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168
cristyabd337d2010-08-17 01:06:59 +0000[diff] [blame]169<p>This page descibed the Image composition methods that is used to define how
170two images should be merged together in various image operations. For the
171Command Line API it is typically set using the <A
172HREF="../www/command-line-options.html#compose" >-compose</A> setting option. </p>
173
174
cristybc9539a2010-08-16 18:06:20 +0000[diff] [blame]175<p>The description of composition uses abstract terminology in order to allow
176the description to be more precise, while avoiding constant values which are
177specific to a particular build configuration. Each image pixel is represented
178by red, green, and blue levels (which are equal for a gray pixel). The
179build-dependent value <em class="QR">QuantumRange</em> is the maximum integral
180value which may be stored, per pixel, in the red, green, or blue channels of
181the image. Each image pixel may also optionally (if the image matte channel is
182enabled) have an associated level of opacity, ranging from <em>opaque</em> to
183<em>transparent</em>, which may be used to determine the influence of the pixel
184color when compositing the pixel with another image pixel. If the image matte
185channel is disabled, then all pixels in the image are treated as opaque. The
186color of an opaque pixel is fully visible while the color of a transparent
187pixel color is entirely absent (pixel color is ignored).</p>
188
189<p>By definition, raster images have a rectangular shape. All image rows are of
190equal length, as are all image columns. By treating the alpha channel as a
191visual "mask" the rectangular image may be given a "shape" by treating the
192alpha channel as a cookie-cutter for the image. This is done by setting the
193pixels within the shape to be opaque, with pixels outside the shape set as
194transparent. Pixels on the boundary of the shape may be between opaque and
195transparent in order to provide antialiasing (visually smooth edges). The
196description of the composition operators use this concept of image "shape" in
197order to make the description of the operators easier to understand. While it
198is convenient to describe the operators in terms of "shapes" they are by no
199means limited to mask-style operations since they are based on continuous
200floating-point mathematics rather than simple boolean operations.</p>
201
202<p>The following alpha blending (Duff-Porter) compose methods are available:</p>
203
204<table class="doc">
205 <tbody>
206 <tr valign="top">
207 <th align="left" style="width: 8%">Method</th>
208 <th align="left">Description</th>
209 </tr>
210
211 <tr valign="top">
212 <td valign="top">clear</td>
213 <td valign="top">Both the color and the alpha of the destination are
214 cleared. Neither the source nor the destination are used (except for
215 destinations size and other meta-data which is always preserved.</td>
216 </tr>
217
218 <tr valign="top">
219 <td valign="top">src</td>
220 <td valign="top">The source is copied to the destination. The destination
221 is not used as input, though it is cleared.</td>
222 </tr>
223
224 <tr valign="top">
225 <td valign="top">dst</td>
226 <td valign="top">The destination is left untouched. The source image is
227 completely ignored.</td>
228 </tr>
229
230 <tr valign="top">
231 <td valign="top">src-over</td>
232 <td valign="top">The source is composited over the destination. this is
233 the default alpha blending compose method, when neither the compose
234 setting is set, nor is set in the image meta-data.</td>
235 </tr>
236
237 <tr valign="top">
238 <td valign="top">dst-over</td>
239 <td valign="top">The destination is composited over the source and the
240 result replaces the destination.</td>
241 </tr>
242
243 <tr valign="top">
244 <td valign="top">src-in</td>
245 <td valign="top">The part of the source lying inside of the destination
246 replaces the destination.</td>
247 </tr>
248
249 <tr valign="top">
250 <td valign="top">dst-in</td>
251 <td valign="top">The part of the destination lying inside of the source
252 replaces the destination. Areas not overlaid are cleared.</td>
253 </tr>
254
255 <tr valign="top">
256 <td valign="top">src-out</td>
257 <td valign="top">The part of the source lying outside of the destination
258 replaces the destination.</td>
259 </tr>
260
261 <tr valign="top">
262 <td valign="top">dst-out</td>
263 <td valign="top">The part of the destination lying outside of the source
264 replaces the destination.</td>
265 </tr>
266
267 <tr valign="top">
268 <td valign="top">src-atop</td>
269 <td valign="top">The part of the source lying inside of the destination is
270 composited onto the destination.</td>
271 </tr>
272
273 <tr valign="top">
274 <td valign="top">dst-atop</td>
275 <td valign="top">The part of the destination lying inside of the source is
276 composited over the source and replaces the destination. Areas not
277 overlaid are cleared. </td>
278 </tr>
279
280 <tr valign="top">
281 <td valign="top">xor</td>
282 <td valign="top">The part of the source that lies outside of the
283 destination is combined with the part of the destination that lies
284 outside of the source. Source or Destination, but not both. </td>
285 </tr>
286
287 </tbody>
288</table>
289
290<p>Any of the 'Src-*' methods can also be specified without the 'Src-' part.
