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150
151</div>
152
153<div class="main">
154
cristyf0d1f5d2010-05-13 16:29:38 +0000[diff] [blame]155<p class="navigation-index">[<a href="#same variable That is the IsNaN">same variable That is the IsNaN</a> &bull; <a href="#AcquireKernelInfo">AcquireKernelInfo</a> &bull; <a href="#AcquireKernelBuiltIn">AcquireKernelBuiltIn</a> &bull; <a href="#CloneKernelInfo">CloneKernelInfo</a> &bull; <a href="#DestroyKernelInfo">DestroyKernelInfo</a> &bull; <a href="#ExpandKernelInfo">ExpandKernelInfo</a> &bull; <a href="#MorphologyImageChannel">MorphologyImageChannel</a> &bull; <a href="#ScaleKernelInfo">ScaleKernelInfo</a>]</p>
cristyd2baf7d2010-03-06 04:26:44 +0000[diff] [blame]156
157<h2><a href="http://www.imagemagick.org/api/MagickCore/morphology
158_8c.html" target="source" name="same variable That is the IsNaN">same variable That is the IsNaN</a></h2>
159<div class="doc-section">
160
161<p>same variable That is the IsNaN() macro is only true if the value is NaN. </p>
162 </div>
163<h2><a href="http://www.imagemagick.org/api/MagickCore/morphology
164_8c.html" target="source" name="AcquireKernelInfo">AcquireKernelInfo</a></h2>
165<div class="doc-section">
166
167<p>AcquireKernelInfo() takes the given string (generally supplied by the user) and converts it into a Morphology/Convolution Kernel. This allows users to specify a kernel from a number of pre-defined kernels, or to fully specify their own kernel for a specific Convolution or Morphology Operation.</p></ol>
168
169<p>The kernel so generated can be any rectangular array of floating point values (doubles) with the 'control point' or 'pixel being affected' anywhere within that array of values.</p></ol>
170
171<p>Previously IM was restricted to a square of odd size using the exact center as origin, this is no longer the case, and any rectangular kernel with any value being declared the origin. This in turn allows the use of highly asymmetrical kernels.</p></ol>
172
173<p>The floating point values in the kernel can also include a special value known as 'nan' or 'not a number' to indicate that this value is not part of the kernel array. This allows you to shaped the kernel within its rectangular area. That is 'nan' values provide a 'mask' for the kernel shape. However at least one non-nan value must be provided for correct working of a kernel.</p></ol>
174
cristyf0d1f5d2010-05-13 16:29:38 +0000[diff] [blame]175<p>The returned kernel should be freed using the DestroyKernelInfo() when you are finished with it. Do not free this memory yourself.</p></ol>
cristyd2baf7d2010-03-06 04:26:44 +0000[diff] [blame]176
177<p>Input kernel defintion strings can consist of any of three types.</p></ol>
178
179<p>"name:args" Select from one of the built in kernels, using the name and geometry arguments supplied. See AcquireKernelBuiltIn()</p></ol>
180
cristyf0d1f5d2010-05-13 16:29:38 +0000[diff] [blame]181<p>"WxH[+X+Y]:num, num, num ..." a kernel of size W by H, with W*H floating point numbers following. the 'center' can be optionally be defined at +X+Y (such that +0+0 is top left corner). If not defined the pixel in the center, for odd sizes, or to the immediate top or left of center for even sizes is automatically selected.</p></ol>
cristyd2baf7d2010-03-06 04:26:44 +0000[diff] [blame]182
183<p>"num, num, num, num, ..." list of floating point numbers defining an 'old style' odd sized square kernel. At least 9 values should be provided for a 3x3 square kernel, 25 for a 5x5 square kernel, 49 for 7x7, etc. Values can be space or comma separated. This is not recommended.</p></ol>
184
