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214
cristyba1758d2011-06-03 01:29:12 +0000[diff] [blame]215<h1>ImageMagick Version 7 Porting Guide</h1>
216
cristya4dfb122011-07-07 19:01:57 +0000[diff] [blame]217<p class="navigation-index">[<a href="#headers">Header Files</a> &bull; <a href="#components">Pixel Components</a> &bull; <a href="#alpha">Alpha</a> &bull; <a href="#grayscale">Grayscale</a> &bull; <a href="#depecate">Deprecated Features Removed</a> &bull; <a href="#summary">Version 7 Change Summary</a> ]</p>
cristyba1758d2011-06-03 01:29:12 +0000[diff] [blame]218
cristya4dfb122011-07-07 19:01:57 +0000[diff] [blame]219<p>The design of ImageMagick is an evolutionary process, with the design and implementation efforts serving to influence and guide further progress in the other. With ImageMagick version 7 we aim to improve the design based on lessons learned from the version 6 implementation. ImageMagick was originally designed to display RGB images to an X Windows server. Over time we extended support to RGBA images and then to the CMYK and CMYKA image format. With ImageMagick version 7, we extend support to arbitrary colorspaces with an arbitrary number of pixel components. Other design changes are in the works and we will document them here so be sure to revisit periodically.</p>
cristy29c5c992011-06-25 13:58:49 +0000[diff] [blame]220
cristya4dfb122011-07-07 19:01:57 +0000[diff] [blame]221<p>To support variable pixel components in the MagickCore API, pixel handling has changed and now requires accessors to get or set the pixel components. There are some modest changes to the MagickWand API. Magick++ and PerlMagick should behave exactly as it does for ImageMagick version 6.</p>
cristy29c5c992011-06-25 13:58:49 +0000[diff] [blame]222
223<p>We intend to make ImageMagick version 7 available as an Alpha release by the end-of-year 2011. Look for a Beta release sometime in 2012. An official ImageMagick version 7 release will depend on how smoothly the Beta cycle progresses. During the Beta cycle, version 6 developers can attempt to port their software to version 7.<p>
224
225<p>During the ImageMagick version 7 development cycle and release, we will continue to support and enhance version 6 for a minimum of 10 years.</p>
cristyba1758d2011-06-03 01:29:12 +0000[diff] [blame]226<h2><a id="headers"></a>Header Files</h2>
227<div class="doc-section">
228<p>Prior versions of ImageMagick (4-6) references the ImageMagick header files as <kbd>magick/</kbd> and <kbd>wand/</kbd>. ImageMagick 7 instead uses <kbd>MagickCore/</kbd> and <kbd>MagickWand/</kbd> respectively. For example,</p>
229<pre class="code">
230#include &lt;MagickCore/MagickCore.h>
231#include &lt;MagickWand/MagickWand.h>
232</pre>
233</div>
234
cristya4dfb122011-07-07 19:01:57 +0000[diff] [blame]235<h2><a id="components"></a>Pixel Components</h2>
cristyba1758d2011-06-03 01:29:12 +0000[diff] [blame]236<div class="doc-section">
cristya4dfb122011-07-07 19:01:57 +0000[diff] [blame]237<p>A pixel is comprised of one or more color values we call <em>components</em> (e.g. red pixel component). However, when we discuss a pixel component across more than one pixel, we call these <em>channels</em> (i.e. the red pixel channel).</p>
238<p>Prior versions of ImageMagick (4-6), supports 4 to 5 pixel components (RGBA or CMYKA). The first 4 components are accessed with the PixelPacket data structure. The structure includes 4 members of type Quantum (typically 16-bits) of red, green, blue, and opacity. The black component or colormap indexes are supported by a separate method and structure, IndexPacket. As an example, here is a code snippet from ImageMagick version 6 that negates image pixels:</p>
cristyba1758d2011-06-03 01:29:12 +0000[diff] [blame]239
240<pre class="code">