cristyabd337d2010-08-17 01:06:59 +0000[diff] [blame]291For example the default compose method can be specified as just 'Over'.</p>
cristybc9539a2010-08-16 18:06:20 +0000[diff] [blame]292
cristyabd337d2010-08-17 01:06:59 +0000[diff] [blame]293<p>Many of these compose methods will clear the destination image which was
294not overlaid by the source image. This is to be expected as part of that
295specific composition methods defintion. Seeing the You can disable this by
296setting the special <A HREF="../www/command-line-options.html#set" >-set</A>
297'option:compose:outside-overlay' to 'false' will turn off this behaviour. </p>
298
299<p>On top of the above 12 Duff-Porter Alpha Composition methods, one special
300related method '<kbd>Copy</kbd>' has been provided. This is equivelent to the
301'<kbd>Src</kbd>' with the special <A HREF="../www/command-line-options.html#set"
302>-set</A> option '<kbd>option:compose:outside-overlay</kbd>' set to
303'<kbd>false></kbd>'. </p>
304
305<br><br>
cristybc9539a2010-08-16 18:06:20 +0000[diff] [blame]306
307<p>The following mathemathical composition methods are also available. </p>
308
309<table class="doc">
310 <tbody>
311 <tr valign="top">
312 <th align="left" style="width: 8%">Method</th>
313 <th align="left">Description</th>
314 </tr>
315
316 <tr valign="top">
317 <td valign="top">multiply</td>
318 <td valign="top">The source is multiplied by the destination and replaces
319 the destination. The resultant color is always at least as dark as
320 either of the two constituent colors. Multiplying any color with black
321 produces black. Multiplying any color with white leaves the original
322 color unchanged.</td>
323 </tr>
324
325 <tr valign="top">
326 <td valign="top">screen</td>
327 <td valign="top">The source and destination are complemented and then
328 multiplied and then replace the destination. The resultant color is
329 always at least as light as either of the two constituent colors.
330 Screening any color with white produces white. Screening any color
331 with black leaves the original color unchanged.</td>
332 </tr>
333
334 <tr valign="top">
335 <td valign="top">plus</td>
336 <td valign="top">The source is added to the destination and replaces the
337 destination. This operator is useful for averaging or a controled
338 merger of two images, rather than a direct overlay.</td>
339 </tr>
340
341 <tr valign="top">
342 <td valign="top">add</td>
343 <td valign="top">As per 'plus' but transparency data is treated as matte
344 values. As such any transparent areas in either image remain
345 transparent. </td>
346 </tr>
347
348 <tr valign="top">
349 <td valign="top">minus</td>
350 <td valign="top">Subtract the colors in the source image from the
351 destination image. When transparency is involved, opaque areas is
352 subtracted from any destination opaque areas. </td>
353 </tr>
354
355 <tr valign="top">
356 <td valign="top">subtract</td>
357 <td valign="top">Subtract the colors in the source image from the
358 destination image. When transparency is involved transparent areas are
359 subtracted, so only the opaque areas in the source remain opaque in
360 the destination image. </td>
361 </tr>
362
363 <tr valign="top">
364 <td valign="top">difference</td>
365 <td valign="top">Subtracts the darker of the two constituent colors from
366 the lighter. Painting with white inverts the destination color.
367 Painting with black produces no change.</td>
368 </tr>
369
370 <tr valign="top">
371 <td valign="top">exclusion</td>
372 <td valign="top">Produces an effect similar to that of 'difference', but
373 appears as lower contrast. Painting with white inverts the
374 destination color. Painting with black produces no change.</td>
375 </tr>
376
377 <tr valign="top">
378 <td valign="top">darken</td>
379 <td valign="top">Selects the darker of the destination and source colors.
