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191<div class="main">
192
cristy350dea42011-02-15 17:31:04 +0000[diff] [blame^]193<h1>Module layer Methods</h1>
cristy6f77f692011-02-15 15:31:39 +0000[diff] [blame]194<p class="navigation-index">[<a href="#CoalesceImages">CoalesceImages</a> &bull; <a href="#DisposeImages">DisposeImages</a> &bull; <a href="#CompareImageLayers">CompareImageLayers</a> &bull; <a href="#DeconstructImages">DeconstructImages</a> &bull; <a href="#OptimizeImageLayers">OptimizeImageLayers</a> &bull; <a href="#OptimizeImagePlusLayers">OptimizeImagePlusLayers</a> &bull; <a href="#OptimizeImageTransparency">OptimizeImageTransparency</a> &bull; <a href="#RemoveDuplicateLayers">RemoveDuplicateLayers</a> &bull; <a href="#RemoveZeroDelayLayers">RemoveZeroDelayLayers</a> &bull; <a href="#CompositeLayers">CompositeLayers</a> &bull; <a href="#MergeImageLayers">MergeImageLayers</a>]</p>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]195
cristy350dea42011-02-15 17:31:04 +0000[diff] [blame^]196<h2><a href="http://www.imagemagick.org/api/MagickCore/layer_8c.html" id="CoalesceImages">CoalesceImages</a></h2>
cristy6f77f692011-02-15 15:31:39 +0000[diff] [blame]197<div class="doc-section">
198
199<p>CoalesceImages() composites a set of images while respecting any page offsets and disposal methods. GIF, MIFF, and MNG animation sequences typically start with an image background and each subsequent image varies in size and offset. A new image sequence is returned with all images the same size as the first images virtual canvas and composited with the next image in the sequence.</p>
200
201<p>The format of the CoalesceImages method is:</p>
202
203<pre class="code">
204 Image *CoalesceImages(Image *image,ExceptionInfo *exception)
205</pre>
206
207<p>A description of each parameter follows:</p>
208
209<h5>image</h5>
210<p>the image sequence.</p>
211
212<h5>exception</h5>
213<p>return any errors or warnings in this structure.</p>
214
215 </div>
cristy350dea42011-02-15 17:31:04 +0000[diff] [blame^]216<h2><a href="http://www.imagemagick.org/api/MagickCore/layer_8c.html" id="DisposeImages">DisposeImages</a></h2>
cristy6f77f692011-02-15 15:31:39 +0000[diff] [blame]217<div class="doc-section">
218
219<p>DisposeImages() returns the coalesced frames of a GIF animation as it would appear after the GIF dispose method of that frame has been applied. That is it returned the appearance of each frame before the next is overlaid.</p>
220
221<p>The format of the DisposeImages method is:</p>
222
223<pre class="code">
224 Image *DisposeImages(Image *image,ExceptionInfo *exception)
225</pre>
226
227<p>A description of each parameter follows:</p>
228
229<h5>image</h5>
230<p>the image sequence.</p>
231
232<h5>exception</h5>
233<p>return any errors or warnings in this structure.</p>
234
235 </div>
cristy350dea42011-02-15 17:31:04 +0000[diff] [blame^]236<h2><a href="http://www.imagemagick.org/api/MagickCore/layer_8c.html" id="CompareImageLayers">CompareImageLayers</a></h2>
cristy6f77f692011-02-15 15:31:39 +0000[diff] [blame]237<div class="doc-section">
238
239<p>CompareImageLayers() compares each image with the next in a sequence and returns the minimum bounding region of all the pixel differences (of the ImageLayerMethod specified) it discovers.</p>
240
241<p>Images do NOT have to be the same size, though it is best that all the images are 'coalesced' (images are all the same size, on a flattened canvas, so as to represent exactly how an specific frame should look).</p>
242
243<p>No GIF dispose methods are applied, so GIF animations must be coalesced before applying this image operator to find differences to them.</p>
244
245<p>The format of the CompareImageLayers method is:</p>
246
247<pre class="code">
248 Image *CompareImageLayers(const Image *images,
249 const ImageLayerMethod method,ExceptionInfo *exception)
250</pre>
251
252<p>A description of each parameter follows:</p>
253
254<h5>image</h5>
255<p>the image.</p>
256
257<h5>method</h5>
258<p>the layers type to compare images with. Must be one of... CompareAnyLayer, CompareClearLayer, CompareOverlayLayer.</p>
259
260<h5>exception</h5>
261<p>return any errors or warnings in this structure.</p>
262
263 </div>
cristy350dea42011-02-15 17:31:04 +0000[diff] [blame^]264<h2><a href="http://www.imagemagick.org/api/MagickCore/layer_8c.html" id="DeconstructImages">DeconstructImages</a></h2>
cristy6f77f692011-02-15 15:31:39 +0000[diff] [blame]265<div class="doc-section">
266
267<p>DeconstructImages() compares each image with the next in a sequence and returns the minimum bounding region of all differences from the first image.</p>
268
269<p>This function is deprecated in favor of the more universal CompareImageLayers() function.</p>
270
271<p>The format of the DeconstructImages method is:</p>
272
273<pre class="code">
274 Image *DeconstructImages(const Image *images, ExceptionInfo *exception)
275</pre>
276
277<p>A description of each parameter follows:</p>
278
279<h5>image</h5>
