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191<div class="main">
192
cristy6f77f692011-02-15 15:31:39 +0000[diff] [blame^]193<h1>Module layer
194 Methods</h1>
195<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]196
cristy6f77f692011-02-15 15:31:39 +0000[diff] [blame^]197<h2><a href="http://www.imagemagick.org/api/MagickCore/layer
198_8c.html" id="CoalesceImages">CoalesceImages</a></h2>
199<div class="doc-section">
200
201<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>
202
203<p>The format of the CoalesceImages method is:</p>
204
205<pre class="code">
206 Image *CoalesceImages(Image *image,ExceptionInfo *exception)
207</pre>
208
209<p>A description of each parameter follows:</p>
210
211<h5>image</h5>
212<p>the image sequence.</p>
213
214<h5>exception</h5>
215<p>return any errors or warnings in this structure.</p>
216
217 </div>
218<h2><a href="http://www.imagemagick.org/api/MagickCore/layer
219_8c.html" id="DisposeImages">DisposeImages</a></h2>
220<div class="doc-section">
221
222<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>
223
224<p>The format of the DisposeImages method is:</p>
225
226<pre class="code">
227 Image *DisposeImages(Image *image,ExceptionInfo *exception)
228</pre>
229
230<p>A description of each parameter follows:</p>
231
232<h5>image</h5>
233<p>the image sequence.</p>
234
235<h5>exception</h5>
236<p>return any errors or warnings in this structure.</p>
237
238 </div>
239<h2><a href="http://www.imagemagick.org/api/MagickCore/layer
240_8c.html" id="CompareImageLayers">CompareImageLayers</a></h2>
241<div class="doc-section">
242
243<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>
244
245<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>
246
247<p>No GIF dispose methods are applied, so GIF animations must be coalesced before applying this image operator to find differences to them.</p>
248
249<p>The format of the CompareImageLayers method is:</p>
250
251<pre class="code">
252 Image *CompareImageLayers(const Image *images,
253 const ImageLayerMethod method,ExceptionInfo *exception)
254</pre>
255
256<p>A description of each parameter follows:</p>
257
258<h5>image</h5>
259<p>the image.</p>
260
261<h5>method</h5>
262<p>the layers type to compare images with. Must be one of... CompareAnyLayer, CompareClearLayer, CompareOverlayLayer.</p>
263
264<h5>exception</h5>
265<p>return any errors or warnings in this structure.</p>
266
267 </div>
268<h2><a href="http://www.imagemagick.org/api/MagickCore/layer
269_8c.html" id="DeconstructImages">DeconstructImages</a></h2>
270<div class="doc-section">
271
272<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>
273
274<p>This function is deprecated in favor of the more universal CompareImageLayers() function.</p>
275
276<p>The format of the DeconstructImages method is:</p>
277
278<pre class="code">
279 Image *DeconstructImages(const Image *images, ExceptionInfo *exception)
280</pre>
281
282<p>A description of each parameter follows:</p>
283
284<h5>image</h5>
285<p>the image.</p>
286
287<h5>exception</h5>
288<p>return any errors or warnings in this structure.</p>
289
290 </div>
291<h2><a href="http://www.imagemagick.org/api/MagickCore/layer
292_8c.html" id="OptimizeImageLayers">OptimizeImageLayers</a></h2>
293<div class="doc-section">
294
295<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>
296
297<p>The format of the OptimizeImageLayers method is:</p>
298
299<pre class="code">
300 Image *OptimizeImageLayers(const Image *image,
301 ExceptionInfo *exception)
302</pre>
303
304<p>A description of each parameter follows:</p>
305
306<h5>image</h5>
307<p>the image.</p>
308
309<h5>exception</h5>
310<p>return any errors or warnings in this structure.</p>
311
312 </div>
313<h2><a href="http://www.imagemagick.org/api/MagickCore/layer
314_8c.html" id="OptimizeImagePlusLayers">OptimizeImagePlusLayers</a></h2>
315<div class="doc-section">
316
317<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>
318
319<p>The format of the OptimizePlusImageLayers method is:</p>
320
321<pre class="code">
322 Image *OptimizePlusImageLayers(const Image *image,
323 ExceptionInfo *exception)
324</pre>
325
326<p>A description of each parameter follows:</p>
327
328<h5>image</h5>
329<p>the image.</p>
330
331<h5>exception</h5>
332<p>return any errors or warnings in this structure.</p>
333
334 </div>
335<h2><a href="http://www.imagemagick.org/api/MagickCore/layer
336_8c.html" id="OptimizeImageTransparency">OptimizeImageTransparency</a></h2>
337<div class="doc-section">
338
339<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>
340