380 The destination is replaced with the source when the source is darker,
381 otherwise it is left unchanged.</td>
382 </tr>
383
384 <tr valign="top">
385 <td valign="top">lighten</td>
386 <td valign="top">Selects the lighter of the destination and source colors.
387 The destination is replaced with the source when the source is
388 lighter, otherwise it is left unchanged. </td>
389 </tr>
390
391 </tbody>
392</table>
393
394<p>Typically these use the default 'Over' alpha blending when transparencies
cristyabd337d2010-08-17 01:06:59 +0000[diff] [blame]395are also involved, except for 'Plus' which uses a 'plus' alpha blending. This
396means the alpha channel of both images will only be used to ensure that any
397visible input remains visible even in parts not overlaid. It also means that
398any values are weighted by the alpha channel of the input and output images.
399This 'Over' alpha blending is also applied to the lighting composition methods
400below. </p>
cristybc9539a2010-08-16 18:06:20 +0000[diff] [blame]401
402<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]403(enabled by default) with the <a href="../www/command-line-options.html#channel"
404>-channel</a> setting, then the above mathematical compositions will nolonger
405syncronise its actiosn with the alpha channel. Instead the math composition
406will be applied on an individual channel basis as defined by the <a
407href="../www/command-line-options.html#channel"
408>-channel</a>. This includes the alpha channel. This special usage
409allows you to perform true mathematics of the image channels, without alpha
410compostion effects, becomming involved. </p>
cristybc9539a2010-08-16 18:06:20 +0000[diff] [blame]411
cristyabd337d2010-08-17 01:06:59 +0000[diff] [blame]412<p>This special flag is not applied to the lighting composition methods (see
413below) even though they are closely related to mathematical composition
414methods.</p>
cristybc9539a2010-08-16 18:06:20 +0000[diff] [blame]415
cristyabd337d2010-08-17 01:06:59 +0000[diff] [blame]416<br><br>
cristybc9539a2010-08-16 18:06:20 +0000[diff] [blame]417
418<p>The following lighting composition methods are also available. </p>
419
420<table class="doc">
421 <tbody>
422 <tr valign="top">
423 <th align="left" style="width: 8%">Method</th>
424 <th align="left">Description</th>
425 </tr>
426
427 <tr valign="top">
428 <td valign="top">linear-dodge</td>
429 <td valign="top">This is equivelent to 'Plus' in that the color channels
430 are simply added, however it does not 'Plus' the alpha channel, but
431 uses the normal 'Over' alpha blending, which transparencies are
432 involved. Produces a sort of additive multiply-like result. Added
433 ImageMagick version 6.5.4-3. </td>
434 </tr>
435
436 <tr valign="top">
437 <td valign="top">linear-burn</td>
438 <td valign="top">As 'Linear-Dodge', but also subtract one from the result.
439 Sort of a additive 'Screen' of the images. Added ImageMagick version
440 6.5.4-3. </td>
441 </tr>
442
443 <tr valign="top">
444 <td valign="top">color-dodge</td>
445 <td valign="top">Brightens the destination color to reflect the source
446 color. Painting with black produces no change.</td>
447 </tr>
448
449 <tr valign="top">
450 <td valign="top">color-burn</td>
451 <td valign="top">Darkens the destination color to reflect the source
452 color. Painting with white produces no change. Fixed in ImageMagick
453 version 6.5.4-3. </td>
454 </tr>
455
456 <tr valign="top">
457 <td valign="top">overlay</td>
458 <td valign="top">Multiplies or screens the colors, dependent on the
459 destination color. Source colors overlay the destination whilst
460 preserving its highlights and shadows. The destination color is not
461 replaced, but is mixed with the source color to reflect the lightness
462 or darkness of the destination.</td>
463 </tr>
464
465 <tr valign="top">
466 <td valign="top">hard-light</td>
