 3456</dd>
6121 <dt> ArchD </dt> <dd> 1728 x 2592</dd>
6122 <dt> ArchC </dt> <dd> 1296 x 1728</dd>
6123 <dt> ArchB </dt> <dd> 864 x 1296</dd>
6124 <dt> ArchA </dt> <dd> 648 x 864</dd>
6125 <dt> A0 </dt> <dd> 2380 x 3368</dd>
6126 <dt> A1 </dt> <dd> 1684 x 2380</dd>
6127 <dt> A2 </dt> <dd> 1190 x 1684</dd>
6128 <dt> A3 </dt> <dd> 842 x 1190</dd>
6129 <dt> A4 </dt> <dd> 595 x 842</dd>
6130 <dt> A4Small </dt> <dd> 595 x 842</dd>
6131 <dt> A5 </dt> <dd> 421 x 595</dd>
6132 <dt> A6 </dt> <dd> 297 x 421</dd>
6133 <dt> A7 </dt> <dd> 210 x 297</dd>
6134 <dt> A8 </dt> <dd> 148 x 210</dd>
6135 <dt> A9 </dt> <dd> 105 x 148</dd>
6136 <dt> A10 </dt> <dd> 74 x 105</dd>
6137 <dt> B0 </dt> <dd> 2836 x 4008</dd>
6138 <dt> B1 </dt> <dd> 2004 x 2836</dd>
6139 <dt> B2 </dt> <dd> 1418 x 2004</dd>
6140 <dt> B3 </dt> <dd> 1002 x 1418</dd>
6141 <dt> B4 </dt> <dd> 709 x 1002</dd>
6142 <dt> B5 </dt> <dd> 501 x 709</dd>
6143 <dt> C0 </dt> <dd> 2600 x 3677</dd>
6144 <dt> C1 </dt> <dd> 1837 x 2600</dd>
6145 <dt> C2 </dt> <dd> 1298 x 1837</dd>
6146 <dt> C3 </dt> <dd> 918 x 1298</dd>
6147 <dt> C4 </dt> <dd> 649 x 918</dd>
6148 <dt> C5 </dt> <dd> 459 x 649</dd>
6149 <dt> C6 </dt> <dd> 323 x 459</dd>
6150 <dt> Flsa </dt> <dd> 612 x 936</dd>
6151 <dt> Flse </dt> <dd> 612 x 936</dd>
6152 <dt> HalfLetter </dt> <dd> 396 x 612</dd>
6155 <p>This option is also used to place subimages when writing to a multi-image
6156 format that supports offsets, such as GIF89 and MNG. When used for this
6157 purpose the offsets are always measured from the top left corner of the canvas
6158 and are not affected by the <a href="command-line-options.html#gravity">-gravity</a> option. To
6159 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
6160 file, a <a href="command-line-options.html#page">-page</a> option appearing ahead of the first image in
6161 the sequence with nonzero width and height defines the width and height values
6162 that are written in the <code>MHDR</code> chunk. Otherwise, the MNG width and
6163 height are computed from the bounding box that contains all images in the
6164 sequence. When writing a GIF89 file, only the bounding box method is used to
6165 determine its dimensions.</p>
6167 <p>For a PostScript page, the image is sized as in <a
6168 href="command-line-options.html#geometry">-geometry</a> but positioned relative to the <var>lower
6169 left-hand corner</var> of the page by {+-}<code>x</code><var>offset</var>{+-}<code>y</code> <var>offset</var>. Use <a
6170 href="command-line-options.html#page">-page 612x792</a>, for example, to center the image within the
6171 page. If the image size exceeds the PostScript page, it is reduced to fit the
6172 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
6173 corner of the page, unless the <a href="command-line-options.html#gravity">-gravity</a> option is
6174 present with a value other than <var>NorthWest</var>.</p>
6176 <p>The default page dimensions for a TEXT image is 612x792.</p>
6178 <p>This option is used in concert with <a href="command-line-options.html#density">-density</a>.</p>
6180 <p>Use <a href="command-line-options.html#page">+page</a> to remove the page settings for an image.</p>
6182 <div style="margin: auto;">
6183 <h3 class="magick-header"><a id="paint"></a>-paint <var>radius</var></h3>
6186 <p class="magick-description">simulate an oil painting.</p>
6188 <p>Each pixel is replaced by the most frequent color in a circular
6189 neighborhood whose width is specified with <var>radius</var>.</p>
6191 <div style="margin: auto;">
6192 <h3 class="magick-header"><a id="path"></a>-path <var>path</var></h3></div>
6194 <p class="magick-description">write images to this path on disk.</p>
6196 <div style="margin: auto;">
6197 <h3 class="magick-header"><a id="pause_animate_"></a>-pause <var>seconds</var></h3>
6200 <p class="magick-description">Pause between animation loops</p>
6202 <p>Pause for the specified number of seconds before repeating the animation.</p>
6204 <div style="margin: auto;">
6205 <h3 class="magick-header"><a id="pause_import_"></a>-pause <var>seconds</var></h3>
6208 <p class="magick-description">Pause between snapshots.</p>
6210 <p>Pause for the specified number of seconds before taking the next snapshot.</p>
6212 <div style="margin: auto;">
6213 <h3 class="magick-header"><a id="perceptible"></a>-perceptible <var>epsilon</var></h3>
6216 <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>
6218 <div style="margin: auto;">
6219 <h3 class="magick-header"><a id="ping"></a>-ping</h3>
6222 <p class="magick-description">efficiently determine image characteristics.</p>
6224 <div style="margin: auto;">
6225 <h3 class="magick-header"><a id="pointsize"></a>-pointsize <var>value</var></h3>
6228 <p class="magick-description">pointsize of the PostScript, OPTION1, or TrueType font.</p>
6230 <div style="margin: auto;">
6231 <h3 class="magick-header"><a id="polaroid"></a>-polaroid <var>angle</var></h3>
6234 <p class="magick-description">simulate a Polaroid picture.</p>
6236 <p>Use <code>+polaroid</code> to rotate the image at a random angle between -15 and +15 degrees.</p>
6238 <div style="margin: auto;">
6239 <h3 class="magick-header"><a id="poly"></a>-poly <var>"wt,exp ..."</var></h3>
6242 <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>
6244 <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>
6246 <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>
6248 <p>The format is: <var>output = wt1*image1^exp1 + wt2*image2^exp2 </var>...</p>
6250 <p>Some simple uses are:</p>
6252 <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>
6253 <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>
6256 <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>
6258 <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>
6261 <div style="margin: auto;">
6262 <h3 class="magick-header"><a id="posterize"></a>-posterize <var>levels</var></h3>
6265 <p class="magick-description">reduce the image to a limited number of color levels per channel.</p>
6267 <p>Very low values of <var>levels</var>, e.g., 2, 3, 4, have the most
6270 <div style="margin: auto;">
6271 <h3 class="magick-header"><a id="precision"></a>-precision <var>value</var></h3>
6274 <p class="magick-description">set the maximum number of significant digits to be printed.</p>
6276 <div style="margin: auto;">
6277 <h3 class="magick-header"><a id="preview"></a>-preview <var>type</var></h3>
6280 <p class="magick-description">image preview type.</p>
6282 <p>Use this option to affect the preview operation of an image (e.g.
6283 <code>convert file.png -preview Gamma Preview:gamma.png</code>). Choose from
6286 <pre class="pre-scrollable">
6318 <p>To print a complete list of previews, use the <a href="command-line-options.html#list">-list preview</a> option.</p>
6320 <p>The default preview is <code>JPEG</code>.</p>
6322 <div style="margin: auto;">
6323 <h3 class="magick-header"><a id="print"></a>-print <var>string</var></h3>
6326 <p class="magick-description">interpret string and print to console.</p>
6328 <div style="margin: auto;">
6329 <h3 class="magick-header"><a id="process"></a>-process <var>command</var></h3>
6332 <p class="magick-description">process the image with a custom image filter.</p>
6334 <p>The command arguments has the form <code>"module arg1 arg2 arg3 ...
6335 argN"</code> where <code>module</code> is the name of the module to invoke (e.g.
6336 "Analyze") and arg1 arg2 arg3 ... argN are an arbitrary number of arguments to
6337 pass to the process module.</p>
6339 <div style="margin: auto;">
6340 <h3 class="magick-header"><a id="profile"></a>-profile <var>filename</var><br/>
6341 +profile <var>profile_name</var></h3>
6344 <p class="magick-description">Manage ICM, IPTC, or generic profiles in an image.</p>
6346 <p>Using <a href="command-line-options.html#profile">-profile</a> <var>filename</var> adds an
6347 ICM (ICC color management), IPTC (newswire information), or a generic profile
6350 <p>Use <a href="command-line-options.html#profile">+profile <var>profile_name</var></a> to
6351 remove the indicated profile. ImageMagick uses standard filename globbing, so
6352 wildcard expressions may be used to remove more than one profile. Here we
6353 remove all profiles from the image except for the XMP profile: <code>+profile
6354 "!xmp,*"</code>. </p>
6356 <p>Use <code>identify -verbose</code> to find out which profiles are in the
6357 image file. Use <a href="command-line-options.html#strip">-strip</a> to remove all profiles (and
6360 <p>To extract a profile, the <a href="command-line-options.html#profile">-profile</a> option is not
6361 used. Instead, simply write the file to an image format such as <var>APP1, 8BIM, ICM,</var> or <var>IPTC</var>.</p>
6363 <p>For example, to extract the Exif data (which is stored in JPEG files in the
6364 <var>APP1</var> profile), use.</p>
6367 convert cockatoo.jpg profile.exif
6370 <p>It is important to note that results may depend on whether or not the
6371 original image already has an included profile. Also, keep in mind that <a
6372 href="command-line-options.html#profile">-profile</a> is an "operator" (as opposed to a "setting") and
6373 therefore a conversion is made each time it is encountered, in order, in the
6374 command-line. For instance, in the following example, if the original image is
6375 CMYK with profile, a CMYK-CMYK-RGB conversion results.</p>
6378 convert CMYK.tif -profile "CMYK.icc" -profile "RGB.icc" RGB.tiff
6381 <p>Furthermore, since ICC profiles are not necessarily symmetric, extra
6382 conversion steps can yield unwanted results. CMYK profiles are often very
6383 asymmetric since they involve 3−>4 and 4−>3 channel mapping.
