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gerrit-public.fairphone.software / platform / external / ImageMagick / 751980dac8acbf24b155ae0d3b45fdf4c452f55c / . / www / compose.html
blob: 4b3dd8c0b3d8e0bb2488438a693eb02e400e9caf [file] [log] [blame]
cristybc9539a2010-08-16 18:06:20 +0000[diff] [blame]1
cristydcca3fa2010-12-29 21:50:07 +0000[diff] [blame]2<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN"
3 "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
cristy2bd2a982011-02-15 00:52:58 +0000[diff] [blame]4<html version="-//W3C//DTD XHTML 1.1//EN"
5 xmlns="http://www.w3.org/1999/xhtml" xml:lang="en"
6 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
7 xsi:schemaLocation="http://www.w3.org/1999/xhtml
8 http://www.w3.org/MarkUp/SCHEMA/xhtml11.xsd">
cristybc9539a2010-08-16 18:06:20 +0000[diff] [blame]9<head>
cristy751980d2012-06-03 23:18:35 +0000[diff] [blame^]10 <meta http-equiv="content-type" content="text/html; charset=UTF-8"/>
cristy1efc1ab2011-08-01 14:47:02 +0000[diff] [blame]11 <meta name="google-site-verification" content="MxsMq6bdLOx0KSuz1MY6yG9ZTIJ7_7DVRfl5NCAT5Yg"/>
cristydcca3fa2010-12-29 21:50:07 +0000[diff] [blame]12 <title>ImageMagick: Alpha Compositing</title>
cristy751980d2012-06-03 23:18:35 +0000[diff] [blame^]13 <meta http-equiv="content-language" content="en-US"/>
14 <meta http-equiv="content-type" content="text/html; charset=utf-8"/>
15 <meta http-equiv="reply-to" content="magick-users@imagemagick.org"/>
16 <meta name="application-name" content="ImageMagick"/>
17 <meta name="description" content="Use ImageMagick to convert, edit, or compose bitmap images in a variety of formats. In addition resize, rotate, shear, distort and transform images automagically."/>
18 <meta name="application-url" content="http://www.imagemagick.org"/>
19 <meta name="generator" content="PHP"/>
20 <meta name="keywords" content="alpha, compositing, ImageMagick, PerlMagick, image processing, OpenMP, software development library, image, photo, software, Magick++, MagickWand"/>
21 <meta name="rating" content="GENERAL"/>
22 <meta name="robots" content="INDEX, FOLLOW"/>
23 <meta name="generator" content="ImageMagick Studio LLC"/>
24 <meta name="author" content="ImageMagick Studio LLC"/>
25 <meta name="revisit-after" content="2 DAYS"/>
26 <meta name="resource-type" content="document"/>
27 <meta name="copyright" content="Copyright (c) 1999-2012 ImageMagick Studio LLC"/>
28 <meta name="distribution" content="Global"/>
cristydcca3fa2010-12-29 21:50:07 +0000[diff] [blame]29 <link rel="icon" href="../images/wand.png"/>
cristybc9539a2010-08-16 18:06:20 +0000[diff] [blame]30 <link rel="shortcut icon" href="../images/wand.ico" type="images/x-icon"/>
cristy29c5c992011-06-25 13:58:49 +0000[diff] [blame]31 <link rel="canonical" href="http://www.imagemagick.org" />
cristybc9539a2010-08-16 18:06:20 +0000[diff] [blame]32 <link rel="meta" type="application/rdf+xml" title="ICI" href="http://imagemagick.org/ici.rdf"/>
cristyeed6cb62012-01-28 19:38:34 +0000[diff] [blame]33 <!-- Add jQuery library -->
34 <script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.7/jquery.min.js"></script>
35
36 <!-- Optionaly include easing and/or mousewheel plugins -->
37 <script type="text/javascript" src="http://www.imagemagick.org/fancybox/jquery.easing-1.3.pack.js"></script>
38 <script type="text/javascript" src="http://www.imagemagick.org/fancybox/jquery.mousewheel-3.0.6.pack.js"></script>
39
40 <!-- Add fancyBox -->
cristy751980d2012-06-03 23:18:35 +0000[diff] [blame^]41 <link rel="stylesheet" href="http://www.imagemagick.org/fancybox/jquery.fancybox.css?v=2.0.4" type="text/css" media="screen" />
42 <script type="text/javascript" src="http://www.imagemagick.org/fancybox/jquery.fancybox.pack.js?v=2.0.4"></script>
cristyeed6cb62012-01-28 19:38:34 +0000[diff] [blame]43
44 <!-- Optionaly include button and/or thumbnail helpers -->
cristy751980d2012-06-03 23:18:35 +0000[diff] [blame^]45 <link rel="stylesheet" href="http://www.imagemagick.org/fancybox/helpers/jquery.fancybox-buttons.css?v=2.0.4" type="text/css" media="screen" />
46 <script type="text/javascript" src="http://www.imagemagick.org/fancybox/helpers/jquery.fancybox-buttons.js?v=2.0.4"></script>
cristyeed6cb62012-01-28 19:38:34 +0000[diff] [blame]47
cristy751980d2012-06-03 23:18:35 +0000[diff] [blame^]48 <link rel="stylesheet" href="http://www.imagemagick.org/fancybox/helpers/jquery.fancybox-thumbs.css?v=2.0.4" type="text/css" media="screen" />
49 <script type="text/javascript" src="http://www.imagemagick.org/fancybox/helpers/jquery.fancybox-thumbs.js?v=2.0.4"></script>
cristyeed6cb62012-01-28 19:38:34 +0000[diff] [blame]50 <script type="text/javascript">
51 $(document).ready(function() {
52 $(".fancybox").fancybox();
53 });
54 </script>
