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12 <title>ImageMagick: MagickCore, C API for ImageMagick: Enhance an Image</title>
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162
163<div class="main">
164
cristy16ff93c2010-01-13 23:18:07 +0000[diff] [blame]165<p class="navigation-index">[<a href="#AutoGammaImage">AutoGammaImage</a> &bull; <a href="#AutoLevelImage">AutoLevelImage</a> &bull; <a href="#Use BrightnessContrastImage">Use BrightnessContrastImage</a> &bull; <a href="#ColorDecisionListImage">ColorDecisionListImage</a> &bull; <a href="#ClutImage">ClutImage</a> &bull; <a href="#ContrastImage">ContrastImage</a> &bull; <a href="#The ContrastStretchImage">The ContrastStretchImage</a> &bull; <a href="#EnhanceImage">EnhanceImage</a> &bull; <a href="#EqualizeImage">EqualizeImage</a> &bull; <a href="#GammaImage">GammaImage</a> &bull; <a href="#HaldClutImage">HaldClutImage</a> &bull; <a href="#LevelImage">LevelImage</a> &bull; <a href="#LevelizeImage">LevelizeImage</a> &bull; <a href="#LevelizeImageChannel">LevelizeImageChannel</a> &bull; <a href="#LevelImageColor">LevelImageColor</a> &bull; <a href="#The LinearStretchImage">The LinearStretchImage</a> &bull; <a href="#ModulateImage">ModulateImage</a> &bull; <a href="#NegateImage">NegateImage</a> &bull; <a href="#The NormalizeImage">The NormalizeImage</a> &bull; <a href="#SigmoidalContrastImage">SigmoidalContrastImage</a>]</p>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]166
167<h2><a href="http://www.imagemagick.org/api/MagickCore/enhance
168_8c.html" target="source" name="AutoGammaImage">AutoGammaImage</a></h2>
169<div class="doc-section">
170
171<p>AutoGammaImage() extract the 'mean' from the image and adjust the image to try make set its gamma appropriatally.</p></ol>
172
cristy5cadd612009-09-21 19:33:41 +0000[diff] [blame]173<p>The format of the AutoGammaImage method is:</p>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]174
175<pre class="code">
176 MagickBooleanType AutoGammaImage(Image *image)
177 MagickBooleanType AutoGammaImageChannel(Image *image,
178 const ChannelType channel)
179</pre>
180
181<p>A description of each parameter follows:</p></ol>
182
183<h5>image</h5>
184<ol><p>The image to auto-level</p></ol>
185
186<h5>channel</h5>
187<ol><p>The channels to auto-level. If the special 'SyncChannels' flag is set all given channels is adjusted in the same way using the mean average of those channels.</p></ol>
188
189 </div>
190<h2><a href="http://www.imagemagick.org/api/MagickCore/enhance
191_8c.html" target="source" name="AutoLevelImage">AutoLevelImage</a></h2>
192<div class="doc-section">
193
194<p>AutoLevelImage() adjusts the levels of a particular image channel by scaling the minimum and maximum values to the full quantum range.</p></ol>
195
196<p>The format of the LevelImage method is:</p>
197
198<pre class="code">
199 MagickBooleanType AutoLevelImage(Image *image)
200 MagickBooleanType AutoLevelImageChannel(Image *image,
201 const ChannelType channel)
202</pre>
203
204<p>A description of each parameter follows:</p></ol>
205
206<h5>image</h5>
207<ol><p>The image to auto-level</p></ol>
208
209<h5>channel</h5>
210<ol><p>The channels to auto-level. If the special 'SyncChannels' flag is set the min/max/mean value of all given channels is used for all given channels, to all channels in the same way.</p></ol>
211
212 </div>
213<h2><a href="http://www.imagemagick.org/api/MagickCore/enhance
cristy16ff93c2010-01-13 23:18:07 +0000[diff] [blame]214_8c.html" target="source" name="Use BrightnessContrastImage">Use BrightnessContrastImage</a></h2>
215<div class="doc-section">
216