6386 <div style="margin: auto;">
6387 <h3 class="magick-header"><a id="quality"></a>-quality <var>value</var></h3>
6390 <p class="magick-description">JPEG/MIFF/PNG compression level.</p>
6392 <p>For the JPEG and MPEG image formats, quality is 1 (lowest image quality and
6393 highest compression) to 100 (best quality but least effective compression).
6394 The default is to use the estimated quality of your input image if it can
6395 be determined, otherwise 92. When the quality is greater than 90, then the
6396 chroma channels are not downsampled.
6397 Use the <a href="command-line-options.html#sampling-factor">-sampling-factor</a> option to specify the
6398 factors for chroma downsampling.</p>
6400 <p>For the JPEG-2000 image format, quality is mapped using a non-linear
6401 equation to the compression ratio required by the Jasper library. This
6402 non-linear equation is intended to loosely approximate the quality provided by
6403 the JPEG v1 format. The default quality value 100, a request for non-lossy
6404 compression. A quality of 75 results in a request for 16:1 compression.</p>
6406 <p>For the MNG and PNG image formats, the quality value sets the zlib
6407 compression level (quality / 10) and filter-type (quality % 10). The default
6408 PNG "quality" is 75, which means compression level 7 with adaptive PNG
6409 filtering, unless the image has a color map, in which case it means
6410 compression level 7 with no PNG filtering.</p>
6412 <p>For compression level 0 (quality value less than 10), the Huffman-only
6413 strategy is used, which is fastest but not necessarily the worst
6416 <p>If filter-type is 4 or less, the specified PNG filter-type is used for
6419 <dl class="dl-horizontal">
6420 <dt>0</dt><dd>none</dd>
6421 <dt>1</dt><dd>sub</dd>
6422 <dt>2</dt><dd>up</dd>
6423 <dt>3</dt><dd>average</dd>
6424 <dt>4</dt><dd>Paeth</dd>
6427 <p>If filter-type is 5, adaptive filtering is used when quality is greater
6428 than 50 and the image does not have a color map, otherwise no filtering is
6431 <p>If filter-type is 6, adaptive filtering
6432 with <var>minimum-sum-of-absolute-values</var> is used.</p>
6434 <p>Only if the output is MNG, if filter-type is 7, the LOCO color
6435 transformation (intrapixel differencing) and adaptive filtering
6436 with <var>minimum-sum-of-absolute-values</var> are used.</p>
6438 <p>If the filter-type is 8 the zlib Z_RLE compression strategy (or the
6439 Z_HUFFMAN_ONLY strategy, when compression level is 0) is used with
6440 adaptive PNG filtering.</p>
6442 <p>If the filter-type is 9 the zlib Z_RLE compression strategy (or the
6443 Z_HUFFMAN_ONLY strategy, when compression level is 0) is used with
6444 no PNG filtering.</p>
6446 <p>The quality setting has no effect on the appearance or signature of PNG
6447 and MNG images, since the compression is always lossless.</p>
6449 <p>Not all combinations of compression level, strategy, and PNG filter type
6450 can be obtained using the -quality option. For more precise control,
6451 you can use the PNG:compression-level=N, PNG:compression-strategy=N, and
6452 PNG:compression-filter=N defines, respectively, instead.
6453 See <a href="command-line-options.html#define">-define</a>. Values from the defines take precedence
6454 over values from the -quality option.</p>
6456 <p>For further information, see
6457 the <a href="http://www.w3.org/pub/WWW/TR">PNG</a> specification.</p>
6459 <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>
6461 <p>For the BPG image format, quality/2 is the actual BPG compression level (range from 0 to 51).</p>
6463 <div style="margin: auto;">
6464 <h3 class="magick-header"><a id="quantize"></a>-quantize <var>colorspace</var></h3>
6467 <p class="magick-description">reduce colors using this colorspace.</p>
6469 <p>This setting defines the colorspace used to sort out and reduce the number
6470 of colors needed by an image (for later dithering) by operators such as <a
6471 href="command-line-options.html#colors" >-colors</a>, Note that color reduction also happens
6472 automatically when saving images to color-limited image file formats, such as
6476 <div style="margin: auto;">
6477 <h3 class="magick-header"><a id="quiet"></a>-quiet</h3>
6480 <p class="magick-description">suppress all warning messages. Error messages are still reported.</p>
6482 <div style="margin: auto;">
6483 <h3 class="magick-header"><a id="radial-blur"></a>-radial-blur <var>angle</var></h3>
6486 <p class="magick-description">Blur around the center of the image.</p>
6488 <p>Note that this is actually a rotational blur rather than a radial and as
6489 such actually mis-named. </p>
6491 <p>The <a href="command-line-options.html#virtual-pixel">-virtual-pixel</a> setting will determine how
6492 pixels which are outside the image proper are blurred into the final result.
6496 <div style="margin: auto;">
6497 <h3 class="magick-header"><a id="raise"></a>-raise <var>thickness</var></h3>
6500 <p class="magick-description">Lighten or darken image edges.</p>
6502 <p>This will create a 3-D effect. Use <a href="command-line-options.html#raise">-raise</a> to create
6503 a raised effect, otherwise use <a href="command-line-options.html#raise">+raise</a>. </p>
6505 <p>Unlike the similar <a href="command-line-options.html#frame">-frame</a> option, <a
6506 href="command-line-options.html#raise">-raise</a> does not alter the dimensions of the image.</p>
6508 <div style="margin: auto;">
6509 <h3 class="magick-header"><a id="random-threshold"></a>-random-threshold <var>low</var>x<var>high</var></h3>
6512 <p class="magick-description">Apply a random threshold to the image.</p>
6514 <div style="margin: auto;">
6515 <h3 class="magick-header"><a id="read-mask"></a>-read-mask
6516 <var>filename</var></h3>
6519 <p class="magick-description">Prevent updates to image pixels specified by the mask.</p>
6521 <p>This the same as using a mask used for composite masking operations, with
6522 grayscale values causing blended updates of the image the mask is attached to.
6525 <p>Use <a href="command-line-options.html#read-mask">+read-mask</a> to remove the mask from images.</p>
6527 <p>Also see <a href="command-line-options.html#clip-mask">-clip-mask</a> which work in the same way,
6528 but with strict boolean masking. </p>
6530 <div style="margin: auto;">
6531 <h3 class="magick-header"><a id="red-primary"></a>-red-primary <var>x,y</var></h3>
6534 <p class="magick-description">Set the red chromaticity primary point.</p>
6536 <div style="margin: auto;">
6537 <h3 class="magick-header"><a id="regard-warnings"></a>-regard-warnings</h3>
6540 <p class="magick-description">Pay attention to warning messages.</p>
6542 <p>This option causes some warnings in some image formats to be treated
6545 <div style="margin: auto;">
6546 <h3 class="magick-header"><a id="remap"></a>-remap <var>filename</var></h3>
6549 <p class="magick-description">Reduce the number of colors in an image to the colors used by this image.</p>
6551 <p>If the <a href="command-line-options.html#dither">-dither</a> setting is enabled (the default) then
6552 the given colors are dithered over the image as necessary, otherwise the closest
6553 color (in RGB colorspace) is selected to replace that pixel in the image. </p>
6555 <p>As a side effect of applying a <a href="command-line-options.html#remap">-remap</a> of colors across all
6556 images in the current image sequence, all the images will have the same color
6557 table. That means that when saved to a file format such as GIF, it will use
6558 that color table as a single common or global color table, for all the images,
6559 without requiring extra local color tables. </p>
6561 <p>Use <a href="command-line-options.html#remap">+remap</a> to reduce all images in the current image
6562 sequence to use a common color map over all the images. This equivalent to
6563 appending all the images together (without extra background colors) and color
6564 reducing those images using <a href="command-line-options.html#colors">-colors</a> with a 256 color
6565 limit, then <a href="command-line-options.html#remap">-remap</a> those colors over the original list of
6566 images. This ensures all the images follow a single color map. </p>
6568 <p>If the number of colors over all the images is less than 256, then <a
6569 href="command-line-options.html#remap">+remap</a> should not perform any color reduction or dithering, as
6570 no color changes are needed. In that case, its only effect is to force the use
6571 of a global color table. This recommended after using either <a
6572 href="command-line-options.html#colors">-colors</a> or <a href="command-line-options.html#ordered-dither">-ordered-dither</a> to
6573 reduce the number of colors in an animated image sequence. </p>
6575 <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>
6577 <div style="margin: auto;">
6578 <h3 class="magick-header"><a id="region"></a>-region <var>geometry</var></h3>
6581 <p class="magick-description">Set a region in which subsequent operations apply.</p>
6583 <p>The <var>x</var> and <var>y</var> offsets are treated
6584 in the same manner as in <a href="command-line-options.html#crop">-crop</a>.</p>
6586 <p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
6588 <p>Use <code>+region</code> to remove any previously set regions.</p>
6590 <div style="margin: auto;">
6591 <h3 class="magick-header"><a id="remote"></a>-remote</h3>
6594 <p class="magick-description">perform a remote operation.</p>
6596 <p>The only command recognized is the name of an image file to load.</p>
6598 <p>If you have more than one <a href="display.html">display</a> application
6599 running simultaneously, use the <a href="command-line-options.html#window"> window</a> option to
6600 specify which application to control.</p>
6602 <div style="margin: auto;">
6603 <h3 class="magick-header"><a id="render"></a>-render</h3>
6606 <p class="magick-description">render vector operations.</p>
6608 <p>Use <a href="command-line-options.html#render">+render</a> to turn off rendering vector operations.