55 <!-- ImageMagick style -->
cristy7a40ba82011-01-08 20:31:18 +0000[diff] [blame]56 <link rel="stylesheet" href="http://www.google.com/cse/style/look/default.css" type="text/css" />
cristybc9539a2010-08-16 18:06:20 +0000[diff] [blame]57 <style type="text/css" media="all">
58 @import url("../www/magick.css");
59 </style>
60</head>
61
62<body id="www-imagemagick-org">
63<div class="titlebar">
cristyb52981c2011-03-19 17:09:31 +0000[diff] [blame]64<div style="margin: 17px auto; float: left;">
65 <script type="text/javascript">
66 <!--
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cristyaf8d6652011-02-04 21:57:45 +0000[diff] [blame]78 <img src="../images/logo.jpg"
79 alt="ImageMagick Logo"
cristy178edaf2011-01-23 03:42:39 +0000[diff] [blame]80 style="width: 123px; height: 118px; border: 0px; float: right;" /></a>
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cristyaf8d6652011-02-04 21:57:45 +0000[diff] [blame]82 <img src="../images/sprite.jpg"
83 alt="ImageMagick Sprite"
cristybc9539a2010-08-16 18:06:20 +0000[diff] [blame]84 style="width: 114px; height: 118px; border: 0px; float: right;" /></a>
85</div>
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87<div class="westbar">
88
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90 <a title="About ImageMagick" href="../index.html">About ImageMagick</a>
91</div>
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238<div class="main">
239
cristydcca3fa2010-12-29 21:50:07 +0000[diff] [blame]240<h1>ImageMagick Image Composition</h1>
cristy751980d2012-06-03 23:18:35 +0000[diff] [blame^]241<div class="doc-section">
cristyabd337d2010-08-17 01:06:59 +0000[diff] [blame]242<p>This page descibed the Image composition methods that is used to define how
243two images should be merged together in various image operations. For the
244Command Line API it is typically set using the <A
cristy751980d2012-06-03 23:18:35 +0000[diff] [blame^]245HREF="command-line-options.html#compose" >-compose</A> setting option. </p>
cristyabd337d2010-08-17 01:06:59 +0000[diff] [blame]246
247
cristybc9539a2010-08-16 18:06:20 +0000[diff] [blame]248<p>The description of composition uses abstract terminology in order to allow
249the description to be more precise, while avoiding constant values which are
250specific to a particular build configuration. Each image pixel is represented
251by red, green, and blue levels (which are equal for a gray pixel). The
252build-dependent value <em class="QR">QuantumRange</em> is the maximum integral
253value which may be stored, per pixel, in the red, green, or blue channels of
254the image. Each image pixel may also optionally (if the image matte channel is
255enabled) have an associated level of opacity, ranging from <em>opaque</em> to
256<em>transparent</em>, which may be used to determine the influence of the pixel
257color when compositing the pixel with another image pixel. If the image matte
258channel is disabled, then all pixels in the image are treated as opaque. The
259color of an opaque pixel is fully visible while the color of a transparent
260pixel color is entirely absent (pixel color is ignored).</p>
261
262<p>By definition, raster images have a rectangular shape. All image rows are of
263equal length, as are all image columns. By treating the alpha channel as a
264visual "mask" the rectangular image may be given a "shape" by treating the
265alpha channel as a cookie-cutter for the image. This is done by setting the
266pixels within the shape to be opaque, with pixels outside the shape set as
267transparent. Pixels on the boundary of the shape may be between opaque and
268transparent in order to provide antialiasing (visually smooth edges). The
269description of the composition operators use this concept of image "shape" in
270order to make the description of the operators easier to understand. While it
271is convenient to describe the operators in terms of "shapes" they are by no
272means limited to mask-style operations since they are based on continuous
273floating-point mathematics rather than simple boolean operations.</p>
274
275<p>The following alpha blending (Duff-Porter) compose methods are available:</p>
276
277<table class="doc">
278 <tbody>
279 <tr valign="top">
280 <th align="left" style="width: 8%">Method</th>
281 <th align="left">Description</th>
282 </tr>
283
284 <tr valign="top">
285 <td valign="top">clear</td>
286 <td valign="top">Both the color and the alpha of the destination are
287 cleared. Neither the source nor the destination are used (except for
288 destinations size and other meta-data which is always preserved.</td>
289 </tr>
290
291 <tr valign="top">
292 <td valign="top">src</td>
293 <td valign="top">The source is copied to the destination. The destination