217<p>Use BrightnessContrastImage() to change the brightness and/or contrast of an image. It converts the brightness and contrast parameters into slope and intercept and calls a polynomical function to apply to the image.</p></ol>
218
219<p>The format of the BrightnessContrastImage method is:</p>
220
221<pre class="code">
222 MagickBooleanType BrightnessContrastImage(Image *image,
223 const double brightness,const double contrast)
224 MagickBooleanType BrightnessContrastImageChannel(Image *image,
225 const ChannelType channel,const double brightness,
226 const double contrast)
227</pre>
228
229<p>A description of each parameter follows:</p></ol>
230
231<h5>image</h5>
232<ol><p>the image.</p></ol>
233
234<h5>channel</h5>
235<ol><p>the channel.</p></ol>
236
237<h5>brightness</h5>
238<ol><p>the brightness percent (-100 .. 100).</p></ol>
239
240<h5>contrast</h5>
241<ol><p>the contrast percent (-100 .. 100).</p></ol>
242
243 </div>
244<h2><a href="http://www.imagemagick.org/api/MagickCore/enhance
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]245_8c.html" target="source" name="ColorDecisionListImage">ColorDecisionListImage</a></h2>
246<div class="doc-section">
247
248<p>ColorDecisionListImage() accepts a lightweight Color Correction Collection (CCC) file which solely contains one or more color corrections and applies the correction to the image. Here is a sample CCC file:</p>
249
250<pre class="text">
251 <ColorCorrectionCollection xmlns="urn:ASC:CDL:v1.2">
252 <ColorCorrection id="cc03345">
253 <SOPNode>
254 <Slope> 0.9 1.2 0.5 </Slope>
255 <Offset> 0.4 -0.5 0.6 </Offset>
256 <Power> 1.0 0.8 1.5 </Power>
257 </SOPNode>
258 <SATNode>
259 <Saturation> 0.85 </Saturation>
260 </SATNode>
261 </ColorCorrection>
262 </ColorCorrectionCollection>
263</pre>
264
265<p>which includes the slop, offset, and power for each of the RGB channels as well as the saturation.</p></ol>
266
267<p>The format of the ColorDecisionListImage method is:</p>
268
269<pre class="code">
270 MagickBooleanType ColorDecisionListImage(Image *image,
271 const char *color_correction_collection)
272</pre>
273
274<p>A description of each parameter follows:</p></ol>
275
276<h5>image</h5>
277<ol><p>the image.</p></ol>
278
279<h5>color_correction_collection</h5>
280<ol><p>the color correction collection in XML.</p></ol>
281
282 </div>
283<h2><a href="http://www.imagemagick.org/api/MagickCore/enhance
284_8c.html" target="source" name="ClutImage">ClutImage</a></h2>
285<div class="doc-section">
286
cristyeaedf062010-05-29 22:36:02 +0000[diff] [blame]287<p>ClutImage() replaces each color value in the given image, by using it as an index to lookup a replacement color value in a Color Look UP Table in the form of an image. The values are extracted along a diagonal of the CLUT image so either a horizontal or vertial gradient image can be used.</p></ol>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]288
289<p>Typically this is used to either re-color a gray-scale image according to a color gradient in the CLUT image, or to perform a freeform histogram (level) adjustment according to the (typically gray-scale) gradient in the CLUT image.</p></ol>
290
291<p>When the 'channel' mask includes the matte/alpha transparency channel but one image has no such channel it is assumed that that image is a simple gray-scale image that will effect the alpha channel values, either for gray-scale coloring (with transparent or semi-transparent colors), or a histogram adjustment of existing alpha channel values. If both images have matte channels, direct and normal indexing is applied, which is rarely used.</p></ol>
292
293<p>The format of the ClutImage method is:</p>
294
295<pre class="code">
296 MagickBooleanType ClutImage(Image *image,Image *clut_image)
