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cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]56<div class="container">
57<div class="magick-header">
58<p class="text-center"><a href="architecture.html#cache">The Pixel Cache</a> • <a href="architecture.html#stream">Streaming Pixels</a> • <a href="architecture.html#properties">Image Properties and Profiles</a> • <a href="architecture.html#tera-pixel">Large Image Support</a> • <a href="architecture.html#threads">Threads of Execution</a> • <a href="architecture.html#distributed">Heterogeneous Distributed Processing</a> • <a href="architecture.html#coders">Custom Image Coders</a> • <a href="architecture.html#filters">Custom Image Filters</a></p>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]59
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]60<p class="lead magick-description">The citizens of Oz were quite content with their benefactor, the all-powerful Wizard. They accepted his wisdom and benevolence without ever questioning the who, why, and where of his power. Like the citizens of Oz, if you feel comfortable that ImageMagick can help you convert, edit, or compose your images without knowing what goes on behind the curtain, feel free to skip this section. However, if you want to know more about the software and algorithms behind ImageMagick, read on. To fully benefit from this discussion, you should be comfortable with image nomenclature and be familiar with computer programming.</p>
61
62<h2 class="magick-header"><a id="overview"></a>Architecture Overview</h2>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]63
64<p>An image typically consists of a rectangular region of pixels and metadata. To convert, edit, or compose an image in an efficient manner we need convenient access to any pixel anywhere within the region (and sometimes outside the region). And in the case of an image sequence, we need access to any pixel of any region of any image in the sequence. However, there are hundreds of image formats such JPEG, TIFF, PNG, GIF, etc., that makes it difficult to access pixels on demand. Within these formats we find differences in:</p>
65
66<ul>
cristy8ee7f242013-06-20 16:08:44 +0000[diff] [blame]67 <li>colorspace (e.g sRGB, linear RGB, linear GRAY, CMYK, YUV, Lab, etc.)</li>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]68 <li>bit depth (.e.g 1, 4, 8, 12, 16, etc.)</li>
69 <li>storage format (e.g. unsigned, signed, float, double, etc.)</li>
70 <li>compression (e.g. uncompressed, RLE, Zip, BZip, etc.)</li>
71 <li>orientation (i.e. top-to-bottom, right-to-left, etc.),</li>
72 <li>layout (.e.g. raw, interspersed with opcodes, etc.)</li>
73</ul>
74
75<p>In addition, some image pixels may require attenuation, some formats permit more than one frame, and some formats contain vector graphics that must first be rasterized (converted from vector to pixels).</p>
76
77<p>An efficient implementation of an image processing algorithm may require we get or set:</p>
78
79<ul>
80 <li>one pixel a time (e.g. pixel at location 10,3)</li>
81 <li>a single scanline (e.g. all pixels from row 4)</li>
82 <li>a few scanlines at once (e.g. pixel rows 4-7)</li>
83 <li>a single column or columns of pixels (e.g. all pixels from column 11)</li>
84 <li>an arbitrary region of pixels from the image (e.g. pixels defined at 10,7 to 10,19)</li>
85 <li>a pixel in random order (e.g. pixel at 14,15 and 640,480)</li>
86 <li>pixels from two different images (e.g. pixel at 5,1 from image 1 and pixel at 5,1 from image 2)</li>
87 <li>pixels outside the boundaries of the image (e.g. pixel at -1,-3)</li>
cristy91469932014-07-25 11:00:25 +0000[diff] [blame]88 <li>a pixel component that is unsigned (65311) or in a floating-point representation (e.g. 0.17836)</li>
89 <li>a high-dynamic range pixel that can include negative values (e.g. -0.00716) as well as values that exceed the quantum depth (e.g. 65931)</li>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]90 <li>one or more pixels simultaneously in different threads of execution</li>
cristyd43a46b2010-01-21 02:13:41 +0000[diff] [blame]91 <li>all the pixels in memory to take advantage of speed-ups offered by executing in concert across heterogeneous platforms consisting of CPUs, GPUs, and other processors</li>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]92</ul>
93
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]94<p>Some images include a clip mask that define which pixels are eligible to be updated. Pixels outside the area defined by the clip mask remain untouched.</p>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]95
cristy91469932014-07-25 11:00:25 +0000[diff] [blame]96<p>Given the varied image formats and image processing requirements, we implemented the ImageMagick <a href="architecture.html#cache">pixel cache</a> to provide convenient sequential or parallel access to any pixel on demand anywhere inside the image region (i.e. <a href="architecture.html#authentic-pixels">authentic pixels</a>) and from any image in a sequence. In addition, the pixel cache permits access to pixels outside the boundaries defined by the image (i.e. <a href="architecture.html#virtual-pixels">virtual pixels</a>).</p>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]97
cristy751980d2012-06-03 23:18:35 +0000[diff] [blame]98<p>In addition to pixels, images have a plethora of <a href="architecture.html#properties">image properties and profiles</a>. Properties include the well known attributes such as width, height, depth, and colorspace. An image may have optional properties which might include the image author, a comment, a create date, and others. Some images also include profiles for color management, or EXIF, IPTC, 8BIM, or XMP informational profiles. ImageMagick provides command line options and programming methods to get, set, or view image properties or profiles or apply profiles.</p>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]99
cristy91469932014-07-25 11:00:25 +0000[diff] [blame]100<p>ImageMagick consists of nearly a half million lines of C code and optionally depends on several million lines of code in dependent libraries (e.g. JPEG, PNG, TIFF libraries). Given that, one might expect a huge architecture document. However, a great majority of image processing is simply accessing pixels and its metadata and our simple, elegant, and efficient implementation makes this easy for the ImageMagick developer. We discuss the implementation of the pixel cache and getting and setting image properties and profiles in the next few sections. Next, we discuss using ImageMagick within a <a href="architecture.html#threads">thread</a> of execution. In the final sections, we discuss <a href="architecture.html#coders">image coders</a> to read or write a particular image format followed by a few words on creating a <a href="architecture.html#filters">filter</a> to access or update pixels based on your custom requirements.</p>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]101
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]102<h2 class="magick-header"><a id="cache"></a>The Pixel Cache</h2>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]103
cristy751980d2012-06-03 23:18:35 +0000[diff] [blame]104<p>The ImageMagick pixel cache is a repository for image pixels with up to 5 channels. The first 4 channels are stored contiguously and an optional second area follows with 1 channel. The channels are at the depth specified when ImageMagick was built. The channel depths are 8 bits-per-pixel component for the Q8 version of ImageMagick, 16 bits-per-pixel component for the Q16 version, and 32 bits-per-pixel component for the Q32 version. By default pixel components are unsigned quantities, however, if you use the <a href="high-dynamic-range.html">high dynamic-range</a> version of ImageMagick, the components are 32-bit floating point. The primary 4 channels can hold any value but typically contain red, green, blue, and alpha intensities or cyan, magenta, yellow, and alpha intensities. The optional fifth channel contains the colormap indexes for colormapped images or the black channel for CMYK images. The pixel cache storage may be heap memory, anonymous memory mapped memory, disk-backed memory mapped, or on disk. The pixel cache is reference-counted. Only the cache properties are copied when the cache is cloned. The cache pixels are subsequently copied only when you signal your intention to update any of the pixels.</p>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]105
106<h3>Create the Pixel Cache</h3>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]107
108<p>The pixel cache is associated with an image when it is created and it is initialized when you try to get or put pixels. Here are three common methods to associate a pixel cache with an image:</p>
109
cristyec6b4752011-01-08 03:16:23 +0000[diff] [blame]110<dl>
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]111<dt>Create an image canvas initialized to the background color:</dt><br>
112<dd><pre>image=AllocateImage(image_info);
cristy8ee7f242013-06-20 16:08:44 +0000[diff] [blame]113if (SetImageExtent(image,640,480) == MagickFalse)
114 { /* an exception was thrown */ }
115(void) QueryMagickColor("red",&amp;image-&gt;background_color,&amp;image-&gt;exception);
116SetImageBackgroundColor(image);
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]117</pre></dd>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]118
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]119<dt>Create an image from a JPEG image on disk:</dt><br>
120<dd><pre>(void) strcpy(image_info-&gt;filename,"image.jpg"):
cristy8ee7f242013-06-20 16:08:44 +0000[diff] [blame]121image=ReadImage(image_info,exception);
122if (image == (Image *) NULL)
123 { /* an exception was thrown */ }
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]124</pre></dd>
125<dt>Create an image from a memory based image:</dt><br>
126<dd><pre>image=BlobToImage(blob_info,blob,extent,exception);
cristy8ee7f242013-06-20 16:08:44 +0000[diff] [blame]127if (image == (Image *) NULL)
128 { /* an exception was thrown */ }
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]129</pre></dd>
cristyec6b4752011-01-08 03:16:23 +0000[diff] [blame]130</dl>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]131
cristy751980d2012-06-03 23:18:35 +0000[diff] [blame]132<p>In our discussion of the pixel cache, we use the <a href="magick-core.html">MagickCore API</a> to illustrate our points, however, the principles are the same for other program interfaces to ImageMagick.</p>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]133
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]134<p>When the pixel cache is initialized, pixels are scaled from whatever bit depth they originated from to that required by the pixel cache. For example, a 1-channel 1-bit monochrome PBM image is scaled to a 4 channel 8-bit RGBA image, if you are using the Q8 version of ImageMagick, and 16-bit RGBA for the Q16 version. You can determine which version you have with the <a href="command-line-options.html#version">‑version</a> option: </p>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]135
cristy44443b92015-05-05 00:06:07 +0000[diff] [blame]136<pre><span class="crtprompt"> </span><span class="crtin">identify -version</span><span class="crtout">Version: ImageMagick 6.9.1-2 2015-03-21 Q16 http://www.imagemagick.org</span></pre>
cristyd43a46b2010-01-21 02:13:41 +0000[diff] [blame]137<p>As you can see, the convenience of the pixel cache sometimes comes with a trade-off in storage (e.g. storing a 1-bit monochrome image as 16-bit RGBA is wasteful) and speed (i.e. storing the entire image in memory is generally slower than accessing one scanline of pixels at a time). In most cases, the benefits of the pixel cache typically outweigh any disadvantages.</p>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]138
cristydcca3fa2010-12-29 21:50:07 +0000[diff] [blame]139<h3><a id="authentic-pixels"></a>Access the Pixel Cache</h3>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]140
cristy91469932014-07-25 11:00:25 +0000[diff] [blame]141<p>Once the pixel cache is associated with an image, you typically want to get, update, or put pixels into it. We refer to pixels inside the image region as <a href="architecture.html#authentic-pixels">authentic pixels</a> and outside the region as <a href="architecture.html#virtual-pixels">virtual pixels</a>. Use these methods to access the pixels in the cache:</p>
cristy2bd2a982011-02-15 00:52:58 +0000[diff] [blame]142<ul>
cristy44443b92015-05-05 00:06:07 +0000[diff] [blame]143 <li><a href="www/api/cache.html#GetVirtualPixels">GetVirtualPixels()</a>: gets pixels that you do not intend to modify or pixels that lie outside the image region (e.g. pixel @ -1,-3)</li>
144 <li><a href="www/api/cache.html#GetAuthenticPixels">GetAuthenticPixels()</a>: gets pixels that you intend to modify</li>
145 <li><a href="www/api/cache.html#QueueAuthenticPixels">QueueAuthenticPixels()</a>: queue pixels that you intend to set</li>
146 <li><a href="www/api/cache.html#SyncAuthenticPixels">SyncAuthenticPixels()</a>: update the pixel cache with any modified pixels</li>
cristy2bd2a982011-02-15 00:52:58 +0000[diff] [blame]147</ul>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]148
cristy751980d2012-06-03 23:18:35 +0000[diff] [blame]149<p>Here is a typical <a href="magick-core.html">MagickCore</a> code snippet for manipulating pixels in the pixel cache. In our example, we copy pixels from the input image to the output image and decrease the intensity by 10%:</p>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]150
