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cristyabd337d2010-08-17 01:06:59 +0000[diff] [blame]175<p>This page descibed the Image composition methods that is used to define how
176two images should be merged together in various image operations. For the
177Command Line API it is typically set using the <A
178HREF="../www/command-line-options.html#compose" >-compose</A> setting option. </p>
179
180
cristybc9539a2010-08-16 18:06:20 +0000[diff] [blame]181<p>The description of composition uses abstract terminology in order to allow
182the description to be more precise, while avoiding constant values which are
183specific to a particular build configuration. Each image pixel is represented
184by red, green, and blue levels (which are equal for a gray pixel). The
185build-dependent value <em class="QR">QuantumRange</em> is the maximum integral
186value which may be stored, per pixel, in the red, green, or blue channels of
187the image. Each image pixel may also optionally (if the image matte channel is
188enabled) have an associated level of opacity, ranging from <em>opaque</em> to
189<em>transparent</em>, which may be used to determine the influence of the pixel
190color when compositing the pixel with another image pixel. If the image matte
191channel is disabled, then all pixels in the image are treated as opaque. The
192color of an opaque pixel is fully visible while the color of a transparent
193pixel color is entirely absent (pixel color is ignored).</p>
194
195<p>By definition, raster images have a rectangular shape. All image rows are of
196equal length, as are all image columns. By treating the alpha channel as a
197visual "mask" the rectangular image may be given a "shape" by treating the
198alpha channel as a cookie-cutter for the image. This is done by setting the
199pixels within the shape to be opaque, with pixels outside the shape set as
200transparent. Pixels on the boundary of the shape may be between opaque and
201transparent in order to provide antialiasing (visually smooth edges). The
202description of the composition operators use this concept of image "shape" in
203order to make the description of the operators easier to understand. While it
204is convenient to describe the operators in terms of "shapes" they are by no
205means limited to mask-style operations since they are based on continuous
206floating-point mathematics rather than simple boolean operations.</p>
207
208<p>The following alpha blending (Duff-Porter) compose methods are available:</p>
209
210<table class="doc">
211 <tbody>
212 <tr valign="top">
213 <th align="left" style="width: 8%">Method</th>
214 <th align="left">Description</th>
215 </tr>
216
217 <tr valign="top">
218 <td valign="top">clear</td>
219 <td valign="top">Both the color and the alpha of the destination are
220 cleared. Neither the source nor the destination are used (except for
221 destinations size and other meta-data which is always preserved.</td>
222 </tr>
223
224 <tr valign="top">
225 <td valign="top">src</td>
226 <td valign="top">The source is copied to the destination. The destination
227 is not used as input, though it is cleared.</td>
228 </tr>
229
230 <tr valign="top">
231 <td valign="top">dst</td>
232 <td valign="top">The destination is left untouched. The source image is
233 completely ignored.</td>
234 </tr>
235
236 <tr valign="top">
237 <td valign="top">src-over</td>
238 <td valign="top">The source is composited over the destination. this is
239 the default alpha blending compose method, when neither the compose
240 setting is set, nor is set in the image meta-data.</td>
241 </tr>
242
243 <tr valign="top">
244 <td valign="top">dst-over</td>
245 <td valign="top">The destination is composited over the source and the
246 result replaces the destination.</td>
247 </tr>
248
249 <tr valign="top">
250 <td valign="top">src-in</td>
251 <td valign="top">The part of the source lying inside of the destination
252 replaces the destination.</td>
253 </tr>
254
255 <tr valign="top">
256 <td valign="top">dst-in</td>
257 <td valign="top">The part of the destination lying inside of the source
258 replaces the destination. Areas not overlaid are cleared.</td>
259 </tr>
260
261 <tr valign="top">
262 <td valign="top">src-out</td>
263 <td valign="top">The part of the source lying outside of the destination
264 replaces the destination.</td>
265 </tr>
266
267 <tr valign="top">
268 <td valign="top">dst-out</td>
269 <td valign="top">The part of the destination lying outside of the source
270 replaces the destination.</td>
271 </tr>
272
273 <tr valign="top">
274 <td valign="top">src-atop</td>
275 <td valign="top">The part of the source lying inside of the destination is
276 composited onto the destination.</td>
277 </tr>
278
279 <tr valign="top">
280 <td valign="top">dst-atop</td>
281 <td valign="top">The part of the destination lying inside of the source is
282 composited over the source and replaces the destination. Areas not
283 overlaid are cleared. </td>
284 </tr>
285
286 <tr valign="top">
287 <td valign="top">xor</td>
288 <td valign="top">The part of the source that lies outside of the
289 destination is combined with the part of the destination that lies
290 outside of the source. Source or Destination, but not both. </td>
291 </tr>
292
293 </tbody>
294</table>
295
296<p>Any of the 'Src-*' methods can also be specified without the 'Src-' part.