297 MagickBooleanType ClutImageChannel(Image *image,
298 const ChannelType channel,Image *clut_image)
299</pre>
300
301<p>A description of each parameter follows:</p></ol>
302
303<h5>image</h5>
304<ol><p>the image, which is replaced by indexed CLUT values</p></ol>
305
306<h5>clut_image</h5>
307<ol><p>the color lookup table image for replacement color values.</p></ol>
308
309<h5>channel</h5>
310<ol><p>the channel.</p></ol>
311
312 </div>
313<h2><a href="http://www.imagemagick.org/api/MagickCore/enhance
314_8c.html" target="source" name="ContrastImage">ContrastImage</a></h2>
315<div class="doc-section">
316
317<p>ContrastImage() enhances the intensity differences between the lighter and darker elements of the image. Set sharpen to a MagickTrue to increase the image contrast otherwise the contrast is reduced.</p></ol>
318
319<p>The format of the ContrastImage method is:</p>
320
321<pre class="code">
322 MagickBooleanType ContrastImage(Image *image,
323 const MagickBooleanType sharpen)
324</pre>
325
326<p>A description of each parameter follows:</p></ol>
327
328<h5>image</h5>
329<ol><p>the image.</p></ol>
330
331<h5>sharpen</h5>
332<ol><p>Increase or decrease image contrast.</p></ol>
333
334 </div>
335<h2><a href="http://www.imagemagick.org/api/MagickCore/enhance
336_8c.html" target="source" name="The ContrastStretchImage">The ContrastStretchImage</a></h2>
337<div class="doc-section">
338
339<p>The ContrastStretchImage() is a simple image enhancement technique that attempts to improve the contrast in an image by `stretching' the range of intensity values it contains to span a desired range of values. It differs from the more sophisticated histogram equalization in that it can only apply a linear scaling function to the image pixel values. As a result the `enhancement' is less harsh.</p></ol>
340
341<p>The format of the ContrastStretchImage method is:</p>
342
343<pre class="code">
344 MagickBooleanType ContrastStretchImage(Image *image,
345 const char *levels)
346 MagickBooleanType ContrastStretchImageChannel(Image *image,
cristybb503372010-05-27 20:51:26 +0000[diff] [blame]347 const size_t channel,const double black_point,
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]348 const double white_point)
349</pre>
350
351<p>A description of each parameter follows:</p></ol>
352
353<h5>image</h5>
354<ol><p>the image.</p></ol>
355
356<h5>channel</h5>
357<ol><p>the channel.</p></ol>
358
359<h5>black_point</h5>
360<ol><p>the black point.</p></ol>
361
362<h5>white_point</h5>
363<ol><p>the white point.</p></ol>
364
365<h5>levels</h5>
366<ol><p>Specify the levels where the black and white points have the range of 0 to number-of-pixels (e.g. 1, 10x90, etc.).</p></ol>
367
368 </div>
369<h2><a href="http://www.imagemagick.org/api/MagickCore/enhance
370_8c.html" target="source" name="EnhanceImage">EnhanceImage</a></h2>
371<div class="doc-section">
372
373<p>EnhanceImage() applies a digital filter that improves the quality of a noisy image.</p></ol>
374
375<p>The format of the EnhanceImage method is:</p>
376
377<pre class="code">
378 Image *EnhanceImage(const Image *image,ExceptionInfo *exception)
379</pre>
380
381<p>A description of each parameter follows:</p></ol>
382
383<h5>image</h5>
384<ol><p>the image.</p></ol>
385
386<h5>exception</h5>
387<ol><p>return any errors or warnings in this structure.</p></ol>
388
389 </div>
390<h2><a href="http://www.imagemagick.org/api/MagickCore/enhance
391_8c.html" target="source" name="EqualizeImage">EqualizeImage</a></h2>
392<div class="doc-section">
393
394<p>EqualizeImage() applies a histogram equalization to the image.</p></ol>
395
396<p>The format of the EqualizeImage method is:</p>
397
398<pre class="code">