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]151<pre class="pre-scrollable">const PixelPacket
cristy8ee7f242013-06-20 16:08:44 +0000[diff] [blame]152 *p;
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]153
cristy8ee7f242013-06-20 16:08:44 +0000[diff] [blame]154PixelPacket
155 *q;
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]156
cristy8ee7f242013-06-20 16:08:44 +0000[diff] [blame]157ssize_t
158 x,
159 y;
cristyde368992010-11-05 14:32:14 +0000[diff] [blame]160
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]161destination=CloneImage(source,source-&gt;columns,source-&gt;rows,MagickTrue,
cristy8ee7f242013-06-20 16:08:44 +0000[diff] [blame]162 exception);
163if (destination == (Image *) NULL)
164 { /* an exception was thrown */ }
165for (y=0; y &lt; (ssize_t) source-&gt;rows; y++)
166{
167 p=GetVirtualPixels(source,0,y,source-&gt;columns,1,exception);
168 q=GetAuthenticPixels(destination,0,y,destination-&gt;columns,1,exception);
169 if ((p == (const PixelPacket *) NULL) || (q == (PixelPacket *) NULL)
170 break;
171 for (x=0; x &lt; (ssize_t) source-&gt;columns; x++)
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]172 {
cristy8ee7f242013-06-20 16:08:44 +0000[diff] [blame]173 SetPixelRed(q,90*p-&gt;red/100);
174 SetPixelGreen(q,90*p-&gt;green/100);
175 SetPixelBlue(q,90*p-&gt;blue/100);
176 SetPixelOpacity(q,90*p-&gt;opacity/100);
177 p++;
178 q++;
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]179 }
cristy8ee7f242013-06-20 16:08:44 +0000[diff] [blame]180 if (SyncAuthenticPixels(destination,exception) == MagickFalse)
181 break;
182}
183if (y &lt; (ssize_t) source-&gt;rows)
184 { /* an exception was thrown */ }
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]185</pre>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]186
cristy44443b92015-05-05 00:06:07 +0000[diff] [blame]187<p>When we first create the destination image by cloning the source image, the pixel cache pixels are not copied. They are only copied when you signal your intentions to modify or set the pixel cache by calling <a href="www/api/cache.html#GetAuthenticPixels">GetAuthenticPixels()</a> or <a href="www/api/cache.html#QueueAuthenticPixels">QueueAuthenticPixels()</a>. Use <a href="www/api/cache.html#QueueAuthenticPixels">QueueAuthenticPixels()</a> if you want to set new pixel values rather than update existing ones. You could use GetAuthenticPixels() to set pixel values but it is slightly more efficient to use QueueAuthenticPixels() instead. Finally, use <a href="www/api/cache.html#SyncAuthenticPixels">SyncAuthenticPixels()</a> to ensure any updated pixels are pushed to the pixel cache.</p>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]188
cristy44443b92015-05-05 00:06:07 +0000[diff] [blame]189<p>Recall how we mentioned that the indexes of a colormapped image or the black channel of a CMYK image are stored separately. Use <a href="www/api/cache.html#GetVirtualIndexQueue">GetVirtualIndexQueue()</a> (to read the indexes) or <a href="www/api/cache.html#GetAuthenticIndexQueue">GetAuthenticIndexQueue()</a> (to update the indexes) to gain access to this channel. For example, to print the colormap indexes, use:</p>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]190
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]191<pre>const IndexPacket
cristy8ee7f242013-06-20 16:08:44 +0000[diff] [blame]192 *indexes;
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]193
cristy8ee7f242013-06-20 16:08:44 +0000[diff] [blame]194for (y=0; y &lt; (ssize_t) source-&gt;rows; y++)
195{
196 p=GetVirtualPixels(source,0,y,source-&gt;columns,1);
197 if (p == (const PixelPacket *) NULL)
198 break;
199 indexes=GetVirtualIndexQueue(source);
200 for (x=0; x &lt; (ssize_t) source-&gt;columns; x++)
201 (void) printf("%d\n",GetPixelIndex(indexes+x));
202}
203if (y &lt; (ssize_t) source-&gt;rows)
204 /* an exception was thrown */
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]205</pre>
206
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]207<p>The pixel cache manager decides whether to give you direct or indirect access to the image pixels. In some cases the pixels are staged to an intermediate buffer-- and that is why you must call SyncAuthenticPixels() to ensure this buffer is <var>pushed</var> out to the pixel cache to guarantee the corresponding pixels in the cache are updated. For this reason we recommend that you only read or update a scanline or a few scanlines of pixels at a time. However, you can get any rectangular region of pixels you want. GetAuthenticPixels() requires that the region you request is within the bounds of the image area. For a 640 by 480 image, you can get a scanline of 640 pixels at row 479 but if you ask for a scanline at row 480, an exception is returned (rows are numbered starting at 0). GetVirtualPixels() does not have this constraint. For example,</p>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]208
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]209<pre>p=GetVirtualPixels(source,-3,-3,source-&gt;columns+3,6,exception);
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]210</pre>
211
212<p>gives you the pixels you asked for without complaint, even though some are not within the confines of the image region.</p>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]213
cristydcca3fa2010-12-29 21:50:07 +0000[diff] [blame]214<h3><a id="virtual-pixels"></a>Virtual Pixels</h3>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]215
cristyc3186d52010-06-04 13:55:23 +0000[diff] [blame]216<p>There are a plethora of image processing algorithms that require a neighborhood of pixels about a pixel of interest. The algorithm typically includes a caveat concerning how to handle pixels around the image boundaries, known as edge pixels. With virtual pixels, you do not need to concern yourself about special edge processing other than choosing which virtual pixel method is most appropriate for your algorithm.</p>
cristy44443b92015-05-05 00:06:07 +0000[diff] [blame]217 <p>Access to the virtual pixels are controlled by the <a href="www/api/cache.html#SetImageVirtualPixelMethod">SetImageVirtualPixelMethod()</a> method from the MagickCore API or the <a href="command-line-options.html#virtual-pixel">‑virtual‑pixel</a> option from the command line. The methods include:</p>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]218
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]219<dl class="dl-horizontal">
220<dt>background</dt>
221<dd>the area surrounding the image is the background color</dd>
222<dt>black</dt>
223<dd>the area surrounding the image is black</dd>
224<dt>checker-tile</dt>
225<dd>alternate squares with image and background color</dd>
226<dt>dither</dt>
227<dd>non-random 32x32 dithered pattern</dd>
228<dt>edge</dt>
229<dd>extend the edge pixel toward infinity (default)</dd>
230<dt>gray</dt>
231<dd>the area surrounding the image is gray</dd>
232<dt>horizontal-tile</dt>
233<dd>horizontally tile the image, background color above/below</dd>
234<dt>horizontal-tile-edge</dt>
235<dd>horizontally tile the image and replicate the side edge pixels</dd>
236<dt>mirror</dt>
237<dd>mirror tile the image</dd>
238<dt>random</dt>
239<dd>choose a random pixel from the image</dd>
240<dt>tile</dt>
241<dd>tile the image</dd>
242<dt>transparent</dt>
243<dd>the area surrounding the image is transparent blackness</dd>
244<dt>vertical-tile</dt>
245<dd>vertically tile the image, sides are background color</dd>
246<dt>vertical-tile-edge</dt>
247<dd>vertically tile the image and replicate the side edge pixels</dd>
248<dt>white</dt>
249<dd>the area surrounding the image is white</dd>
250</dl>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]251
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]252
253<h3>Cache Storage and Resource Requirements</h3>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]254
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]255<p>Recall that this simple and elegant design of the ImageMagick pixel cache comes at a cost in terms of storage and processing speed. The pixel cache storage requirements scales with the area of the image and the bit depth of the pixel components. For example, if we have a 640 by 480 image and we are using the Q16 version of ImageMagick, the pixel cache consumes image <var>width * height * bit-depth / 8 * channels</var> bytes or approximately 2.3 mebibytes (i.e. 640 * 480 * 2 * 4). Not too bad, but what if your image is 25000 by 25000 pixels? The pixel cache requires approximately 4.7 gibibytes of storage. Ouch. ImageMagick accounts for possible huge storage requirements by caching large images to disk rather than memory. Typically the pixel cache is stored in memory using heap memory. If heap memory is exhausted, pixels are stored in in an anonymous map; if the anonymous memory map is exhausted, we create the pixel cache on disk and attempt to memory-map it; and if memory-map memory is exhausted, we simply use standard disk I/O. Disk storage is cheap but it is also very slow, upwards of 1000 times slower than memory. We can get some speed improvements, up to 5 times, if we use memory mapping to the disk-based cache. These decisions about storage are made <var>automagically</var> by the pixel cache manager negotiating with the operating system. However, you can influence how the pixel cache manager allocates the pixel cache with <var>cache resource limits</var>. The limits include:</p>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]256
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]257<dl class="dl-horizontal">
258 <dt>width</dt>
259 <dd>maximum width of an image. Exceed this limit and an exception is thrown and processing stops.</dd>
260 <dt>height</dt>
261 <dd>maximum height of an image. Exceed this limit and an exception is thrown and processing stops.</dd>
262 <dt>area</dt>
cristyeed6cb62012-01-28 19:38:34 +0000[diff] [blame]263 <dd>maximum area in bytes of any one image that can reside in the pixel cache memory. If this limit is exceeded, the image is automagically cached to disk and optionally memory-mapped.</dd>
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]264 <dt>memory</dt>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]265 <dd>maximum amount of memory in bytes to allocate for the pixel cache from the anonymous mapped memory or the heap.</dd>
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]266 <dt>map</dt>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]267 <dd>maximum amount of memory map in bytes to allocate for the pixel cache.</dd>
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]268 <dt>disk</dt>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]269 <dd>maximum amount of disk space in bytes permitted for use by the pixel cache. If this limit is exceeded, the pixel cache is not created and a fatal exception is thrown.</dd>
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]270 <dt>files</dt>
271 <dd>maximum number of open pixel cache files. When this limit is exceeded, any subsequent pixels cached to disk are closed and reopened on demand. This behavior permits a large number of images to be accessed simultaneously on disk, but without a speed penalty due to repeated open/close calls.</dd>
272 <dt>thread</dt>
cristy4103d562010-12-10 01:38:54 +0000[diff] [blame]273 <dd>maximum number of threads that are permitted to run in parallel.</dd>
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]274 <dt>time</dt>
275 <dd>maximum number of seconds that the process is permitted to execute. Exceed this limit and an exception is thrown and processing stops.</dd>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]276</dl>
277
278<p>To determine the current setting of these limits, use this command:</p>
279
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]280<pre>
281-&gt; identify -list resource
cristy37b3d442015-02-28 14:00:30 +0000[diff] [blame]282Resource limits:
283 Width: 100MP
284 Height: 100MP
285 Area: 25.181GB
286 Memory: 11.726GiB
287 Map: 23.452GiB
288 Disk: unlimited
289 File: 768
290 Thread: 12
291 Throttle: 0
292 Time: unlimited
cristydcca3fa2010-12-29 21:50:07 +0000[diff] [blame]293</pre>
294
cristy44443b92015-05-05 00:06:07 +0000[diff] [blame]295<p>You can set these limits either as a <a href="resources.html#configure">policy</a> (see <a href="../source/policy.xml">policy.xml</a>), with an <a href="resources.html#environment">environment variable</a>, with the <a href="command-line-options.html#limit">-limit</a> command line option, or with the <a href="www/api/resource.html#SetMagickResourceLimit">SetMagickResourceLimit()</a> MagickCore API method. As an example, our online web interface to ImageMagick, <a href="http://www.imagemagick.org/MagickStudio/scripts/MagickStudio.cgi">ImageMagick Studio</a>, includes these policy limits to help prevent a denial-of-service:</p>
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]296<pre>
297&lt;policymap&gt;
298 &lt;policy domain="resource" name="temporary-path" value="/tmp"/&gt;
299 &lt;policy domain="resource" name="memory" value="256MiB"/&gt;
300 &lt;policy domain="resource" name="map" value="512MiB"/&gt;
301 &lt;policy domain="resource" name="width" value="8KP"/&gt;
302 &lt;policy domain="resource" name="height" value="8KP"/&gt;
303 &lt;policy domain="resource" name="area" value="128MB"/&gt;
304 &lt;policy domain="resource" name="disk" value="1GiB"/&gt;