294 is not used as input, though it is cleared.</td>
295 </tr>
296
297 <tr valign="top">
298 <td valign="top">dst</td>
299 <td valign="top">The destination is left untouched. The source image is
300 completely ignored.</td>
301 </tr>
302
303 <tr valign="top">
304 <td valign="top">src-over</td>
305 <td valign="top">The source is composited over the destination. this is
306 the default alpha blending compose method, when neither the compose
307 setting is set, nor is set in the image meta-data.</td>
308 </tr>
309
310 <tr valign="top">
311 <td valign="top">dst-over</td>
312 <td valign="top">The destination is composited over the source and the
313 result replaces the destination.</td>
314 </tr>
315
316 <tr valign="top">
317 <td valign="top">src-in</td>
318 <td valign="top">The part of the source lying inside of the destination
319 replaces the destination.</td>
320 </tr>
321
322 <tr valign="top">
323 <td valign="top">dst-in</td>
324 <td valign="top">The part of the destination lying inside of the source
325 replaces the destination. Areas not overlaid are cleared.</td>
326 </tr>
327
328 <tr valign="top">
329 <td valign="top">src-out</td>
330 <td valign="top">The part of the source lying outside of the destination
331 replaces the destination.</td>
332 </tr>
333
334 <tr valign="top">
335 <td valign="top">dst-out</td>
336 <td valign="top">The part of the destination lying outside of the source
337 replaces the destination.</td>
338 </tr>
339
340 <tr valign="top">
341 <td valign="top">src-atop</td>
342 <td valign="top">The part of the source lying inside of the destination is
343 composited onto the destination.</td>
344 </tr>
345
346 <tr valign="top">
347 <td valign="top">dst-atop</td>
348 <td valign="top">The part of the destination lying inside of the source is
349 composited over the source and replaces the destination. Areas not
350 overlaid are cleared. </td>
351 </tr>
352
353 <tr valign="top">
354 <td valign="top">xor</td>
355 <td valign="top">The part of the source that lies outside of the
356 destination is combined with the part of the destination that lies
357 outside of the source. Source or Destination, but not both. </td>
358 </tr>
359
360 </tbody>
361</table>
362
363<p>Any of the 'Src-*' methods can also be specified without the 'Src-' part.
cristyabd337d2010-08-17 01:06:59 +0000[diff] [blame]364For example the default compose method can be specified as just 'Over'.</p>
cristybc9539a2010-08-16 18:06:20 +0000[diff] [blame]365
cristyabd337d2010-08-17 01:06:59 +0000[diff] [blame]366<p>Many of these compose methods will clear the destination image which was
367not overlaid by the source image. This is to be expected as part of that
cristy075ad252010-10-30 21:56:17 +0000[diff] [blame]368specific composition methods defintion. You can disable this by setting the
cristy751980d2012-06-03 23:18:35 +0000[diff] [blame^]369special <A HREF="command-line-options.html#define"
cristy075ad252010-10-30 21:56:17 +0000[diff] [blame]370>-define</A> 'compose:outside-overlay' to a value of 'false' will turn off
371this behaviour. </p>
cristyabd337d2010-08-17 01:06:59 +0000[diff] [blame]372
373<p>On top of the above 12 Duff-Porter Alpha Composition methods, one special
cristybaacd172011-04-30 23:11:03 +0000[diff] [blame]374related method '<kbd>Copy</kbd>' has been provided. This is equivalent to
cristy751980d2012-06-03 23:18:35 +0000[diff] [blame^]375using the '<kbd>Src</kbd>' with the special <A HREF="command-line-options.html#define"
cristy075ad252010-10-30 21:56:17 +0000[diff] [blame]376>-define</A> option '<kbd>compose:outside-overlay</kbd>' set to
377'<kbd>false</kbd>', so as to only modify the overlaid area, without clearing
378the rest of the image outside the overlaid area. </p>
cristyabd337d2010-08-17 01:06:59 +0000[diff] [blame]379
cristybc9539a2010-08-16 18:06:20 +0000[diff] [blame]380<p>The following mathemathical composition methods are also available. </p>
381
382<table class="doc">
383 <tbody>
384 <tr valign="top">
385 <th align="left" style="width: 8%">Method</th>
386 <th align="left">Description</th>
387 </tr>
388
389 <tr valign="top">
390 <td valign="top">multiply</td>
391 <td valign="top">The source is multiplied by the destination and replaces
392 the destination. The resultant color is always at least as dark as
393 either of the two constituent colors. Multiplying any color with black
394 produces black. Multiplying any color with white leaves the original
395 color unchanged.</td>
396 </tr>
397
398 <tr valign="top">
399 <td valign="top">screen</td>
400 <td valign="top">The source and destination are complemented and then
401 multiplied and then replace the destination. The resultant color is
402 always at least as light as either of the two constituent colors.
