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cristy29f2c972015-07-28 13:37:46 +0000[diff] [blame]9 <title>ImageMagick: MagickCore, C API for ImageMagick: Dealing with Image Layers</title>
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Cristy594d2772015-11-15 10:47:42 -0500[diff] [blame]55<p class="text-center"><a href="layer.html#CoalesceImages">CoalesceImages</a> &#8226; <a href="layer.html#DisposeImages">DisposeImages</a> &#8226; <a href="layer.html#CompareImagesLayers">CompareImagesLayers</a> &#8226; <a href="layer.html#OptimizeImageLayers">OptimizeImageLayers</a> &#8226; <a href="layer.html#OptimizeImagePlusLayers">OptimizeImagePlusLayers</a> &#8226; <a href="layer.html#OptimizeImageTransparency">OptimizeImageTransparency</a> &#8226; <a href="layer.html#RemoveDuplicateLayers">RemoveDuplicateLayers</a> &#8226; <a href="layer.html#RemoveZeroDelayLayers">RemoveZeroDelayLayers</a> &#8226; <a href="layer.html#CompositeLayers">CompositeLayers</a> &#8226; <a href="layer.html#MergeImageLayers">MergeImageLayers</a></p>
cristy06f63f22012-10-31 00:50:07 +0000[diff] [blame]56
Cristye93be682015-11-26 09:07:51 -0500[diff] [blame]57<h2><a href="http://www.imagemagick.org/api/MagickCore/layer_8c.html" id="CoalesceImages">CoalesceImages</a></h2>
cristycecc9492015-06-09 16:53:50 +0000[diff] [blame]58
59<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>
60
61<p>The format of the CoalesceImages method is:</p>
62
63<pre class="text">
64Image *CoalesceImages(Image *image,ExceptionInfo *exception)
65</pre>
66
67<p>A description of each parameter follows:</p>
68
69<dd>
70</dd>
71
72<dd> </dd>
73<dl class="dl-horizontal">
74<dt>image</dt>
75<dd>the image sequence. </dd>
76
77<dd> </dd>
78<dt>exception</dt>
79<dd>return any errors or warnings in this structure. </dd>
80
81<dd> </dd>
82</dl>
Cristye93be682015-11-26 09:07:51 -0500[diff] [blame]83<h2><a href="http://www.imagemagick.org/api/MagickCore/layer_8c.html" id="DisposeImages">DisposeImages</a></h2>
cristycecc9492015-06-09 16:53:50 +0000[diff] [blame]84
85<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>
86
87<p>The format of the DisposeImages method is:</p>
88
89<pre class="text">
90Image *DisposeImages(Image *image,ExceptionInfo *exception)
91</pre>
92
93<p>A description of each parameter follows:</p>
94
95<dd>
96</dd>
97
98<dd> </dd>
99<dl class="dl-horizontal">
100<dt>images</dt>
101<dd>the image sequence. </dd>
102
103<dd> </dd>
104<dt>exception</dt>
105<dd>return any errors or warnings in this structure. </dd>
106
107<dd> </dd>
108</dl>
Cristye93be682015-11-26 09:07:51 -0500[diff] [blame]109<h2><a href="http://www.imagemagick.org/api/MagickCore/layer_8c.html" id="CompareImagesLayers">CompareImagesLayers</a></h2>
cristycecc9492015-06-09 16:53:50 +0000[diff] [blame]110
111<p>CompareImagesLayers() compares each image with the next in a sequence and returns the minimum bounding region of all the pixel differences (of the LayerMethod specified) it discovers.</p>
112
113<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>
114
115<p>No GIF dispose methods are applied, so GIF animations must be coalesced before applying this image operator to find differences to them.</p>
116
117<p>The format of the CompareImagesLayers method is:</p>
118
119<pre class="text">
120Image *CompareImagesLayers(const Image *images,
121 const LayerMethod method,ExceptionInfo *exception)
122</pre>
123
124<p>A description of each parameter follows:</p>
125
126<dd>
127</dd>
128
129<dd> </dd>
130<dl class="dl-horizontal">
131<dt>image</dt>
132<dd>the image. </dd>
133
134<dd> </dd>
135<dt>method</dt>
136<dd>the layers type to compare images with. Must be one of... CompareAnyLayer, CompareClearLayer, CompareOverlayLayer. </dd>
137
138<dd> </dd>
139<dt>exception</dt>
140<dd>return any errors or warnings in this structure. </dd>
141
142<dd> </dd>
143</dl>
