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<div class="document" id="effect">
<h1 class="title">effect</h1>
<h2 class="subtitle" id="image-effects-methods">Image effects methods</h2>
<div class="contents topic" id="contents">
<p class="topic-title first">Contents</p>
<ul class="simple">
<li><a class="reference internal" href="#adaptivethresholdimage" id="id51">AdaptiveThresholdImage</a></li>
<li><a class="reference internal" href="#addnoiseimage" id="id52">AddNoiseImage</a></li>
<li><a class="reference internal" href="#addnoiseimagechannel" id="id53">AddNoiseImageChannel</a></li>
<li><a class="reference internal" href="#blackthresholdimage" id="id54">BlackThresholdImage</a></li>
<li><a class="reference internal" href="#blurimage" id="id55">BlurImage</a></li>
<li><a class="reference internal" href="#blurimagechannel" id="id56">BlurImageChannel</a></li>
<li><a class="reference internal" href="#channelthresholdimage" id="id57">ChannelThresholdImage</a></li>
<li><a class="reference internal" href="#convolveimage" id="id58">ConvolveImage</a></li>
<li><a class="reference internal" href="#despeckleimage" id="id59">DespeckleImage</a></li>
<li><a class="reference internal" href="#edgeimage" id="id60">EdgeImage</a></li>
<li><a class="reference internal" href="#embossimage" id="id61">EmbossImage</a></li>
<li><a class="reference internal" href="#enhanceimage" id="id62">EnhanceImage</a></li>
<li><a class="reference internal" href="#gaussianblurimage" id="id63">GaussianBlurImage</a></li>
<li><a class="reference internal" href="#gaussianblurimagechannel" id="id64">GaussianBlurImageChannel</a></li>
<li><a class="reference internal" href="#medianfilterimage" id="id65">MedianFilterImage</a></li>
<li><a class="reference internal" href="#motionblurimage" id="id66">MotionBlurImage</a></li>
<li><a class="reference internal" href="#randomchannelthresholdimage" id="id67">RandomChannelThresholdImage</a></li>
<li><a class="reference internal" href="#reducenoiseimage" id="id68">ReduceNoiseImage</a></li>
<li><a class="reference internal" href="#shadeimage" id="id69">ShadeImage</a></li>
<li><a class="reference internal" href="#sharpenimage" id="id70">SharpenImage</a></li>
<li><a class="reference internal" href="#sharpenimagechannel" id="id71">SharpenImageChannel</a></li>
<li><a class="reference internal" href="#spreadimage" id="id72">SpreadImage</a></li>
<li><a class="reference internal" href="#thresholdimage" id="id73">ThresholdImage</a></li>
<li><a class="reference internal" href="#unsharpmaskimage" id="id74">UnsharpMaskImage</a></li>
<li><a class="reference internal" href="#unsharpmaskimagechannel" id="id75">UnsharpMaskImageChannel</a></li>
<li><a class="reference internal" href="#whitethresholdimage" id="id76">WhiteThresholdImage</a></li>
</ul>
</div>
<div class="section" id="adaptivethresholdimage">
<h1><a class="toc-backref" href="#id51">AdaptiveThresholdImage</a></h1>
<div class="section" id="synopsis">
<h2>Synopsis</h2>
<pre class="literal-block">
<a class="reference external" href="../api/types.html#image">Image</a> *AdaptiveThresholdImage( <a class="reference external" href="../api/types.html#image">Image</a> *image, const unsigned long width,
const unsigned long height, const unsigned long unsigned long,
<a class="reference external" href="../api/types.html#exceptioninfo">ExceptionInfo</a> *exception );
</pre>
</div>
<div class="section" id="description">
<h2>Description</h2>
<p>AdaptiveThresholdImage() selects an individual threshold for each pixel
based on the range of intensity values in its local neighborhood. This
allows for thresholding of an image whose global intensity histogram
doesn't contain distinctive peaks.</p>
<p>The format of the AdaptiveThresholdImage method is:</p>
<pre class="literal-block">
<a class="reference external" href="../api/types.html#image">Image</a> *AdaptiveThresholdImage( <a class="reference external" href="../api/types.html#image">Image</a> *image, const unsigned long width,
const unsigned long height, const unsigned long unsigned long,
<a class="reference external" href="../api/types.html#exceptioninfo">ExceptionInfo</a> *exception );
</pre>
<dl class="docutils">
<dt>image:</dt>
<dd>The image.</dd>
<dt>width:</dt>
<dd>The width of the local neighborhood.</dd>
<dt>height:</dt>
<dd>The height of the local neighborhood.</dd>
<dt>offset:</dt>
<dd>The mean offset.</dd>
<dt>exception:</dt>
<dd>Return any errors or warnings in this structure.</dd>
</dl>
</div>
</div>
<div class="section" id="addnoiseimage">
<h1><a class="toc-backref" href="#id52">AddNoiseImage</a></h1>
<div class="section" id="id1">
<h2>Synopsis</h2>
<pre class="literal-block">