cristyabd337d2010-08-17 01:06:59 +0000[diff] [blame]297For example the default compose method can be specified as just 'Over'.</p>
cristybc9539a2010-08-16 18:06:20 +0000[diff] [blame]298
cristyabd337d2010-08-17 01:06:59 +0000[diff] [blame]299<p>Many of these compose methods will clear the destination image which was
300not overlaid by the source image. This is to be expected as part of that
301specific composition methods defintion. Seeing the You can disable this by
302setting the special <A HREF="../www/command-line-options.html#set" >-set</A>
303'option:compose:outside-overlay' to 'false' will turn off this behaviour. </p>
304
305<p>On top of the above 12 Duff-Porter Alpha Composition methods, one special
306related method '<kbd>Copy</kbd>' has been provided. This is equivelent to the
307'<kbd>Src</kbd>' with the special <A HREF="../www/command-line-options.html#set"
308>-set</A> option '<kbd>option:compose:outside-overlay</kbd>' set to
309'<kbd>false></kbd>'. </p>
310
311<br><br>
cristybc9539a2010-08-16 18:06:20 +0000[diff] [blame]312
313<p>The following mathemathical composition methods are also available. </p>
314
315<table class="doc">
316 <tbody>
317 <tr valign="top">
318 <th align="left" style="width: 8%">Method</th>
319 <th align="left">Description</th>
320 </tr>
321
322 <tr valign="top">
323 <td valign="top">multiply</td>
324 <td valign="top">The source is multiplied by the destination and replaces
325 the destination. The resultant color is always at least as dark as
326 either of the two constituent colors. Multiplying any color with black
327 produces black. Multiplying any color with white leaves the original
328 color unchanged.</td>
329 </tr>
330
331 <tr valign="top">
332 <td valign="top">screen</td>
333 <td valign="top">The source and destination are complemented and then
334 multiplied and then replace the destination. The resultant color is
335 always at least as light as either of the two constituent colors.
336 Screening any color with white produces white. Screening any color
337 with black leaves the original color unchanged.</td>
338 </tr>
339
340 <tr valign="top">
341 <td valign="top">plus</td>
342 <td valign="top">The source is added to the destination and replaces the
343 destination. This operator is useful for averaging or a controled
344 merger of two images, rather than a direct overlay.</td>
345 </tr>
346
347 <tr valign="top">
348 <td valign="top">add</td>
349 <td valign="top">As per 'plus' but transparency data is treated as matte
350 values. As such any transparent areas in either image remain
351 transparent. </td>
352 </tr>
353
354 <tr valign="top">
355 <td valign="top">minus</td>
356 <td valign="top">Subtract the colors in the source image from the
357 destination image. When transparency is involved, opaque areas is
358 subtracted from any destination opaque areas. </td>
359 </tr>
360
361 <tr valign="top">
362 <td valign="top">subtract</td>
363 <td valign="top">Subtract the colors in the source image from the
364 destination image. When transparency is involved transparent areas are
365 subtracted, so only the opaque areas in the source remain opaque in
366 the destination image. </td>
367 </tr>
368
369 <tr valign="top">
370 <td valign="top">difference</td>
371 <td valign="top">Subtracts the darker of the two constituent colors from
372 the lighter. Painting with white inverts the destination color.
373 Painting with black produces no change.</td>
374 </tr>
375
376 <tr valign="top">
377 <td valign="top">exclusion</td>
378 <td valign="top">Produces an effect similar to that of 'difference', but
379 appears as lower contrast. Painting with white inverts the
380 destination color. Painting with black produces no change.</td>
381 </tr>
382
383 <tr valign="top">
384 <td valign="top">darken</td>
385 <td valign="top">Selects the darker of the destination and source colors.
386 The destination is replaced with the source when the source is darker,
387 otherwise it is left unchanged.</td>
388 </tr>
389
390 <tr valign="top">
391 <td valign="top">lighten</td>
392 <td valign="top">Selects the lighter of the destination and source colors.