403 Screening any color with white produces white. Screening any color
404 with black leaves the original color unchanged.</td>
405 </tr>
406
407 <tr valign="top">
408 <td valign="top">plus</td>
409 <td valign="top">The source is added to the destination and replaces the
410 destination. This operator is useful for averaging or a controled
411 merger of two images, rather than a direct overlay.</td>
412 </tr>
413
414 <tr valign="top">
415 <td valign="top">add</td>
416 <td valign="top">As per 'plus' but transparency data is treated as matte
417 values. As such any transparent areas in either image remain
418 transparent. </td>
419 </tr>
420
421 <tr valign="top">
422 <td valign="top">minus</td>
423 <td valign="top">Subtract the colors in the source image from the
424 destination image. When transparency is involved, opaque areas is
425 subtracted from any destination opaque areas. </td>
426 </tr>
427
428 <tr valign="top">
429 <td valign="top">subtract</td>
430 <td valign="top">Subtract the colors in the source image from the
431 destination image. When transparency is involved transparent areas are
432 subtracted, so only the opaque areas in the source remain opaque in
433 the destination image. </td>
434 </tr>
435
436 <tr valign="top">
437 <td valign="top">difference</td>
438 <td valign="top">Subtracts the darker of the two constituent colors from
439 the lighter. Painting with white inverts the destination color.
440 Painting with black produces no change.</td>
441 </tr>
442
443 <tr valign="top">
444 <td valign="top">exclusion</td>
445 <td valign="top">Produces an effect similar to that of 'difference', but
446 appears as lower contrast. Painting with white inverts the
447 destination color. Painting with black produces no change.</td>
448 </tr>
449
450 <tr valign="top">
451 <td valign="top">darken</td>
452 <td valign="top">Selects the darker of the destination and source colors.
453 The destination is replaced with the source when the source is darker,
454 otherwise it is left unchanged.</td>
455 </tr>
456
457 <tr valign="top">
458 <td valign="top">lighten</td>
459 <td valign="top">Selects the lighter of the destination and source colors.
460 The destination is replaced with the source when the source is
461 lighter, otherwise it is left unchanged. </td>
462 </tr>
463
464 </tbody>
465</table>
466
467<p>Typically these use the default 'Over' alpha blending when transparencies
cristyabd337d2010-08-17 01:06:59 +0000[diff] [blame]468are also involved, except for 'Plus' which uses a 'plus' alpha blending. This
469means the alpha channel of both images will only be used to ensure that any
470visible input remains visible even in parts not overlaid. It also means that
471any values are weighted by the alpha channel of the input and output images.