305 &lt;policy domain="resource" name="file" value="768"/&gt;
306 &lt;policy domain="resource" name="thread" value="2"/&gt;
307 &lt;policy domain="resource" name="throttle" value="0"/&gt;
308 &lt;policy domain="resource" name="time" value="120"/&gt;
309 &lt;policy domain="system" name="precision" value="6"/&gt;
310 &lt;policy domain="cache" name="shared-secret" value="********"/&gt;
311&lt;/policymap&gt;
cristy8ee7f242013-06-20 16:08:44 +0000[diff] [blame]312</pre>
313<p>Since we process multiple simultaneous sessions, we don't want any one session consuming all the available memory. Instead large images are cached to disk. If the image is too large and exceeds the pixel cache disk limit, the program exits. In addition, we place a time limit to prevent any run-away processing tasks.</p>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]314
cristy91469932014-07-25 11:00:25 +0000[diff] [blame]315<p>Note, the cache limits are global to each invocation of ImageMagick, meaning if you create several images, the combined resource requirements are compared to the limit to determine the pixel cache storage disposition.</p>
cristy8ee7f242013-06-20 16:08:44 +0000[diff] [blame]316
cristy91469932014-07-25 11:00:25 +0000[diff] [blame]317<p>To determine which type and how much resources are consumed by the pixel cache, add the <a href="command-line-options.html#debug">-debug cache</a> option to the command-line:</p>
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]318<pre>-&gt; convert -debug cache logo: -sharpen 3x2 null:
cristy91469932014-07-25 11:00:25 +0000[diff] [blame]3192013-12-17T13:33:42-05:00 0:00.000 0.000u 7.0.0 Cache convert: cache.c/DestroyPixelCache/1275/Cache
cristy8ee7f242013-06-20 16:08:44 +0000[diff] [blame]320 destroy
cristy91469932014-07-25 11:00:25 +0000[diff] [blame]3212013-12-17T13:33:42-05:00 0:00.000 0.000u 7.0.0 Cache convert: cache.c/OpenPixelCache/3834/Cache
cristy8ee7f242013-06-20 16:08:44 +0000[diff] [blame]322 open LOGO[0] (Heap Memory, 640x480x4 4.688MiB)
cristy91469932014-07-25 11:00:25 +0000[diff] [blame]3232013-12-17T13:33:42-05:00 0:00.010 0.000u 7.0.0 Cache convert: cache.c/OpenPixelCache/3834/Cache
cristy8ee7f242013-06-20 16:08:44 +0000[diff] [blame]324 open LOGO[0] (Heap Memory, 640x480x3 3.516MiB)
cristy91469932014-07-25 11:00:25 +0000[diff] [blame]3252013-12-17T13:33:42-05:00 0:00.010 0.000u 7.0.0 Cache convert: cache.c/ClonePixelCachePixels/1044/Cache
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]326 Memory =&gt; Memory
cristy91469932014-07-25 11:00:25 +0000[diff] [blame]3272013-12-17T13:33:42-05:00 0:00.020 0.010u 7.0.0 Cache convert: cache.c/ClonePixelCachePixels/1044/Cache
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]328 Memory =&gt; Memory
cristy91469932014-07-25 11:00:25 +0000[diff] [blame]3292013-12-17T13:33:42-05:00 0:00.020 0.010u 7.0.0 Cache convert: cache.c/OpenPixelCache/3834/Cache
cristy8ee7f242013-06-20 16:08:44 +0000[diff] [blame]330 open LOGO[0] (Heap Memory, 640x480x3 3.516MiB)
cristy91469932014-07-25 11:00:25 +0000[diff] [blame]3312013-12-17T13:33:42-05:00 0:00.050 0.100u 7.0.0 Cache convert: cache.c/DestroyPixelCache/1275/Cache
cristy8ee7f242013-06-20 16:08:44 +0000[diff] [blame]332 destroy LOGO[0]
cristy91469932014-07-25 11:00:25 +0000[diff] [blame]3332013-12-17T13:33:42-05:00 0:00.050 0.100u 7.0.0 Cache convert: cache.c/DestroyPixelCache/1275/Cache
cristy8ee7f242013-06-20 16:08:44 +0000[diff] [blame]334 destroy LOGO[0]
335</pre>
336<p>This command utilizes a pixel cache in memory. The logo consumed 4.688MiB and after it was sharpened, 3.516MiB.</p>
cristy8ee7f242013-06-20 16:08:44 +0000[diff] [blame]337
338
cristyac1b4322013-07-28 13:58:06 +0000[diff] [blame]339<h3>Distributed Pixel Cache</h3>
cristy91469932014-07-25 11:00:25 +0000[diff] [blame]340<p>A distributed pixel cache is an extension of the traditional pixel cache available on a single host. The distributed pixel cache may span multiple servers so that it can grow in size and transactional capacity to support very large images. Start up the pixel cache server on one or more machines. When you read or operate on an image and the local pixel cache resources are exhausted, ImageMagick contacts one or more of these remote pixel servers to store or retrieve pixels. The distributed pixel cache relies on network bandwidth to marshal pixels to and from the remote server. As such, it will likely be significantly slower than a pixel cache utilizing local storage (e.g. memory, disk, etc.).</p>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]341
342<h3>Cache Views</h3>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]343
cristy44443b92015-05-05 00:06:07 +0000[diff] [blame]344<p>GetVirtualPixels(), GetAuthenticPixels(), QueueAuthenticPixels(), and SyncAuthenticPixels(), from the MagickCore API, can only deal with one pixel cache area per image at a time. Suppose you want to access the first and last scanline from the same image at the same time? The solution is to use a <var>cache view</var>. A cache view permits you to access as many areas simultaneously in the pixel cache as you require. The cache view <a href="www/api/cache-view.html">methods</a> are analogous to the previous methods except you must first open a view and close it when you are finished with it. Here is a snippet of MagickCore code that permits us to access the first and last pixel row of the image simultaneously:</p>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]345
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]346<pre class="pre-scrollable">CacheView
cristy8ee7f242013-06-20 16:08:44 +0000[diff] [blame]347 *view_1,
348 *view_2;
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]349
cristy8ee7f242013-06-20 16:08:44 +0000[diff] [blame]350view_1=AcquireVirtualCacheView(source,exception);
351view_2=AcquireVirtualCacheView(source,exception);
352for (y=0; y &lt; (ssize_t) source-&gt;rows; y++)
353{
354 u=GetCacheViewVirtualPixels(view_1,0,y,source-&gt;columns,1,exception);
cristy91469932014-07-25 11:00:25 +0000[diff] [blame]355 v=GetCacheViewVirtualPixels(view_2,0,source-&gt;rows-y-1,source-&gt;columns,1,exception);
cristy8ee7f242013-06-20 16:08:44 +0000[diff] [blame]356 if ((u == (const PixelPacket *) NULL) || (v == (const PixelPacket *) NULL))
357 break;
358 for (x=0; x &lt; (ssize_t) source-&gt;columns; x++)
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]359 {
cristy8ee7f242013-06-20 16:08:44 +0000[diff] [blame]360 /* do something with u &amp; v here */
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]361 }
cristy8ee7f242013-06-20 16:08:44 +0000[diff] [blame]362}
363view_2=DestroyCacheView(view_2);
364view_1=DestroyCacheView(view_1);
365if (y &lt; (ssize_t) source-&gt;rows)
366 { /* an exception was thrown */ }
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]367</pre>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]368
369<h3>Magick Persistent Cache Format</h3>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]370
cristy8ee7f242013-06-20 16:08:44 +0000[diff] [blame]371<p>Recall that each image format is decoded by ImageMagick and the pixels are deposited in the pixel cache. If you write an image, the pixels are read from the pixel cache and encoded as required by the format you are writing (e.g. GIF, PNG, etc.). The Magick Persistent Cache (MPC) format is designed to eliminate the overhead of decoding and encoding pixels to and from an image format. MPC writes two files. One, with the extension <code>.mpc</code>, retains all the properties associated with the image or image sequence (e.g. width, height, colorspace, etc.) and the second, with the extension <code>.cache</code>, is the pixel cache in the native raw format. When reading an MPC image file, ImageMagick reads the image properties and memory maps the pixel cache on disk eliminating the need for decoding the image pixels. The tradeoff is in disk space. MPC is generally larger in file size than most other image formats.</p>
cristy5063d812010-10-19 16:28:10 +0000[diff] [blame]372<p>The most efficient use of MPC image files is a write-once, read-many-times pattern. For example, your workflow requires extracting random blocks of pixels from the source image. Rather than re-reading and possibly decompressing the source image each time, we use MPC and map the image directly to memory.</p>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]373
374<h3>Best Practices</h3>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]375
cristyeed6cb62012-01-28 19:38:34 +0000[diff] [blame]376<p>Although you can request any pixel from the pixel cache, any block of pixels, any scanline, multiple scanlines, any row, or multiple rows with the GetVirtualPixels(), GetAuthenticPixels(), QueueAuthenticPixels, GetCacheViewVirtualPixels(), GetCacheViewAuthenticPixels(), and QueueCacheViewAuthenticPixels() methods, ImageMagick is optimized to return a few pixels or a few pixels rows at time. There are additional optimizations if you request a single scanline or a few scanlines at a time. These methods also permit random access to the pixel cache, however, ImageMagick is optimized for sequential access. Although you can access scanlines of pixels sequentially from the last row of the image to the first, you may get a performance boost if you access scanlines from the first row of the image to the last, in sequentual order.</p>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]377
cristy91469932014-07-25 11:00:25 +0000[diff] [blame]378<p>You can get, modify, or set pixels in row or column order. However, it is more efficient to access the pixels by row rather than by column.</p>
379
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]380<p>If you update pixels returned from GetAuthenticPixels() or GetCacheViewAuthenticPixels(), don't forget to call SyncAuthenticPixels() or SyncCacheViewAuthenticPixels() respectively to ensure your changes are synchronized with the pixel cache.</p>
381
cristy91469932014-07-25 11:00:25 +0000[diff] [blame]382<p>Use QueueAuthenticPixels() or QueueCacheViewAuthenticPixels() if you are setting an initial pixel value. The GetAuthenticPixels() or GetCacheViewAuthenticPixels() method reads pixels from the cache and if you are setting an initial pixel value, this read is unnecessary. Don't forget to call SyncAuthenticPixels() or SyncCacheViewAuthenticPixels() respectively to push any pixel changes to the pixel cache.</p>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]383
cristy751980d2012-06-03 23:18:35 +0000[diff] [blame]384<p>GetVirtualPixels(), GetAuthenticPixels(), QueueAuthenticPixels(), and SyncAuthenticPixels() are slightly more efficient than their cache view counter-parts. However, cache views are required if you need access to more than one region of the image simultaneously or if more than one <a href="architecture.html#threads">thread of execution</a> is accessing the image.</p>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]385
386<p>You can request pixels outside the bounds of the image with GetVirtualPixels() or GetCacheViewVirtualPixels(), however, it is more efficient to request pixels within the confines of the image region.</p>
387
388<p>Although you can force the pixel cache to disk using appropriate resource limits, disk access can be upwards of 1000 times slower than memory access. For fast, efficient, access to the pixel cache, try to keep the pixel cache in heap memory or anonymous mapped memory.</p>
389
cristy91469932014-07-25 11:00:25 +0000[diff] [blame]390<p>The ImageMagick Q16 version of ImageMagick permits you to read and write 16 bit images without scaling but the pixel cache consumes twice as many resources as the Q8 version. If your system has constrained memory or disk resources, consider the Q8 version of ImageMagick. In addition, the Q8 version typically executes faster than the Q16 version.</p>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]391
cristy8ee7f242013-06-20 16:08:44 +0000[diff] [blame]392<p>A great majority of image formats and algorithms restrict themselves to a fixed range of pixel values from 0 to some maximum value, for example, the Q16 version of ImageMagick permit intensities from 0 to 65535. High dynamic-range imaging (HDRI), however, permits a far greater dynamic range of exposures (i.e. a large difference between light and dark areas) than standard digital imaging techniques. HDRI accurately represents the wide range of intensity levels found in real scenes ranging from the brightest direct sunlight to the deepest darkest shadows. Enable <a href="high-dynamic-range.html">HDRI</a> at ImageMagick build time to deal with high dynamic-range images, but be mindful that each pixel component is a 32-bit floating point value. In addition, pixel values are not clamped by default so some algorithms may may have unexpected results due to out-of-band pixel values than the non-HDRI version.</p>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]393
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]394<p>If you are dealing with large images, make sure the pixel cache is written to a disk area with plenty of free space. Under Unix, this is typically <code>/tmp</code> and for Windows, <code>c:/temp</code>. You can tell ImageMagick to write the pixel cache to an alternate location and conserve memory with these options:</p>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]395
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]396<pre>
397convert -limit memory 2GB -limit map 4GB -define registry:temporary-path=/data/tmp ...