393 The destination is replaced with the source when the source is
394 lighter, otherwise it is left unchanged. </td>
395 </tr>
396
397 </tbody>
398</table>
399
400<p>Typically these use the default 'Over' alpha blending when transparencies
cristyabd337d2010-08-17 01:06:59 +0000[diff] [blame]401are also involved, except for 'Plus' which uses a 'plus' alpha blending. This
402means the alpha channel of both images will only be used to ensure that any
403visible input remains visible even in parts not overlaid. It also means that
404any values are weighted by the alpha channel of the input and output images.
405This 'Over' alpha blending is also applied to the lighting composition methods
406below. </p>
cristybc9539a2010-08-16 18:06:20 +0000[diff] [blame]407
408<p>As of IM v6.6.1-6, if the special '<kbd>Sync</kbd>' flag is not specified
cristyabd337d2010-08-17 01:06:59 +0000[diff] [blame]409(enabled by default) with the <a href="../www/command-line-options.html#channel"
410>-channel</a> setting, then the above mathematical compositions will nolonger
411syncronise its actiosn with the alpha channel. Instead the math composition
412will be applied on an individual channel basis as defined by the <a
413href="../www/command-line-options.html#channel"
414>-channel</a>. This includes the alpha channel. This special usage
415allows you to perform true mathematics of the image channels, without alpha
416compostion effects, becomming involved. </p>
cristybc9539a2010-08-16 18:06:20 +0000[diff] [blame]417
cristyabd337d2010-08-17 01:06:59 +0000[diff] [blame]418<p>This special flag is not applied to the lighting composition methods (see
419below) even though they are closely related to mathematical composition
420methods.</p>
cristybc9539a2010-08-16 18:06:20 +0000[diff] [blame]421
cristyabd337d2010-08-17 01:06:59 +0000[diff] [blame]422<br><br>
cristybc9539a2010-08-16 18:06:20 +0000[diff] [blame]423
424<p>The following lighting composition methods are also available. </p>
425
426<table class="doc">
427 <tbody>
428 <tr valign="top">
429 <th align="left" style="width: 8%">Method</th>
430 <th align="left">Description</th>
431 </tr>
432
433 <tr valign="top">
434 <td valign="top">linear-dodge</td>
435 <td valign="top">This is equivelent to 'Plus' in that the color channels
436 are simply added, however it does not 'Plus' the alpha channel, but
437 uses the normal 'Over' alpha blending, which transparencies are
438 involved. Produces a sort of additive multiply-like result. Added
439 ImageMagick version 6.5.4-3. </td>
440 </tr>
441
442 <tr valign="top">
443 <td valign="top">linear-burn</td>
444 <td valign="top">As 'Linear-Dodge', but also subtract one from the result.
445 Sort of a additive 'Screen' of the images. Added ImageMagick version
446 6.5.4-3. </td>
447 </tr>
448
449 <tr valign="top">
450 <td valign="top">color-dodge</td>
451 <td valign="top">Brightens the destination color to reflect the source
452 color. Painting with black produces no change.</td>
453 </tr>
454
455 <tr valign="top">
456 <td valign="top">color-burn</td>
457 <td valign="top">Darkens the destination color to reflect the source
458 color. Painting with white produces no change. Fixed in ImageMagick
459 version 6.5.4-3. </td>
460 </tr>
461
462 <tr valign="top">
463 <td valign="top">overlay</td>
464 <td valign="top">Multiplies or screens the colors, dependent on the
465 destination color. Source colors overlay the destination whilst
466 preserving its highlights and shadows. The destination color is not
467 replaced, but is mixed with the source color to reflect the lightness
468 or darkness of the destination.</td>
469 </tr>
470
471 <tr valign="top">
472 <td valign="top">hard-light</td>
473 <td valign="top">Multiplies or screens the colors, dependent on the source