241 for (y=0; y &lt; (ssize_t) image->rows; y++)
242 {
243 register IndexPacket
244 *indexes;
245
246 register PixelPacket
247 *q;
248
249 q=GetCacheViewAuthenticPixels(image_view,0,y,image->columns,1,exception);
250 if (q == (PixelPacket *) NULL)
251 {
252 status=MagickFalse;
253 continue;
254 }
255 indexes=GetCacheViewAuthenticIndexQueue(image_view);
256 for (x=0; x &lt; (ssize_t) image->columns; x++)
257 {
cristya4dfb122011-07-07 19:01:57 +0000[diff] [blame]258 if ((channel & RedChannel) != 0)
cristyba1758d2011-06-03 01:29:12 +0000[diff] [blame]259 q->red=(Quantum) QuantumRange-q->red;
cristya4dfb122011-07-07 19:01:57 +0000[diff] [blame]260 if ((channel & GreenChannel) != 0)
cristyba1758d2011-06-03 01:29:12 +0000[diff] [blame]261 q->green=(Quantum) QuantumRange-q->green;
cristya4dfb122011-07-07 19:01:57 +0000[diff] [blame]262 if ((channel & BlueChannel) != 0)
cristyba1758d2011-06-03 01:29:12 +0000[diff] [blame]263 q->blue=(Quantum) QuantumRange-q->blue;
cristya4dfb122011-07-07 19:01:57 +0000[diff] [blame]264 if ((channel & OpacityChannel) != 0)
cristyba1758d2011-06-03 01:29:12 +0000[diff] [blame]265 q->opacity=(Quantum) QuantumRange-q->opacity;
cristya4dfb122011-07-07 19:01:57 +0000[diff] [blame]266 if (((channel & IndexChannel) != 0) &&
cristyba1758d2011-06-03 01:29:12 +0000[diff] [blame]267 (image->colorspace == CMYKColorspace))
268 indexes[x]=(IndexPacket) QuantumRange-indexes[x];
269 q++;
270 }
271 if (SyncCacheViewAuthenticPixels(image_view,exception) == MagickFalse)
272 status=MagickFalse;
273 }
274</pre>
275
cristya4dfb122011-07-07 19:01:57 +0000[diff] [blame]276<p>ImageMagick version 7 supports any number of components from 1 to 100 (and beyond) and simplifies access with a single method that returns an array of pixel components of type Quantum. Source code that compiles against prior versions of ImageMagick will require refactoring to work with ImageMagick version 7. We illustrate with an example. Let's naively refactor the version 6 code snippet from above so it works with the ImageMagick version 7 API:</p>
cristyba1758d2011-06-03 01:29:12 +0000[diff] [blame]277
278<pre class="code">
279 for (y=0; y &lt; (ssize_t) image->rows; y++)
280 {
281 register Quantum
282 *q;
283
284 q=GetCacheViewAuthenticPixels(image_view,0,y,image->columns,1,exception);
285 if (q == (Quantum *) NULL)
286 {
287 status=MagickFalse;
288 continue;
289 }
290 for (x=0; x &lt; (ssize_t) image->columns; x++)
cristy29c5c992011-06-25 13:58:49 +0000[diff] [blame]291 {
cristya4dfb122011-07-07 19:01:57 +0000[diff] [blame]292 if ((GetPixelRedTraits(image) & ActivePixelTrait) != 0)
cristy29c5c992011-06-25 13:58:49 +0000[diff] [blame]293 SetPixelRed(image,QuantumRange-GetPixelRed(image,q),q);
cristya4dfb122011-07-07 19:01:57 +0000[diff] [blame]294 if ((GetPixelGreenTraits(image) & ActivePixelTrait) != 0)
cristy29c5c992011-06-25 13:58:49 +0000[diff] [blame]295 SetPixelGreen(image,QuantumRange-GetPixelGreen(image,q),q);
cristya4dfb122011-07-07 19:01:57 +0000[diff] [blame]296 if ((GetPixelBlueTraits(image) & ActivePixelTrait) != 0)
cristy29c5c992011-06-25 13:58:49 +0000[diff] [blame]297 SetPixelBlue(image,QuantumRange-GetPixelBlue(image,q),q);
cristya4dfb122011-07-07 19:01:57 +0000[diff] [blame]298 if ((GetPixelBlackTraits(image) & BlackPixelTrait) != 0)
cristy29c5c992011-06-25 13:58:49 +0000[diff] [blame]299 SetPixelBlack(image,QuantumRange-GetPixelBlack(image,q),q);
cristya4dfb122011-07-07 19:01:57 +0000[diff] [blame]300 if ((GetPixelAlphaTraits(image) & ActivePixelTrait) != 0)
cristy29c5c992011-06-25 13:58:49 +0000[diff] [blame]301 SetPixelAlpha(image,QuantumRange-GetPixelAlpha(image,q),q);
cristya4dfb122011-07-07 19:01:57 +0000[diff] [blame]302 q+=GetPixelComponents(image);
cristy29c5c992011-06-25 13:58:49 +0000[diff] [blame]303 }