399 MagickBooleanType EqualizeImage(Image *image)
400 MagickBooleanType EqualizeImageChannel(Image *image,
401 const ChannelType channel)
402</pre>
403
404<p>A description of each parameter follows:</p></ol>
405
406<h5>image</h5>
407<ol><p>the image.</p></ol>
408
409<h5>channel</h5>
410<ol><p>the channel.</p></ol>
411
412 </div>
413<h2><a href="http://www.imagemagick.org/api/MagickCore/enhance
414_8c.html" target="source" name="GammaImage">GammaImage</a></h2>
415<div class="doc-section">
416
417<p>GammaImage() gamma-corrects a particular image channel. The same image viewed on different devices will have perceptual differences in the way the image's intensities are represented on the screen. Specify individual gamma levels for the red, green, and blue channels, or adjust all three with the gamma parameter. Values typically range from 0.8 to 2.3.</p></ol>
418
419<p>You can also reduce the influence of a particular channel with a gamma value of 0.</p></ol>
420
421<p>The format of the GammaImage method is:</p>
422
423<pre class="code">
424 MagickBooleanType GammaImage(Image *image,const double gamma)
425 MagickBooleanType GammaImageChannel(Image *image,
426 const ChannelType channel,const double gamma)
427</pre>
428
429<p>A description of each parameter follows:</p></ol>
430
431<h5>image</h5>
432<ol><p>the image.</p></ol>
433
434<h5>channel</h5>
435<ol><p>the channel.</p></ol>
436
437<h5>gamma</h5>
438<ol><p>the image gamma.</p></ol>
439
440 </div>
441<h2><a href="http://www.imagemagick.org/api/MagickCore/enhance
442_8c.html" target="source" name="HaldClutImage">HaldClutImage</a></h2>
443<div class="doc-section">
444
445<p>HaldClutImage() applies a Hald color lookup table to the image. A Hald color lookup table is a 3-dimensional color cube mapped to 2 dimensions. Create it with the HALD coder. You can apply any color transformation to the Hald image and then use this method to apply the transform to the image.</p></ol>
446
447<p>The format of the HaldClutImage method is:</p>
448
449<pre class="code">
450 MagickBooleanType HaldClutImage(Image *image,Image *hald_image)
451 MagickBooleanType HaldClutImageChannel(Image *image,
452 const ChannelType channel,Image *hald_image)
453</pre>
454
455<p>A description of each parameter follows:</p></ol>
456
457<h5>image</h5>
458<ol><p>the image, which is replaced by indexed CLUT values</p></ol>
459
460<h5>hald_image</h5>
461<ol><p>the color lookup table image for replacement color values.</p></ol>
462
463<h5>channel</h5>
464<ol><p>the channel.</p></ol>
465
466 </div>
467<h2><a href="http://www.imagemagick.org/api/MagickCore/enhance
468_8c.html" target="source" name="LevelImage">LevelImage</a></h2>
469<div class="doc-section">
470
471<p>LevelImage() adjusts the levels of a particular image channel by scaling the colors falling between specified white and black points to the full available quantum range.</p></ol>
472
473<p>The parameters provided represent the black, and white points. The black point specifies the darkest color in the image. Colors darker than the black point are set to zero. White point specifies the lightest color in the image. Colors brighter than the white point are set to the maximum quantum value.</p></ol>
474
475<p>If a '!' flag is given, map black and white colors to the given levels rather than mapping those levels to black and white. See LevelizeImageChannel() and LevelizeImageChannel(), below.</p></ol>
476
477<p>Gamma specifies a gamma correction to apply to the image.</p></ol>
478
479<p>The format of the LevelImage method is:</p>
480
481<pre class="code">
482 MagickBooleanType LevelImage(Image *image,const char *levels)
483</pre>
484