<a class="reference external" href="../api/types.html#image">Image</a> *AddNoiseImage( const <a class="reference external" href="../api/types.html#image">Image</a> *image, const <a class="reference external" href="../api/types.html#noisetype">NoiseType</a> noise_type,
<a class="reference external" href="../api/types.html#exceptioninfo">ExceptionInfo</a> *exception );
</pre>
</div>
<div class="section" id="id2">
<h2>Description</h2>
<p>AddNoiseImage() adds random noise to the image.</p>
<p>The format of the AddNoiseImage method is:</p>
<pre class="literal-block">
<a class="reference external" href="../api/types.html#image">Image</a> *AddNoiseImage( const <a class="reference external" href="../api/types.html#image">Image</a> *image, const <a class="reference external" href="../api/types.html#noisetype">NoiseType</a> noise_type,
<a class="reference external" href="../api/types.html#exceptioninfo">ExceptionInfo</a> *exception );
</pre>
<dl class="docutils">
<dt>image:</dt>
<dd>The image.</dd>
<dt>noise_type:</dt>
<dd>The type of noise: Uniform, Gaussian, Multiplicative,
Impulse, Laplacian, Poisson, or Random.</dd>
<dt>exception:</dt>
<dd>Return any errors or warnings in this structure.</dd>
</dl>
</div>
</div>
<div class="section" id="addnoiseimagechannel">
<h1><a class="toc-backref" href="#id53">AddNoiseImageChannel</a></h1>
<div class="section" id="id3">
<h2>Synopsis</h2>
<pre class="literal-block">
<a class="reference external" href="../api/types.html#image">Image</a> *AddNoiseImageChannel( const <a class="reference external" href="../api/types.html#image">Image</a> *image, const <a class="reference external" href="../api/types.html#channeltype">ChannelType</a> channel,
const <a class="reference external" href="../api/types.html#noisetype">NoiseType</a> noise_type, <a class="reference external" href="../api/types.html#exceptioninfo">ExceptionInfo</a> *exception );
</pre>
</div>
<div class="section" id="id4">
<h2>Description</h2>
<p>AddNoiseImageChannel() adds random noise to one image channel.</p>
<p>The format of the AddNoiseImageChannel method is:</p>
<pre class="literal-block">
<a class="reference external" href="../api/types.html#image">Image</a> *AddNoiseImageChannel( const <a class="reference external" href="../api/types.html#image">Image</a> *image, const <a class="reference external" href="../api/types.html#channeltype">ChannelType</a> channel,
const <a class="reference external" href="../api/types.html#noisetype">NoiseType</a> noise_type, <a class="reference external" href="../api/types.html#exceptioninfo">ExceptionInfo</a> *exception );
</pre>
<dl class="docutils">
<dt>image:</dt>
<dd>The image.</dd>
<dt>channel:</dt>
<dd>The image channel to apply noise to.</dd>
<dt>noise_type:</dt>
<dd>The type of noise: Uniform, Gaussian, Multiplicative,
Impulse, Laplacian, Poisson, or Random.</dd>
<dt>exception:</dt>
<dd>Return any errors or warnings in this structure.</dd>
</dl>
</div>
</div>
<div class="section" id="blackthresholdimage">
<h1><a class="toc-backref" href="#id54">BlackThresholdImage</a></h1>
<div class="section" id="id5">
<h2>Synopsis</h2>
<pre class="literal-block">
MagickPassFail BlackThresholdImage( <a class="reference external" href="../api/types.html#image">Image</a> *image, const char *thresholds );
</pre>
</div>
<div class="section" id="id6">
<h2>Description</h2>
<p>BlackThresholdImage() adjusts the levels of image channels such that
values below a specified threshold are set to the minimum value (black)
while the remaining pixels are unchanged.</p>
<p>The format of the BlackThresholdImage method is:</p>
<pre class="literal-block">
MagickPassFail BlackThresholdImage( <a class="reference external" href="../api/types.html#image">Image</a> *image, const char *thresholds );
</pre>
<p>A description of each parameter follows:</p>
<dl class="docutils">
<dt>image:</dt>
<dd>The image.</dd>
<dt>thresholds:</dt>
<dd>Channel thresholds which are specified as a comma delimited
list containing the thresholds for red, green, blue, and opacity. If
the list contains a percent symbol (%) then all values are treated as
a percentage of MaxRGB.</dd>
</dl>
</div>
</div>
<div class="section" id="blurimage">
<h1><a class="toc-backref" href="#id55">BlurImage</a></h1>
<div class="section" id="id7">
<h2>Synopsis</h2>
<pre class="literal-block">
<a class="reference external" href="../api/types.html#image">Image</a> *BlurImage( const <a class="reference external" href="../api/types.html#image">Image</a> *image, const double radius, const double sigma,
<a class="reference external" href="../api/types.html#exceptioninfo">ExceptionInfo</a> *exception );
</pre>
</div>
<div class="section" id="id8">
<h2>Description</h2>
<p>BlurImage() blurs an image. We convolve the image with a Gaussian
operator of the given radius and standard deviation (sigma).