304 if (SyncCacheViewAuthenticPixels(image_view,exception) == MagickFalse)
305 status=MagickFalse;
306 }
307</pre>
308
cristya4dfb122011-07-07 19:01:57 +0000[diff] [blame]309<p>Let's do that again but take full advantage of the new variable pixel component support:</p>
cristy29c5c992011-06-25 13:58:49 +0000[diff] [blame]310<pre class="code">
311 for (y=0; y &lt; (ssize_t) image->rows; y++)
312 {
313 register Quantum
314 *q;
315
316 q=GetCacheViewAuthenticPixels(image_view,0,y,image->columns,1,exception);
317 if (q == (Quantum *) NULL)
318 {
319 status=MagickFalse;
320 continue;
321 }
322 for (x=0; x &lt; (ssize_t) image->columns; x++)
cristya4dfb122011-07-07 19:01:57 +0000[diff] [blame]323 for (component=0; component &lt; GetPixelComponents(image); component++)
cristyba1758d2011-06-03 01:29:12 +0000[diff] [blame]324 {
cristya4dfb122011-07-07 19:01:57 +0000[diff] [blame]325 if ((GetPixelComponentTraits(image,component) & ActivePixelTrait) != 0)
cristyba1758d2011-06-03 01:29:12 +0000[diff] [blame]326 *q=(Quantum) QuantumRange-(*q);
327 q++;
328 }
329 if (SyncCacheViewAuthenticPixels(image_view,exception) == MagickFalse)
330 status=MagickFalse;
331 }
332</pre>
333
cristya4dfb122011-07-07 19:01:57 +0000[diff] [blame]334<p>Use GetPixelComponents() to advance to the next set of pixel components.</p>
cristye6e84152011-06-06 14:16:49 +0000[diff] [blame]335
cristya4dfb122011-07-07 19:01:57 +0000[diff] [blame]336<p>The colormap indexes and black pixel component (for the CMYK colorspace) are no longer stored in the index component, previously accessed with GetAuthenticIndexQueue() and GetCacheViewAuthenticIndexQueue((). Instead they are now a pixel component and accessed with the convenience pixel macros GetPixelIndex(), SetPixelIndex(), GetPixelBlack(), and SetPixelBlack().</p>
cristy2dcd6822011-06-13 16:21:20 +0000[diff] [blame]337
cristya4dfb122011-07-07 19:01:57 +0000[diff] [blame]338<p>In addition to supporting any number of components, version 7 simplifies working with components and provides opportunity for compiler optimiziations that were previously not possible. Our benchmarking shows version 7 has increased performance for virtually all image operations.</p>
cristy29c5c992011-06-25 13:58:49 +0000[diff] [blame]339
cristy87a7f072011-07-01 00:08:52 +0000[diff] [blame]340<h4></a>Pixel Accessors</h4>
341<p>Use accessors to get or set pixel components:</p>
342
343<pre class="text">
344 GetPixelAlpha()
345 GetPixelBlack()
346 GetPixelBlue()
347 GetPixelCb()
cristya4dfb122011-07-07 19:01:57 +0000[diff] [blame]348 GetPixelComponents()
cristy87a7f072011-07-01 00:08:52 +0000[diff] [blame]349 GetPixelCr()
350 GetPixelCyan()
351 GetPixelGray()
352 GetPixelGreen()
353 GetPixelIndex()
354 GetPixelInfoIntensity()
355 GetPixelInfoLuminance()
356 GetPixelMagenta()
357 GetPixelRed()
358 GetPixelPacket()
359 GetPixelPacketIntensity()
360 GetPixelY()
361 GetPixelYellow()
362 GetPixelIntensity()
363 SetPixelAlpha()
364 SetPixelBlack()
365 SetPixelBlue()
366 SetPixelCb()
cristya4dfb122011-07-07 19:01:57 +0000[diff] [blame]367 SetPixelComponents()
cristy87a7f072011-07-01 00:08:52 +0000[diff] [blame]368 SetPixelCr()
369 SetPixelCyan()
370 SetPixelGray()
371 SetPixelGreen()
372 SetPixelIndex()
373 SetPixelInfo()
374 SetPixelInfoBias()
375 SetPixelInfoPacket()
376 SetPixelMagenta()
377 SetPixelRed()
378 SetPixelPacket()
379 SetPixelPixelInfo()
380 SetPixelYellow()
381 SetPixelY()
382</pre>
383
384<p>You can find these accessors defined in the header file, <kbd>MagickCore/pixel-accessor.h</kbd></p>
385
cristya4dfb122011-07-07 19:01:57 +0000[diff] [blame]386<h4></a>Pixel Traits</h4>
387<p>Each pixel component includes one or more of these traits:</p>
388<dl>
389<dt>Undefined</dt>
390<dd>no traits associated with this pixel component<dd>
391<dt>Active</dt>