6609 This useful when saving the result to vector formats such as MVG or SVG.</p>
6611 <div style="margin: auto;">
6612 <h3 class="magick-header"><a id="repage"></a>-repage <var>geometry</var></h3>
6615 <p class="magick-description">Adjust the canvas and offset information of the image.</p>
6617 <p>This option is like <a href="command-line-options.html#page">-page</a> but acts as an image operator
6618 rather than a setting. You can separately set the canvas size or the offset
6619 of the image on that canvas by only providing those components. </p>
6621 <p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
6623 <p>If a <code>!</code> flag is given the offset given is added to the existing
6624 offset to move the image relative to its previous position. This useful for
6625 animation sequences. </p>
6627 <p>A given a canvas size of zero such as '<code>0x0</code>' forces it to
6628 recalculate the canvas size so the image (at its current offset) will appear
6629 completely on that canvas (unless it has a negative offset).</p>
6631 <p>Use <a href="command-line-options.html#repage">+repage</a> to completely remove/reset the virtual
6632 canvas meta-data from the images. </p>
6634 <p>The <a href="command-line-options.html#set">-set</a> '<code>page</code>' option can be used to
6635 directly assign virtual canvas meta-data. </p>
6638 <div style="margin: auto;">
6639 <h3 class="magick-header"><a id="resample"></a>-resample <var>horizontal</var>x<var>vertical</var></h3>
6642 <p class="magick-description">Resample image to specified horizontal and vertical resolution.</p>
6644 <p>Resize the image so that its rendered size remains the same as the original
6645 at the specified target resolution. For example, if a 300 DPI image renders at
6646 3 inches by 2 inches on a 300 DPI device, when the image has been resampled to
6647 72 DPI, it will render at 3 inches by 2 inches on a 72 DPI device. Note that
6648 only a small number of image formats (e.g. JPEG, PNG, and TIFF) are capable of
6649 storing the image resolution. For formats which do not support an image
6650 resolution, the original resolution of the image must be specified via <a
6651 href="command-line-options.html#density">-density</a> on the command line prior to specifying the
6652 resample resolution.</p>
6654 <p>Note that Photoshop stores and obtains image resolution from a proprietary
6655 embedded profile. If this profile exists in the image, then Photoshop will
6656 continue to treat the image using its former resolution, ignoring the image
6657 resolution specified in the standard file header.</p>
6659 <div style="margin: auto;">
6660 <h3 class="magick-header"><a id="resize"></a>-resize <var>geometry</var></h3>
6663 <p class="magick-description">Resize an image.</p>
6665 <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
6666 ignored, and the <a href="command-line-options.html#gravity">-gravity</a> option has no effect.</p>
6668 <p>If the <a href="command-line-options.html#filter">-filter</a> option
6669 or <code>-define filter:option=value</code> precedes the <a
6670 href="command-line-options.html#resize">-resize</a> option, the image is resized with the specified
6673 <p>Many image processing algorithms assume your image is in a linear-light
6674 coding. If your image is gamma-corrected, you can remove the nonlinear gamma
6675 correction, apply the transform, then restore it like this:</p>
6678 convert portrait.jpg -gamma .45455 -resize 25% -gamma 2.2 \
6679 -quality 92 passport.jpg
6682 <div style="margin: auto;">
6683 <h3 class="magick-header"><a id="respect-parentheses"></a>-respect-parentheses</h3>
6686 <p class="magick-description">settings remain in effect until parenthesis boundary.</p>
6688 <div style="margin: auto;">
6689 <h3 class="magick-header"><a id="reverse"></a>-reverse</h3>
6692 <p class="magick-description">Reverse the order of images in the current image list.</p>
6695 <div style="margin: auto;">
6696 <h3 class="magick-header"><a id="roll"></a>-roll {<var>+-</var>}<var>x</var>{<var>+-</var>}<var>y</var></h3>
6699 <p class="magick-description">roll an image vertically or horizontally by the amount given.</p>
6701 <p>A negative <var>x</var> offset rolls the image right-to-left.
6702 A negative <var>y</var> offset rolls the image bottom-to-top.</p>
6705 <div style="margin: auto;">
6706 <h3 class="magick-header"><a id="rotate"></a>-rotate <var>degrees</var>{<var><</var>}{<var>></var>}</h3>
6709 <p class="magick-description">Apply Paeth image rotation (using shear operations) to the image.</p>
6711 <p>Use <code>></code> to rotate the image only if its width exceeds the
6712 height. <code><</code> rotates the image <var>only</var> if its width is less
6713 than the height. For example, if you specify <code>-rotate "-90>"</code> and
6714 the image size is 480x640, the image is not rotated. However, if the image is
6715 640x480, it is rotated by -90 degrees. If you use <code>></code> or
6716 <code><</code>, enclose it in quotation marks to prevent it from being
6717 misinterpreted as a file redirection.</p>
6719 <p>Empty triangles in the corners, left over from rotating the image, are
6720 filled with the <code>background</code> color. </p>
6722 <p>See also the <a href="command-line-options.html#distort">-distort</a> operator and specifically the
6723 '<code>ScaleRotateTranslate</code>' distort method. </p>
6726 <div style="margin: auto;">
6727 <h3 class="magick-header"><a id="sample"></a>-sample <var>geometry</var></h3>
6730 <p class="magick-description">minify / magnify the image with pixel subsampling and pixel replication, respectively.</p>
6732 <p>Change the image size simply by directly sampling the pixels original
6733 from the image. When magnifying, pixels are replicated in blocks. When
6734 minifying, pixels are sub-sampled (i.e., some rows and columns are skipped
6737 <p>The results are thus equivalent to using <a href="command-line-options.html#resize">-resize</a> with
6738 a <a href="command-line-options.html#filter">-filter</a> setting of <code>point</code> (nearest
6739 neighbor), though <a href="command-line-options.html#sample">-sample</a> is a lot faster, as it
6740 avoids all the filter processing of the image. As such it completely ignores
6741 the current <a href="command-line-options.html#filter">-filter</a> setting. </p>
6743 <p>The key feature of the <a href="command-line-options.html#sample">-sample</a> is that no new colors
6744 will be added to the resulting image, though some colors may disappear. </p>
6746 <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
6747 ignored, unlike <a href="command-line-options.html#resize">-resize</a>. </p>
6750 <p>The actual sampling point is the middle of the sub-region being sampled.
6751 As such a single pixel sampling of an image will take the middle pixel, (or
6752 top-left-middle if image has even dimensions). However the <a
6753 href="command-line-options.html#define">-define</a> '<code>sample:offset</code>' can be set to modify
6754 this position some other location within each sub-region being sampled, as
6755 a percentage offset.</p>
6757 <p>By default this value is '<code>50</code>' for the midpoint, but could be set
6758 to '<code>0</code>' for top-left, '<code>100</code>' for bottom-right, or with
6759 separate X and Y offsets such as '<code>0x50</code>' for left-middle edge of
6760 sampling sub-region.</p>
6763 <div style="margin: auto;">
6764 <h3 class="magick-header"><a id="sampling-factor"></a>-sampling-factor <var>horizontal-factor</var>x<var>vertical-factor</var></h3>
6767 <p class="magick-description">sampling factors used by JPEG or MPEG-2 encoder and YUV decoder/encoder.</p>
6769 <p>This option specifies the sampling factors to be used by the JPEG encoder
6770 for chroma downsampling. If this option is omitted, the JPEG library will use
6771 its own default values. When reading or writing the YUV format and when
6772 writing the M2V (MPEG-2) format, use <a
6773 href="command-line-options.html#sampling-factor">-sampling-factor 2x1</a> or <a
6774 href="command-line-options.html#sampling-factor">-sampling-factor 4:2:2</a> to specify the 4:2:2
6775 downsampling method.</p>
6777 <div style="margin: auto;">
6778 <h3 class="magick-header"><a id="scale"></a>-scale <var>geometry</var></h3>
6781 <p class="magick-description">minify / magnify the image with pixel block averaging and pixel replication, respectively.</p>
6783 <p>Change the image size simply by replacing pixels by averaging pixels
6784 together when minifying, or replacing pixels when magnifying. </p>
6786 <p>The results are thus equivalent to using <a href="command-line-options.html#resize">-resize</a> with
6787 a <a href="command-line-options.html#filter">-filter</a> setting of <code>box</code>. Though it is a lot
6788 faster, as it avoids all the filter processing of the image. As such it
6789 completely ignores the current <a href="command-line-options.html#filter">-filter</a> setting. </p>
6791 <p>If when shrinking (minifying) images the original image is some integer
6792 multiple of the new image size, the number of pixels averaged together to
6793 produce the new pixel color is the same across the whole image. This is
6794 a special case known as 'binning' and is often used as a method of reducing
6795 noise in image such as those generated by digital cameras, especially in low
6796 light conditions. </p>
6799 <div style="margin: auto;">
6800 <h3 class="magick-header"><a id="scene"></a>-scene <var>value</var></h3>
6803 <p class="magick-description">set scene number.</p>
6805 <p>This option sets the scene number of an image or the first image in an image sequence.</p>
6807 <div style="margin: auto;">
6808 <h3 class="magick-header"><a id="screen"></a>-screen</h3>
6811 <p class="magick-description">specify the screen to capture.</p>
6813 <p>This option indicates that the GetImage request used to obtain the image
6814 should be done on the root window, rather than directly on the specified
6815 window. In this way, you can obtain pieces of other windows that overlap the
6816 specified window, and more importantly, you can capture menus or other popups
6817 that are independent windows but appear over the specified window.</p>
6819 <div style="margin: auto;">
6820 <h3 class="magick-header"><a id="seed"></a>-seed</h3>
6823 <p class="magick-description">seed a new sequence of pseudo-random numbers</p>
6825 <div style="margin: auto;">
6826 <h3 class="magick-header"><a id="segment"></a>-segment <var>cluster-threshold</var>x<var>smoothing-threshold</var></h3>
6829 <p class="magick-description">segment the colors of an image.</p>
6831 <p>Segment an image by analyzing the histograms of the color components and
6832 identifying units that are homogeneous with the fuzzy c-means technique. This
6833 is part of the ImageMagick color quantization routines. </p>
6835 <p>Specify <var>cluster threshold</var> as the number of pixels in
6836 each cluster that must exceed the cluster threshold to be considered valid.