280<p>the image.</p>
281
282<h5>exception</h5>
283<p>return any errors or warnings in this structure.</p>
284
285 </div>
cristy350dea42011-02-15 17:31:04 +0000[diff] [blame^]286<h2><a href="http://www.imagemagick.org/api/MagickCore/layer_8c.html" id="OptimizeImageLayers">OptimizeImageLayers</a></h2>
cristy6f77f692011-02-15 15:31:39 +0000[diff] [blame]287<div class="doc-section">
288
289<p>OptimizeImageLayers() compares each image the GIF disposed forms of the previous image in the sequence. From this it attempts to select the smallest cropped image to replace each frame, while preserving the results of the GIF animation.</p>
290
291<p>The format of the OptimizeImageLayers method is:</p>
292
293<pre class="code">
294 Image *OptimizeImageLayers(const Image *image,
295 ExceptionInfo *exception)
296</pre>
297
298<p>A description of each parameter follows:</p>
299
300<h5>image</h5>
301<p>the image.</p>
302
303<h5>exception</h5>
304<p>return any errors or warnings in this structure.</p>
305
306 </div>
cristy350dea42011-02-15 17:31:04 +0000[diff] [blame^]307<h2><a href="http://www.imagemagick.org/api/MagickCore/layer_8c.html" id="OptimizeImagePlusLayers">OptimizeImagePlusLayers</a></h2>
cristy6f77f692011-02-15 15:31:39 +0000[diff] [blame]308<div class="doc-section">
309
310<p>OptimizeImagePlusLayers() is exactly as OptimizeImageLayers(), but may also add or even remove extra frames in the animation, if it improves the total number of pixels in the resulting GIF animation.</p>
311
312<p>The format of the OptimizePlusImageLayers method is:</p>
313
314<pre class="code">
315 Image *OptimizePlusImageLayers(const Image *image,
316 ExceptionInfo *exception)
317</pre>
318
319<p>A description of each parameter follows:</p>
320
321<h5>image</h5>
322<p>the image.</p>
323
324<h5>exception</h5>
325<p>return any errors or warnings in this structure.</p>
326
327 </div>
cristy350dea42011-02-15 17:31:04 +0000[diff] [blame^]328<h2><a href="http://www.imagemagick.org/api/MagickCore/layer_8c.html" id="OptimizeImageTransparency">OptimizeImageTransparency</a></h2>
cristy6f77f692011-02-15 15:31:39 +0000[diff] [blame]329<div class="doc-section">
330
331<p>OptimizeImageTransparency() takes a frame optimized GIF animation, and compares the overlayed pixels against the disposal image resulting from all the previous frames in the animation. Any pixel that does not change the disposal image (and thus does not effect the outcome of an overlay) is made transparent.</p>
332
333<p>WARNING: This modifies the current images directly, rather than generate a new image sequence.</p>
334
335<p>The format of the OptimizeImageTransperency method is:</p>
336
337<pre class="code">
338 void OptimizeImageTransperency(Image *image,ExceptionInfo *exception)
339</pre>
340
341<p>A description of each parameter follows:</p>
342
343<h5>image</h5>
344<p>the image sequence</p>
345
346<h5>exception</h5>
347<p>return any errors or warnings in this structure.</p>
348
349 </div>
cristy350dea42011-02-15 17:31:04 +0000[diff] [blame^]350<h2><a href="http://www.imagemagick.org/api/MagickCore/layer_8c.html" id="RemoveDuplicateLayers">RemoveDuplicateLayers</a></h2>
cristy6f77f692011-02-15 15:31:39 +0000[diff] [blame]351<div class="doc-section">
352
353<p>RemoveDuplicateLayers() removes any image that is exactly the same as the next image in the given image list. Image size and virtual canvas offset must also match, though not the virtual canvas size itself.</p>
354
355<p>No check is made with regards to image disposal setting, though it is the dispose setting of later image that is kept. Also any time delays are also added together. As such coalesced image animations should still produce the same result, though with duplicte frames merged into a single frame.</p>
356
357<p>The format of the RemoveDuplicateLayers method is:</p>
358
359<pre class="code">
360 void RemoveDuplicateLayers(Image **image, ExceptionInfo *exception)
361</pre>
362
363<p>A description of each parameter follows:</p>
364
365<h5>images</h5>
366<p>the image list</p>
367
368<h5>exception</h5>
369<p>return any errors or warnings in this structure.</p>
370
371 </div>
cristy350dea42011-02-15 17:31:04 +0000[diff] [blame^]372<h2><a href="http://www.imagemagick.org/api/MagickCore/layer_8c.html" id="RemoveZeroDelayLayers">RemoveZeroDelayLayers</a></h2>
cristy6f77f692011-02-15 15:31:39 +0000[diff] [blame]373<div class="doc-section">
374
375<p>RemoveZeroDelayLayers() removes any image that as a zero delay time. Such images generally represent intermediate or partial updates in GIF animations used for file optimization. They are not ment to be displayed to users of the animation. Viewable images in an animation should have a time delay of 3 or more centi-seconds (hundredths of a second).</p>
376
377<p>However if all the frames have a zero time delay, then either the animation is as yet incomplete, or it is not a GIF animation. This a non-sensible situation, so no image will be removed and a 'Zero Time Animation' warning (exception) given.</p>