185<p>Note that 'name' kernels will start with an alphabetic character while the new kernel specification has a ':' character in its specification string. If neither is the case, it is assumed an old style of a simple list of numbers generating a odd-sized square kernel has been given.</p></ol>
186
cristyf0d1f5d2010-05-13 16:29:38 +0000[diff] [blame]187<p>You can define a 'list of kernels' which can be used by some morphology operators A list is defined as a semi-colon seperated list kernels.</p></ol>
188
189<p>" kernel ; kernel ; kernel ; "</p></ol>
190
191<p>Extra ';' characters are simply ignored.</p></ol>
192
cristyd2baf7d2010-03-06 04:26:44 +0000[diff] [blame]193<p>The format of the AcquireKernal method is:</p>
194
195<pre class="code">
196 KernelInfo *AcquireKernelInfo(const char *kernel_string)
197</pre>
198
199<p>A description of each parameter follows:</p></ol>
200
201<h5>kernel_string</h5>
202<ol><p>the Morphology/Convolution kernel wanted.</p></ol>
203
204 </div>
205<h2><a href="http://www.imagemagick.org/api/MagickCore/morphology
206_8c.html" target="source" name="AcquireKernelBuiltIn">AcquireKernelBuiltIn</a></h2>
207<div class="doc-section">
208
209<p>AcquireKernelBuiltIn() returned one of the 'named' built-in types of kernels used for special purposes such as gaussian blurring, skeleton pruning, and edge distance determination.</p></ol>
210
211<p>They take a KernelType, and a set of geometry style arguments, which were typically decoded from a user supplied string, or from a more complex Morphology Method that was requested.</p></ol>
212
213<p>The format of the AcquireKernalBuiltIn method is:</p>
214
215<pre class="code">
216 KernelInfo *AcquireKernelBuiltIn(const KernelInfoType type,
217 const GeometryInfo args)
218</pre>
219
220<p>A description of each parameter follows:</p></ol>
221
222<h5>type</h5>
223<ol><p>the pre-defined type of kernel wanted</p></ol>
224
225<h5>args</h5>
226<ol><p>arguments defining or modifying the kernel</p></ol>
227
228<p>Convolution Kernels</p></ol>
229
cristyf1310b52010-05-15 16:42:04 +0000[diff] [blame]230<p>Gaussian:{radius},{sigma} Generate a two-dimentional gaussian kernel, as used by -gaussian. The sigma for the curve is required. The resulting kernel is normalized,</p></ol>
231
232<p>If 'sigma' is zero, you get a single pixel on a field of zeros.</p></ol>
cristyd2baf7d2010-03-06 04:26:44 +0000[diff] [blame]233
234<p>NOTE: that the 'radius' is optional, but if provided can limit (clip) the final size of the resulting kernel to a square 2*radius+1 in size. The radius should be at least 2 times that of the sigma value, or sever clipping and aliasing may result. If not given or set to 0 the radius will be determined so as to produce the best minimal error result, which is usally much larger than is normally needed.</p></ol>
235
cristyf1310b52010-05-15 16:42:04 +0000[diff] [blame]236<p>DOG:{radius},{sigma1},{sigma2} "Difference of Gaussians" Kernel. As "Gaussian" but with a gaussian produced by 'sigma2' subtracted from the gaussian produced by 'sigma1'. Typically sigma2 > sigma1. The result is a zero-summing kernel.</p></ol>
cristyd2baf7d2010-03-06 04:26:44 +0000[diff] [blame]237
cristyf1310b52010-05-15 16:42:04 +0000[diff] [blame]238<p>Blur:{radius},{sigma}[,{angle}] Generates a 1 dimensional or linear gaussian blur, at the angle given (current restricted to orthogonal angles). If a 'radius' is given the kernel is clipped to a width of 2*radius+1. Kernel can be rotated by a 90 degree angle.</p></ol>
239
240<p>If 'sigma' is zero, you get a single pixel on a field of zeros.</p></ol>
241