472This 'Over' alpha blending is also applied to the lighting composition methods
473below. </p>
cristybc9539a2010-08-16 18:06:20 +0000[diff] [blame]474
475<p>As of IM v6.6.1-6, if the special '<kbd>Sync</kbd>' flag is not specified
cristy751980d2012-06-03 23:18:35 +0000[diff] [blame^]476(enabled by default) with the <a href="command-line-options.html#channel"
cristyabd337d2010-08-17 01:06:59 +0000[diff] [blame]477>-channel</a> setting, then the above mathematical compositions will nolonger
cristy2dcd6822011-06-13 16:21:20 +0000[diff] [blame]478synchronise its actions with the alpha channel. Instead the math composition
cristyabd337d2010-08-17 01:06:59 +0000[diff] [blame]479will be applied on an individual channel basis as defined by the <a
cristy751980d2012-06-03 23:18:35 +0000[diff] [blame^]480href="command-line-options.html#channel"
cristyabd337d2010-08-17 01:06:59 +0000[diff] [blame]481>-channel</a>. This includes the alpha channel. This special usage
482allows you to perform true mathematics of the image channels, without alpha
483compostion effects, becomming involved. </p>
cristybc9539a2010-08-16 18:06:20 +0000[diff] [blame]484
cristyabd337d2010-08-17 01:06:59 +0000[diff] [blame]485<p>This special flag is not applied to the lighting composition methods (see
486below) even though they are closely related to mathematical composition
487methods.</p>
cristybc9539a2010-08-16 18:06:20 +0000[diff] [blame]488
cristybc9539a2010-08-16 18:06:20 +0000[diff] [blame]489<p>The following lighting composition methods are also available. </p>
490
491<table class="doc">
492 <tbody>
493 <tr valign="top">
494 <th align="left" style="width: 8%">Method</th>
495 <th align="left">Description</th>
496 </tr>
497
498 <tr valign="top">
499 <td valign="top">linear-dodge</td>
cristybaacd172011-04-30 23:11:03 +0000[diff] [blame]500 <td valign="top">This is equivalent to 'Plus' in that the color channels
cristybc9539a2010-08-16 18:06:20 +0000[diff] [blame]501 are simply added, however it does not 'Plus' the alpha channel, but
502 uses the normal 'Over' alpha blending, which transparencies are
503 involved. Produces a sort of additive multiply-like result. Added
504 ImageMagick version 6.5.4-3. </td>
505 </tr>
506
507 <tr valign="top">
508 <td valign="top">linear-burn</td>
509 <td valign="top">As 'Linear-Dodge', but also subtract one from the result.
510 Sort of a additive 'Screen' of the images. Added ImageMagick version
511 6.5.4-3. </td>
512 </tr>
513
514 <tr valign="top">
515 <td valign="top">color-dodge</td>
516 <td valign="top">Brightens the destination color to reflect the source
517 color. Painting with black produces no change.</td>
518 </tr>
519
520 <tr valign="top">
521 <td valign="top">color-burn</td>
522 <td valign="top">Darkens the destination color to reflect the source
523 color. Painting with white produces no change. Fixed in ImageMagick
524 version 6.5.4-3. </td>
525 </tr>
526
527 <tr valign="top">
528 <td valign="top">overlay</td>
529 <td valign="top">Multiplies or screens the colors, dependent on the
530 destination color. Source colors overlay the destination whilst
531 preserving its highlights and shadows. The destination color is not
532 replaced, but is mixed with the source color to reflect the lightness
533 or darkness of the destination.</td>
534 </tr>
535
536 <tr valign="top">
537 <td valign="top">hard-light</td>
538 <td valign="top">Multiplies or screens the colors, dependent on the source
539 color value. If the source color is lighter than 0.5, the destination
540 is lightened as if it were screened. If the source color is darker
541 than 0.5, the destination is darkened, as if it were multiplied. The
542 degree of lightening or darkening is proportional to the difference
543 between the source color and 0.5. If it is equal to 0.5 the
544 destination is unchanged. Painting with pure black or white produces
545 black or white.</td>
546 </tr>
547
548
549 <tr valign="top">
550 <td valign="top">linear-light</td>
551 <td valign="top">Like 'Hard-Light' but using linear-dodge and linear-burn
552 instead. Increases contrast slightly with an impact on the
553 foreground's tonal values.</td>
554 </tr>
555
556 <tr valign="top">
557 <td valign="top">soft-light</td>
558 <td valign="top">Darkens or lightens the colors, dependent on the source
559 color value. If the source color is lighter than 0.5, the destination
560 is lightened. If the source color is darker than 0.5, the destination
561 is darkened, as if it were burned in. The degree of darkening or
562 lightening is proportional to the difference between the source color
563 and 0.5. If it is equal to 0.5, the destination is unchanged. Painting
564 with pure black or white produces a distinctly darker or lighter area,
565 but does not result in pure black or white. Fixed in ImageMagick
566 version 6.5.4-3. </td>
567 </tr>
568
569 <tr valign="top">
570 <td valign="top">pegtop-light</td>
cristybaacd172011-04-30 23:11:03 +0000[diff] [blame]571 <td valign="top">Almost equivalent to 'Soft-Light', but using a
cristybc9539a2010-08-16 18:06:20 +0000[diff] [blame]572 continuious mathematical formula rather than two conditionally
573 selected formulae. Added ImageMagick version 6.5.4-3. </td>
574 </tr>
575
576 <tr valign="top">
577 <td valign="top">vivid-light</td>
578 <td valign="top">A modified 'Linear-Light' designed to preserve very stong
579 primary and secondary colors in the image. Added ImageMagick version