Cristye93be682015-11-26 09:07:51 -0500[diff] [blame]144<h2><a href="http://www.imagemagick.org/api/MagickCore/layer_8c.html" id="OptimizeImageLayers">OptimizeImageLayers</a></h2>
cristycecc9492015-06-09 16:53:50 +0000[diff] [blame]145
146<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>
147
148<p>The format of the OptimizeImageLayers method is:</p>
149
150<pre class="text">
151Image *OptimizeImageLayers(const Image *image,
152 ExceptionInfo *exception)
153</pre>
154
155<p>A description of each parameter follows:</p>
156
157<dd>
158</dd>
159
160<dd> </dd>
161<dl class="dl-horizontal">
162<dt>image</dt>
163<dd>the image. </dd>
164
165<dd> </dd>
166<dt>exception</dt>
167<dd>return any errors or warnings in this structure. </dd>
168
169<dd> </dd>
170</dl>
Cristye93be682015-11-26 09:07:51 -0500[diff] [blame]171<h2><a href="http://www.imagemagick.org/api/MagickCore/layer_8c.html" id="OptimizeImagePlusLayers">OptimizeImagePlusLayers</a></h2>
cristycecc9492015-06-09 16:53:50 +0000[diff] [blame]172
173<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>
174
175<p>The format of the OptimizePlusImageLayers method is:</p>
176
177<pre class="text">
178Image *OptimizePlusImageLayers(const Image *image,
179 ExceptionInfo *exception)
180</pre>
181
182<p>A description of each parameter follows:</p>
183
184<dd>
185</dd>
186
187<dd> </dd>
188<dl class="dl-horizontal">
189<dt>image</dt>
190<dd>the image. </dd>
191
192<dd> </dd>
193<dt>exception</dt>
194<dd>return any errors or warnings in this structure. </dd>
195
196<dd> </dd>
197</dl>
Cristye93be682015-11-26 09:07:51 -0500[diff] [blame]198<h2><a href="http://www.imagemagick.org/api/MagickCore/layer_8c.html" id="OptimizeImageTransparency">OptimizeImageTransparency</a></h2>
cristycecc9492015-06-09 16:53:50 +0000[diff] [blame]199
200<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>
201
202<p>WARNING: This modifies the current images directly, rather than generate a new image sequence.</p>
203
204<p>The format of the OptimizeImageTransperency method is:</p>
205
206<pre class="text">
207void OptimizeImageTransperency(Image *image,ExceptionInfo *exception)
208</pre>
209
210<p>A description of each parameter follows:</p>
211
212<dd>
213</dd>
214
215<dd> </dd>
216<dl class="dl-horizontal">
217<dt>image</dt>
218<dd>the image sequence </dd>
219
220<dd> </dd>
221<dt>exception</dt>
222<dd>return any errors or warnings in this structure. </dd>
223
224<dd> </dd>
225</dl>
Cristye93be682015-11-26 09:07:51 -0500[diff] [blame]226<h2><a href="http://www.imagemagick.org/api/MagickCore/layer_8c.html" id="RemoveDuplicateLayers">RemoveDuplicateLayers</a></h2>
cristycecc9492015-06-09 16:53:50 +0000[diff] [blame]227
228<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>
229
230<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>
231
232<p>The format of the RemoveDuplicateLayers method is:</p>
233
234<pre class="text">
235void RemoveDuplicateLayers(Image **image, ExceptionInfo *exception)
236</pre>
237
238<p>A description of each parameter follows:</p>
239
240<dd>
241</dd>
242
243<dd> </dd>
244<dl class="dl-horizontal">
245<dt>images</dt>
246<dd>the image list </dd>
247
248<dd> </dd>
249<dt>exception</dt>
250<dd>return any errors or warnings in this structure. </dd>
251
252<dd> </dd>
253</dl>
Cristye93be682015-11-26 09:07:51 -0500[diff] [blame]254<h2><a href="http://www.imagemagick.org/api/MagickCore/layer_8c.html" id="RemoveZeroDelayLayers">RemoveZeroDelayLayers</a></h2>
cristycecc9492015-06-09 16:53:50 +0000[diff] [blame]255
256<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>
257
258<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>
259
260<p>No warning will be given if no image was removed because all images had an appropriate non-zero time delay set.</p>
261
262<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>
263
264<p>The format of the RemoveZeroDelayLayers method is:</p>
265
266<pre class="text">
267void RemoveZeroDelayLayers(Image **image, ExceptionInfo *exception)
268</pre>
269