474 color value. If the source color is lighter than 0.5, the destination
475 is lightened as if it were screened. If the source color is darker
476 than 0.5, the destination is darkened, as if it were multiplied. The
477 degree of lightening or darkening is proportional to the difference
478 between the source color and 0.5. If it is equal to 0.5 the
479 destination is unchanged. Painting with pure black or white produces
480 black or white.</td>
481 </tr>
482
483
484 <tr valign="top">
485 <td valign="top">linear-light</td>
486 <td valign="top">Like 'Hard-Light' but using linear-dodge and linear-burn
487 instead. Increases contrast slightly with an impact on the
488 foreground's tonal values.</td>
489 </tr>
490
491 <tr valign="top">
492 <td valign="top">soft-light</td>
493 <td valign="top">Darkens or lightens the colors, dependent on the source
494 color value. If the source color is lighter than 0.5, the destination
495 is lightened. If the source color is darker than 0.5, the destination
496 is darkened, as if it were burned in. The degree of darkening or
497 lightening is proportional to the difference between the source color
498 and 0.5. If it is equal to 0.5, the destination is unchanged. Painting
499 with pure black or white produces a distinctly darker or lighter area,
500 but does not result in pure black or white. Fixed in ImageMagick
501 version 6.5.4-3. </td>
502 </tr>
503
504 <tr valign="top">
505 <td valign="top">pegtop-light</td>
506 <td valign="top">Almost equivelent to 'Soft-Light', but using a
507 continuious mathematical formula rather than two conditionally
508 selected formulae. Added ImageMagick version 6.5.4-3. </td>
509 </tr>
510
511 <tr valign="top">
512 <td valign="top">vivid-light</td>
513 <td valign="top">A modified 'Linear-Light' designed to preserve very stong
514 primary and secondary colors in the image. Added ImageMagick version
515 6.5.4-3. </td>
516 </tr>
517
518 <tr valign="top">
519 <td valign="top">pin-light</td>
520 <td valign="top">Similar to 'Hard-Light', but using sharp linear shadings,
521 to similate the effects of a strong 'pinhole' light source. Added
522 ImageMagick version 6.5.4-3. </td>
523 </tr>
524
525 </tbody>
526</table>
527
528
cristyabd337d2010-08-17 01:06:59 +0000[diff] [blame]529<br><br>
cristybc9539a2010-08-16 18:06:20 +0000[diff] [blame]530
531<p>Also included are these special purpose compose methods:</p>
532
533<table class="doc">
534 <tbody>
535 <tr valign="top">
536 <th align="left" style="width: 8%">Method</th>
537 <th align="left">Description</th>
538 </tr>
539
540 <tr valign="top">
cristyabd337d2010-08-17 01:06:59 +0000[diff] [blame]541 <td valign="top">copy</td>
542 <td valign="top">This is equivelent to the Duff-Porter composition method
543 '<kbd>Src,<kbd>' but withotu clearing the parts of the destination
544 image that is not overlaid. </td>
545 </tr>
546
547 <tr valign="top">
cristybc9539a2010-08-16 18:06:20 +0000[diff] [blame]548 <td valign="top">copy-*</td>
549 <td valign="top">Copy the specified channel (Red, Green, Blue, Cyan,
550 Magenta, Yellow, Black, or Opacity) in the source image to the
551 same channel in the destination image. If the channel specified
552 does not exist in the source image, (which can only happen for methods,
553 '<kbd>copy-opacity</kbd>' or '<kbd>copy-black</kbd>') then it is
554 assumed that the source image is a special grayscale channel image
555 of the values to be copied. </td>
556 </tr>
557
558 <tr valign="top">
559 <td valign="top">change-mask</td>
cristyabd337d2010-08-17 01:06:59 +0000[diff] [blame]560 <td valign="top">Replace any destination pixel that is the similar to the
561 source images pixel (as defined by the current <a
562 href="../www/command-line-options.html#fuzz">-fuzz</a> factor), with transparency.