467 <td valign="top">Multiplies or screens the colors, dependent on the source
468 color value. If the source color is lighter than 0.5, the destination
469 is lightened as if it were screened. If the source color is darker
470 than 0.5, the destination is darkened, as if it were multiplied. The
471 degree of lightening or darkening is proportional to the difference
472 between the source color and 0.5. If it is equal to 0.5 the
473 destination is unchanged. Painting with pure black or white produces
474 black or white.</td>
475 </tr>
476
477
478 <tr valign="top">
479 <td valign="top">linear-light</td>
480 <td valign="top">Like 'Hard-Light' but using linear-dodge and linear-burn
481 instead. Increases contrast slightly with an impact on the
482 foreground's tonal values.</td>
483 </tr>
484
485 <tr valign="top">
486 <td valign="top">soft-light</td>
487 <td valign="top">Darkens or lightens the colors, dependent on the source
488 color value. If the source color is lighter than 0.5, the destination
489 is lightened. If the source color is darker than 0.5, the destination
490 is darkened, as if it were burned in. The degree of darkening or
491 lightening is proportional to the difference between the source color
492 and 0.5. If it is equal to 0.5, the destination is unchanged. Painting
493 with pure black or white produces a distinctly darker or lighter area,
494 but does not result in pure black or white. Fixed in ImageMagick
495 version 6.5.4-3. </td>
496 </tr>
497
498 <tr valign="top">
499 <td valign="top">pegtop-light</td>
500 <td valign="top">Almost equivelent to 'Soft-Light', but using a
501 continuious mathematical formula rather than two conditionally
502 selected formulae. Added ImageMagick version 6.5.4-3. </td>
503 </tr>
504
505 <tr valign="top">
506 <td valign="top">vivid-light</td>
507 <td valign="top">A modified 'Linear-Light' designed to preserve very stong
508 primary and secondary colors in the image. Added ImageMagick version
509 6.5.4-3. </td>
510 </tr>
511
512 <tr valign="top">
513 <td valign="top">pin-light</td>
514 <td valign="top">Similar to 'Hard-Light', but using sharp linear shadings,
515 to similate the effects of a strong 'pinhole' light source. Added
516 ImageMagick version 6.5.4-3. </td>
517 </tr>
518
519 </tbody>
520</table>
521
522
cristyabd337d2010-08-17 01:06:59 +0000[diff] [blame]523<br><br>
cristybc9539a2010-08-16 18:06:20 +0000[diff] [blame]524
525<p>Also included are these special purpose compose methods:</p>
526
527<table class="doc">
528 <tbody>
529 <tr valign="top">
530 <th align="left" style="width: 8%">Method</th>
531 <th align="left">Description</th>
532 </tr>
533
534 <tr valign="top">
cristyabd337d2010-08-17 01:06:59 +0000[diff] [blame]535 <td valign="top">copy</td>
536 <td valign="top">This is equivelent to the Duff-Porter composition method
537 '<kbd>Src,<kbd>' but withotu clearing the parts of the destination
538 image that is not overlaid. </td>
539 </tr>
540
541 <tr valign="top">
cristybc9539a2010-08-16 18:06:20 +0000[diff] [blame]542 <td valign="top">copy-*</td>
543 <td valign="top">Copy the specified channel (Red, Green, Blue, Cyan,
544 Magenta, Yellow, Black, or Opacity) in the source image to the
545 same channel in the destination image. If the channel specified
546 does not exist in the source image, (which can only happen for methods,
547 '<kbd>copy-opacity</kbd>' or '<kbd>copy-black</kbd>') then it is
548 assumed that the source image is a special grayscale channel image
549 of the values to be copied. </td>
550 </tr>
551
552 <tr valign="top">
553 <td valign="top">change-mask</td>
cristyabd337d2010-08-17 01:06:59 +0000[diff] [blame]554 <td valign="top">Replace any destination pixel that is the similar to the
555 source images pixel (as defined by the current <a
556 href="../www/command-line-options.html#fuzz">-fuzz</a> factor), with transparency.