270<p>A description of each parameter follows:</p>
271
272<dd>
273</dd>
274
275<dd> </dd>
276<dl class="dl-horizontal">
277<dt>images</dt>
278<dd>the image list </dd>
279
280<dd> </dd>
281<dt>exception</dt>
282<dd>return any errors or warnings in this structure. </dd>
283
284<dd> </dd>
285</dl>
Cristye93be682015-11-26 09:07:51 -0500[diff] [blame]286<h2><a href="http://www.imagemagick.org/api/MagickCore/layer_8c.html" id="CompositeLayers">CompositeLayers</a></h2>
cristycecc9492015-06-09 16:53:50 +0000[diff] [blame]287
288<p>CompositeLayers() compose the source image sequence over the destination image sequence, starting with the current image in both lists.</p>
289
290<p>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>
291
292<p>Composition uses given x and y offsets, as the 'origin' location of the source images virtual canvas (not the real image) allowing you to compose a list of 'layer images' into the destiantioni images. This makes it well sutiable for directly composing 'Clears Frame Animations' or 'Coaleased Animations' onto a static or other 'Coaleased Animation' destination image list. GIF disposal handling is not looked at.</p>
293
294<p>Special case:- If one of the image sequences is the last image (just a single image remaining), 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>
295
296<p>In the case of a single destination image (or last image given), that image will ve cloned to match the number of images remaining in the source image list.</p>
297
298<p>This is equivelent to the "-layer Composite" Shell API operator.</p>
299
300
301<p>The format of the CompositeLayers method is:</p>
302
303<pre class="text">
304void CompositeLayers(Image *destination, const CompositeOperator
305compose, Image *source, const ssize_t x_offset, const ssize_t y_offset,
306ExceptionInfo *exception);
307</pre>
308
309<p>A description of each parameter follows:</p>
310
311<dd>
312</dd>
313
314<dd> </dd>
315<dl class="dl-horizontal">
316<dt>destination</dt>
317<dd>the destination images and results </dd>
318
319<dd> </dd>
320<dt>source</dt>
321<dd>source image(s) for the layer composition </dd>
322
323<dd> </dd>
324<dt>compose, x_offset, y_offset</dt>
325<dd> arguments passed on to CompositeImages() </dd>
326
327<dd> </dd>
328<dt>exception</dt>
329<dd>return any errors or warnings in this structure. </dd>
330
331<dd> </dd>
332</dl>
Cristye93be682015-11-26 09:07:51 -0500[diff] [blame]333<h2><a href="http://www.imagemagick.org/api/MagickCore/layer_8c.html" id="MergeImageLayers">MergeImageLayers</a></h2>
cristycecc9492015-06-09 16:53:50 +0000[diff] [blame]334
335<p>MergeImageLayers() composes all the image layers from the current given image onward to produce a single image of the merged layers.</p>
336
337<p>The inital canvas's size depends on the given LayerMethod, 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>
338
339<p>The format of the MergeImageLayers is:</p>
340
341<pre class="text">
342Image *MergeImageLayers(const Image *image,
343 const LayerMethod method, ExceptionInfo *exception)
344</pre>
345
346<p>A description of each parameter follows:</p>
347
348<dd>
349</dd>
350
351<dd> </dd>
352<dl class="dl-horizontal">
353<dt>image</dt>
354<dd>the image list to be composited together </dd>
355
356<dd> </dd>
357<dt>method</dt>
358<dd>the method of selecting the size of the initial canvas. </dd>
359
360<dd> 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. </dd>
361
362<dd> 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. </dd>
363
364<dd> 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. </dd>
365
366<dd> 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. </dd>
367
368<dd> WARNING: a new image is not returned, the original image sequence page data is modified instead. </dd>
369
370<dd> </dd>
371<dt>exception</dt>
372<dd>return any errors or warnings in this structure. </dd>
373
374<dd> </dd>
375</dl>
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