6837 <var>Smoothing threshold</var> eliminates noise in the second
6838 derivative of the histogram. As the value is increased, you can expect
6839 a smoother second derivative. The default is 1.5.</p>
6841 <p>If the <a href="command-line-options.html#verbose">-verbose</a> setting is defined, a detailed report
6842 of the color clusters is returned.</p>
6845 <div style="margin: auto;">
6846 <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>
6849 <p class="magick-description">Selectively blur pixels within a contrast threshold.</p>
6851 <p>Blurs those pixels that are less than or equal to the threshold in
6852 contrast. The threshold may be expressed as a fraction of <var>QuantumRange</var> or as a percentage.</p>
6854 <div style="margin: auto;">
6855 <h3 class="magick-header"><a id="separate"></a>-separate</h3>
6858 <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>
6860 <div style="margin: auto;">
6861 <h3 class="magick-header"><a id="sepia-tone"></a>-sepia-tone <var>percent-threshold</var></h3>
6864 <p class="magick-description">simulate a sepia-toned photo.</p>
6866 <p>Specify <var>threshold</var> as the percent threshold of the intensity (0 - 99.9%).</p>
6868 <p>This option applies a special effect to the image, similar to the effect
6869 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
6870 toning. A threshold of 80% is a good starting point for a reasonable
6875 <div style="margin: auto;">
6876 <h3 class="magick-header"><a id="set"></a>-set <var>key value</var></h3>
6877 <h3 class="magick-header">+set <var>key</var></h3>
6880 <p class="magick-description">sets image attributes and properties for images in the current image sequence.</p>
6882 <p>This will assign (or modify) specific settings attached to all the images
6883 in the current image sequence. Using the <a href="command-line-options.html#set">+set</a> form of the
6884 option will either remove, or reset that setting to a default state, as
6887 <p>For example, it will modify specific well known image meta-data
6888 'attributes' such as those normally overridden by: the options <a
6889 href="command-line-options.html#delay" >-delay</a>, <a href="command-line-options.html#dispose" >-dispose</a>, and <a
6890 href="command-line-options.html#page" >-page</a>, <a href="command-line-options.html#colorspace" >-colorspace</a>; generally
6891 assigned before the image is read in, by using a <var>key</var> of
6894 <p>If the given <var>key</var> does not match a specific known
6895 'attribute ', such as shown above, the setting is stored as a a free form
6896 'property' string. Such settings are listed in <a href="command-line-options.html#verbose"
6897 >-verbose</a> information ("<code>info:</code>" output format) as "Properties".
6900 <p>This includes string 'properties' that are set by and assigned to images
6901 using the options <a href="command-line-options.html#comment" >-comment</a>, <a href="command-line-options.html#label"
6902 >-label</a>, <a href="command-line-options.html#caption" >-caption</a>. These options actually assign
6903 a global 'artifact' which are automatically assigned (and any <a href="escape.html" >Format Percent
6904 Escapes</a> expanded) to images as they are read in. For example:</p>
6907 -> convert rose: -set comment 'Rose is a rose is a rose is a rose' rose.png
6908 identify -format %c rose.png
6909 Rose is a rose is a rose is a rose
6912 <p>The set value can also make use of <a href="escape.html" >Format and Print Image
6913 Properties</a> in the defined value. For example:</p>
6916 -> convert rose: -set origsize '%wx%h' -resize 50% \
6917 -format 'Old size = %[origsize] New size = %wx%h' info:
6918 Old size = 70x46 New size = 35x23
6921 <p>Other well known 'properties' that are available include:
6922 '<code>date:create</code>' and '<code>date:modify</code>' and
6923 '<code>signature</code>'. </p>
6925 <p>The <a href="command-line-options.html#repage">-repage</a> operator will also allow you to modify
6926 the '<code>page</code>' attribute of an image for images already in memory (also
6927 see <a href="command-line-options.html#repage">-page</a>). However it is designed to provide a finer
6928 control of the sub-parts of this 'attribute'. The <a href="command-line-options.html#set">-set page</a>
6929 option will only provide a direct, unmodified assignment of '<code>page</code>'
6932 <p>This option can also associate a colorspace or profile with your image.
6936 convert image.psd -set profile ISOcoated_v2_eci.icc image-icc.psd
6939 <p>Some 'properties' must be defined in a specific way to be used. For
6940 example only 'properties' prefixed with "<code>filename:</code>" can be used to
6941 modify the output filename of an image. For example</p>
6944 convert rose: -set filename:mysize '%wx%h' 'rose_%[filename:mysize].png'
6947 <p>If the setting value is prefixed with "<code>option:</code>" the setting will
6948 be saved as a global "Artifact" exactly as if it was set using the <a
6949 href="command-line-options.html#define" >-define</a> option. As such settings are global in scope, they
6950 can be used to pass 'attributes' and 'properties' of one specific image,
6951 in a way that allows you to use them in a completely different image, even if
6952 the original image has long since been modified or destroyed. For example: </p>
6955 convert rose: -set option:rosesize '%wx%h' -delete 0 \
6956 label:'%[rosesize]' label_size_of_rose.gif"
6959 <p>Note that <a href="escape.html" >Format Percent Escapes</a> will only match
6960 a 'artifact' if the given <var>key</var> does not match an existing
6961 'attribute' or 'property'. </p>
6963 <p>You can set the attributes of the image registry by prefixing the value
6964 with <code>registry:</code>.</p>
6966 <p>The <a href="command-line-options.html#set">-set profile</a> option can also be used to inject
6967 previously-formatted ancillary chunks into the output PNG file, using
6968 the commandline option as shown below or by setting the profile via a
6969 programming interface:</p>
6972 convert in.png -set profile PNG-chunk-x:<filename> out.png
6975 <p>where <var>x</var> is a location flag and
6976 <var>filename</var> is a file containing the chunk
6977 name in the first 4 bytes, then a colon (":"), followed by the chunk data.
6978 This encoder will compute the chunk length and CRC, so those must not
6979 be included in the file.</p>
6981 <p>"x" can be "b" (before PLTE), "m" (middle, i.e., between PLTE and IDAT),
6982 or "e" (end, i.e., after IDAT). If you want to write multiple chunks
6983 of the same type, then add a short unique string after the "x" to prevent
6984 subsequent profiles from overwriting the preceding ones, e.g.,</p>
6988 convert in.png -set profile PNG-chunk-b01:file01 \
6989 -profile PNG-chunk-b02:file02 out.png
6992 <div style="margin: auto;">
6993 <h3 class="magick-header"><a id="shade"></a>-shade <var>azimuth</var>x<var>elevation</var></h3>
6996 <p class="magick-description">shade the image using a distant light source.</p>
6998 <p>Specify <var>azimuth</var> and <var>elevation</var> as
6999 the position of the light source. Use <a href="command-line-options.html#shade">+shade</a> to return
7000 the shading results as a grayscale image.</p>
7002 <div style="margin: auto;">
7003 <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>
7006 <p class="magick-description">simulate an image shadow.</p>
7008 <div style="margin: auto;">
7009 <h3 class="magick-header"><a
7010 id="shared-memory"></a>-shared-memory</h3>
7013 <p class="magick-description">use shared memory.</p>
7015 <p>This option specifies whether the utility should attempt to use shared
7016 memory for pixmaps. ImageMagick must be compiled with shared memory support,
7017 and the display must support the <var>MIT-SHM</var> extension.
7018 Otherwise, this option is ignored. The default is <code>True</code>.</p>
7020 <div style="margin: auto;">
7021 <h3 class="magick-header"><a id="sharpen"></a>-sharpen <var>radius</var><br />-sharpen <var>radius</var>x<var>sigma</var></h3>
7024 <p class="magick-description">sharpen the image.</p>
7026 <p>Use a Gaussian operator of the given radius and standard deviation (sigma).</p>
7028 <div style="margin: auto;">
7029 <h3 class="magick-header"><a id="shave"></a>-shave <var>geometry</var></h3>
7032 <p class="magick-description">Shave pixels from the image edges.</p>
7034 <p>The <var>size</var> portion of the <var>geometry</var>
7035 argument specifies the width of the region to be removed from both sides of
7036 the image and the height of the regions to be removed from top and bottom.
7037 Offsets are ignored.</p>
7039 <p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
7041 <div style="margin: auto;">
7042 <h3 class="magick-header"><a id="shear"></a>-shear <var>Xdegrees</var>[x<var>Ydegrees</var>]</h3>
7045 <p class="magick-description">Shear the image along the x-axis and/or y-axis.</p>
7047 <p>The shear angles may be positive, negative, or zero. When <var>Ydegrees</var> is omitted it defaults to 0. When both angles are
7048 given, the horizontal component of the shear is performed before the vertical
7051 <p>Shearing slides one edge of an image along the x-axis or y-axis (i.e.,
7052 horizontally or vertically, respectively),creating a parallelogram. The amount
7053 of each is controlled by the respective shear angle. For horizontal shears,
7054 <var>Xdegrees</var> is measured clockwise relative to "up" (the
7055 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
7056 positive x-axis), sliding the right edge down when 0°<<var>Ydegrees</var><90° and up when 90°<<var>Ydegrees</var><180°.</p>
7058 <p>Empty triangles left over from shearing the image are filled with the color
7059 defined by the <a href="command-line-options.html#fill">-background</a> option. The color is specified
7060 using the format described under the <a href="command-line-options.html#fill">-fill</a> option.</p>
7062 <p>The horizontal shear is performed before the vertical part. This is
7063 important to note, since horizontal and vertical shears do not
7064 <var>commute</var>, i.e., the order matters in a sequence of shears. For
7065 example, the following two commands are not equivalent.</p>
7068 convert logo: -shear 20x0 -shear 0x60 logo-sheared.png
7069 convert logo: -shear 0x60 -shear 20x0 logo-sheared.png
7072 <p>The first of the two commands above is equivalent to the following, except
7073 for the amount of empty space created; the command that follows generates
7074 a smaller image, and so is a better choice in terms of time and space.</p>
7077 convert logo: -shear 20x60 logo-sheared.png
7080 <div style="margin: auto;">
7081 <h3 class="magick-header"><a id="sigmoidal-contrast"></a>-sigmoidal-contrast <var>contrast</var>x<var>mid-point</var></h3>
7084 <p class="magick-description">increase the contrast without saturating highlights or shadows.</p>
7086 <p>Increase the contrast of the image using a sigmoidal transfer function
7087 without saturating highlights or shadows. <var>Contrast</var>
7088 indicates how much to increase the contrast. For example, 0 is none, 3 is
7089 typical and 20 is a lot.