378
379<p>No warning will be given if no image was removed because all images had an appropriate non-zero time delay set.</p>
380
381<p>Due to the special requirements of GIF disposal handling, GIF animations should be coalesced first, before calling this function, though that is not a requirement.</p>
382
383<p>The format of the RemoveZeroDelayLayers method is:</p>
384
385<pre class="code">
386 void RemoveZeroDelayLayers(Image **image, ExceptionInfo *exception)
387</pre>
388
389<p>A description of each parameter follows:</p>
390
391<h5>images</h5>
392<p>the image list</p>
393
394<h5>exception</h5>
395<p>return any errors or warnings in this structure.</p>
396
397 </div>
cristy350dea42011-02-15 17:31:04 +0000[diff] [blame^]398<h2><a href="http://www.imagemagick.org/api/MagickCore/layer_8c.html" id="CompositeLayers">CompositeLayers</a></h2>
cristy6f77f692011-02-15 15:31:39 +0000[diff] [blame]399<div class="doc-section">
400
401<p>CompositeLayers() compose first image sequence (source) over the second image sequence (destination), using the given compose method and offsets.</p>
402
403<p>The pointers to the image list does not have to be the start of that image list, but may start somewhere in the middle. Each layer from the two image lists are composted together until the end of one of the image lists is reached. The offset of each composition is also adjusted to match the virtual canvas offsets of each layer. As such the given offset is relative to the virtual canvas, and not the actual image.</p>
404
405<p>No GIF disposal handling is performed, so GIF animations should be coalesced before use. However this not a requirement, and individual layer images may have any size or offset, for special compositions.</p>
406
407<p>Special case:- If one of the image sequences is just a single image that image is repeatally composed with all the images in the other image list. Either the source or destination lists may be the single image, for this situation.</p>
408
409<p>The destination list will be expanded as needed to match number of source image overlaid (from current position to end of list).</p>
410
411<p>The format of the CompositeLayers method is:</p>
412
413<pre class="code">
414 void CompositeLayers(Image *destination,
415 const CompositeOperator compose, Image *source,
416 const ssize_t x_offset, const ssize_t y_offset,
417 ExceptionInfo *exception);
418</pre>
419
420<p>A description of each parameter follows:</p>
421
422<h5>destination</h5>
423<p>the destination images and results</p>
424
425<h5>source</h5>
426<p>source image(s) for the layer composition</p>
427
428<h5>compose, x_offset, y_offset</h5>
429<p>arguments passed on to CompositeImages()</p>
430
431<h5>exception</h5>
432<p>return any errors or warnings in this structure.</p>
433
434 </div>
cristy350dea42011-02-15 17:31:04 +0000[diff] [blame^]435<h2><a href="http://www.imagemagick.org/api/MagickCore/layer_8c.html" id="MergeImageLayers">MergeImageLayers</a></h2>
cristy6f77f692011-02-15 15:31:39 +0000[diff] [blame]436<div class="doc-section">
437
438<p>MergeImageLayers() composes all the image layers from the current given image onward to produce a single image of the merged layers.</p>
439
440<p>The inital canvas's size depends on the given ImageLayerMethod, and is initialized using the first images background color. The images are then compositied onto that image in sequence using the given composition that has been assigned to each individual image.</p>
441
442<p>The format of the MergeImageLayers is:</p>
443
444<pre class="text">
445 Image *MergeImageLayers(const Image *image,
446 const ImageLayerMethod method, ExceptionInfo *exception)
447</pre>
448
449<p>A description of each parameter follows:</p>
450
451<h5>image</h5>
452<p>the image list to be composited together</p>
453
454<h5>method</h5>
455<p>the method of selecting the size of the initial canvas.</p>
456
457<p>MergeLayer: Merge all layers onto a canvas just large enough to hold all the actual images. The virtual canvas of the first image is preserved but otherwise ignored.</p>
458
459<p>FlattenLayer: Use the virtual canvas size of first image. Images which fall outside this canvas is clipped. This can be used to 'fill out' a given virtual canvas.</p>
460
461<p>MosaicLayer: Start with the virtual canvas of the first image, enlarging left and right edges to contain all images. Images with negative offsets will be clipped.</p>
462
463<p>TrimBoundsLayer: Determine the overall bounds of all the image layers just as in "MergeLayer", then adjust the the canvas and offsets to be relative to those bounds, without overlaying the images.</p>
464
465<p>WARNING: a new image is not returned, the original image sequence page data is modified instead.</p>
466
467<h5>exception</h5>
468<p>return any errors or warnings in this structure.</p>
469
470 </div>
cristy3eaa0ef2010-03-06 20:35:26 +0000[diff] [blame]471
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