398</pre>
399
400<p>Set global resource limits for your environment in the <code>policy.xml</code> configuration file.</p>
401
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]402<p>If you plan on processing the same image many times, consider the MPC format. Reading a MPC image has near-zero overhead because its in the native pixel cache format eliminating the need for decoding the image pixels. Here is an example:</p>
403
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]404<pre>
405convert image.tif image.mpc
406convert image.mpc -crop 100x100+0+0 +repage 1.png
407convert image.mpc -crop 100x100+100+0 +repage 2.png
408convert image.mpc -crop 100x100+200+0 +repage 3.png
409</pre>
410
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]411<p>MPC is ideal for web sites. It reduces the overhead of reading and writing an image. We use it exclusively at our <a href="http://www.imagemagick.org/MagickStudio/scripts/MagickStudio.cgi">online image studio</a>.</p>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]412
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]413<h2 class="magick-header"><a id="stream"></a>Streaming Pixels</h2>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]414
415<p>ImageMagick provides for streaming pixels as they are read from or written to an image. This has several advantages over the pixel cache. The time and resources consumed by the pixel cache scale with the area of an image, whereas the pixel stream resources scale with the width of an image. The disadvantage is the pixels must be consumed as they are streamed so there is no persistence.</p>
416
cristy44443b92015-05-05 00:06:07 +0000[diff] [blame]417<p>Use <a href="www/api/stream.html#ReadStream">ReadStream()</a> or <a href="www/api/stream.html#WriteStream">WriteStream()</a> with an appropriate callback method in your MagickCore program to consume the pixels as they are streaming. Here's an abbreviated example of using ReadStream:</p>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]418
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]419<pre class="pre-scrollable">static size_t StreamPixels(const Image *image,const void *pixels,const size_t columns)
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]420{
cristy2bd2a982011-02-15 00:52:58 +0000[diff] [blame]421 register const PixelPacket
422 *p;
423
424 MyData
425 *my_data;
426
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]427 my_data=(MyData *) image-&gt;client_data;
cristy2bd2a982011-02-15 00:52:58 +0000[diff] [blame]428 p=(PixelPacket *) pixels;
429 if (p != (const PixelPacket *) NULL)
430 {
431 /* process pixels here */
432 }
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]433 return(columns);
434}
435
436...
cristy8ee7f242013-06-20 16:08:44 +0000[diff] [blame]437
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]438/* invoke the pixel stream here */
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]439image_info-&gt;client_data=(void *) MyData;
cristy2bd2a982011-02-15 00:52:58 +0000[diff] [blame]440image=ReadStream(image_info,&amp;StreamPixels,exception);
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]441</pre>
442
cristy751980d2012-06-03 23:18:35 +0000[diff] [blame]443<p>We also provide a lightweight tool, <a href="stream.html">stream</a>, to stream one or more pixel components of the image or portion of the image to your choice of storage formats. It writes the pixel components as they are read from the input image a row at a time making <a href="stream.html">stream</a> desirable when working with large images or when you require raw pixel components. A majority of the image formats stream pixels (red, green, and blue) from left to right and top to bottom. However, a few formats do not support this common ordering (e.g. the PSD format).</p>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]444
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]445<h2 class="magick-header"><a id="properties"></a>Image Properties and Profiles</h2>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]446
447<p>Images have metadata associated with them in the form of properties (e.g. width, height, description, etc.) and profiles (e.g. EXIF, IPTC, color management). ImageMagick provides convenient methods to get, set, or update image properties and get, set, update, or apply profiles. Some of the more popular image properties are associated with the Image structure in the MagickCore API. For example:</p>
448
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]449<pre>(void) printf("image width: %lu, height: %lu\n",image-&gt;columns,image-&gt;rows);
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]450</pre>
451
cristy44443b92015-05-05 00:06:07 +0000[diff] [blame]452<p>For a great majority of image properties, such as an image comment or description, we use the <a href="www/api/property.html#GetImageProperty">GetImageProperty()</a> and <a href="www/api/property.html#SetImageProperty">SetImageProperty()</a> methods. Here we set a property and fetch it right back:</p>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]453
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]454<pre>const char
cristy8ee7f242013-06-20 16:08:44 +0000[diff] [blame]455 *comment;
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]456
cristy8ee7f242013-06-20 16:08:44 +0000[diff] [blame]457(void) SetImageProperty(image,"comment","This space for rent");
458comment=GetImageProperty(image,"comment");
459if (comment == (const char *) NULL)
460 (void) printf("Image comment: %s\n",comment);
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]461</pre>
462
cristy8030a5b2010-09-17 18:31:49 +0000[diff] [blame]463<p>ImageMagick supports artifacts with the GetImageArtifact() and SetImageArtifact() methods. Artifacts are stealth properties that are not exported to image formats (e.g. PNG).</p>
cristyd43a46b2010-01-21 02:13:41 +0000[diff] [blame]464
cristy44443b92015-05-05 00:06:07 +0000[diff] [blame]465<p>Image profiles are handled with <a href="www/api/profile.html#GetImageProfile">GetImageProfile()</a>, <a href="www/api/profile.html#SetImageProfile">SetImageProfile()</a>, and <a href="www/api/profile.html#ProfileImage">ProfileImage()</a> methods. Here we set a profile and fetch it right back:</p>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]466
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]467<pre>StringInfo
cristy8ee7f242013-06-20 16:08:44 +0000[diff] [blame]468 *profile;
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]469
cristy8ee7f242013-06-20 16:08:44 +0000[diff] [blame]470profile=AcquireStringInfo(length);
471SetStringInfoDatum(profile,my_exif_profile);
472(void) SetImageProfile(image,"EXIF",profile);
473DestroyStringInfo(profile);
474profile=GetImageProfile(image,"EXIF");
475if (profile != (StringInfo *) NULL)
476 (void) PrintStringInfo(stdout,"EXIF",profile);
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]477</pre>
478
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]479<h2 class="magick-header"><a id="tera-pixel"></a>Large Image Support</h2>
cristy94fb0312010-06-09 16:06:13 +0000[diff] [blame]480<p>ImageMagick can read, process, or write mega-, giga-, or tera-pixel image sizes. An image width or height can range from 1 to 2 giga-pixels on a 32 bit OS and up to 9 exa-pixels on a 64-bit OS. Note, that some image formats have restrictions on image size. For example, Photoshop images are limited to 300,000 pixels for width or height. Here we resize an image to a quarter million pixels square:</p>
cristyd43a46b2010-01-21 02:13:41 +0000[diff] [blame]481
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]482<pre>
483convert logo: -resize 250000x250000 logo.miff
484</pre>
485
cristyc3186d52010-06-04 13:55:23 +0000[diff] [blame]486<p>For large images, ImageMagick will likely create a pixel cache on disk. Make sure you have plenty of temporary disk space. If your default temporary disk partition is too small, tell ImageMagick to use another partition with plenty of free space. For example:</p>
cristyd43a46b2010-01-21 02:13:41 +0000[diff] [blame]487
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]488<pre>
489convert -define registry:temporary-path=/data/tmp logo: \ <br> -resize 250000x250000 logo.miff
490</pre>
491
cristyd43a46b2010-01-21 02:13:41 +0000[diff] [blame]492<p>To ensure large images do not consume all the memory on your system, force the image pixels to memory-mapped disk with resource limits:</p>
493
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]494<pre>
495convert -define registry:temporary-path=/data/tmp -limit memory 16mb \
496 logo: -resize 250000x250000 logo.miff
497</pre>
498
cristyd43a46b2010-01-21 02:13:41 +0000[diff] [blame]499<p>Here we force all image pixels to disk:</p>
500
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]501<pre>
502convert -define registry:temporary-path=/data/tmp -limit area 0 \
503 logo: -resize 250000x250000 logo.miff
504</pre>
505
cristybac7a162010-06-15 19:57:29 +0000[diff] [blame]506<p>Caching pixels to disk is about 1000 times slower than memory. Expect long run times when processing large images on disk with ImageMagick. You can monitor progress with this command:</p>
cristyd43a46b2010-01-21 02:13:41 +0000[diff] [blame]507
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]508<pre>convert -monitor -limit memory 2GiB -limit map 4GiB -define registry:temporary-path=/data/tmp \
509 logo: -resize 250000x250000 logo.miff
510</pre>
511
512<p>For really large images, or if there is limited resources on your host, you can utilize a distributed pixel cache on one or more remote hosts:</p>
513<pre>
cristyac1b4322013-07-28 13:58:06 +0000[diff] [blame]514convert -distribute-cache 6668 &amp; // start on 192.168.100.50
515convert -distribute-cache 6668 &amp; // start on 192.168.100.51
cristy8ee7f242013-06-20 16:08:44 +0000[diff] [blame]516convert -limit memory 2mb -limit map 2mb -limit disk 2gb \
517 -define registry:cache:hosts=192.168.100.50:6668,192.168.100.51:6668 \
518 myhugeimage.jpg -sharpen 5x2 myhugeimage.png
519</pre>
cristyd43a46b2010-01-21 02:13:41 +0000[diff] [blame]520
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]521<h2 class="magick-header"><a id="threads"></a>Threads of Execution</h2>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]522