7092 <p>The <var>mid-point</var> indicates where the maximum change
7093 'slope' in contrast should fall in the resultant image (0 is white; 50% is
7094 middle-gray; 100% is black). </p>
7096 <p>By default the image contrast is increased, use <var>+sigmoidal-contrast</var> to decrease the contrast.</p>
7098 <p>To achieve the equivalent of a sigmoidal brightness change (similar to
7099 a gamma adjustment), you would use <var>-sigmoidal-contrast
7100 {brightness}x0%</var> to increase brightness and <var>+sigmoidal-contrast {brightness}x0%</var> to decrease brightness.
7101 Note the use of '0' fo rthe mid-point of the sigmoidal curve. </p>
7103 <p>Using a very high <var>contrast</var> will produce a sort of
7104 'smoothed thresholding' of the image. Not as sharp (with high aliasing
7105 effects) of a true threshold, but with tapered gray-levels around the threshold
7106 <var>mid-point</var>. </p>
7108 <div style="margin: auto;">
7109 <h3 class="magick-header"><a id="silent"></a>-silent</h3>
7114 <p class="magick-description">operate silently. This option is only used
7115 by the <a href="import.html">import</a> tool.</p>
7117 <div style="margin: auto;">
7118 <h3 class="magick-header"><a id="similarity-threshold"></a>-similarity-threshold <var>value</var></h3>
7121 <p class="magick-description">minimum RMSE for subimage match.</p>
7123 <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>
7125 <div style="margin: auto;">
7126 <h3 class="magick-header"><a id="size"></a>-size <var>width</var>[x<var>height</var>][<var>+offset</var>]</h3>
7129 <p class="magick-description">set the width and height of the image.</p>
7131 <p>Use this option to specify the width and height of raw images whose
7132 dimensions are unknown such as <code>GRAY</code>, <code>RGB</code>, or
7133 <code>CMYK</code>. In addition to width and height, use <a
7134 href="command-line-options.html#size">-size</a> with an offset to skip any header information in the
7135 image or tell the number of colors in a <code>MAP</code> image file, (e.g. -size
7138 <p>For Photo CD images, choose from these sizes:</p>
7148 <div style="margin: auto;">
7149 <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>
7152 <p class="magick-description">simulate a pencil sketch.</p>
7154 <p>Sketch with the given radius, standard deviation (sigma), and angle. The
7155 angle given is the angle toward which the image is sketched. That is the
7156 direction people would consider the object is coming from. </p>
7158 <div style="margin: auto;">
7159 <h3 class="magick-header"><a id="smush"></a>-smush <var>offset</var></h3>
7162 <p class="magick-description">appends an image sequence together ignoring transparency.</p>
7164 <p>Smush is a more flexible version of <a href="command-line-options.html#append">-append</a>, joining the images in the sequence top-to-bottom (<a href="command-line-options.html#smush">-smush</a>) or left-to-right (<a href="command-line-options.html#smush">+smush</a>), with a gap between images according to the specified offset.</p>
7166 <p>If the offset is negative, images will overlap by that amount.</p>
7168 <p><a href="command-line-options.html#smush">-smush</a> respects <a href="command-line-options.html#gravity">-gravity</a>. Any empty space will be filled with the <a href="command-line-options.html#background">-background</a> color.</p>
7170 <p>For zero offset and transparent images, the non-transparent parts of the two images will be aligned as close as possible without overlapping.</p>
7172 <div style="margin: auto;">
7173 <h3 class="magick-header"><a id="snaps"></a>-snaps <var>value</var></h3>
7176 <p class="magick-description">Set the number of screen snapshots.</p>
7178 <p>Use this option to grab more than one image from the X server screen, to create an animation sequence.</p>
7180 <div style="margin: auto;">
7181 <h3 class="magick-header"><a id="solarize"></a>-solarize <var>percent-threshold</var></h3>
7184 <p class="magick-description">negate all pixels above the threshold level.</p>
7186 <p>Specify <var>factor</var> as the percent threshold of the intensity (0 - 99.9%).</p>
7188 <p>This option produces a <var>solarization</var> effect seen when
7189 exposing a photographic film to light during the development process.</p>
7191 <div style="margin: auto;">
7192 <h3 class="magick-header"><a id="sparse-color"></a>-sparse-color <var>method</var> '<var>x</var>,<var>y</var> <var>color</var> ...'</h3>
7195 <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>
7198 <dl class="dl-horizontal">
7199 <dt>barycentric</dt>
7200 <dd>three point triangle of color given 3 points.
7201 Giving only 2 points will form a linear gradient between those points.
7202 The gradient generated extends beyond the triangle created by those
7205 <dd>Like barycentric but for 4 points. Less than 4 points
7206 fall back to barycentric. </dd>
7208 <dd>Simply map each pixel to the to nearest color point
7209 given. The result are polygonal 'cells' of solid color. </dd>
7211 <dd>Like voronoi, but resulting polygonal 'cells' are mapped to a fixed coordinate system.</dd>
7213 <dd>Colors points biased on the ratio of inverse distance
7214 squared. Generating spots of color in a sea of the average of
7217 <dd>Colors points biased on the ratio of inverse distance.
7218 This generates sharper points of color rather than rounded spots of
7219 '<code>shepards</code>' Generating spots of color in a sea of the
7220 average of colors. </dd>
7223 <p>The points are placed according to the images location on the virtual
7224 canvas (<a href="command-line-options.html#page" >-page</a> or <a href="command-line-options.html#repage" >-repage</a>
7225 offset), and do not actually have to exist on the given image, but may be
7226 some point beyond the edge of the image. All points are floating point values.
7229 <p>Only the color channels defined by the <a href="command-line-options.html#channel" >-channel</a> are
7230 modified, which means that by default matte/alpha transparency channel is not
7231 effected. Typically transparency channel is turned off either before or after
7234 <p>Of course if some color points are transparent to generate a transparent
7235 gradient, then the image also requires transparency enabled to store the
7238 <p>All the above methods when given a single point of color will replace all
7239 the colors in the image with the color given, regardless of the point. This is
7240 logical, and provides an alternative technique to recolor an image to some
7244 <div style="margin: auto;">
7245 <h3 class="magick-header"><a id="splice"></a>-splice <var>geometry</var></h3>
7248 <p class="magick-description">Splice the current background color into the image.</p>
7250 <p>This will add rows and columns of the current <a
7251 href="command-line-options.html#background">-background</a> color into the given image according to the
7252 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
7253 image into four quadrants, separating them by the inserted rows and columns.