580 6.5.4-3. </td>
581 </tr>
582
583 <tr valign="top">
584 <td valign="top">pin-light</td>
585 <td valign="top">Similar to 'Hard-Light', but using sharp linear shadings,
586 to similate the effects of a strong 'pinhole' light source. Added
587 ImageMagick version 6.5.4-3. </td>
588 </tr>
589
590 </tbody>
591</table>
592
cristybc9539a2010-08-16 18:06:20 +0000[diff] [blame]593<p>Also included are these special purpose compose methods:</p>
594
595<table class="doc">
596 <tbody>
597 <tr valign="top">
598 <th align="left" style="width: 8%">Method</th>
599 <th align="left">Description</th>
600 </tr>
601
602 <tr valign="top">
cristyabd337d2010-08-17 01:06:59 +0000[diff] [blame]603 <td valign="top">copy</td>
cristybaacd172011-04-30 23:11:03 +0000[diff] [blame]604 <td valign="top">This is equivalent to the Duff-Porter composition method
cristy075ad252010-10-30 21:56:17 +0000[diff] [blame]605 '<kbd>Src,</kbd>' but without clearing the parts of the destination
cristyabd337d2010-08-17 01:06:59 +0000[diff] [blame]606 image that is not overlaid. </td>
607 </tr>
608
609 <tr valign="top">
cristybc9539a2010-08-16 18:06:20 +0000[diff] [blame]610 <td valign="top">copy-*</td>
611 <td valign="top">Copy the specified channel (Red, Green, Blue, Cyan,
612 Magenta, Yellow, Black, or Opacity) in the source image to the
613 same channel in the destination image. If the channel specified
614 does not exist in the source image, (which can only happen for methods,
615 '<kbd>copy-opacity</kbd>' or '<kbd>copy-black</kbd>') then it is
616 assumed that the source image is a special grayscale channel image
cristy075ad252010-10-30 21:56:17 +0000[diff] [blame]617 of the values that is to be copied. </td>
cristybc9539a2010-08-16 18:06:20 +0000[diff] [blame]618 </tr>
619
620 <tr valign="top">
621 <td valign="top">change-mask</td>
cristyabd337d2010-08-17 01:06:59 +0000[diff] [blame]622 <td valign="top">Replace any destination pixel that is the similar to the
623 source images pixel (as defined by the current <a
cristy751980d2012-06-03 23:18:35 +0000[diff] [blame^]624 href="command-line-options.html#fuzz">-fuzz</a> factor), with transparency.
cristyabd337d2010-08-17 01:06:59 +0000[diff] [blame]625 </td>
cristybc9539a2010-08-16 18:06:20 +0000[diff] [blame]626 </tr>
627 </tbody>
628</table>
629
630<p>On top of these composed methods are a few special ones that not only require
631the two images that are being merged or overlaid, but have some extra numerical
632arguments, which are tabled below. </p>
633
634<p>In the "<code>composite</code>" command these composition methods are
635selected using special options with the arguments needed. They are usually,
636but not always, the same name as the composte 'method' they use, and replaces
cristy751980d2012-06-03 23:18:35 +0000[diff] [blame^]637the normal use of the <a href="command-line-options.html#compose" >-compose</a>
cristyabd337d2010-08-17 01:06:59 +0000[diff] [blame]638setting in the "<code>composite</code>" command. For example... </p>
cristybc9539a2010-08-16 18:06:20 +0000[diff] [blame]639
cristyeed6cb62012-01-28 19:38:34 +0000[diff] [blame]640<p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>composite ... -blend 50x50 ...</span></p>
cristybc9539a2010-08-16 18:06:20 +0000[diff] [blame]641<p>As of IM v6.5.3-4 the "<code>convert</code>" command can now also supply
cristy751980d2012-06-03 23:18:35 +0000[diff] [blame^]642these extra arguments to its <a href="command-line-options.html#composite"
643>-composite</a> operator, using the special <a href="command-line-options.html#define">-define</a>
cristy075ad252010-10-30 21:56:17 +0000[diff] [blame]644attribute of '<kbd class="arg">compose:args</kbd>'. This means you can now
cristy751980d2012-06-03 23:18:35 +0000[diff] [blame^]645make use of these special argumented <a href="command-line-options.html#compose"
cristyabd337d2010-08-17 01:06:59 +0000[diff] [blame]646>-compose</a> methods, those the argument and the method both need to be set
cristy29c5c992011-06-25 13:58:49 +0000[diff] [blame]647separately. For example... </p>
cristybc9539a2010-08-16 18:06:20 +0000[diff] [blame]648
cristyeed6cb62012-01-28 19:38:34 +0000[diff] [blame]649<p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert ... -compose blend -define compose:args=50,50 -composite ...</span></p>
cristybc9539a2010-08-16 18:06:20 +0000[diff] [blame]650<p>The following is a table of these special 'argumented' compose methods,
651with a brief summary of what they do. For more details see the equivalent
652"composite" command option name. </p>
653
654<table class="doc">
655 <tbody>
656 <tr valign="top">
657 <th align="left" style="width: 8%">Method</th>
658 <th align="left">Description</th>
659 </tr>
660
661 <tr valign="top">
662 <td valign="top">dissolve</td>
663 <td valign="top">Arguments:
664 <em class="arg">src_percent</em>[x<em class="arg">dst_percent</em>]
cristy751980d2012-06-03 23:18:35 +0000[diff] [blame^]665 <br>Equivalent to "<code>composite</code>" <a href="command-line-options.html#dissolve">-dissolve</a>
cristybc9539a2010-08-16 18:06:20 +0000[diff] [blame]666 <br>Dissolve the 'source' image by the percentage given before overlaying
667 'over' the 'destination' image. If <em class="arg">src_percent</em> is
668 greater than 100, it starts dissolving the main image so it will
669 become transparent at a value of '<kbd class="arg">200</kbd>'. If
670 both percentages are given, each image are dissolved to the
671 percentages given.