cristy44443b92015-05-05 00:06:07 +0000[diff] [blame]523<p>Many of ImageMagick's internal algorithms are threaded to take advantage of speed-ups offered by the multicore processor chips. However, you are welcome to use ImageMagick algorithms in your threads of execution with the exception of the MagickCore's GetVirtualPixels(), GetAuthenticPixels(), QueueAuthenticPixels(), or SyncAuthenticPixels() pixel cache methods. These methods are intended for one thread of execution only with the exception of an OpenMP parallel section. To access the pixel cache with more than one thread of execution, use a cache view. We do this for the <a href="www/api/composite.html#CompositeImage">CompositeImage()</a> method, for example. Suppose we want to composite a single image over a different image in each thread of execution. If we use GetVirtualPixels(), the results are unpredictable because multiple threads would likely be asking for different areas of the pixel cache simultaneously. Instead we use GetCacheViewVirtualPixels() which creates a unique view for each thread of execution ensuring our program behaves properly regardless of how many threads are invoked. The other program interfaces, such as the <a href="magick-wand.html">MagickWand API</a>, are completely thread safe so there are no special precautions for threads of execution.</p>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]524
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]525<p>Here is an MagickCore code snippet that takes advantage of threads of execution with the <a href="openmp.html">OpenMP</a> programming paradigm:</p>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]526
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]527<pre class="pre-scrollable">CacheView
cristy91469932014-07-25 11:00:25 +0000[diff] [blame]528 *image_view;
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]529
cristy91469932014-07-25 11:00:25 +0000[diff] [blame]530MagickBooleanType
531 status;
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]532
cristy91469932014-07-25 11:00:25 +0000[diff] [blame]533ssize_t
534 y;
cristyde368992010-11-05 14:32:14 +0000[diff] [blame]535
cristy91469932014-07-25 11:00:25 +0000[diff] [blame]536status=MagickTrue;
537image_view=AcquireVirtualCacheView(image,exception);
538#pragma omp parallel for schedule(dynamic,4) shared(status)
539for (y=0; y &lt; (ssize_t) image-&gt;rows; y++)
540{
541 register IndexPacket
542 *indexes;
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]543
cristy91469932014-07-25 11:00:25 +0000[diff] [blame]544 register PixelPacket
545 *q;
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]546
cristy91469932014-07-25 11:00:25 +0000[diff] [blame]547 register ssize_t
548 x;
cristyde368992010-11-05 14:32:14 +0000[diff] [blame]549
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]550 if (status == MagickFalse)
cristy91469932014-07-25 11:00:25 +0000[diff] [blame]551 continue;
552 q=GetCacheViewAuthenticPixels(image_view,0,y,image-&gt;columns,1,exception);
553 if (q == (PixelPacket *) NULL)
554 {
555 status=MagickFalse;
556 continue;
557 }
558 indexes=GetCacheViewAuthenticIndexQueue(image_view);
559 for (x=0; x &lt; (ssize_t) image-&gt;columns; x++)
560 {
561 SetPixelRed(q,...);
562 SetPixelGreen(q,...);
563 SetPixelBlue(q,...);
564 SetPixelOpacity(q,...);
565 if (indexes != (IndexPacket *) NULL)
566 SetPixelIndex(indexes+x,...);
567 q++;
568 }
569 if (SyncCacheViewAuthenticPixels(image_view,exception) == MagickFalse)
570 status=MagickFalse;
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]571}
cristy91469932014-07-25 11:00:25 +0000[diff] [blame]572image_view=DestroyCacheView(image_view);
573if (status == MagickFalse)
574 perror("something went wrong");
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]575</pre>
576
cristy52923442011-01-15 22:54:31 +0000[diff] [blame]577<p>This code snippet converts an uncompressed Windows bitmap to a Magick++ image:</p>
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]578
579<pre class="pre-scrollable">#include "Magick++.h"
cristy52923442011-01-15 22:54:31 +0000[diff] [blame]580#include &lt;assert.h&gt;
581#include "omp.h"
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]582
cristy52923442011-01-15 22:54:31 +0000[diff] [blame]583void ConvertBMPToImage(const BITMAPINFOHEADER *bmp_info,
584 const unsigned char *restrict pixels,Magick::Image *image)
585{
586 /*
587 Prepare the image so that we can modify the pixels directly.
588 */
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]589 assert(bmp_info-&gt;biCompression == BI_RGB);
590 assert(bmp_info-&gt;biWidth == image-&gt;columns());
591 assert(abs(bmp_info-&gt;biHeight) == image-&gt;rows());
592 image-&gt;modifyImage();
593 if (bmp_info-&gt;biBitCount == 24)
594 image-&gt;type(MagickCore::TrueColorType);
cristy52923442011-01-15 22:54:31 +0000[diff] [blame]595 else
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]596 image-&gt;type(MagickCore::TrueColorMatteType);
597 register unsigned int bytes_per_row=bmp_info-&gt;biWidth*bmp_info-&gt;biBitCount/8;
cristy52923442011-01-15 22:54:31 +0000[diff] [blame]598 if (bytes_per_row % 4 != 0) {
599 bytes_per_row=bytes_per_row+(4-bytes_per_row % 4); // divisible by 4.
600 }
601 /*
602 Copy all pixel data, row by row.
603 */
604 #pragma omp parallel for
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]605 for (int y=0; y &lt; int(image-&gt;rows()); y++)
cristy52923442011-01-15 22:54:31 +0000[diff] [blame]606 {
cristy29c5c992011-06-25 13:58:49 +0000[diff] [blame]607 int
608 row;
609
610 register const unsigned char
611 *restrict p;
612
613 register MagickCore::PixelPacket
614 *restrict q;
615
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]616 row=(bmp_info-&gt;biHeight &gt; 0) ? (image-&gt;rows()-y-1) : y;
cristy29c5c992011-06-25 13:58:49 +0000[diff] [blame]617 p=pixels+row*bytes_per_row;
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]618 q=image-&gt;setPixels(0,y,image-&gt;columns(),1);
619 for (int x=0; x &lt; int(image-&gt;columns()); x++)
cristy52923442011-01-15 22:54:31 +0000[diff] [blame]620 {
cristy29c5c992011-06-25 13:58:49 +0000[diff] [blame]621 SetPixelBlue(q,p[0]);
622 SetPixelGreen(q,p[1]);
623 SetPixelRed(q,p[2]);
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]624 if (bmp_info-&gt;biBitCount == 32) {
cristy29c5c992011-06-25 13:58:49 +0000[diff] [blame]625 SetPixelOpacity(q,p[3]);
cristy52923442011-01-15 22:54:31 +0000[diff] [blame]626 }
627 q++;
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]628 p+=bmp_info-&gt;biBitCount/8;
cristy52923442011-01-15 22:54:31 +0000[diff] [blame]629 }
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]630 image-&gt;syncPixels(); // sync pixels to pixel cache.
cristy52923442011-01-15 22:54:31 +0000[diff] [blame]631 }
632 return;
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]633}</pre>
cristyfbb4a972010-06-30 17:42:22 +0000[diff] [blame]634
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]635<p>If you call the ImageMagick API from your OpenMP-enabled application and you intend to dynamically increase the number of threads available in subsequent parallel regions, be sure to perform the increase <var>before</var> you call the API otherwise ImageMagick may fault.</p>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]636
cristy44443b92015-05-05 00:06:07 +0000[diff] [blame]637<p><a href="www/api/wand-view.html">MagickWand</a> supports wand views. A view iterates over the entire, or portion, of the image in parallel and for each row of pixels, it invokes a callback method you provide. This limits most of your parallel programming activity to just that one module. There are similar methods in <a href="www/api/image-view.html">MagickCore</a>. For an example, see the same sigmoidal contrast algorithm implemented in both <a href="magick-wand.html#wand-view">MagickWand</a> and <a href="magick-core.html#image-view">MagickCore</a>.</p>
cristyfe7ce342010-06-22 15:41:50 +0000[diff] [blame]638
cristy8ee7f242013-06-20 16:08:44 +0000[diff] [blame]639<p>In most circumstances, the default number of threads is set to the number of processor cores on your system for optimal performance. However, if your system is hyperthreaded or if you are running on a virtual host and only a subset of the processors are available to your server instance, you might get an increase in performance by setting the thread <a href="resources.html#configure">policy</a> or the <a href="resources.html#environment">MAGICK_THREAD_LIMIT</a> environment variable. For example, your virtual host has 8 processors but only 2 are assigned to your server instance. The default of 8 threads can cause severe performance problems. One solution is to limit the number of threads to the available processors in your <a href="../source/policy.xml">policy.xml</a> configuration file:</p>
cristyce66ab12010-10-21 23:36:32 +0000[diff] [blame]640
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]641<pre>
642&lt;policy domain="resource" name="thread" value="2"/&gt;
cristyce66ab12010-10-21 23:36:32 +0000[diff] [blame]643</pre>
644
645<p>Or suppose your 12 core hyperthreaded computer defaults to 24 threads. Set the MAGICK_THREAD_LIMIT environment variable and you will likely get improved performance:</p>
646
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]647<pre>
cristy8ee7f242013-06-20 16:08:44 +0000[diff] [blame]648export MAGICK_THREAD_LIMIT=12
cristyce66ab12010-10-21 23:36:32 +0000[diff] [blame]649</pre>
650
cristy8ee7f242013-06-20 16:08:44 +0000[diff] [blame]651<p>The OpenMP committee has not defined the behavior of mixing OpenMP with other threading models such as Posix threads. However, using modern releases of Linux, OpenMP and Posix threads appear to interoperate without complaint. If you want to use Posix threads from a program module that calls one of the ImageMagick application programming interfaces (e.g. MagickCore, MagickWand, Magick++, etc.) from Mac OS X or an older Linux release, you may need to disable OpenMP support within ImageMagick. Add the <code>--disable-openmp</code> option to the configure script command line and rebuild and reinstall ImageMagick.</p>
cristyce66ab12010-10-21 23:36:32 +0000[diff] [blame]652
cristyeed6cb62012-01-28 19:38:34 +0000[diff] [blame]653<h4>Threading Performance</h4>
cristy8ee7f242013-06-20 16:08:44 +0000[diff] [blame]654<p>It can be difficult to predict behavior in a parallel environment. Performance might depend on a number of factors including the compiler, the version of the OpenMP library, the processor type, the number of cores, the amount of memory, whether hyperthreading is enabled, the mix of applications that are executing concurrently with ImageMagick, or the particular image-processing algorithm you utilize. The only way to be certain of optimal performance, in terms of the number of threads, is to benchmark. ImageMagick includes progressive threading when benchmarking a command and returns the elapsed time and efficiency for one or more threads. This can help you identify how many threads is the most efficient in your environment. For this benchmark we sharpen a 1920x1080 image of a model 10 times with 1 to 12 threads:</p>
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]655<pre>