7256 <p>If a dimension of geometry is zero no rows or columns will be added for that
7257 dimension. Similarly using a zero offset with the appropriate <a
7258 href="command-line-options.html#gravity">-gravity</a> setting will add rows and columns to the edges of
7259 the image, padding the image only along that one edge. Edge padding is what <a
7260 href="command-line-options.html#splice">-splice</a> is most commonly used for. </p>
7262 <p>If the exact same <var>geometry</var> and <a
7263 href="command-line-options.html#gravity">-gravity</a> is later used with <a href="command-line-options.html#chop">-chop</a> the
7264 added added all splices removed. </p>
7266 <div style="margin: auto;">
7267 <h3 class="magick-header"><a id="spread"></a>-spread <var>amount</var></h3>
7270 <p class="magick-description">displace image pixels by a random amount.</p>
7272 <p>The argument <var>amount</var> defines the size of the
7273 neighborhood around each pixel from which to choose a candidate pixel to
7276 <p>The lookup is controlled by the <a href="command-line-options.html#interpolate">-interpolate</a> setting.</p>
7278 <div style="margin: auto;">
7279 <h3 class="magick-header"><a id="statistic"></a>-statistic <var>type</var> <var>geometry</var></h3>
7282 <p class="magick-description">replace each pixel with corresponding statistic from the neighborhood.</p>
7284 <p>Choose from these statistic types:</p>
7285 <dl class="dl-horizontal">
7286 <dt>Gradient</dt><dd>maximum difference (max - min) value in neighborhood</dd>
7287 <dt>Maximum</dt><dd>maximum value per channel in neighborhood</dd>
7288 <dt>Minimum</dt><dd>minimum value per channel in neighborhood</dd>
7289 <dt>Mean</dt><dd>average value per channel in neighborhood</dd>
7290 <dt>Median</dt><dd>median value per channel in neighborhood</dd>
7291 <dt>Mode</dt><dd>mode (most frequent) value per channel in neighborhood</dd>
7292 <dt>Nonpeak</dt><dd>value just before or after the median value per channel in neighborhood</dd>
7293 <dt>RMS</dt><dd>root mean square value per channel in neighborhood</dd>
7294 <dt>StandardDeviation</dt><dd> standard deviation value per channel in neighborhood</dd>
7297 <div style="margin: auto;">
7298 <h3 class="magick-header"><a id="stegano"></a>-stegano <var>offset</var></h3>
7301 <p class="magick-description">hide watermark within an image.</p>
7303 <p>Use an offset to start the image hiding some number of pixels from the
7304 beginning of the image. Note this offset and the image size. You will need
7305 this information to recover the steganographic image (e.g. display -size
7306 320x256+35 stegano:image.png).</p>
7308 <div style="margin: auto;">
7309 <h3 class="magick-header"><a id="stereo"></a>-stereo <var>+x</var>{<var>+y</var>}</h3>
7312 <p class="magick-description">composite two images to create a red / cyan stereo anaglyph.</p>
7314 <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>
7316 <div style="margin: auto;">
7317 <h3 class="magick-header"><a id="storage-type"></a>-storage-type <var>type</var></h3>
7320 <p class="magick-description">pixel storage type. Here are the valid types:</p>
7322 <dl class="dl-horizontal">
7323 <dt>char</dt><dd>unsigned characters</dd>
7324 <dt>double</dt><dd>doubles</dd>
7325 <dt>float</dt><dd>floats</dd>
7326 <dt>integer</dt><dd>integers</dd>
7327 <dt>long</dt><dd>longs</dd>
7328 <dt>quantum</dt><dd>pixels in the native depth of your ImageMagick distribution</dd>
7329 <dt>short</dt><dd>unsigned shorts</dd>
7332 <p>Float and double types are normalized from 0.0 to 1.0 otherwise the pixels
7333 values range from 0 to the maximum value the storage type can support.</p>
7335 <div style="margin: auto;">
7336 <h3 class="magick-header"><a id="stretch"></a>-stretch <var>fontStretch</var></h3>
7339 <p class="magick-description">Set a type of stretch style for fonts.</p>
7341 <p>This setting suggests a type of stretch that ImageMagick should try to
7342 apply to the currently selected font family. Select <var>fontStretch</var> from the following.</p>
7357 <p>To print a complete list of stretch types, use <a href="command-line-options.html#list">-list
7360 <p>For other settings that affect fonts, see the options <a
7361 href="command-line-options.html#font">-font</a>, <a href="command-line-options.html#family">-family</a>, <a
7362 href="command-line-options.html#style">-style</a>, and <a href="command-line-options.html#weight">-weight</a>. </p>
7364 <div style="margin: auto;">
7365 <h3 class="magick-header"><a id="strip"></a>-strip</h3>
7368 <p class="magick-description">strip the image of any profiles, comments or these PNG chunks: bKGD,cHRM,EXIF,gAMA,iCCP,iTXt,sRGB,tEXt,zCCP,zTXt,date.</p>
7370 <div style="margin: auto;">
7371 <h3 class="magick-header"><a id="stroke"></a>-stroke <var>color</var></h3>
7374 <p class="magick-description">color to use when stroking a graphic primitive.</p>
7376 <p>The color is specified using the format described under the <a href="command-line-options.html#fill">-fill</a> option.</p>
7378 <p>See <a href="command-line-options.html#draw">-draw</a> for further details.</p>
7380 <div style="margin: auto;">
7381 <h3 class="magick-header"><a id="strokewidth"></a>-strokewidth <var>value</var></h3>
7384 <p class="magick-description">set the stroke width.</p>
7386 <p>See <a href="command-line-options.html#draw">-draw</a> for further details.</p>
7388 <div style="margin: auto;">
7389 <h3 class="magick-header"><a id="style"></a>-style <var>fontStyle</var></h3>
7392 <p class="magick-description">Set a font style for text.</p>
7394 <p>This setting suggests a font style that ImageMagick should try to apply to
7395 the currently selected font family. Select <var>fontStyle</var> from
7405 <p>For other settings that affect fonts, see the options <a
7406 href="command-line-options.html#font">-font</a>, <a href="command-line-options.html#family">-family</a>, <a
7407 href="command-line-options.html#stretch">-stretch</a>, and <a href="command-line-options.html#weight">-weight</a>. </p>
7409 <div style="margin: auto;">
7410 <h3 class="magick-header"><a id="subimage-search"></a>-subimage-search</h3>
7413 <p class="magick-description">search for subimage.</p>
7415 <p>This option is required to have compare search for the best match location
7416 of a small image within a larger image. This search will produce two images
7417 (or two frames). The first is the "difference" image and the second will
7418 be the "match score" image.</p>
7420 <p>The "match-score" image is smaller containing a pixel for ever possible
7421 position of the top-left corner of the given sub-image. that is its size will
7422 be the size of the larger_image - sub_image + 1. The brightest location in
7423 this image is the location s the locate on the best match that is also
7424 reported. Note that this may or may not be a perfect match, and the actual
7425 brightness will reflect this. Other bright 'peaks' can be used to locate other
7426 possible matching locations. </p>
7428 <p>Note that the search will try to compare the sub-image at every possible
7429 location in the larger image, as such it can be very slow. The smaller the
7430 sub-image the faster this search is. </p>
7433 <div style="margin: auto;">
7434 <h3 class="magick-header"><a id="swap"></a>-swap <var>index,index</var></h3>
7437 <p class="magick-description">Swap the positions of two images in the image sequence.</p>
7439 <p>For example, <a href="command-line-options.html#swap">-swap 0,2</a> swaps the first and the third
7440 images in the current image sequence. Use <a href="command-line-options.html#swap">+swap</a> to switch
7441 the last two images in the sequence.</p>
7443 <div style="margin: auto;">
7444 <h3 class="magick-header"><a id="swirl"></a>-swirl <var>degrees</var></h3>
7447 <p class="magick-description">swirl image pixels about the center.</p>
7449 <p><var>Degrees</var> defines the tightness of the swirl.</p>
7451 <div style="margin: auto;">
7452 <h3 class="magick-header"><a id="synchronize"></a>-synchronize</h3>
7455 <p class="magick-description">synchronize image to storage device.</p>
7457 <p>Set to "true" to ensure all image data is fully flushed and synchronized
7458 to disk. There is a performance penalty, but the benefits include ensuring a
7459 valid image file in the event of a system crash and early reporting if there
7460 is not enough disk space for the image pixel cache.</p>
7462 <div style="margin: auto;">
7463 <h3 class="magick-header"><a id="taint"></a>-taint</h3>
7466 <p class="magick-description">Mark the image as modified.</p>
7468 <div style="margin: auto;">
7469 <h3 class="magick-header"><a id="text-font"></a>-text-font <var>name</var></h3>
7472 <p class="magick-description">font for writing fixed-width text.</p>
7474 <p>Specifies the name of the preferred font to use in fixed (typewriter style)
7475 formatted text. The default is 14 point <var>Courier</var>.</p>
7477 <p>You can tag a font to specify whether it is a PostScript, TrueType, or
7478 OPTION1 font. For example, <code>Courier.ttf</code> is a TrueType font and
7479 <code>x:fixed</code> is OPTION1.</p>
7481 <div style="margin: auto;">
7482 <h3 class="magick-header"><a id="texture"></a>-texture <var>filename</var></h3>
7485 <p class="magick-description">name of texture to tile onto the image background.</p>
7487 <div style="margin: auto;">
7488 <h3 class="magick-header"><a id="threshold"></a>-threshold <var>value</var>{<var>%</var>}</h3>
7491 <!-- {<var>green,blue,opacity</var>}
7492 <p>If the green or blue value is omitted, these channels use the same value as
7493 the first one provided. If all three color values are the same, the result is
7494 a bi-level image. If the opacity threshold is omitted, OpaqueOpacity is used
7495 and any partially transparent pixel becomes fully transparent.</p>
7498 <p class="magick-description">Apply simultaneous black/white threshold to the image.</p>
7500 <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
7501 maximum channel value, while all other values are assigned the minimum.</p>
7503 <p> The threshold value can be given as a percentage or as an absolute integer
7504 value corresponding to the desired channel value. When given as an integer,
7505 the minimum attainable value is 0 (corresponding to black when all channels
7506 are affected), but the maximum value (corresponding to white) is that of the
7507 <code>quantum depth</code> of the particular build of ImageMagick, and is
7508 therefore dependent on the installation. For that reason, a reasonable
7509 recommendation for most applications is to specify the threshold values as
7512 <p> The following would force pixels with red values above 50% to have 100%
7513 red values, while those at or below 50% red would be set to 0 in the red
7514 channel. The green, blue, and alpha channels (if present) would be unchanged.
7518 convert in.png -channel red -threshold 50% out.png
7521 <p>As (possibly) impractical but instructive examples, the following would
7522 generate an all-black and an all-white image with the same dimensions as the
7527 convert in.png -threshold 100% black.png
7528 convert in.png -threshold -1 white.png
7531 <p>Note that the values of the transparency channel is treated as 'matte'
7532 values (0 is opaque) and not as 'alpha' values (0 is transparent).</p>
7534 <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>.
7537 <div style="margin: auto;">
7538 <h3 class="magick-header"><a id="thumbnail"></a>-thumbnail <var>geometry</var></h3>
7541 <p class="magick-description">Create a thumbnail of the image.</p>
7543 <p>This is similar to <a href="command-line-options.html#resize">-resize</a>, except it is optimized
7544 for speed and any image profile, other than a color profile, is removed to
7545 reduce the thumbnail size. To strip the color profiles as well, add <a
7546 href="command-line-options.html#strip">-strip</a> just before of after this option.</p>
7548 <p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
7550 <div style="margin: auto;">
7551 <h3 class="magick-header"><a id="tile"></a>-tile <var>filename</var></h3>
7554 <p class="magick-description">Set the tile image used for filling a subsequent graphic primitive.</p>
7556 <div style="margin: auto;">
7557 <h3 class="magick-header">-tile <var>geometry</var></h3>
7560 <p class="magick-description">Specify the layout of images.</p>
7562 <p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
7564 <div style="margin: auto;">
7565 <h3 class="magick-header">-tile</h3>
7568 <p class="magick-description">Specifies that a subsequent composite operation is repeated across and down image.</p>
7570 <div style="margin: auto;">
7571 <h3 class="magick-header"><a id="tile-offset"></a>-tile-offset {<var>+-</var>}<var>x</var>{<var>+-</var>}<var>y</var></h3>
7574 <p class="magick-description">Specify the offset for tile images, relative to the background image it is tiled on.</p>
7576 <p>This should be set before the tiling image is set by <a href="command-line-options.html#tile"
7577 >-tile</a> or <a href="command-line-options.html#texture" >-texture</a>, or directly applied for
7578 creating a tiled canvas using <code>TILE:</code> or <code>PATTERN:</code> input
7581 <p>Internally ImageMagick does a <a href="command-line-options.html#roll" >-roll</a> of the tile image
7582 by the arguments given when the tile image is set. </p>
7584 <div style="margin: auto;">
7585 <h3 class="magick-header"><a id="tint"></a>-tint <var>value</var></h3>
7588 <p class="magick-description">Tint the image with the fill color.</p>
7590 <p>Tint the image with the fill color.</p>
7592 <p>Specify the amount of tinting as a percentage. Pure colors like black,
7593 white red, yellow, will not be affected by -tint. Only mid-range colors such
7594 as the various shades of grey.</p>
7596 <div style="margin: auto;">
7597 <h3 class="magick-header"><a id="title"></a>-title <var>string</var></h3>
7600 <p class="magick-description">Assign a title to displayed image.", "animate", "display", "montage</p>
7602 <p>Use this option to assign a specific title to the image. This assigned to
7603 the image window and is typically displayed in the window title bar.