485<p>A description of each parameter follows:</p></ol>
486
487<h5>image</h5>
488<ol><p>the image.</p></ol>
489
490<h5>levels</h5>
491<ol><p>Specify the levels where the black and white points have the range of 0-QuantumRange, and gamma has the range 0-10 (e.g. 10x90+2). A '!' flag inverts the re-mapping.</p></ol>
492
493 </div>
494<h2><a href="http://www.imagemagick.org/api/MagickCore/enhance
cristy5cadd612009-09-21 19:33:41 +0000[diff] [blame]495_8c.html" target="source" name="LevelizeImage">LevelizeImage</a></h2>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]496<div class="doc-section">
497
cristy5cadd612009-09-21 19:33:41 +0000[diff] [blame]498<p>LevelizeImage() applies the normal level operation to the image, spreading out the values between the black and white points over the entire range of values. Gamma correction is also applied after the values has been mapped.</p></ol>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]499
500<p>It is typically used to improve image contrast, or to provide a controlled linear threshold for the image. If the black and white points are set to the minimum and maximum values found in the image, the image can be normalized. or by swapping black and white values, negate the image.</p></ol>
501
cristy5cadd612009-09-21 19:33:41 +0000[diff] [blame]502<p>The format of the LevelizeImage method is:</p>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]503
504<pre class="code">
cristy5cadd612009-09-21 19:33:41 +0000[diff] [blame]505 MagickBooleanType LevelizeImage(Image *image,const double black_point,
506 const double white_point,const double gamma)
507 MagickBooleanType LevelizeImageChannel(Image *image,
508 const ChannelType channel,const double black_point,
509 const double white_point,const double gamma)
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]510</pre>
511
512<p>A description of each parameter follows:</p></ol>
513
514<h5>image</h5>
515<ol><p>the image.</p></ol>
516
517<h5>channel</h5>
518<ol><p>the channel.</p></ol>
519
520<h5>black_point</h5>
521<ol><p>The level which is to be mapped to zero (black)</p></ol>
522
523<h5>white_point</h5>
524<ol><p>The level which is to be mapped to QuantiumRange (white)</p></ol>
525
526<h5>gamma</h5>
527<ol><p>adjust gamma by this factor before mapping values. use 1.0 for purely linear stretching of image color values</p></ol>
528
529 </div>
530<h2><a href="http://www.imagemagick.org/api/MagickCore/enhance
531_8c.html" target="source" name="LevelizeImageChannel">LevelizeImageChannel</a></h2>
532<div class="doc-section">
533
534<p>LevelizeImageChannel() applies the reversed LevelImage() operation to just the specific channels specified. It compresses the full range of color values, so that they lie between the given black and white points. Gamma is applied before the values are mapped.</p></ol>
535
536<p>LevelizeImageChannel() can be called with by using a +level command line API option, or using a '!' on a -level or LevelImage() geometry string.</p></ol>
537
538<p>It can be used for example de-contrast a greyscale image to the exact levels specified. Or by using specific levels for each channel of an image you can convert a gray-scale image to any linear color gradient, according to those levels.</p></ol>
539
540<p>The format of the LevelizeImageChannel method is:</p>
541
542<pre class="code">
543 MagickBooleanType LevelizeImageChannel(Image *image,
544 const ChannelType channel,const char *levels)
545</pre>
546
547<p>A description of each parameter follows:</p></ol>
548
549<h5>image</h5>
550<ol><p>the image.</p></ol>
551
552<h5>channel</h5>
553<ol><p>the channel.</p></ol>
554
555<h5>black_point</h5>
556<ol><p>The level to map zero (black) to.</p></ol>
557