672 </td>
673 </tr>
674
675 <tr valign="top">
676 <td valign="top">blend</td>
677 <td valign="top">Arguments:
678 <em class="arg">src_percent</em>[x<em class="arg">dst_percent</em>]
cristyabd337d2010-08-17 01:06:59 +0000[diff] [blame]679 <br>Equivalent to "<code>composite</code>" <a
cristy751980d2012-06-03 23:18:35 +0000[diff] [blame^]680 href="command-line-options.html#blend">-blend</a>
cristybc9539a2010-08-16 18:06:20 +0000[diff] [blame]681 <br>Average the images together ('plus') according to the percentages
682 given and each pixels transparency. If only a single percentage value
683 is given it sets the weight of the composite or 'source' image, while
684 the background image is weighted by the exact opposite amount. That is
685 a <kbd>-blend 30</kbd> merges 30% of the 'source' image with 70% of
686 the 'destination' image. Thus it is equivalent to <kbd>-blend
687 30x70</kbd>.
688 </td>
689 </tr>
690
691 <tr valign="top">
692 <td valign="top">mathematics</td>
693 <td valign="top">Arguments: <em class="arg">A, B, C, D</em>
694 <br>Not available in "<code>composite</code>" at this time.
695 <br>Merge the source and destination images according to the formula
696 <br>&nbsp; &nbsp; &nbsp;<code>A*Sc*Dc + B*Sc + C*Dc + D</code>
697 <br>Can be used to generate a custom composition method that would
cristyabd337d2010-08-17 01:06:59 +0000[diff] [blame]698 otherwise need to be implemented using the slow <a
cristy751980d2012-06-03 23:18:35 +0000[diff] [blame^]699 href="command-line-options.html#fx">-fx</a> DIY image operator. Added
cristyabd337d2010-08-17 01:06:59 +0000[diff] [blame]700 to ImageMagick version 6.5.4-3.
cristybc9539a2010-08-16 18:06:20 +0000[diff] [blame]701 <br>As of IM v6.6.1-6 this method will do per-channel math compositions
cristyabd337d2010-08-17 01:06:59 +0000[diff] [blame]702 if the 'Sync' flag is removed from <a
cristy751980d2012-06-03 23:18:35 +0000[diff] [blame^]703 href="command-line-options.html#channel" >-channel</a>, just like all
cristyabd337d2010-08-17 01:06:59 +0000[diff] [blame]704 the other mathematical compostion methods above.
cristybc9539a2010-08-16 18:06:20 +0000[diff] [blame]705 </td>
706 </tr>
707
708 <tr valign="top">
709 <td valign="top">modulate</td>
710 <td valign="top">Arguments:
711 <em class="arg">brightness</em>[x<em class="arg">saturation</em>]
cristy751980d2012-06-03 23:18:35 +0000[diff] [blame^]712 <br>Equivalent to "<code>composite</code>" <a href="command-line-options.html#watermark">-watermark</a>
cristybc9539a2010-08-16 18:06:20 +0000[diff] [blame]713 <br>Take a grayscale image (with alpha mask) and modify the destination
714 image's brightness according to watermark image's grayscale value and
715 the <em class="arg">brightness</em> percentage. The destinations
716 color saturation attribute is just direct modified by the <em
717 class="arg">saturation</em> percentage, which defaults to 100 percent
718 (no color change).