7604 Optionally you can include the image filename, type, width, height, Exif data,
7605 or other image attribute by embedding special format characters described
7606 under the <a href="command-line-options.html#format">-format</a> option.</p>
7611 -title "%m:%f %wx%h"
7614 <p>produces an image title of <code>MIFF:bird.miff 512x480</code> for an image
7615 titled <code>bird.miff</code> and whose width is 512 and height is 480.</p>
7618 <div style="margin: auto;">
7619 <h3 class="magick-header"><a id="transform"></a>-transform</h3>
7622 <p class="magick-description">transform the image.</p>
7624 <p>This option applies the transformation matrix from a previous <a href="command-line-options.html#affine">-affine</a> option.</p>
7627 convert -affine 2,2,-2,2,0,0 -transform bird.ppm bird.jpg
7631 <p>This operator has been now been superseded by the <a
7632 href="command-line-options.html#distort">-distort</a> '<code>AffineProjection</code>' method. </p>
7635 <div style="margin: auto;">
7636 <h3 class="magick-header"><a id="transparent"></a>-transparent <var>color</var></h3>
7639 <p class="magick-description">Make this color transparent within the image.</p>
7641 <p>The <var>color</var> argument is defined using the format
7642 described under the <a href="command-line-options.html#fill">-fill</a> option. The <a href="command-line-options.html#fuzz"
7643 >-fuzz</a> setting can be used to match and replace colors similar to the one
7646 <p>Use <a href="command-line-options.html#transparent" >+transparent</a> to invert the pixels matched.
7647 that is make all non-matching colors transparent. </p>
7649 <p>The <a href="command-line-options.html#opaque">-opaque</a> operator is exactly the same as <a
7650 href="command-line-options.html#transparent" >-transparent</a> but replaces the matching color with the
7651 current <a href="command-line-options.html#fill">-fill</a> color setting, rather than transparent.
7652 However the <a href="command-line-options.html#transparent" >-transparent</a> operator also ensures
7653 that the image has an alpha channel enabled, as per "<code><a href="command-line-options.html#alpha"
7654 >-alpha</a> set</code>", and does not require you to modify the <a
7655 href="command-line-options.html#channel">-channel</a> to enable alpha channel handling. </p>
7657 <p>Note that this does not define the color as being the 'transparency color'
7658 used for color-mapped image formats, such as GIF. For that use <a
7659 href="command-line-options.html#transparent-color" >-transparent-color</a> </p>
7662 <div style="margin: auto;">
7663 <h3 class="magick-header"><a id="transparent-color"></a>-transparent-color <var>color</var></h3>
7666 <p class="magick-description">Set the transparent color.</p>
7668 <p>Sometimes this is used for saving to image formats such as
7669 GIF and PNG8 which uses this color to represent boolean transparency. This
7670 does not make a color transparent, it only defines what color the transparent
7671 color is in the color palette of the saved image. Use <a
7672 href="command-line-options.html#transparent">-transparent</a> to make an opaque color transparent.</p>
7674 <p>This option allows you to have both an opaque visible color, as well as a
7675 transparent color of the same color value without conflict. That is, you can
7676 use the same color for both the transparent and opaque color areas within an
7677 image. This, in turn, frees to you to select a transparent color that is
7678 appropriate when an image is displayed by an application that does not handle a
7679 transparent color index, while allowing ImageMagick to correctly handle images of this
7682 <p>The default transparent color is <code>#00000000</code>, which is fully transparent black.</p>
7684 <div style="margin: auto;">
7685 <h3 class="magick-header"><a id="transpose"></a>-transpose</h3>
7688 <p class="magick-description">Mirror the image along the top-left to bottom-right diagonal.</p>
7690 <p> This option mathematically transposes the pixel array. It is equivalent to the sequence <code>-flip -rotate 90</code>.
7693 <div style="margin: auto;">
7694 <h3 class="magick-header"><a id="transverse"></a>-transverse</h3>
7697 <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>
7700 <div style="margin: auto;">
7701 <h3 class="magick-header"><a id="treedepth"></a>-treedepth <var>value</var></h3>
7704 <p class="magick-description">tree depth for the color reduction algorithm.</p>
7706 <p>Normally, this integer value is zero or one. A value of zero or one causes
7707 the use of an optimal tree depth for the color reduction algorithm.</p>
7709 <p>An optimal depth generally allows the best representation of the source
7710 image with the fastest computational speed and the least amount of memory.
7711 However, the default depth is inappropriate for some images. To assure the
7712 best representation, try values between 2 and 8 for this parameter. Refer to
7713 the <a href="http://www.imagemagick.org/www/quantize.html"
7714 >color reduction algorithm</a> for more details.</p>
7716 <p>The <a href="command-line-options.html#colors">-colors</a> or <a href="command-line-options.html#monochrome">-monochrome</a>
7717 option, or writing to an image format which requires color reduction, is
7718 required for this option to take effect.</p>
7720 <div style="margin: auto;">
7721 <h3 class="magick-header"><a id="trim"></a>-trim</h3>
7724 <p class="magick-description">trim an image.</p>
7726 <p>This option removes any edges that are exactly the same color as the corner
7727 pixels. Use <a href="command-line-options.html#fuzz">-fuzz</a> to make <a href="command-line-options.html#trim">-trim</a> remove
7728 edges that are nearly the same color as the corner pixels.</p>
7730 <p>The page or virtual canvas information of the image is preserved allowing
7731 you to extract the result of the <a href="command-line-options.html#trim">-trim</a> operation from the
7732 image. Use a <a href="command-line-options.html#repage">+repage</a> to remove the virtual canvas page
7733 information if it is unwanted.</p>
7735 <p>If the trimmed image 'disappears' an warning is produced, and a special
7736 single pixel transparent 'missed' image is returned, in the same way as when a
7737 <a href="command-line-options.html#crop">-crop</a> operation 'misses' the image proper. </p>
7740 <div style="margin: auto;">
7741 <h3 class="magick-header"><a id="type"></a>-type <var>type</var></h3>
7744 <p class="magick-description">the image type.</p> <p>Choose from: <code>Bilevel</code>,
7745 <code>Grayscale</code>, <code>GrayscaleMatte</code>, <code>Palette</code>,
7746 <code>PaletteMatte</code>, <code>TrueColor</code>, <code>TrueColorMatte</code>,
7747 <code>ColorSeparation</code>, or <code>ColorSeparationMatte</code>.</p>
7749 <p>Normally, when a format supports different subformats such as grayscale and
7750 truecolor, the encoder will try to choose an efficient subformat. The <a
7751 href="command-line-options.html#type">-type</a> option can be used to override this behavior. For
7752 example, to prevent a JPEG from being written in grayscale format even though
7753 only gray pixels are present, use.</p>
7756 convert bird.png -type TrueColor bird.jpg
7759 <p>Similarly, use <a href="command-line-options.html#type">-type TrueColorMatte</a> to force the
7760 encoder to write an alpha channel even though the image is opaque, if the
7761 output format supports transparency.</p>
7763 <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>
7765 <div style="margin: auto;">
7766 <h3 class="magick-header"><a id="undercolor"></a>-undercolor <var>color</var></h3>
7769 <p class="magick-description">set the color of the annotation bounding box.</p>
7771 <p>The color is specified using the format described under the <a href="command-line-options.html#fill">-fill</a> option.</p>
7773 <p>See <a href="command-line-options.html#draw">-draw</a> for further details.</p>
7776 <div style="margin: auto;">
7777 <h3 class="magick-header"><a id="update"></a>-update <var>seconds</var></h3>
7780 <p class="magick-description">detect when image file is modified and redisplay.</p>
7782 <p>Suppose that while you are displaying an image the file that is currently
7783 displayed is over-written. <code>display</code> will automagically detect that
7784 the input file has been changed and update the displayed image
7788 <div style="margin: auto;">
7789 <h3 class="magick-header"><a id="unique-colors"></a>-unique-colors</h3>
7792 <p class="magick-description">discard all but one of any pixel color.</p>
7795 <div style="margin: auto;">
7796 <h3 class="magick-header"><a id="units"></a>-units <var>type</var></h3>
7799 <p class="magick-description">the units of image resolution.</p>
7801 <p>Choose from: <code>Undefined</code>, <code>PixelsPerInch</code>, or
7802 <code>PixelsPerCentimeter</code>. This option is normally used in conjunction
7803 with the <a href="command-line-options.html#density">-density</a> option.</p>
7806 <div style="margin: auto;">
7807 <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>
7810 <p class="magick-description">sharpen the image with an unsharp mask operator.</p>
7812 <p>The <a href="command-line-options.html#unsharp">-unsharp</a> option sharpens an image. The image is
7813 convolved with a Gaussian operator of the given radius and standard deviation
7814 (sigma). For reasonable results, radius should be larger than sigma. Use
7815 a radius of 0 to have the method select a suitable radius.</p>
7817 <p>The parameters are:</p>
7819 <dl class="dl-horizontal">
7821 <dd>The radius of the Gaussian, in pixels, not counting the center pixel (default 0).</dd>