242<p>Note that two convolutions with two "Blur" kernels perpendicular to each other, is equivelent to a far larger "Gaussian" kernel with the same sigma value, However it is much faster to apply. This is how the "-blur" operator actually works.</p></ol>
243
244<p>DOB:{radius},{sigma1},{sigma2}[,{angle}] "Difference of Blurs" Kernel. As "Blur" but with the 1D gaussian produced by 'sigma2' subtracted from thethe 1D gaussian produced by 'sigma1'. The result is a zero-summing kernel.</p></ol>
245
246<p>This can be used to generate a faster "DOG" convolution, in the same way "Blur" can.</p></ol>
cristyd2baf7d2010-03-06 04:26:44 +0000[diff] [blame]247
cristyf0d1f5d2010-05-13 16:29:38 +0000[diff] [blame]248<p>Comet:{width},{sigma},{angle} Blur in one direction only, much like how a bright object leaves a comet like trail. The Kernel is actually half a gaussian curve, Adding two such blurs in opposite directions produces a Blur Kernel. Angle can be rotated in multiples of 90 degrees.</p></ol>
cristyd2baf7d2010-03-06 04:26:44 +0000[diff] [blame]249
cristyf0d1f5d2010-05-13 16:29:38 +0000[diff] [blame]250<p>Note that the first argument is the width of the kernel and not the radius of the kernel.</p></ol>
cristyd2baf7d2010-03-06 04:26:44 +0000[diff] [blame]251
cristyf1310b52010-05-15 16:42:04 +0000[diff] [blame]252<p># Still to be implemented... # # Filter2D # Filter1D # Set kernel values using a resize filter, and given scale (sigma) # Cylindrical or Linear. Is this posible with an image? #</p></ol>
cristyf0d1f5d2010-05-13 16:29:38 +0000[diff] [blame]253
254<p>Named Constant Convolution Kernels</p></ol>
255
cristyf1310b52010-05-15 16:42:04 +0000[diff] [blame]256<p>All these are unscaled, zero-summing kernels by default. As such for non-HDRI version of ImageMagick some form of normalization, user scaling, and biasing the results is recommended, to prevent the resulting image being 'clipped'.</p></ol>
cristyf0d1f5d2010-05-13 16:29:38 +0000[diff] [blame]257
cristyf1310b52010-05-15 16:42:04 +0000[diff] [blame]258<p>The 3x3 kernels (most of these) can be circularly rotated in multiples of 45 degrees to generate the 8 angled varients of each of the kernels.</p></ol>
259
260<p>Laplacian:{type} Generate Lapacian kernel of the type specified. (1 is the default) Type 0 : 3x3 with center:8 surounded by -1 (8 neighbourhood) Type 1 : 3x3 with center:4 edge:-1 corner:0 (4 neighbourhood) Type 2 : 3x3 with center:4 edge:-2 corner:1 Type 3 : 3x3 with center:4 edge:1 corner:-2 Type 4 : 5x5 laplacian Type 5 : 7x7 laplacian</p></ol>
261
262<p>Sobel:{angle} Sobel 3x3 'Edge' convolution kernel (3x3) -1, 0, 1 -2, 0,-2 -1, 0, 1 Roberts:{angle} Roberts 3x3 convolution kernel (3x3) 0, 0, 0 -1, 1, 0 0, 0, 0 Compass:{angle} Prewitt's "Compass" convolution kernel (3x3) -1, 1, 1 -1,-2, 1 -1, 1, 1 Prewitt:{angle} Prewitt Edge convolution kernel (3x3) -1, 0, 1 -1, 0, 1 -1, 0, 1</p></ol>
cristyd2baf7d2010-03-06 04:26:44 +0000[diff] [blame]263
264<p>Boolean Kernels</p></ol>
265
cristyf0d1f5d2010-05-13 16:29:38 +0000[diff] [blame]266<p>Diamond:[{radius}[,{scale}]] Generate a diamond shaped kernel with given radius to the points. Kernel size will again be radius*2+1 square and defaults to radius 1, generating a 3x3 kernel that is slightly larger than a square.</p></ol>
cristyd2baf7d2010-03-06 04:26:44 +0000[diff] [blame]267
cristyf0d1f5d2010-05-13 16:29:38 +0000[diff] [blame]268<p>Square:[{radius}[,{scale}]] Generate a square shaped kernel of size radius*2+1, and defaulting to a 3x3 (radius 1).</p></ol>
cristyd2baf7d2010-03-06 04:26:44 +0000[diff] [blame]269