563 </td>
cristybc9539a2010-08-16 18:06:20 +0000[diff] [blame]564 </tr>
565 </tbody>
566</table>
567
cristyabd337d2010-08-17 01:06:59 +0000[diff] [blame]568<br><br>
569
cristybc9539a2010-08-16 18:06:20 +0000[diff] [blame]570<p>On top of these composed methods are a few special ones that not only require
571the two images that are being merged or overlaid, but have some extra numerical
572arguments, which are tabled below. </p>
573
574<p>In the "<code>composite</code>" command these composition methods are
575selected using special options with the arguments needed. They are usually,
576but not always, the same name as the composte 'method' they use, and replaces
cristyabd337d2010-08-17 01:06:59 +0000[diff] [blame]577the normal use of the <a href="../www/command-line-options.html#compose" >-compose</a>
578setting in the "<code>composite</code>" command. For example... </p>
cristybc9539a2010-08-16 18:06:20 +0000[diff] [blame]579
580<p class='crt'><span class="crtprompt"> $magick&gt; </span><span class='crtin'>composite ... -blend 50x50 ...</span></p>
581<p>As of IM v6.5.3-4 the "<code>convert</code>" command can now also supply
cristyabd337d2010-08-17 01:06:59 +0000[diff] [blame]582these extra arguments to its <a href="../www/command-line-options.html#composite"
583>-composite</a> operator, using the special <a
584href="../www/command-line-options.html#set">-set</a> attribute of '<kbd
585class="arg">option:compose:args</kbd>'. This means you can now make use of
586these special argumented <a href="../www/command-line-options.html#compose"
587>-compose</a> methods, those the argument and the method both need to be set
588separatally. For example... </p>
cristybc9539a2010-08-16 18:06:20 +0000[diff] [blame]589
cristyabd337d2010-08-17 01:06:59 +0000[diff] [blame]590<p class='crt'><span class="crtprompt"> $magick&gt; </span><span class='crtin'>convert ... -compose blend -set option:compose:args 50x50 -composite ...</span></p>
cristybc9539a2010-08-16 18:06:20 +0000[diff] [blame]591<p>The following is a table of these special 'argumented' compose methods,
592with a brief summary of what they do. For more details see the equivalent
593"composite" command option name. </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">
603 <td valign="top">dissolve</td>
604 <td valign="top">Arguments:
605 <em class="arg">src_percent</em>[x<em class="arg">dst_percent</em>]
cristyabd337d2010-08-17 01:06:59 +0000[diff] [blame]606 <br>Equivalent to "<code>composite</code>" <a href="../www/command-line-options.html#dissolve">-dissolve</a>
cristybc9539a2010-08-16 18:06:20 +0000[diff] [blame]607 <br>Dissolve the 'source' image by the percentage given before overlaying
608 'over' the 'destination' image. If <em class="arg">src_percent</em> is
609 greater than 100, it starts dissolving the main image so it will
610 become transparent at a value of '<kbd class="arg">200</kbd>'. If
611 both percentages are given, each image are dissolved to the
612 percentages given.
613 </td>
614 </tr>
615
616 <tr valign="top">
617 <td valign="top">blend</td>
618 <td valign="top">Arguments:
619 <em class="arg">src_percent</em>[x<em class="arg">dst_percent</em>]
cristyabd337d2010-08-17 01:06:59 +0000[diff] [blame]620 <br>Equivalent to "<code>composite</code>" <a
621 href="../www/command-line-options.html#blend">-blend</a>
cristybc9539a2010-08-16 18:06:20 +0000[diff] [blame]622 <br>Average the images together ('plus') according to the percentages
623 given and each pixels transparency. If only a single percentage value
624 is given it sets the weight of the composite or 'source' image, while
625 the background image is weighted by the exact opposite amount. That is
626 a <kbd>-blend 30</kbd> merges 30% of the 'source' image with 70% of
627 the 'destination' image. Thus it is equivalent to <kbd>-blend
628 30x70</kbd>.
629 </td>
630 </tr>
631
632 <tr valign="top">
633 <td valign="top">mathematics</td>
634 <td valign="top">Arguments: <em class="arg">A, B, C, D</em>
635 <br>Not available in "<code>composite</code>" at this time.
636 <br>Merge the source and destination images according to the formula
637 <br>&nbsp; &nbsp; &nbsp;<code>A*Sc*Dc + B*Sc + C*Dc + D</code>
638 <br>Can be used to generate a custom composition method that would
cristyabd337d2010-08-17 01:06:59 +0000[diff] [blame]639 otherwise need to be implemented using the slow <a
640 href="../www/command-line-options.html#fx">-fx</a> DIY image operator. Added
641 to ImageMagick version 6.5.4-3.
cristybc9539a2010-08-16 18:06:20 +0000[diff] [blame]642 <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]643 if the 'Sync' flag is removed from <a
644 href="../www/command-line-options.html#channel" >-channel</a>, just like all
645 the other mathematical compostion methods above.
cristybc9539a2010-08-16 18:06:20 +0000[diff] [blame]646 </td>
647 </tr>
648
649 <tr valign="top">
650 <td valign="top">modulate</td>
651 <td valign="top">Arguments:
652 <em class="arg">brightness</em>[x<em class="arg">saturation</em>]
cristyabd337d2010-08-17 01:06:59 +0000[diff] [blame]653 <br>Equivalent to "<code>composite</code>" <a href="../www/command-line-options.html#watermark">-watermark</a>
cristybc9539a2010-08-16 18:06:20 +0000[diff] [blame]654 <br>Take a grayscale image (with alpha mask) and modify the destination
655 image's brightness according to watermark image's grayscale value and
656 the <em class="arg">brightness</em> percentage. The destinations
657 color saturation attribute is just direct modified by the <em
658 class="arg">saturation</em> percentage, which defaults to 100 percent
659 (no color change).