7823 <dd>The standard deviation of the Gaussian, in pixels (default 1.0).</dd>
7825 <dd>The fraction of the difference between the original and the blur image that is added back into the original (default 1.0).</dd>
7827 <dd>The threshold, as a fraction of <var>QuantumRange</var>, needed to apply the difference amount (default 0.05).</dd>
7830 <div style="margin: auto;">
7831 <h3 class="magick-header"><a id="verbose"></a>-verbose</h3>
7834 <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>
7837 <div style="margin: auto;">
7838 <h3 class="magick-header"><a id="version"></a>-version</h3>
7841 <p class="magick-description">print ImageMagick version string and exit.</p>
7844 <div style="margin: auto;">
7845 <h3 class="magick-header"><a id="view"></a>-view <var>string</var></h3>
7848 <p class="magick-description">FlashPix viewing parameters.</p>
7851 <div style="margin: auto;">
7852 <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>
7855 <p class="magick-description">soften the edges of the image in vignette style.</p>
7857 <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>
7859 <div style="margin: auto;">
7860 <h3 class="magick-header"><a id="virtual-pixel"></a>-virtual-pixel <var>method</var></h3>
7863 <p class="magick-description">Specify contents of <var>virtual pixels</var>.</p>
7865 <p>This option defines what color source should be used if and when a color
7866 lookup completely 'misses' the source image. The color(s) that appear to
7867 surround the source image. Generally this color is derived from the source
7868 image, but could also be set to a specify background color. </p>
7870 <p>Choose from these methods:</p>
7872 <dl class="dl-horizontal">
7873 <dt>background</dt><dd>the area surrounding the image is the background color</dd>
7874 <dt>black</dt><dd>the area surrounding the image is black</dd>
7875 <dt>checker-tile</dt><dd>alternate squares with image and background color</dd>
7876 <dt>dither</dt><dd>non-random 32x32 dithered pattern</dd>
7877 <dt>edge</dt><dd>extend the edge pixel toward infinity</dd>
7878 <dt>gray</dt><dd>the area surrounding the image is gray</dd>
7879 <dt>horizontal-tile</dt><dd>horizontally tile the image, background color above/below</dd>
7880 <dt>horizontal-tile-edge</dt><dd>horizontally tile the image and replicate the side edge pixels</dd>
7881 <dt>mirror</dt><dd>mirror tile the image</dd>
7882 <dt>random</dt><dd>choose a random pixel from the image</dd>
7883 <dt>tile</dt><dd>tile the image (default)</dd>
7884 <dt>transparent</dt><dd>the area surrounding the image is transparent blackness</dd>
7885 <dt>vertical-tile</dt><dd>vertically tile the image, sides are background color</dd>
7886 <dt>vertical-tile-edge</dt><dd>vertically tile the image and replicate the side edge pixels</dd>
7887 <dt>white</dt><dd>the area surrounding the image is white</dd>
7890 <p>The default value is "edge".</p>
7892 <p>This most important for distortion operators such as <a href="command-line-options.html#distort"
7893 >-distort</a>, <a href="command-line-options.html#implode" >-implode</a>, and <a href="command-line-options.html#fx" >-fx</a>.
7894 However it also effects operations that may access pixels just outside the
7895 image proper, such as <a href="command-line-options.html#convolve">-convolve</a>, <a
7896 href="command-line-options.html#blur">-blur</a>, and <a href="command-line-options.html#sharpen">-sharpen</a>. </p>
7898 <p>To print a complete list of virtual pixel types, use the <a
7899 href="command-line-options.html#list">-list virtual-pixel</a> option.</p>
7902 <div style="margin: auto;">
7903 <h3 class="magick-header"><a id="visual"></a>-visual <var>type</var></h3>
7906 <p class="magick-description">Animate images using this X visual type.", 'animate', 'display'</p>
7908 <p>Choose from these visual classes:</p>
7911 StaticGray TrueColor
7912 GrayScale DirectColor
7914 PseudoColor visual id
7917 <p>The X server must support the visual you choose, otherwise an error occurs.
7918 If a visual is not specified, the visual class that can display the most
7919 simultaneous colors on the default screen is chosen.</p>
7922 <div style="margin: auto;">
7923 <h3 class="magick-header"><a id="watermark"></a>-watermark <var>brightness</var>x<var>saturation</var></h3>
7926 <p class="magick-description">Watermark an image using the given percentages of brightness and saturation.</p>
7928 <p>Take a grayscale image (with alpha mask) and modify the destination image's
7929 brightness according to watermark image's grayscale value and the
7930 <var>brightness</var> percentage. The destinations color saturation
7931 attribute is just direct modified by the <var>saturation</var>
7932 percentage, which defaults to 100 percent (no color change). </p>
7935 <div style="margin: auto;">
7936 <h3 class="magick-header"><a id="wave"></a>-wave <var>amplitude</var><br />-wave <var>amplitude</var>x<var>wavelength</var></h3>
7939 <p class="magick-description">Shear the columns of an image into a sine wave.</p>
7941 <div style="margin: auto;">
7942 <h3 class="magick-header"><a id="wavelet-denoise"></a>-wavelet-denoise <var>threshold</var><br />-wavelet-denoise <var>threshold</var>x<var>softness</var></h3>
7945 <p class="magick-description">removes noise from the image using a wavelet transform. The threshold is the value below which everything is considered noise and ranges from 0.0 (none) to QuantumRange or use percent (e.g. 5%). Softness attenuates the threshold and typically ranges from 0.0 (none) to 1.0. The higher the value the more noise that remains in the image.</p>
7947 <div style="margin: auto;">
7948 <h3 class="magick-header"><a id="weight"></a>-weight <var>fontWeight</var></h3>
7951 <p class="magick-description">Set a font weight for text.</p>
7953 <p>This setting suggests a font weight that ImageMagick should try to apply to
7954 the currently selected font family. Use a positive integer for
7955 <var>fontWeight</var> or select from the following.</p>
7957 <dl class="dl-horizontal">
7959 <dd>Same as <var>fontWeight</var> = 100.</dd>
7960 <dt>ExtraLight </dt>
7961 <dd>Same as <var>fontWeight</var> = 200.</dd>
7963 <dd>Same as <var>fontWeight</var> = 300.</dd>
7965 <dd>Same as <var>fontWeight</var> = 400.</dd>
7967 <dd>Same as <var>fontWeight</var> = 500.</dd>
7969 <dd>Same as <var>fontWeight</var> = 600.</dd>
7971 <dd>Same as <var>fontWeight</var> = 700.</dd>
7973 <dd>Same as <var>fontWeight</var> = 800.</dd>
7975 <dd>Same as <var>fontWeight</var> = 900.</dd>
7979 <p>To print a complete list of weight types, use <a href="command-line-options.html#list">-list weight</a>.</p>
7981 <p>For other settings that affect fonts, see the options <a
7982 href="command-line-options.html#font">-font</a>, <a href="command-line-options.html#family">-family</a>, <a
7983 href="command-line-options.html#stretch">-stretch</a>, and <a href="command-line-options.html#style">-style</a>. </p>
7985 <div style="margin: auto;">
7986 <h3 class="magick-header"><a id="white-point"></a>-white-point <var>x,y</var></h3>
7989 <p class="magick-description">chromaticity white point.</p>
7991 <div style="margin: auto;">
7992 <h3 class="magick-header"><a id="white-threshold"></a>-white-threshold <var>value</var>{<var>%</var>}</h3>
7995 <p class="magick-description">Force to white all pixels above the threshold while leaving all pixels at or below the threshold unchanged.</p>
7997 <p> The threshold value can be given as a percentage or as an absolute integer
7998 value within [0, <var>QuantumRange</var>] corresponding to the
7999 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>
8001 <div style="margin: auto;">
8002 <h3 class="magick-header"><a id="window"></a>-window <var>id</var></h3>
8005 <p class="magick-description">Make the image the background of a window.", 'animate', 'display'</p>
8007 <p><var>id</var> can be a window id or name. Specify <code>root</code>
8008 to select X's root window as the target window.</p>
8010 <p>By default the image is tiled onto the background of the target window. If
8011 <code>backdrop</code> or <a href="command-line-options.html#geometry">-resize</a> are specified, the
8012 image is surrounded by the background color. Refer to <code>X RESOURCES</code>
8015 <p>The image will not display on the root window if the image has more unique
8016 colors than the target window colormap allows. Use <a
8017 href="command-line-options.html#colors">-colors</a> to reduce the number of colors.</p>
8019 <div style="margin: auto;">
8020 <h3 class="magick-header"><a id="window-group"></a>-window-group</h3>
8023 <p class="magick-description">specify the window group.</p>
8025 <div style="margin: auto;">
8026 <h3 class="magick-header"><a id="write"></a>-write <var>filename</var></h3>
8029 <p class="magick-description">write an image sequence.</p>
8031 <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>
8033 <p>Use <a href="command-line-options.html#compress">-compress</a> to specify the type of image compression.</p>
8035 <div style="margin: auto;">
8036 <h3 class="magick-header"><a id="write-mask"></a>-write-mask <var>filename</var></h3>
8039 <p class="magick-description">Prevent updates to image pixels specified by the mask.</p>
8041 <p>This the same as using a mask used for composite masking operations, with
8042 grayscale values causing blended updates of the image the mask is attached to.
8045 <p>Use <a href="command-line-options.html#write-mask">+write-mask</a> to remove the mask from images.</p>
8047 <p>Also see <a href="command-line-options.html#clip-mask">-clip-mask</a> which work in the same way,
8048 but with strict boolean masking. </p>
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