392<dd>an image processing algorithm operates on this pixel component if this trait is enabled, conversely if this trait is not enabled, the pixel component is skipped (e.g. negate red pixel component but not blue or green)<dd>
393<dt>Blend</dt>
394<dd>blend this pixel component with the alpha mask if it's enabled<dd>
395</dl>
396<p>We provide these methods to set and get pixel traits:</p>
397<pre class="text">
398 GetPixelAlphaTraits()
399 GetPixelBlackTraits()
400 GetPixelBlueTraits()
401 GetPixelCbTraits()
402 GetPixelCrTraits()
403 GetPixelCyanTraits()
404 GetPixelGrayTraits()
405 GetPixelGreenTraits()
406 GetPixelIndexTraits()
407 GetPixelMagentaTraits()
408 GetPixelRedTraits()
409 GetPixelComponentTraits()
410 GetPixelYTraits()
411 GetPixelYellowTraits()
412 SetPixelAlphaTraits()
413 SetPixelBlackTraits()
414 SetPixelBlueTraits()
415 SetPixelCbTraits()
416 SetPixelComponentTraits()
417 SetPixelCrTraits()
418 SetPixelGrayTraits()
419 SetPixelGreenTraits()
420 SetPixelIndexTraits()
421 SetPixelMagentaTraits()
422 SetPixelRedTraits()
423 SetPixelYellowTraits()
424 SetPixelYTraits()
425</pre>
426<p>For convenience you can set the active trait for a set of pixel components with a channel mask and these methods:</p>
427<pre class="text">
428 PopPixelComponentMap()
429 PushPixelComponentMap()
430 SetPixelComponentMap()
431</pre>
432
433<p>Previously MagickCore methods had channel analogs, for example, NegateImage() and NegateImageChannels(). The channel analog methods are no longer necessary because the pixel component traits specify whether to act on a particular pixel component and whether to blend with the alpha mask. For example, instead of</p>
434<pre class="text">
435 NegateImageChannel(image,channel);
436</pre>
437<p>we use:</p>
438<pre class="text">
439 PushPixelComponentMap(image,channel);
440 NegateImage(image);
441 PopPixelComponentMap(image);
442</pre>
443
cristy87a7f072011-07-01 00:08:52 +0000[diff] [blame]444<h4></a>Pixel Metacontent</h4>
445<p>In version 7, we introduce pixel metacontent. Metacontent is content about content. So rather than being the content itself, it's something that describes or amplifies the content. Here the content is a pixel. The pixel metacontent is for your exclusive use and is accessed with these MagickCore API methods:</p>
446<pre class="text">
447 SetImageMetacontentExtent()
448 GetImageMetacontentExtent()
449 GetVirtualMetacontent()
450 GetAuthenticMetacontent()
451 GetCacheViewAuthenticMetacontent()
452 GetCacheViewVirtualMetacontent()
453</pre>
cristyba1758d2011-06-03 01:29:12 +0000[diff] [blame]454</div>
455
456<h2><a id="alpha"></a>Alpha</h2>
457<div class="doc-section">
cristy2dcd6822011-06-13 16:21:20 +0000[diff] [blame]458<p>We support alpha now, previously opacity. With alpha, a value of 0 means that the pixel does not have any coverage information and is transparent; i.e. there was no color contribution from any geometry because the geometry did not overlap this pixel. A value of QuantumRange means that the pixel is opaque because the geometry completely overlapped the pixel. As a consequence, in version 7, the PixelPacket structure member alpha has replaced the previous opacity member.</p>
cristyba1758d2011-06-03 01:29:12 +0000[diff] [blame]459</div>
cristy87a7f072011-07-01 00:08:52 +0000[diff] [blame]460<h2><a id="grayscale"></a>Grayscale</h2>
461<div class="doc-section">
cristya4dfb122011-07-07 19:01:57 +0000[diff] [blame]462<p>Previously, grayscale images consumed 4 components: red, green, blue, and alpha. With version 7, grayscale consumes only 1 component consuming far less resources as a result. However, there may be unintended consequences. With 1 component, all image processing algorithms write to this one component. Drawing yellow text on a grayscale image will produce gray lettering. To get the expected results, simply modify the colorspace to RGB (e.g. -colorspace rgb).</p>