558<h5>white_point</h5>
559<ol><p>The level to map QuantiumRange (white) to.</p></ol>
560
561<h5>gamma</h5>
562<ol><p>adjust gamma by this factor before mapping values.</p></ol>
563
564 </div>
565<h2><a href="http://www.imagemagick.org/api/MagickCore/enhance
566_8c.html" target="source" name="LevelImageColor">LevelImageColor</a></h2>
567<div class="doc-section">
568
cristye7f8fdd2009-09-20 14:43:12 +0000[diff] [blame]569<p>LevelImageColor() maps the given color to "black" and "white" values, linearly spreading out the colors, and level values on a channel by channel bases, as per LevelImage(). The given colors allows you to specify different level ranges for each of the color channels seperatally.</p></ol>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]570
571<p>If the boolean 'invert' is set true the image values will modifyed in the reverse direction. That is any existing "black" and "white" colors in the image will become the color values given, with all other values compressed appropriatally. This effectivally maps a greyscale gradient into the given color gradient.</p></ol>
572
cristy5cadd612009-09-21 19:33:41 +0000[diff] [blame]573<p>The format of the LevelColorsImageChannel method is:</p>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]574
575<pre class="code">
cristy5cadd612009-09-21 19:33:41 +0000[diff] [blame]576 MagickBooleanType LevelColorsImage(Image *image,
cristye7f8fdd2009-09-20 14:43:12 +0000[diff] [blame]577 const MagickPixelPacket *black_color,
578 const MagickPixelPacket *white_color,const MagickBooleanType invert)
cristy5cadd612009-09-21 19:33:41 +0000[diff] [blame]579 MagickBooleanType LevelColorsImageChannel(Image *image,
580 const ChannelType channel,const MagickPixelPacket *black_color,
581 const MagickPixelPacket *white_color,const MagickBooleanType invert)
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]582</pre>
583
584<p>A description of each parameter follows:</p></ol>
585
586<h5>image</h5>
587<ol><p>the image.</p></ol>
588
589<h5>channel</h5>
590<ol><p>the channel.</p></ol>
591
592<h5>black_color</h5>
593<ol><p>The color to map black to/from</p></ol>
594
595<h5>white_point</h5>
596<ol><p>The color to map white to/from</p></ol>
597
598<h5>invert</h5>
599<ol><p>if true map the colors (levelize), rather than from (level)</p></ol>
600
601 </div>
602<h2><a href="http://www.imagemagick.org/api/MagickCore/enhance
603_8c.html" target="source" name="The LinearStretchImage">The LinearStretchImage</a></h2>
604<div class="doc-section">
605
606<p>The LinearStretchImage() discards any pixels below the black point and above the white point and levels the remaining pixels.</p></ol>
607
608<p>The format of the LinearStretchImage method is:</p>
609
610<pre class="code">
611 MagickBooleanType LinearStretchImage(Image *image,
612 const double black_point,const double white_point)
613</pre>
614
615<p>A description of each parameter follows:</p></ol>
616
617<h5>image</h5>
618<ol><p>the image.</p></ol>
619
620<h5>black_point</h5>
621<ol><p>the black point.</p></ol>
622
623<h5>white_point</h5>
624<ol><p>the white point.</p></ol>
625
626 </div>
627<h2><a href="http://www.imagemagick.org/api/MagickCore/enhance
628_8c.html" target="source" name="ModulateImage">ModulateImage</a></h2>
629<div class="doc-section">
630
631<p>ModulateImage() lets you control the brightness, saturation, and hue of an image. Modulate represents the brightness, saturation, and hue as one parameter (e.g. 90,150,100). If the image colorspace is HSL, the modulation is lightness, saturation, and hue. And if the colorspace is HWB, use blackness, whiteness, and hue.</p></ol>
632
633<p>The format of the ModulateImage method is:</p>
634