cristy8ee7f242013-06-20 16:08:44 +0000[diff] [blame]656convert -bench 10 model.png -sharpen 5x2 null:
657Performance[1]: 10i 1.135ips 1.000e 8.760u 0:08.810
658Performance[2]: 10i 2.020ips 0.640e 9.190u 0:04.950
659Performance[3]: 10i 2.786ips 0.710e 9.400u 0:03.590
660Performance[4]: 10i 3.378ips 0.749e 9.580u 0:02.960
661Performance[5]: 10i 4.032ips 0.780e 9.580u 0:02.480
662Performance[6]: 10i 4.566ips 0.801e 9.640u 0:02.190
663Performance[7]: 10i 3.788ips 0.769e 10.980u 0:02.640
664Performance[8]: 10i 4.115ips 0.784e 12.030u 0:02.430
665Performance[9]: 10i 4.484ips 0.798e 12.860u 0:02.230
666Performance[10]: 10i 4.274ips 0.790e 14.830u 0:02.340
667Performance[11]: 10i 4.348ips 0.793e 16.500u 0:02.300
668Performance[12]: 10i 4.525ips 0.799e 18.320u 0:02.210
cristyeed6cb62012-01-28 19:38:34 +0000[diff] [blame]669</pre>
cristy91469932014-07-25 11:00:25 +0000[diff] [blame]670<p>The sweet spot for this example is 6 threads. This makes sense since there are 6 physical cores. The other 6 are hyperthreads. It appears that sharpening does not benefit from hyperthreading.</p>
cristy8ee7f242013-06-20 16:08:44 +0000[diff] [blame]671<p>In certain cases, it might be optimal to set the number of threads to 1 or to disable OpenMP completely with the <a href="resources.html#environment">MAGICK_THREAD_LIMIT</a> environment variable, <a href="command-line-options.html#limit">-limit</a> command line option, or the <a href="resources.html#configure">policy.xml</a> configuration file.</p>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]672
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]673<h2 class="magick-header"><a id="distributed"></a>Heterogeneous Distributed Processing</h2>
cristy16ff93c2010-01-13 23:18:07 +0000[diff] [blame]674<p>ImageMagick includes support for heterogeneous distributed processing with the <a href="http://en.wikipedia.org/wiki/OpenCL">OpenCL</a> framework. OpenCL kernels within ImageMagick permit image processing algorithms to execute across heterogeneous platforms consisting of CPUs, GPUs, and other processors. Depending on your platform, speed-ups can be an order of magnitude faster than the traditional single CPU.</p>
675
cristyd43a46b2010-01-21 02:13:41 +0000[diff] [blame]676<p>First verify that your version of ImageMagick includes support for the OpenCL feature:</p>
cristy16ff93c2010-01-13 23:18:07 +0000[diff] [blame]677
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]678<pre>
679identify -version
680Features: OpenMP OpenCL
681</pre>
682
cristyd43a46b2010-01-21 02:13:41 +0000[diff] [blame]683<p>If so, run this command to realize a significant speed-up for image convolution:</p>
684
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]685<pre>
686convert image.png -convolve '-1, -1, -1, -1, 9, -1, -1, -1, -1' convolve.png
687</pre>
688
cristyd43a46b2010-01-21 02:13:41 +0000[diff] [blame]689<p>If an accelerator is not available or if the accelerator fails to respond, ImageMagick reverts to the non-accelerated convolution algorithm.</p>
690
cristy16ff93c2010-01-13 23:18:07 +0000[diff] [blame]691<p>Here is an example OpenCL kernel that convolves an image:</p>
692
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]693<pre class="pre-scrollable">static inline long ClampToCanvas(const long offset,const ulong range)
cristy16ff93c2010-01-13 23:18:07 +0000[diff] [blame]694{
695 if (offset &lt; 0L)
696 return(0L);
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]697 if (offset &gt;= range)
cristy16ff93c2010-01-13 23:18:07 +0000[diff] [blame]698 return((long) (range-1L));
699 return(offset);
700}
701
cristyeed6cb62012-01-28 19:38:34 +0000[diff] [blame]702static inline CLQuantum ClampToQuantum(const float value)
cristy16ff93c2010-01-13 23:18:07 +0000[diff] [blame]703{
704 if (value &lt; 0.0)
705 return((CLQuantum) 0);
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]706 if (value &gt;= (float) QuantumRange)
cristy16ff93c2010-01-13 23:18:07 +0000[diff] [blame]707 return((CLQuantum) QuantumRange);
708 return((CLQuantum) (value+0.5));
709}
710
cristyeed6cb62012-01-28 19:38:34 +0000[diff] [blame]711__kernel void Convolve(const __global CLPixelType *source,__constant float *filter,
cristy16ff93c2010-01-13 23:18:07 +0000[diff] [blame]712 const ulong width,const ulong height,__global CLPixelType *destination)
713{
714 const ulong columns = get_global_size(0);
715 const ulong rows = get_global_size(1);
716
717 const long x = get_global_id(0);
718 const long y = get_global_id(1);
719
cristyeed6cb62012-01-28 19:38:34 +0000[diff] [blame]720 const float scale = (1.0/QuantumRange);
cristy16ff93c2010-01-13 23:18:07 +0000[diff] [blame]721 const long mid_width = (width-1)/2;
722 const long mid_height = (height-1)/2;
cristyeed6cb62012-01-28 19:38:34 +0000[diff] [blame]723 float4 sum = { 0.0, 0.0, 0.0, 0.0 };
724 float gamma = 0.0;
cristy16ff93c2010-01-13 23:18:07 +0000[diff] [blame]725 register ulong i = 0;
726
727 for (long v=(-mid_height); v &lt;= mid_height; v++)
728 {
729 for (long u=(-mid_width); u &lt;= mid_width; u++)
730 {
cristy4103d562010-12-10 01:38:54 +0000[diff] [blame]731 register const ulong index=ClampToCanvas(y+v,rows)*columns+ClampToCanvas(x+u,
732 columns);
cristyeed6cb62012-01-28 19:38:34 +0000[diff] [blame]733 const float alpha=scale*(QuantumRange-source[index].w);
cristy16ff93c2010-01-13 23:18:07 +0000[diff] [blame]734 sum.x+=alpha*filter[i]*source[index].x;
735 sum.y+=alpha*filter[i]*source[index].y;
736 sum.z+=alpha*filter[i]*source[index].z;
737 sum.w+=filter[i]*source[index].w;
738 gamma+=alpha*filter[i];
739 i++;
740 }
741 }
742
743 gamma=1.0/(fabs(gamma) &lt;= MagickEpsilon ? 1.0 : gamma);
744 const ulong index=y*columns+x;
745 destination[index].x=ClampToQuantum(gamma*sum.x);
746 destination[index].y=ClampToQuantum(gamma*sum.y);
747 destination[index].z=ClampToQuantum(gamma*sum.z);
748 destination[index].w=ClampToQuantum(sum.w);
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]749};</pre>
cristy16ff93c2010-01-13 23:18:07 +0000[diff] [blame]750
cristy8ee7f242013-06-20 16:08:44 +0000[diff] [blame]751<p>See <a href="http://trac.imagemagick.org/browser/ImageMagick/branches/ImageMagick-6/magick/accelerate.c">magick/accelerate.c</a> for a complete implementation of image convolution with an OpenCL kernel.</p>
cristy16ff93c2010-01-13 23:18:07 +0000[diff] [blame]752
cristy91469932014-07-25 11:00:25 +0000[diff] [blame]753<p>Note, that under Windows, you might have an issue with TDR (Timeout Detection and Recovery of GPUs). Its purpose is to detect runaway tasks hanging the GPU by using an execution time threshold. For some older low-end GPUs running the OpenCL filters in ImageMagick, longer execution times might trigger the TDR mechanism and pre-empt the GPU image filter. When this happens, ImageMagick automatically falls back to the CPU code path and returns the expected results. To avoid pre-emption, increase the <a href="http://msdn.microsoft.com/en-us/library/windows/hardware/gg487368.aspx">TdrDelay</a> registry key.</p>
754
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]755<h2 class="magick-header"><a id="coders"></a>Custom Image Coders</h2>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]756
757<p>An image coder (i.e. encoder / decoder) is responsible for registering, optionally classifying, optionally reading, optionally writing, and unregistering one image format (e.g. PNG, GIF, JPEG, etc.). Registering an image coder alerts ImageMagick a particular format is available to read or write. While unregistering tells ImageMagick the format is no longer available. The classifying method looks at the first few bytes of an image and determines if the image is in the expected format. The reader sets the image size, colorspace, and other properties and loads the pixel cache with the pixels. The reader returns a single image or an image sequence (if the format supports multiple images per file), or if an error occurs, an exception and a null image. The writer does the reverse. It takes the image properties and unloads the pixel cache and writes them as required by the image format.</p>
758
cristy8ee7f242013-06-20 16:08:44 +0000[diff] [blame]759<p>Here is a listing of a sample <a href="../source/mgk.c">custom coder</a>. It reads and writes images in the MGK image format which is simply an ID followed by the image width and height followed by the RGB pixel values.</p>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]760
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]761<pre class="pre-scrollable">/*
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]762 Include declarations.
763*/
764#include "magick/studio.h"
765#include "magick/blob.h"
766#include "magick/blob-private.h"
767#include "magick/colorspace.h"
768#include "magick/exception.h"
769#include "magick/exception-private.h"
770#include "magick/image.h"
771#include "magick/image-private.h"
772#include "magick/list.h"
773#include "magick/magick.h"
774#include "magick/memory_.h"
775#include "magick/monitor.h"
776#include "magick/monitor-private.h"
777#include "magick/quantum-private.h"
778#include "magick/static.h"
779#include "magick/string_.h"
780#include "magick/module.h"
781
782/*
783 Forward declarations.
784*/
785static MagickBooleanType
786 WriteMGKImage(const ImageInfo *,Image *);
787
788/*
789%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
790% %
791% %
792% %
793% I s M G K %
794% %
795% %
796% %
797%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
798%
799% IsMGK() returns MagickTrue if the image format type, identified by the
800% magick string, is MGK.
801%
802% The format of the IsMGK method is:
803%
804% MagickBooleanType IsMGK(const unsigned char *magick,const size_t length)
805%
806% A description of each parameter follows:
807%
808% o magick: This string is generally the first few bytes of an image file
809% or blob.
810%
811% o length: Specifies the length of the magick string.
812%
813*/
814static MagickBooleanType IsMGK(const unsigned char *magick,const size_t length)
815{
816 if (length &lt; 7)
817 return(MagickFalse);
818 if (LocaleNCompare((char *) magick,"id=mgk",7) == 0)
819 return(MagickTrue);
820 return(MagickFalse);
821}
822
823/*
824%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
825% %
826% %
827% %
828% R e a d M G K I m a g e %
829% %
830% %
831% %
832%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
833%
834% ReadMGKImage() reads a MGK image file and returns it. It allocates
835% the memory necessary for the new Image structure and returns a pointer to
836% the new image.
837%
838% The format of the ReadMGKImage method is:
839%
840% Image *ReadMGKImage(const ImageInfo *image_info,ExceptionInfo *exception)
841%
842% A description of each parameter follows:
843%
844% o image_info: the image info.
845%
846% o exception: return any errors or warnings in this structure.