341<p>WARNING: This modifies the current images directly, rather than generate a new image sequence.</p>
342
343<p>The format of the OptimizeImageTransperency method is:</p>
344
345<pre class="code">
346 void OptimizeImageTransperency(Image *image,ExceptionInfo *exception)
347</pre>
348
349<p>A description of each parameter follows:</p>
350
351<h5>image</h5>
352<p>the image sequence</p>
353
354<h5>exception</h5>
355<p>return any errors or warnings in this structure.</p>
356
357 </div>
358<h2><a href="http://www.imagemagick.org/api/MagickCore/layer
359_8c.html" id="RemoveDuplicateLayers">RemoveDuplicateLayers</a></h2>
360<div class="doc-section">
361
362<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>
363
364<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>
365
366<p>The format of the RemoveDuplicateLayers method is:</p>
367
368<pre class="code">
369 void RemoveDuplicateLayers(Image **image, ExceptionInfo *exception)
370</pre>
371
372<p>A description of each parameter follows:</p>
373
374<h5>images</h5>
375<p>the image list</p>
376
377<h5>exception</h5>
378<p>return any errors or warnings in this structure.</p>
379
380 </div>
381<h2><a href="http://www.imagemagick.org/api/MagickCore/layer
382_8c.html" id="RemoveZeroDelayLayers">RemoveZeroDelayLayers</a></h2>
383<div class="doc-section">
384
385<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>
386
387<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>
388
389<p>No warning will be given if no image was removed because all images had an appropriate non-zero time delay set.</p>
390
391<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>
392
393<p>The format of the RemoveZeroDelayLayers method is:</p>
394
395<pre class="code">
396 void RemoveZeroDelayLayers(Image **image, ExceptionInfo *exception)
397</pre>
398
399<p>A description of each parameter follows:</p>
400
401<h5>images</h5>
402<p>the image list</p>
403
404<h5>exception</h5>
405<p>return any errors or warnings in this structure.</p>
406
407 </div>
408<h2><a href="http://www.imagemagick.org/api/MagickCore/layer
409_8c.html" id="CompositeLayers">CompositeLayers</a></h2>
410<div class="doc-section">
411
412<p>CompositeLayers() compose first image sequence (source) over the second image sequence (destination), using the given compose method and offsets.</p>
413
414<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>
415
416<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>
417
418<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>
419
420<p>The destination list will be expanded as needed to match number of source image overlaid (from current position to end of list).</p>
421
422<p>The format of the CompositeLayers method is:</p>
423
424<pre class="code">
425 void CompositeLayers(Image *destination,
426 const CompositeOperator compose, Image *source,
427 const ssize_t x_offset, const ssize_t y_offset,
428 ExceptionInfo *exception);
429</pre>
430
431<p>A description of each parameter follows:</p>
432
433<h5>destination</h5>
434<p>the destination images and results</p>
435
436<h5>source</h5>
437<p>source image(s) for the layer composition</p>
438
439<h5>compose, x_offset, y_offset</h5>
440<p>arguments passed on to CompositeImages()</p>
441
442<h5>exception</h5>
443<p>return any errors or warnings in this structure.</p>
444
445 </div>
446<h2><a href="http://www.imagemagick.org/api/MagickCore/layer
447_8c.html" id="MergeImageLayers">MergeImageLayers</a></h2>
448<div class="doc-section">
449
450<p>MergeImageLayers() composes all the image layers from the current given image onward to produce a single image of the merged layers.</p>
451
452<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>
453
454<p>The format of the MergeImageLayers is:</p>
455
456<pre class="text">
457 Image *MergeImageLayers(const Image *image,
458 const ImageLayerMethod method, ExceptionInfo *exception)
459</pre>
460
461<p>A description of each parameter follows:</p>
462
463<h5>image</h5>
464<p>the image list to be composited together</p>
465
466<h5>method</h5>
467<p>the method of selecting the size of the initial canvas.</p>
468
469<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>
470
471<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>
472
473<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>
474
475<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>
476
477<p>WARNING: a new image is not returned, the original image sequence page data is modified instead.</p>
478
479<h5>exception</h5>
480<p>return any errors or warnings in this structure.</p>
481
482 </div>
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