635<pre class="code">
636 MagickBooleanType ModulateImage(Image *image,const char *modulate)
637</pre>
638
639<p>A description of each parameter follows:</p></ol>
640
641<h5>image</h5>
642<ol><p>the image.</p></ol>
643
644<h5>modulate</h5>
645<ol><p>Define the percent change in brightness, saturation, and hue.</p></ol>
646
647 </div>
648<h2><a href="http://www.imagemagick.org/api/MagickCore/enhance
649_8c.html" target="source" name="NegateImage">NegateImage</a></h2>
650<div class="doc-section">
651
652<p>NegateImage() negates the colors in the reference image. The grayscale option means that only grayscale values within the image are negated.</p></ol>
653
654<p>The format of the NegateImageChannel method is:</p>
655
656<pre class="code">
657 MagickBooleanType NegateImage(Image *image,
658 const MagickBooleanType grayscale)
659 MagickBooleanType NegateImageChannel(Image *image,
660 const ChannelType channel,const MagickBooleanType grayscale)
661</pre>
662
663<p>A description of each parameter follows:</p></ol>
664
665<h5>image</h5>
666<ol><p>the image.</p></ol>
667
668<h5>channel</h5>
669<ol><p>the channel.</p></ol>
670
671<h5>grayscale</h5>
672<ol><p>If MagickTrue, only negate grayscale pixels within the image.</p></ol>
673
674 </div>
675<h2><a href="http://www.imagemagick.org/api/MagickCore/enhance
676_8c.html" target="source" name="The NormalizeImage">The NormalizeImage</a></h2>
677<div class="doc-section">
678
679<p>The NormalizeImage() method enhances the contrast of a color image by mapping the darkest 2 percent of all pixel to black and the brightest 1 percent to white.</p></ol>
680
681<p>The format of the NormalizeImage method is:</p>
682
683<pre class="code">
684 MagickBooleanType NormalizeImage(Image *image)
685 MagickBooleanType NormalizeImageChannel(Image *image,
686 const ChannelType channel)
687</pre>
688
689<p>A description of each parameter follows:</p></ol>
690
691<h5>image</h5>
692<ol><p>the image.</p></ol>
693
694<h5>channel</h5>
695<ol><p>the channel.</p></ol>
696
697 </div>
698<h2><a href="http://www.imagemagick.org/api/MagickCore/enhance
699_8c.html" target="source" name="SigmoidalContrastImage">SigmoidalContrastImage</a></h2>
700<div class="doc-section">
701
702<p>SigmoidalContrastImage() adjusts the contrast of an image with a non-linear sigmoidal contrast algorithm. Increase the contrast of the image using a sigmoidal transfer function without saturating highlights or shadows. Contrast indicates how much to increase the contrast (0 is none; 3 is typical; 20 is pushing it); mid-point indicates where midtones fall in the resultant image (0 is white; 50 is middle-gray; 100 is black). Set sharpen to MagickTrue to increase the image contrast otherwise the contrast is reduced.</p></ol>
703
704<p>The format of the SigmoidalContrastImage method is:</p>
705
706<pre class="code">
707 MagickBooleanType SigmoidalContrastImage(Image *image,
708 const MagickBooleanType sharpen,const char *levels)
709 MagickBooleanType SigmoidalContrastImageChannel(Image *image,
710 const ChannelType channel,const MagickBooleanType sharpen,
711 const double contrast,const double midpoint)
712</pre>
713
714<p>A description of each parameter follows:</p></ol>
715
716<h5>image</h5>
717<ol><p>the image.</p></ol>
718
719<h5>channel</h5>
720<ol><p>the channel.</p></ol>
721
722<h5>sharpen</h5>
723<ol><p>Increase or decrease image contrast.</p></ol>
724
725<h5>contrast</h5>
726<ol><p>control the "shoulder" of the contast curve.</p></ol>
727
728<h5>midpoint</h5>
729<ol><p>control the "toe" of the contast curve.</p></ol>
730
731 </div>
cristy3eaa0ef2010-03-06 20:35:26 +0000[diff] [blame]732
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