cristyf1310b52010-05-15 16:42:04 +0000[diff] [blame]270<p>Note that using a larger radius for the "Square" or the "Diamond" is also equivelent to iterating the basic morphological method that many times. However iterating with the smaller radius is actually faster than using a larger kernel radius.</p></ol>
cristyd2baf7d2010-03-06 04:26:44 +0000[diff] [blame]271
cristyf1310b52010-05-15 16:42:04 +0000[diff] [blame]272<p>Rectangle:{geometry} Simply generate a rectangle of 1's with the size given. You can also specify the location of the 'control point', otherwise the closest pixel to the center of the rectangle is selected.</p></ol>
273
274<p>Properly centered and odd sized rectangles work the best.</p></ol>
275
276<p>Disk:[{radius}[,{scale}]] Generate a binary disk of the radius given, radius may be a float. Kernel size will be ceil(radius)*2+1 square. NOTE: Here are some disk shapes of specific interest "Disk:1" => "diamond" or "cross:1" "Disk:1.5" => "square" "Disk:2" => "diamond:2" "Disk:2.5" => a general disk shape of radius 2 "Disk:2.9" => "square:2" "Disk:3.5" => default - octagonal/disk shape of radius 3 "Disk:4.2" => roughly octagonal shape of radius 4 "Disk:4.3" => a general disk shape of radius 4 After this all the kernel shape becomes more and more circular.</p></ol>
cristyd2baf7d2010-03-06 04:26:44 +0000[diff] [blame]277
278<p>Because a "disk" is more circular when using a larger radius, using a larger radius is preferred over iterating the morphological operation.</p></ol>
279
cristyf1310b52010-05-15 16:42:04 +0000[diff] [blame]280<p>Symbol Dilation Kernels</p></ol>
cristyd2baf7d2010-03-06 04:26:44 +0000[diff] [blame]281
cristyf1310b52010-05-15 16:42:04 +0000[diff] [blame]282<p>These kernel is not a good general morphological kernel, but is used more for highlighting and marking any single pixels in an image using, a "Dilate" method as appropriate.</p></ol>
cristy6f6c2962010-05-14 01:39:00 +0000[diff] [blame]283
284<p>For the same reasons iterating these kernels does not produce the same result as using a larger radius for the symbol.</p></ol>
285
cristyf1310b52010-05-15 16:42:04 +0000[diff] [blame]286<p>Plus:[{radius}[,{scale}]] Cross:[{radius}[,{scale}]] Generate a kernel in the shape of a 'plus' or a 'cross' with a each arm the length of the given radius (default 2).</p></ol>
287
288<p>NOTE: "plus:1" is equivelent to a "Diamond" kernel.</p></ol>
289
290<p>Ring:{radius1},{radius2}[,{scale}] A ring of the values given that falls between the two radii. Defaults to a ring of approximataly 3 radius in a 7x7 kernel. This is the 'edge' pixels of the default "Disk" kernel, More specifically, "Ring" -> "Ring:2.5,3.5,1.0"</p></ol>
291
cristy6f6c2962010-05-14 01:39:00 +0000[diff] [blame]292<p>Hit and Miss Kernels</p></ol>
293
cristyf1310b52010-05-15 16:42:04 +0000[diff] [blame]294<p>Peak:radius1,radius2 Find any peak larger than the pixels the fall between the two radii. The default ring of pixels is as per "Ring". Corners Find corners of a binary shape LineEnds Find end points of lines (for pruning a skeletion) LineJunctions Find three line junctions (in a skeletion) ConvexHull Octagonal thicken kernel, to generate convex hulls of 45 degrees Skeleton Thinning kernel, which leaves behind a skeletion of a shape</p></ol>
cristyd2baf7d2010-03-06 04:26:44 +0000[diff] [blame]295
296<p>Distance Measuring Kernels</p></ol>
297
cristyd2baf7d2010-03-06 04:26:44 +0000[diff] [blame]298<p>Different types of distance measuring methods, which are used with the a 'Distance' morphology method for generating a gradient based on distance from an edge of a binary shape, though there is a technique for handling a anti-aliased shape.</p></ol>