719
720 </td>
721 </tr>
722
723 <tr valign="top">
724 <td valign="top">displace</td>
725 <td valign="top">Arguments:
726 <em class="arg">X-scale</em>[x<em class="arg">Y-scale</em>][!][%]
cristy751980d2012-06-03 23:18:35 +0000[diff] [blame^]727 <br>Equivalent to "<code>composite</code>" <a href="command-line-options.html#displace">-displace</a>
cristybc9539a2010-08-16 18:06:20 +0000[diff] [blame]728 <br>With this option, the 'overlay' image, and optionally the 'mask'
729 image, is used as a relative displacement map, which is used to
730 displace the lookup of what part of the destination image is seen at
731 each point of the overlaid area. Much like the displacement map is a
732 'lens' that distorts the original 'background' image behind it.
733 <br><br>
cristy29c5c992011-06-25 13:58:49 +0000[diff] [blame]734 The X-scale is modulated by the 'red' channel of the overlay image
cristybc9539a2010-08-16 18:06:20 +0000[diff] [blame]735 while the Y-scale is modulated by the green channel, (the mask image
736 if given is rolled into green channel of the overlay image. This
737 separation allows you to modulate the X and Y lookup displacement
cristy29c5c992011-06-25 13:58:49 +0000[diff] [blame]738 separately allowing you to do 2-dimensional displacements, rather
739 than 1-dimensional verctored displacements (using grayscale image).
cristybc9539a2010-08-16 18:06:20 +0000[diff] [blame]740 <br><br>
741 If the overlay image contains transparency this is used as a mask
742 of the resulting image to remove 'invalid' pixels.
743 <br><br>
744 The '%' flag makes the displacement scale relative to the size of the
745 overlay image (100% = half width/height of image). Using '!' switches
746 percentage arguments to refer to the destination image size instead.
747 <br><br>
748 Special flags were added Added to ImageMagick version 6.5.3-5.
749 </td>
750 </tr>
751
752 <tr valign="top">
753 <td valign="top">distort</td>
754 <td valign="top">Arguments:
755 <em class="arg">X-scale</em>[x<em class="arg">Y-scale</em
756 >[+<em class="arg">X-center</em>+<em class="arg">Y-center</em>]][!][%]
757 <br>Not available in "<code>composite</code>" at this time.
758 <br>Exactly as per 'Displace' (above), but using absolute coordinates,
759 relative to the center of the overlay (or that given). Basically
760 allows you to generate absolute distortion maps where 'black' will
761 look up the left/top edge, and 'white' looks up the bottom/right
762 edge of the destination image, according to the scale given.
763 <br><br>
764 The '!' flag not only switches percentage scaling, to use the
765 destination image, but also the image the center offset of the lookup.
766 This means the overlay can lookup a completely different region of the
767 destination image.
768 <br><br>
769 Added to ImageMagick version 6.5.3-5.
770 </td>
771 </tr>
772
773 <tr valign="top">
774 <td valign="top">blur</td>
775 <td valign="top">Arguments:
776 <em class="arg">Width</em>[x<em class="arg">Height</em
cristy075ad252010-10-30 21:56:17 +0000[diff] [blame]777 >[+<em class="arg">Angle</em>][+<em class="arg">Angle2</em>]]
cristy751980d2012-06-03 23:18:35 +0000[diff] [blame^]778 <br>Equivalent to "<code>composite</code>" <a href="command-line-options.html#blur-composite">-blur</a>
cristybc9539a2010-08-16 18:06:20 +0000[diff] [blame]779 <br>A Variable Blur Mapping Composition method, where each pixel in the
780 overlaid region is replaced with an Elliptical Weighted Average (EWA),
781 with an ellipse (typically a circle) of the given sigma size, scaled
782 according to overlay (source image) grayscale mapping.
783 <br><br>
784 As per 'Displace' and 'Distort', the red channel will modulate the
785 width of the ellipse, while the green channel will modulate the height
cristy075ad252010-10-30 21:56:17 +0000[diff] [blame]786 of the ellipse. If a single Angle value is given in the arguments,
787 then the ellipse will then be rotated by the angle specifed.
788 <br><br>
789 Normally the blue channel of the mapping overlay image is ignored.
790 However if a second ellipse angle is given, then it is assumed that
791 the blue channel defines a variable angle for the ellipse ranging from
792 the first angle to the second angle given. This allows to generate
793 radial blurs, or a rough approximation for rotational blur. Or any mix
794 of the two.
cristybc9539a2010-08-16 18:06:20 +0000[diff] [blame]795 <br><br>
796 Added to ImageMagick version 6.5.4-0.
797 </td>
798 </tr>
799
800 </tbody>
801</table>
802
803<p>To print a complete list of all the available compose operators, use <a
cristy751980d2012-06-03 23:18:35 +0000[diff] [blame^]804href="command-line-options.html#list">-list compose</a>.</p>
805</div>
cristybc9539a2010-08-16 18:06:20 +0000[diff] [blame]806
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