557 </td>
cristybc9539a2010-08-16 18:06:20 +0000[diff] [blame]558 </tr>
559 </tbody>
560</table>
561
cristyabd337d2010-08-17 01:06:59 +0000[diff] [blame]562<br><br>
563
cristybc9539a2010-08-16 18:06:20 +0000[diff] [blame]564<p>On top of these composed methods are a few special ones that not only require
565the two images that are being merged or overlaid, but have some extra numerical
566arguments, which are tabled below. </p>
567
568<p>In the "<code>composite</code>" command these composition methods are
569selected using special options with the arguments needed. They are usually,
570but not always, the same name as the composte 'method' they use, and replaces
cristyabd337d2010-08-17 01:06:59 +0000[diff] [blame]571the normal use of the <a href="../www/command-line-options.html#compose" >-compose</a>
572setting in the "<code>composite</code>" command. For example... </p>
cristybc9539a2010-08-16 18:06:20 +0000[diff] [blame]573
574<p class='crt'><span class="crtprompt"> $magick&gt; </span><span class='crtin'>composite ... -blend 50x50 ...</span></p>
575<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]576these extra arguments to its <a href="../www/command-line-options.html#composite"
577>-composite</a> operator, using the special <a
578href="../www/command-line-options.html#set">-set</a> attribute of '<kbd
579class="arg">option:compose:args</kbd>'. This means you can now make use of
580these special argumented <a href="../www/command-line-options.html#compose"
581>-compose</a> methods, those the argument and the method both need to be set
582separatally. For example... </p>
cristybc9539a2010-08-16 18:06:20 +0000[diff] [blame]583
cristyabd337d2010-08-17 01:06:59 +0000[diff] [blame]584<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]585<p>The following is a table of these special 'argumented' compose methods,
586with a brief summary of what they do. For more details see the equivalent
587"composite" command option name. </p>
588
589<table class="doc">
590 <tbody>
591 <tr valign="top">
592 <th align="left" style="width: 8%">Method</th>
593 <th align="left">Description</th>
594 </tr>
595
596 <tr valign="top">
597 <td valign="top">dissolve</td>
598 <td valign="top">Arguments:
599 <em class="arg">src_percent</em>[x<em class="arg">dst_percent</em>]
cristyabd337d2010-08-17 01:06:59 +0000[diff] [blame]600 <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]601 <br>Dissolve the 'source' image by the percentage given before overlaying
602 'over' the 'destination' image. If <em class="arg">src_percent</em> is
603 greater than 100, it starts dissolving the main image so it will
604 become transparent at a value of '<kbd class="arg">200</kbd>'. If
605 both percentages are given, each image are dissolved to the
606 percentages given.
607 </td>
608 </tr>
609
610 <tr valign="top">
611 <td valign="top">blend</td>
612 <td valign="top">Arguments:
613 <em class="arg">src_percent</em>[x<em class="arg">dst_percent</em>]
cristyabd337d2010-08-17 01:06:59 +0000[diff] [blame]614 <br>Equivalent to "<code>composite</code>" <a
615 href="../www/command-line-options.html#blend">-blend</a>
cristybc9539a2010-08-16 18:06:20 +0000[diff] [blame]616 <br>Average the images together ('plus') according to the percentages
617 given and each pixels transparency. If only a single percentage value
618 is given it sets the weight of the composite or 'source' image, while
619 the background image is weighted by the exact opposite amount. That is
620 a <kbd>-blend 30</kbd> merges 30% of the 'source' image with 70% of
621 the 'destination' image. Thus it is equivalent to <kbd>-blend
622 30x70</kbd>.
623 </td>
624 </tr>
625
626 <tr valign="top">
627 <td valign="top">mathematics</td>
628 <td valign="top">Arguments: <em class="arg">A, B, C, D</em>
629 <br>Not available in "<code>composite</code>" at this time.
630 <br>Merge the source and destination images according to the formula
631 <br>&nbsp; &nbsp; &nbsp;<code>A*Sc*Dc + B*Sc + C*Dc + D</code>
632 <br>Can be used to generate a custom composition method that would
cristyabd337d2010-08-17 01:06:59 +0000[diff] [blame]633 otherwise need to be implemented using the slow <a
634 href="../www/command-line-options.html#fx">-fx</a> DIY image operator. Added
635 to ImageMagick version 6.5.4-3.
cristybc9539a2010-08-16 18:06:20 +0000[diff] [blame]636 <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]637 if the 'Sync' flag is removed from <a
638 href="../www/command-line-options.html#channel" >-channel</a>, just like all
639 the other mathematical compostion methods above.
cristybc9539a2010-08-16 18:06:20 +0000[diff] [blame]640 </td>
641 </tr>
642
643 <tr valign="top">
644 <td valign="top">modulate</td>
645 <td valign="top">Arguments:
646 <em class="arg">brightness</em>[x<em class="arg">saturation</em>]
cristyabd337d2010-08-17 01:06:59 +0000[diff] [blame]647 <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]648 <br>Take a grayscale image (with alpha mask) and modify the destination
649 image's brightness according to watermark image's grayscale value and
650 the <em class="arg">brightness</em> percentage. The destinations
651 color saturation attribute is just direct modified by the <em
652 class="arg">saturation</em> percentage, which defaults to 100 percent
653 (no color change).