660
661 </td>
662 </tr>
663
664 <tr valign="top">
665 <td valign="top">displace</td>
666 <td valign="top">Arguments:
667 <em class="arg">X-scale</em>[x<em class="arg">Y-scale</em>][!][%]
cristyabd337d2010-08-17 01:06:59 +0000[diff] [blame]668 <br>Equivalent to "<code>composite</code>" <a href="../www/command-line-options.html#displace">-displace</a>
cristybc9539a2010-08-16 18:06:20 +0000[diff] [blame]669 <br>With this option, the 'overlay' image, and optionally the 'mask'
670 image, is used as a relative displacement map, which is used to
671 displace the lookup of what part of the destination image is seen at
672 each point of the overlaid area. Much like the displacement map is a
673 'lens' that distorts the original 'background' image behind it.
674 <br><br>
675 The X-scale is modilated by the 'red' channel of the overlay image
676 while the Y-scale is modulated by the green channel, (the mask image
677 if given is rolled into green channel of the overlay image. This
678 separation allows you to modulate the X and Y lookup displacement
679 separatally allowing you to di 2 dimentional displacements, rather
680 than 1 dimentional verctored displacements (using grayscale image).
681 <br><br>
682 If the overlay image contains transparency this is used as a mask
683 of the resulting image to remove 'invalid' pixels.
684 <br><br>
685 The '%' flag makes the displacement scale relative to the size of the
686 overlay image (100% = half width/height of image). Using '!' switches
687 percentage arguments to refer to the destination image size instead.
688 <br><br>
689 Special flags were added Added to ImageMagick version 6.5.3-5.
690 </td>
691 </tr>
692
693 <tr valign="top">
694 <td valign="top">distort</td>
695 <td valign="top">Arguments:
696 <em class="arg">X-scale</em>[x<em class="arg">Y-scale</em
697 >[+<em class="arg">X-center</em>+<em class="arg">Y-center</em>]][!][%]
698 <br>Not available in "<code>composite</code>" at this time.
699 <br>Exactly as per 'Displace' (above), but using absolute coordinates,
700 relative to the center of the overlay (or that given). Basically
701 allows you to generate absolute distortion maps where 'black' will
702 look up the left/top edge, and 'white' looks up the bottom/right
703 edge of the destination image, according to the scale given.
704 <br><br>
705 The '!' flag not only switches percentage scaling, to use the
706 destination image, but also the image the center offset of the lookup.
707 This means the overlay can lookup a completely different region of the
708 destination image.
709 <br><br>
710 Added to ImageMagick version 6.5.3-5.
711 </td>
712 </tr>
713
714 <tr valign="top">
715 <td valign="top">blur</td>
716 <td valign="top">Arguments:
717 <em class="arg">Width</em>[x<em class="arg">Height</em
718 >[+<em class="arg">Angle</em>]]
cristyabd337d2010-08-17 01:06:59 +0000[diff] [blame]719 <br>Equivalent to "<code>composite</code>" <a href="../www/command-line-options.html#blur-composite">-blur</a>
cristybc9539a2010-08-16 18:06:20 +0000[diff] [blame]720 <br>A Variable Blur Mapping Composition method, where each pixel in the
721 overlaid region is replaced with an Elliptical Weighted Average (EWA),
722 with an ellipse (typically a circle) of the given sigma size, scaled
723 according to overlay (source image) grayscale mapping.
724 <br><br>
725 As per 'Displace' and 'Distort', the red channel will modulate the
726 width of the ellipse, while the green channel will modulate the height
727 of the ellipse. However at this time the ellipse angle is not
728 modulated though this may be a future posibility (perhaps with a
729 special flag to enable use of blur channel for this purpose).
730 <br><br>
731 Added to ImageMagick version 6.5.4-0.
732 </td>
733 </tr>
734
735 </tbody>
736</table>
737
738<p>To print a complete list of all the available compose operators, use <a
cristyabd337d2010-08-17 01:06:59 +0000[diff] [blame]739href="../www/command-line-options.html#list">-list compose</a>.</p>
cristybc9539a2010-08-16 18:06:20 +0000[diff] [blame]740
741
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