cristy87a7f072011-07-01 00:08:52 +0000[diff] [blame]463</div>
cristyba1758d2011-06-03 01:29:12 +0000[diff] [blame]464
465<h2><a id="deprecate"></a>Deprecated Features Removed</h2>
466<div class="doc-section">
cristye6e84152011-06-06 14:16:49 +0000[diff] [blame]467<p>All deprecated features from ImageMagick version 6 are removed in version 7. These include the <kbd>Magick-config</kbd> and <kbd>Wand-config</kbd> configuration utilities. Instead use:</p>
cristyba1758d2011-06-03 01:29:12 +0000[diff] [blame]468
469<pre class="code">
470 MagickCore-config
471 MagickWand-config
472</pre>
473
474<p>In addition, all deprecated <a href="http://magick.imagemagick.org/api/deprecate.html">MagickCore</a> and <a href="http://magick.imagemagick.org/api/magick-deprecate.html">MagickWand</a> methods are no longer available in version 7.</p>
475</div>
476<h2><a id="summary"></a>Version 7 Change Summary</h2>
477<div class="doc-section">
cristye6e84152011-06-06 14:16:49 +0000[diff] [blame]478<p>Changes from ImageMagick version 6 to version 7 are summarized here:</p>
cristyba1758d2011-06-03 01:29:12 +0000[diff] [blame]479<h5>Pixels</h5>
480<dl>
cristya4dfb122011-07-07 19:01:57 +0000[diff] [blame]481<li>Pixels are no longer addressed with PixelPacket structure members (e.g. red, green, blue, opacity) but as an array of components (e.g. pixel[PixelRedComponent]).</li>
cristy29c5c992011-06-25 13:58:49 +0000[diff] [blame]482<li>Use convenience macros to access pixel components (e.g. GetPixelRed(), SetPixelRed()).</li>
cristya4dfb122011-07-07 19:01:57 +0000[diff] [blame]483<li>The black component for the CMYK colorspace is no longer stored in the index component, previously accessed with GetAuthenticIndexQueue() and GetCacheViewAuthenticIndexQueue((). Instead it is now a pixel component and accessed with the convenience pixel macros GetPixelBlack() and SetPixelBlack().</li>
484<li>The index component for colormapped images are no longer stored in the index component, previously accessed with GetAuthenticIndexQueue() and GetCacheViewAuthenticIndexQueue((). Instead it is now a pixel component and accessed with the convenience pixel macros GetPixelIndex() and SetPixelIndex().</li>
485<li>Use GetPixelComponents() to advance to the next set of pixel components.</li>
486<li>Use the <em>metacontent</em> component to associate metacontent with each pixel.</li>
cristyba1758d2011-06-03 01:29:12 +0000[diff] [blame]487</dl>
488<h5>Alpha</h5>
489<dl>
490<li>We support alpha rather than opacity (0 transparent; QuantumRange opaque).</li>
cristy29c5c992011-06-25 13:58:49 +0000[diff] [blame]491<li>Use GetPixelAlpha() or SetPixelAlpha() to get or set the alpha pixel component value.</li>
cristyba1758d2011-06-03 01:29:12 +0000[diff] [blame]492</dl>
cristy87a7f072011-07-01 00:08:52 +0000[diff] [blame]493<h5>Grayscale</h5>
494<dl>
cristya4dfb122011-07-07 19:01:57 +0000[diff] [blame]495<li>Grayscale images consume one pixel component in ImageMagick version 7. To process RGB, set the colorspace to RGB (e.g. -colorspace rgb).</li>
cristy87a7f072011-07-01 00:08:52 +0000[diff] [blame]496</dl>
cristyba1758d2011-06-03 01:29:12 +0000[diff] [blame]497<h5>Deprecated Methods</h5>
498<dl>
cristy2dcd6822011-06-13 16:21:20 +0000[diff] [blame]499<li>All ImageMagick version 6 MagickCore and MagickWand deprecated methods are removed and no longer available in ImageMagick version 7.</li>
cristya4dfb122011-07-07 19:01:57 +0000[diff] [blame]500<li>All MagickCore channel method analogs are removed (e.g. NegateImageChannels()). For version 7, use pixel traits instead.</li>
cristyba1758d2011-06-03 01:29:12 +0000[diff] [blame]501</dl>
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