299
cristyf1310b52010-05-15 16:42:04 +0000[diff] [blame]300<p>See the 'Distance' Morphological Method, for information of how it is applied.</p></ol>
cristyd2baf7d2010-03-06 04:26:44 +0000[diff] [blame]301
cristyf1310b52010-05-15 16:42:04 +0000[diff] [blame]302<p>Chebyshev:[{radius}][x{scale}[!]] Chebyshev Distance (also known as Tchebychev Distance) is a value of one to any neighbour, orthogonal or diagonal. One why of thinking of it is the number of squares a 'King' or 'Queen' in chess needs to traverse reach any other position on a chess board. It results in a 'square' like distance function, but one where diagonals are closer than expected.</p></ol>
cristyd2baf7d2010-03-06 04:26:44 +0000[diff] [blame]303
cristyf1310b52010-05-15 16:42:04 +0000[diff] [blame]304<p>Manhatten:[{radius}][x{scale}[!]] Manhatten Distance (also known as Rectilinear Distance, or the Taxi Cab metric), is the distance needed when you can only travel in orthogonal (horizontal or vertical) only. It is the distance a 'Rook' in chess would travel. It results in a diamond like distances, where diagonals are further than expected.</p></ol>
305
306<p>Euclidean:[{radius}][x{scale}[!]] Euclidean Distance is the 'direct' or 'as the crow flys distance. However by default the kernel size only has a radius of 1, which limits the distance to 'Knight' like moves, with only orthogonal and diagonal measurements being correct. As such for the default kernel you will get octagonal like distance function, which is reasonally accurate.</p></ol>
cristyd2baf7d2010-03-06 04:26:44 +0000[diff] [blame]307
308<p>However if you use a larger radius such as "Euclidean:4" you will get a much smoother distance gradient from the edge of the shape. Of course a larger kernel is slower to use, and generally not needed.</p></ol>
309
310<p>To allow the use of fractional distances that you get with diagonals the actual distance is scaled by a fixed value which the user can provide. This is not actually nessary for either ""Chebyshev" or "Manhatten" distance kernels, but is done for all three distance kernels. If no scale is provided it is set to a value of 100, allowing for a maximum distance measurement of 655 pixels using a Q16 version of IM, from any edge. However for small images this can result in quite a dark gradient.</p></ol>
311
cristyd2baf7d2010-03-06 04:26:44 +0000[diff] [blame]312 </div>
313<h2><a href="http://www.imagemagick.org/api/MagickCore/morphology
314_8c.html" target="source" name="CloneKernelInfo">CloneKernelInfo</a></h2>
315<div class="doc-section">
316
cristyf0d1f5d2010-05-13 16:29:38 +0000[diff] [blame]317<p>CloneKernelInfo() creates a new clone of the given Kernel List so that its can be modified without effecting the original. The cloned kernel should be destroyed using DestoryKernelInfo() when no longer needed.</p></ol>
cristyd2baf7d2010-03-06 04:26:44 +0000[diff] [blame]318
cristy0291e2d2010-04-04 17:50:18 +0000[diff] [blame]319<p>The format of the CloneKernelInfo method is:</p>
cristyd2baf7d2010-03-06 04:26:44 +0000[diff] [blame]320
321<pre class="code">
322 KernelInfo *CloneKernelInfo(const KernelInfo *kernel)
323</pre>
324
325<p>A description of each parameter follows:</p></ol>
326
327<h5>kernel</h5>
328<ol><p>the Morphology/Convolution kernel to be cloned</p></ol>
329
330 </div>
331<h2><a href="http://www.imagemagick.org/api/MagickCore/morphology
332_8c.html" target="source" name="DestroyKernelInfo">DestroyKernelInfo</a></h2>
333<div class="doc-section">
334
335<p>DestroyKernelInfo() frees the memory used by a Convolution/Morphology kernel.</p></ol>
336
337<p>The format of the DestroyKernelInfo method is:</p>