654
655 </td>
656 </tr>
657
658 <tr valign="top">
659 <td valign="top">displace</td>
660 <td valign="top">Arguments:
661 <em class="arg">X-scale</em>[x<em class="arg">Y-scale</em>][!][%]
cristyabd337d2010-08-17 01:06:59 +0000[diff] [blame]662 <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]663 <br>With this option, the 'overlay' image, and optionally the 'mask'
664 image, is used as a relative displacement map, which is used to
665 displace the lookup of what part of the destination image is seen at
666 each point of the overlaid area. Much like the displacement map is a
667 'lens' that distorts the original 'background' image behind it.
668 <br><br>
669 The X-scale is modilated by the 'red' channel of the overlay image
670 while the Y-scale is modulated by the green channel, (the mask image
671 if given is rolled into green channel of the overlay image. This
672 separation allows you to modulate the X and Y lookup displacement
673 separatally allowing you to di 2 dimentional displacements, rather
674 than 1 dimentional verctored displacements (using grayscale image).
675 <br><br>
676 If the overlay image contains transparency this is used as a mask
677 of the resulting image to remove 'invalid' pixels.
678 <br><br>
679 The '%' flag makes the displacement scale relative to the size of the
680 overlay image (100% = half width/height of image). Using '!' switches
681 percentage arguments to refer to the destination image size instead.
682 <br><br>
683 Special flags were added Added to ImageMagick version 6.5.3-5.
684 </td>
685 </tr>
686
687 <tr valign="top">
688 <td valign="top">distort</td>
689 <td valign="top">Arguments:
690 <em class="arg">X-scale</em>[x<em class="arg">Y-scale</em
691 >[+<em class="arg">X-center</em>+<em class="arg">Y-center</em>]][!][%]
692 <br>Not available in "<code>composite</code>" at this time.
693 <br>Exactly as per 'Displace' (above), but using absolute coordinates,
694 relative to the center of the overlay (or that given). Basically
695 allows you to generate absolute distortion maps where 'black' will
696 look up the left/top edge, and 'white' looks up the bottom/right
697 edge of the destination image, according to the scale given.
698 <br><br>
699 The '!' flag not only switches percentage scaling, to use the
700 destination image, but also the image the center offset of the lookup.
701 This means the overlay can lookup a completely different region of the
702 destination image.
703 <br><br>
704 Added to ImageMagick version 6.5.3-5.
705 </td>
706 </tr>
707
708 <tr valign="top">
709 <td valign="top">blur</td>
710 <td valign="top">Arguments:
711 <em class="arg">Width</em>[x<em class="arg">Height</em
712 >[+<em class="arg">Angle</em>]]
cristyabd337d2010-08-17 01:06:59 +0000[diff] [blame]713 <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]714 <br>A Variable Blur Mapping Composition method, where each pixel in the
715 overlaid region is replaced with an Elliptical Weighted Average (EWA),
716 with an ellipse (typically a circle) of the given sigma size, scaled
717 according to overlay (source image) grayscale mapping.
718 <br><br>
719 As per 'Displace' and 'Distort', the red channel will modulate the
720 width of the ellipse, while the green channel will modulate the height
721 of the ellipse. However at this time the ellipse angle is not
722 modulated though this may be a future posibility (perhaps with a
723 special flag to enable use of blur channel for this purpose).
724 <br><br>
725 Added to ImageMagick version 6.5.4-0.
726 </td>
727 </tr>
728
729 </tbody>
730</table>
731
732<p>To print a complete list of all the available compose operators, use <a
cristyabd337d2010-08-17 01:06:59 +0000[diff] [blame]733href="../www/command-line-options.html#list">-list compose</a>.</p>
cristybc9539a2010-08-16 18:06:20 +0000[diff] [blame]734
735
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