847%
848*/
849static Image *ReadMGKImage(const ImageInfo *image_info,
850 ExceptionInfo *exception)
851{
852 char
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]853 buffer[MaxTextExtent];
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]854
855 Image
856 *image;
857
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]858 MagickBooleanType
859 status;
860
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]861 register PixelPacket
862 *q;
863
cristyde368992010-11-05 14:32:14 +0000[diff] [blame]864 register size_t
865 x;
866
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]867 register unsigned char
868 *p;
869
870 ssize_t
cristyde368992010-11-05 14:32:14 +0000[diff] [blame]871 count,
872 y;
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]873
874 unsigned char
875 *pixels;
876
877 unsigned long
878 columns,
879 rows;
880
881 /*
882 Open image file.
883 */
884 assert(image_info != (const ImageInfo *) NULL);
885 assert(image_info-&gt;signature == MagickSignature);
886 if (image_info-&gt;debug != MagickFalse)
887 (void) LogMagickEvent(TraceEvent,GetMagickModule(),"%s",image_info-&gt;filename);
888 assert(exception != (ExceptionInfo *) NULL);
889 assert(exception-&gt;signature == MagickSignature);
890 image=AcquireImage(image_info);
891 status=OpenBlob(image_info,image,ReadBinaryBlobMode,exception);
892 if (status == MagickFalse)
893 {
894 image=DestroyImageList(image);
895 return((Image *) NULL);
896 }
897 /*
898 Read MGK image.
899 */
900 (void) ReadBlobString(image,buffer); /* read magic number */
901 if (IsMGK(buffer,7) == MagickFalse)
902 ThrowReaderException(CorruptImageError,"ImproperImageHeader");
903 (void) ReadBlobString(image,buffer);
904 count=(ssize_t) sscanf(buffer,"%lu %lu\n",&amp;columns,&amp;rows);
905 if (count &lt;= 0)
906 ThrowReaderException(CorruptImageError,"ImproperImageHeader");
907 do
908 {
909 /*
910 Initialize image structure.
911 */
912 image-&gt;columns=columns;
913 image-&gt;rows=rows;
914 image-&gt;depth=8;
915 if ((image_info-&gt;ping != MagickFalse) &amp;&amp; (image_info-&gt;number_scenes != 0))
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]916 if (image-&gt;scene &gt;= (image_info-&gt;scene+image_info-&gt;number_scenes-1))
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]917 break;
918 /*
919 Convert MGK raster image to pixel packets.
920 */
921 if (SetImageExtent(image,0,0) == MagickFalse)
922 {
923 InheritException(exception,&amp;image-&gt;exception);
924 return(DestroyImageList(image));
925 }
926 pixels=(unsigned char *) AcquireQuantumMemory((size_t) image-&gt;columns,3UL*sizeof(*pixels));
927 if (pixels == (unsigned char *) NULL)
928 ThrowReaderException(ResourceLimitError,"MemoryAllocationFailed");
cristyde368992010-11-05 14:32:14 +0000[diff] [blame]929 for (y=0; y &lt; (ssize_t) image-&gt;rows; y++)
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]930 {
931 count=(ssize_t) ReadBlob(image,(size_t) (3*image-&gt;columns),pixels);
932 if (count != (ssize_t) (3*image-&gt;columns))
933 ThrowReaderException(CorruptImageError,"UnableToReadImageData");
934 p=pixels;
935 q=QueueAuthenticPixels(image,0,y,image-&gt;columns,1,exception);
936 if (q == (PixelPacket *) NULL)
937 break;
cristyde368992010-11-05 14:32:14 +0000[diff] [blame]938 for (x=0; x &lt; (ssize_t) image-&gt;columns; x++)
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]939 {
cristy29c5c992011-06-25 13:58:49 +0000[diff] [blame]940 SetPixelRed(q,ScaleCharToQuantum(*p++));
941 SetPixelGreen(q,ScaleCharToQuantum(*p++));
942 SetPixelBlue(q,ScaleCharToQuantum(*p++));
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]943 q++;
944 }
945 if (SyncAuthenticPixels(image,exception) == MagickFalse)
946 break;
cristydcca3fa2010-12-29 21:50:07 +0000[diff] [blame]947 if ((image-&gt;previous == (Image *) NULL) &amp;&amp;
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]948 (SetImageProgress(image,LoadImageTag,y,image&gt;&gt;rows) == MagickFalse))
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]949 break;
950 }
951 pixels=(unsigned char *) RelinquishMagickMemory(pixels);
952 if (EOFBlob(image) != MagickFalse)
953 {
954 ThrowFileException(exception,CorruptImageError,"UnexpectedEndOfFile",image-&gt;filename);
955 break;
956 }
957 /*
958 Proceed to next image.
959 */
960 if (image_info-&gt;number_scenes != 0)
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]961 if (image-&gt;scene &gt;= (image_info-&gt;scene+image_info-&gt;number_scenes-1))
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]962 break;
963 *buffer='\0';
964 (void) ReadBlobString(image,buffer);
965 count=(ssize_t) sscanf(buffer,"%lu %lu\n",&amp;columns,&amp;rows);
966 if (count != 0)
967 {
968 /*
969 Allocate next image structure.
970 */
971 AcquireNextImage(image_info,image);
972 if (GetNextImageInList(image) == (Image *) NULL)
973 {
974 image=DestroyImageList(image);
975 return((Image *) NULL);
976 }
977 image=SyncNextImageInList(image);
978 status=SetImageProgress(image,LoadImageTag,TellBlob(image),GetBlobSize(image));
979 if (status == MagickFalse)
980 break;
981 }
982 } while (count != 0);
983 (void) CloseBlob(image);
984 return(GetFirstImageInList(image));
985}
986
987/*
988%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
989% %
990% %
991% %
992% R e g i s t e r M G K I m a g e %
993% %
994% %
995% %
996%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
997%
998% RegisterMGKImage() adds attributes for the MGK image format to
999% the list of supported formats. The attributes include the image format
1000% tag, a method to read and/or write the format, whether the format
1001% supports the saving of more than one frame to the same file or blob,
1002% whether the format supports native in-memory I/O, and a brief
1003% description of the format.
1004%
1005% The format of the RegisterMGKImage method is:
1006%
1007% unsigned long RegisterMGKImage(void)
1008%
1009*/
1010ModuleExport unsigned long RegisterMGKImage(void)
1011{
1012 MagickInfo
1013 *entry;
1014
1015 entry=SetMagickInfo("MGK");
1016 entry-&gt;decoder=(DecodeImageHandler *) ReadMGKImage;
1017 entry-&gt;encoder=(EncodeImageHandler *) WriteMGKImage;
1018 entry-&gt;magick=(IsImageFormatHandler *) IsMGK;
1019 entry-&gt;description=ConstantString("MGK");
1020 entry-&gt;module=ConstantString("MGK");
1021 (void) RegisterMagickInfo(entry);
1022 return(MagickImageCoderSignature);
1023}
1024
1025/*
1026%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
1027% %
1028% %
1029% %
1030% U n r e g i s t e r M G K I m a g e %
1031% %
1032% %
1033% %
1034%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
1035%
1036% UnregisterMGKImage() removes format registrations made by the
1037% MGK module from the list of supported formats.
1038%
1039% The format of the UnregisterMGKImage method is:
1040%
1041% UnregisterMGKImage(void)
1042%
1043*/
1044ModuleExport void UnregisterMGKImage(void)
1045{
1046 (void) UnregisterMagickInfo("MGK");
1047}
1048
1049/*
1050%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
1051% %
1052% %
1053% %
1054% W r i t e M G K I m a g e %
1055% %
1056% %
1057% %
1058%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
1059%
1060% WriteMGKImage() writes an image to a file in red, green, and blue
1061% MGK rasterfile format.
1062%
1063% The format of the WriteMGKImage method is:
1064%
1065% MagickBooleanType WriteMGKImage(const ImageInfo *image_info,Image *image)
1066%
1067% A description of each parameter follows.
1068%
1069% o image_info: the image info.
1070%
1071% o image: The image.
1072%
1073*/
1074static MagickBooleanType WriteMGKImage(const ImageInfo *image_info,Image *image)
1075{
1076 char
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]1077 buffer[MaxTextExtent];
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]1078
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]1079 MagickBooleanType
1080 status;
1081
1082 MagickOffsetType
1083 scene;
1084
1085 register const PixelPacket
1086 *p;
1087
cristyde368992010-11-05 14:32:14 +0000[diff] [blame]1088 register ssize_t
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]1089 x;
1090
1091 register unsigned char
1092 *q;
1093
cristyde368992010-11-05 14:32:14 +0000[diff] [blame]1094 ssize_t
1095 y;
1096
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]1097 unsigned char
1098 *pixels;
1099
1100 /*
1101 Open output image file.
1102 */
1103 assert(image_info != (const ImageInfo *) NULL);
1104 assert(image_info-&gt;signature == MagickSignature);
1105 assert(image != (Image *) NULL);
1106 assert(image-&gt;signature == MagickSignature);
1107 if (image-&gt;debug != MagickFalse)
1108 (void) LogMagickEvent(TraceEvent,GetMagickModule(),"%s",image-&gt;filename);
1109 status=OpenBlob(image_info,image,WriteBinaryBlobMode,&amp;image-&gt;exception);
1110 if (status == MagickFalse)
1111 return(status);
1112 scene=0;
1113 do
1114 {
1115 /*
1116 Allocate memory for pixels.
1117 */
1118 if (image-&gt;colorspace != RGBColorspace)
1119 (void) SetImageColorspace(image,RGBColorspace);
1120 pixels=(unsigned char *) AcquireQuantumMemory((size_t) image-&gt;columns,
1121 3UL*sizeof(*pixels));
1122 if (pixels == (unsigned char *) NULL)
1123 ThrowWriterException(ResourceLimitError,"MemoryAllocationFailed");
1124 /*
1125 Initialize raster file header.
1126 */
1127 (void) WriteBlobString(image,"id=mgk\n");
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]1128 (void) FormatLocaleString(buffer,MaxTextExtent,"%lu %lu\n",
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]1129 image-&gt;columns,image-&gt;rows);
1130 (void) WriteBlobString(image,buffer);
cristyde368992010-11-05 14:32:14 +0000[diff] [blame]1131 for (y=0; y &lt; (ssize_t) image-&gt;rows; y++)
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]1132 {
1133 p=GetVirtualPixels(image,0,y,image-&gt;columns,1,&amp;image-&gt;exception);
1134 if (p == (const PixelPacket *) NULL)
1135 break;
1136 q=pixels;
cristyde368992010-11-05 14:32:14 +0000[diff] [blame]1137 for (x=0; x &lt; (ssize_t) image-&gt;columns; x++)
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]1138 {
cristy29c5c992011-06-25 13:58:49 +0000[diff] [blame]1139 *q++=ScaleQuantumToChar(GetPixelRed(p));
1140 *q++=ScaleQuantumToChar(GetPixelGreen(p));
1141 *q++=ScaleQuantumToChar(GetPixelBlue(p));
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]1142 p++;
1143 }
1144 (void) WriteBlob(image,(size_t) (q-pixels),pixels);
cristydcca3fa2010-12-29 21:50:07 +0000[diff] [blame]1145 if ((image-&gt;previous == (Image *) NULL) &amp;&amp;
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]1146 (SetImageProgress(image,SaveImageTag,y,image-&gt;rows) == MagickFalse))
1147 break;
1148 }
1149 pixels=(unsigned char *) RelinquishMagickMemory(pixels);
1150 if (GetNextImageInList(image) == (Image *) NULL)
1151 break;
1152 image=SyncNextImageInList(image);
1153 status=SetImageProgress(image,SaveImagesTag,scene,
1154 GetImageListLength(image));
1155 if (status == MagickFalse)
1156 break;
1157 scene++;
1158 } while (image_info-&gt;adjoin != MagickFalse);
1159 (void) CloseBlob(image);
1160 return(MagickTrue);
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]1161}</pre>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]1162
1163<p>To invoke the custom coder from the command line, use these commands:</p>
1164
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]1165<pre>convert logo: logo.mgk
1166display logo.mgk
1167</pre>
1168
cristy91469932014-07-25 11:00:25 +0000[diff] [blame]1169<p>We provide the <a href="http://www.imagemagick.org/download/kits/">Magick Coder Kit</a> to help you get started writing your own custom coder.</p>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]1170
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]1171<h2 class="magick-header"><a id="filters"></a>Custom Image Filters</h2>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]1172
cristy44443b92015-05-05 00:06:07 +0000[diff] [blame]1173<p>ImageMagick provides a convenient mechanism for adding your own custom image processing algorithms. We call these image filters and they are invoked from the command line with the <a href="command-line-options.html#process">-process</a> option or from the MagickCore API method <a href="www/api/module.html#ExecuteModuleProcess">ExecuteModuleProcess()</a>.</p>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]1174
cristy8ee7f242013-06-20 16:08:44 +0000[diff] [blame]1175<p>Here is a listing of a sample <a href="../source/analyze.c">custom image filter</a>. It computes a few statistics such as the pixel brightness and saturation mean and standard-deviation.</p>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]1176
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]1177<pre class="pre-scrollable">#include &lt;stdio.h&gt;
cristy76e378e2009-12-21 18:20:04 +0000[diff] [blame]1178#include &lt;stdlib.h&gt;
1179#include &lt;string.h&gt;
1180#include &lt;time.h&gt;
1181#include &lt;assert.h&gt;
1182#include &lt;math.h&gt;
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]1183#include "magick/MagickCore.h"
cristydcca3fa2010-12-29 21:50:07 +0000[diff] [blame]1184
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]1185/*
1186%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
1187% %
1188% %
1189% %
1190% a n a l y z e I m a g e %
1191% %
1192% %
1193% %
1194%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
1195%
cristy76e378e2009-12-21 18:20:04 +0000[diff] [blame]1196% analyzeImage() computes the brightness and saturation mean, standard
cristy52923442011-01-15 22:54:31 +0000[diff] [blame]1197% deviation, kurtosis and skewness and stores these values as attributes
cristy76e378e2009-12-21 18:20:04 +0000[diff] [blame]1198% of the image.