338
339<pre class="code">
340 KernelInfo *DestroyKernelInfo(KernelInfo *kernel)
341</pre>
342
343<p>A description of each parameter follows:</p></ol>
344
345<h5>kernel</h5>
346<ol><p>the Morphology/Convolution kernel to be destroyed</p></ol>
347
348 </div>
349<h2><a href="http://www.imagemagick.org/api/MagickCore/morphology
cristyf0d1f5d2010-05-13 16:29:38 +0000[diff] [blame]350_8c.html" target="source" name="ExpandKernelInfo">ExpandKernelInfo</a></h2>
351<div class="doc-section">
352
353<p>ExpandKernelInfo() takes a single kernel, and expands it into a list of kernels each incrementally rotated the angle given.</p></ol>
354
355<p>WARNING: 45 degree rotations only works for 3x3 kernels. While 90 degree roatations only works for linear and square kernels</p></ol>
356
357<p>The format of the RotateKernelInfo method is:</p>
358
359<pre class="code">
360 void ExpandKernelInfo(KernelInfo *kernel, double angle)
361</pre>
362
363<p>A description of each parameter follows:</p></ol>
364
365<h5>kernel</h5>
366<ol><p>the Morphology/Convolution kernel</p></ol>
367
368<h5>angle</h5>
369<ol><p>angle to rotate in degrees</p></ol>
370
371<p>This function is only internel to this module, as it is not finalized, especially with regard to non-orthogonal angles, and rotation of larger 2D kernels. </p>
372 </div>
373<h2><a href="http://www.imagemagick.org/api/MagickCore/morphology
cristyd2baf7d2010-03-06 04:26:44 +0000[diff] [blame]374_8c.html" target="source" name="MorphologyImageChannel">MorphologyImageChannel</a></h2>
375<div class="doc-section">
376
377<p>MorphologyImageChannel() applies a user supplied kernel to the image according to the given mophology method.</p></ol>
378
379<p>The given kernel is assumed to have been pre-scaled appropriatally, usally by the kernel generator.</p></ol>
380
381<p>The format of the MorphologyImage method is:</p>
382
383<pre class="code">
384 Image *MorphologyImage(const Image *image,MorphologyMethod method,
385 const long iterations,KernelInfo *kernel,ExceptionInfo *exception)
386 Image *MorphologyImageChannel(const Image *image, const ChannelType
387 channel,MorphologyMethod method,const long iterations,
388 KernelInfo *kernel,ExceptionInfo *exception)
389</pre>
390
391<p>A description of each parameter follows:</p></ol>
392
393<h5>image</h5>
394<ol><p>the image.</p></ol>
395
396<h5>method</h5>
397<ol><p>the morphology method to be applied.</p></ol>
398
399<h5>iterations</h5>
400<ol><p>apply the operation this many times (or no change). A value of -1 means loop until no change found. How this is applied may depend on the morphology method. Typically this is a value of 1.</p></ol>
401
402<h5>channel</h5>
403<ol><p>the channel type.</p></ol>
404
405<h5>kernel</h5>
406<ol><p>An array of double representing the morphology kernel. Warning: kernel may be normalized for the Convolve method.</p></ol>
407
408<h5>exception</h5>
409<ol><p>return any errors or warnings in this structure.</p></ol>
410
411
412<p>TODO: bias and auto-scale handling of the kernel for convolution The given kernel is assumed to have been pre-scaled appropriatally, usally by the kernel generator.</p></ol>
413
414 </div>
415<h2><a href="http://www.imagemagick.org/api/MagickCore/morphology
416_8c.html" target="source" name="ScaleKernelInfo">ScaleKernelInfo</a></h2>
417<div class="doc-section">
418
cristyf0d1f5d2010-05-13 16:29:38 +0000[diff] [blame]419<p>ScaleKernelInfo() scales the given kernel list by the given amount, with or without normalization of the sum of the kernel values (as per given flags).</p></ol>
cristyd2baf7d2010-03-06 04:26:44 +0000[diff] [blame]420