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]1199%
1200% The format of the analyzeImage method is:
1201%
cristy178edaf2011-01-23 03:42:39 +0000[diff] [blame]1202% size_t analyzeImage(Image *images,const int argc,char **argv,
1203% ExceptionInfo *exception)
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]1204%
1205% A description of each parameter follows:
1206%
1207% o image: the address of a structure of type Image.
1208%
1209% o argc: Specifies a pointer to an integer describing the number of
1210% elements in the argument vector.
1211%
1212% o argv: Specifies a pointer to a text array containing the command line
1213% arguments.
1214%
1215% o exception: return any errors or warnings in this structure.
1216%
1217*/
cristy178edaf2011-01-23 03:42:39 +0000[diff] [blame]1218ModuleExport size_t analyzeImage(Image **images,const int argc,const char **argv,
1219 ExceptionInfo *exception)
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]1220{
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]1221 char
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]1222 text[MaxTextExtent];
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]1223
1224 double
1225 area,
cristy76e378e2009-12-21 18:20:04 +0000[diff] [blame]1226 brightness,
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]1227 brightness_mean,
1228 brightness_standard_deviation,
1229 brightness_kurtosis,
1230 brightness_skewness,
1231 brightness_sum_x,
1232 brightness_sum_x2,
1233 brightness_sum_x3,
1234 brightness_sum_x4,
cristy76e378e2009-12-21 18:20:04 +0000[diff] [blame]1235 hue,
1236 saturation,
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]1237 saturation_mean,
1238 saturation_standard_deviation,
1239 saturation_kurtosis,
1240 saturation_skewness,
1241 saturation_sum_x,
1242 saturation_sum_x2,
1243 saturation_sum_x3,
1244 saturation_sum_x4;
1245
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]1246 Image
1247 *image;
1248
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]1249 assert(images != (Image **) NULL);
1250 assert(*images != (Image *) NULL);
cristy76e378e2009-12-21 18:20:04 +0000[diff] [blame]1251 assert((*images)-&gt;signature == MagickSignature);
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]1252 (void) argc;
1253 (void) argv;
1254 image=(*images);
1255 for ( ; image != (Image *) NULL; image=GetNextImageInList(image))
1256 {
cristy76e378e2009-12-21 18:20:04 +0000[diff] [blame]1257 CacheView
1258 *image_view;
1259
cristy76e378e2009-12-21 18:20:04 +0000[diff] [blame]1260 MagickBooleanType
1261 status;
1262
cristyde368992010-11-05 14:32:14 +0000[diff] [blame]1263 ssize_t
1264 y;
1265
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]1266 brightness_sum_x=0.0;
1267 brightness_sum_x2=0.0;
1268 brightness_sum_x3=0.0;
1269 brightness_sum_x4=0.0;
1270 brightness_mean=0.0;
1271 brightness_standard_deviation=0.0;
1272 brightness_kurtosis=0.0;
1273 brightness_skewness=0.0;
1274 saturation_sum_x=0.0;
1275 saturation_sum_x2=0.0;
1276 saturation_sum_x3=0.0;
1277 saturation_sum_x4=0.0;
1278 saturation_mean=0.0;
1279 saturation_standard_deviation=0.0;
1280 saturation_kurtosis=0.0;
1281 saturation_skewness=0.0;
1282 area=0.0;
cristy76e378e2009-12-21 18:20:04 +0000[diff] [blame]1283 status=MagickTrue;
cristy8ee7f242013-06-20 16:08:44 +0000[diff] [blame]1284 image_view=AcquireVirtualCacheView(image,exception);
cristy76e378e2009-12-21 18:20:04 +0000[diff] [blame]1285#if defined(MAGICKCORE_OPENMP_SUPPORT)
1286 #pragma omp parallel for schedule(dynamic,4) shared(status)
1287#endif
cristyde368992010-11-05 14:32:14 +0000[diff] [blame]1288 for (y=0; y &lt; (ssize_t) image-&gt;rows; y++)
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]1289 {
cristy76e378e2009-12-21 18:20:04 +0000[diff] [blame]1290 register const PixelPacket
1291 *p;
1292
cristyde368992010-11-05 14:32:14 +0000[diff] [blame]1293 register ssize_t
cristy76e378e2009-12-21 18:20:04 +0000[diff] [blame]1294 x;
1295
1296 if (status == MagickFalse)
1297 continue;
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]1298 p=GetCacheViewVirtualPixels(image_view,0,y,image-&gt;columns,1,exception);
1299 if (p == (const PixelPacket *) NULL)
cristy76e378e2009-12-21 18:20:04 +0000[diff] [blame]1300 {
1301 status=MagickFalse;
1302 continue;
1303 }
cristyde368992010-11-05 14:32:14 +0000[diff] [blame]1304 for (x=0; x &lt; (ssize_t) image-&gt;columns; x++)
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]1305 {
cristy29c5c992011-06-25 13:58:49 +0000[diff] [blame]1306 ConvertRGBToHSB(GetPixelRed(p),GetPixelGreen(p),GetPixelBue(p),&amp;hue,&amp;saturation,&amp;brightness);
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]1307 brightness*=QuantumRange;
1308 brightness_sum_x+=brightness;
1309 brightness_sum_x2+=brightness*brightness;
1310 brightness_sum_x3+=brightness*brightness*brightness;
1311 brightness_sum_x4+=brightness*brightness*brightness*brightness;
1312 saturation*=QuantumRange;
1313 saturation_sum_x+=saturation;
1314 saturation_sum_x2+=saturation*saturation;
1315 saturation_sum_x3+=saturation*saturation*saturation;
1316 saturation_sum_x4+=saturation*saturation*saturation*saturation;
1317 area++;
1318 p++;
1319 }
1320 }
1321 image_view=DestroyCacheView(image_view);
1322 if (area &lt;= 0.0)
1323 break;
1324 brightness_mean=brightness_sum_x/area;
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]1325 (void) FormatLocaleString(text,MaxTextExtent,"%g",brightness_mean);
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]1326 (void) SetImageProperty(image,"filter:brightness:mean",text);
1327 brightness_standard_deviation=sqrt(brightness_sum_x2/area-(brightness_sum_x/
1328 area*brightness_sum_x/area));
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]1329 (void) FormatLocaleString(text,MaxTextExtent,"%g",
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]1330 brightness_standard_deviation);
1331 (void) SetImageProperty(image,"filter:brightness:standard-deviation",text);
1332 if (brightness_standard_deviation != 0)
1333 brightness_kurtosis=(brightness_sum_x4/area-4.0*brightness_mean*
1334 brightness_sum_x3/area+6.0*brightness_mean*brightness_mean*
1335 brightness_sum_x2/area-3.0*brightness_mean*brightness_mean*
1336 brightness_mean*brightness_mean)/(brightness_standard_deviation*
1337 brightness_standard_deviation*brightness_standard_deviation*
1338 brightness_standard_deviation)-3.0;
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]1339 (void) FormatLocaleString(text,MaxTextExtent,"%g",brightness_kurtosis);
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]1340 (void) SetImageProperty(image,"filter:brightness:kurtosis",text);
1341 if (brightness_standard_deviation != 0)
1342 brightness_skewness=(brightness_sum_x3/area-3.0*brightness_mean*
1343 brightness_sum_x2/area+2.0*brightness_mean*brightness_mean*
1344 brightness_mean)/(brightness_standard_deviation*
1345 brightness_standard_deviation*brightness_standard_deviation);
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]1346 (void) FormatLocaleString(text,MaxTextExtent,"%g",brightness_skewness);
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]1347 (void) SetImageProperty(image,"filter:brightness:skewness",text);
1348 saturation_mean=saturation_sum_x/area;
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]1349 (void) FormatLocaleString(text,MaxTextExtent,"%g",saturation_mean);
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]1350 (void) SetImageProperty(image,"filter:saturation:mean",text);
1351 saturation_standard_deviation=sqrt(saturation_sum_x2/area-(saturation_sum_x/
1352 area*saturation_sum_x/area));
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]1353 (void) FormatLocaleString(text,MaxTextExtent,"%g",
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]1354 saturation_standard_deviation);
1355 (void) SetImageProperty(image,"filter:saturation:standard-deviation",text);
1356 if (saturation_standard_deviation != 0)
1357 saturation_kurtosis=(saturation_sum_x4/area-4.0*saturation_mean*
1358 saturation_sum_x3/area+6.0*saturation_mean*saturation_mean*
1359 saturation_sum_x2/area-3.0*saturation_mean*saturation_mean*
1360 saturation_mean*saturation_mean)/(saturation_standard_deviation*
1361 saturation_standard_deviation*saturation_standard_deviation*
1362 saturation_standard_deviation)-3.0;
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]1363 (void) FormatLocaleString(text,MaxTextExtent,"%g",saturation_kurtosis);
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]1364 (void) SetImageProperty(image,"filter:saturation:kurtosis",text);
1365 if (saturation_standard_deviation != 0)
1366 saturation_skewness=(saturation_sum_x3/area-3.0*saturation_mean*
1367 saturation_sum_x2/area+2.0*saturation_mean*saturation_mean*
1368 saturation_mean)/(saturation_standard_deviation*
1369 saturation_standard_deviation*saturation_standard_deviation);
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]1370 (void) FormatLocaleString(text,MaxTextExtent,"%g",saturation_skewness);
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]1371 (void) SetImageProperty(image,"filter:saturation:skewness",text);
1372 }
1373 return(MagickImageFilterSignature);
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]1374}</pre>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]1375
1376<p>To invoke the custom filter from the command line, use this command:</p>
1377
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame]1378<pre>convert logo: -process \"analyze\" -verbose info:
1379 Image: logo:
1380 Format: LOGO (ImageMagick Logo)
1381 Class: PseudoClass
1382 Geometry: 640x480
1383 ...
1384 filter:brightness:kurtosis: 8.17947
1385 filter:brightness:mean: 60632.1
1386 filter:brightness:skewness: -2.97118
1387 filter:brightness:standard-deviation: 13742.1
1388 filter:saturation:kurtosis: 4.33554
1389 filter:saturation:mean: 5951.55
1390 filter:saturation:skewness: 2.42848
1391 filter:saturation:standard-deviation: 15575.9
1392</pre>
1393
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]1394
cristy91469932014-07-25 11:00:25 +0000[diff] [blame]1395<p>We provide the <a href="http://www.imagemagick.org/download/kits/">Magick Filter Kit</a> to help you get started writing your own custom image filter.</p>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]1396
1397</div>
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