cristyf0d1f5d2010-05-13 16:29:38 +0000[diff] [blame]421<p>By default (no flags given) the values within the kernel is scaled directly using given scaling factor without change.</p></ol>
cristyd2baf7d2010-03-06 04:26:44 +0000[diff] [blame]422
cristyf0d1f5d2010-05-13 16:29:38 +0000[diff] [blame]423<p>If any 'normalize_flags' are given the kernel will first be normalized and then further scaled by the scaling factor value given. A 'PercentValue' flag will cause the given scaling factor to be divided by one hundred percent.</p></ol>
cristyd2baf7d2010-03-06 04:26:44 +0000[diff] [blame]424
cristyf0d1f5d2010-05-13 16:29:38 +0000[diff] [blame]425<p>Kernel normalization ('normalize_flags' given) is designed to ensure that any use of the kernel scaling factor with 'Convolve' or 'Correlate' morphology methods will fall into -1.0 to +1.0 range. Note that for non-HDRI versions of IM this may cause images to have any negative results clipped, unless some 'bias' is used.</p></ol>
cristyd2baf7d2010-03-06 04:26:44 +0000[diff] [blame]426
cristyf0d1f5d2010-05-13 16:29:38 +0000[diff] [blame]427<p>More specifically. Kernels which only contain positive values (such as a 'Gaussian' kernel) will be scaled so that those values sum to +1.0, ensuring a 0.0 to +1.0 output range for non-HDRI images.</p></ol>
cristyd2baf7d2010-03-06 04:26:44 +0000[diff] [blame]428
429<p>For Kernels that contain some negative values, (such as 'Sharpen' kernels) the kernel will be scaled by the absolute of the sum of kernel values, so that it will generally fall within the +/- 1.0 range.</p></ol>
430
431<p>For kernels whose values sum to zero, (such as 'Laplician' kernels) kernel will be scaled by just the sum of the postive values, so that its output range will again fall into the +/- 1.0 range.</p></ol>
432
433<p>For special kernels designed for locating shapes using 'Correlate', (often only containing +1 and -1 values, representing foreground/brackground matching) a special normalization method is provided to scale the positive values seperatally to those of the negative values, so the kernel will be forced to become a zero-sum kernel better suited to such searches.</p></ol>
434
cristyf0d1f5d2010-05-13 16:29:38 +0000[diff] [blame]435<p>WARNING: Correct normalization of the kernel assumes that the '*_range' attributes within the kernel structure have been correctly set during the kernels creation.</p></ol>
cristyd2baf7d2010-03-06 04:26:44 +0000[diff] [blame]436
437<p>NOTE: The values used for 'normalize_flags' have been selected specifically to match the use of geometry options, so that '!' means NormalizeValue, '^' means CorrelateNormalizeValue, and '' means PercentValue. All other GeometryFlags values are ignored.</p></ol>
438
439<p>The format of the ScaleKernelInfo method is:</p>
440
441<pre class="code">
442 void ScaleKernelInfo(KernelInfo *kernel, const double scaling_factor,
443 const MagickStatusType normalize_flags )
444</pre>
445
446<p>A description of each parameter follows:</p></ol>
447
448<h5>kernel</h5>
449<ol><p>the Morphology/Convolution kernel</p></ol>
450
451<p>o scaling_factor:</p>
452
453<pre class="text">
454 zero. If the kernel is normalized regardless of any flags.
455</pre>
456
457<p>o normalize_flags:</p>
458
459<pre class="text">
460 specifically: NormalizeValue, CorrelateNormalizeValue,
461 and/or PercentValue
462</pre>
463
464<p>This function is internal to this module only at this time, but can be exported to other modules if needed. </p>
465 </div>
cristy3eaa0ef2010-03-06 20:35:26 +0000[diff] [blame]466
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