For reasonable results, the radius should be larger than sigma. Use a
radius of 0 and BlurImage() selects a suitable radius for you.</p>
<p>The format of the BlurImage method is:</p>
<pre class="literal-block">
<a class="reference external" href="../api/types.html#image">Image</a> *BlurImage( const <a class="reference external" href="../api/types.html#image">Image</a> *image, const double radius, const double sigma,
<a class="reference external" href="../api/types.html#exceptioninfo">ExceptionInfo</a> *exception );
</pre>
<dl class="docutils">
<dt>radius:</dt>
<dd>The radius of the Gaussian, in pixels, not counting the center
pixel.</dd>
<dt>sigma:</dt>
<dd>The standard deviation of the Gaussian, in pixels.</dd>
<dt>exception:</dt>
<dd>Return any errors or warnings in this structure.</dd>
</dl>
</div>
</div>
<div class="section" id="blurimagechannel">
<h1><a class="toc-backref" href="#id56">BlurImageChannel</a></h1>
<div class="section" id="id9">
<h2>Synopsis</h2>
<pre class="literal-block">
<a class="reference external" href="../api/types.html#image">Image</a> *BlurImageChannel( const <a class="reference external" href="../api/types.html#image">Image</a> *image, const <a class="reference external" href="../api/types.html#channeltype">ChannelType</a> channel,
const double radius, const double sigma,
<a class="reference external" href="../api/types.html#exceptioninfo">ExceptionInfo</a> *exception );
</pre>
</div>
<div class="section" id="id10">
<h2>Description</h2>
<p>BlurImageChannel() blurs the specified image channel. We convolve the
image channel with a Gaussian operator of the given radius and standard
deviation (sigma). For reasonable results, the radius should be larger
than sigma. Use a radius of 0 and BlurImageChannel() selects a suitable
radius for you.</p>
<p>The format of the BlurImageChannel method is:</p>
<pre class="literal-block">
<a class="reference external" href="../api/types.html#image">Image</a> *BlurImageChannel( const <a class="reference external" href="../api/types.html#image">Image</a> *image, const <a class="reference external" href="../api/types.html#channeltype">ChannelType</a> channel,
const double radius, const double sigma,
<a class="reference external" href="../api/types.html#exceptioninfo">ExceptionInfo</a> *exception );
</pre>
<dl class="docutils">
<dt>channel:</dt>
<dd>The channel to blur.</dd>
<dt>radius:</dt>
<dd>The radius of the Gaussian, in pixels, not counting the center
pixel.</dd>
<dt>sigma:</dt>
<dd>The standard deviation of the Gaussian, in pixels.</dd>
<dt>exception:</dt>
<dd>Return any errors or warnings in this structure.</dd>
</dl>
</div>
</div>
<div class="section" id="channelthresholdimage">
<h1><a class="toc-backref" href="#id57">ChannelThresholdImage</a></h1>
<div class="section" id="id11">
<h2>Synopsis</h2>
<pre class="literal-block">
MagickPassFail ChannelThresholdImage( <a class="reference external" href="../api/types.html#image">Image</a> *image, const char *threshold );
</pre>
</div>
<div class="section" id="id12">
<h2>Description</h2>
<p>ChannelThresholdImage() changes the value of individual pixels based on
the level of each pixel channel. The result sets the affected channels
to the minimum or maximum channel value. A negative threshold value
disables thresholding for that channel. Append a percent symbol to
have threshold values automatically scaled from a percentage to MaxRGB.</p>
<p>Invoked by the '-threshold' option.</p>
<p>The format of the ChannelThresholdImage method is:</p>
<pre class="literal-block">
MagickPassFail ChannelThresholdImage( <a class="reference external" href="../api/types.html#image">Image</a> *image, const char *threshold );
</pre>
<p>A description of each parameter follows:</p>
<dl class="docutils">
<dt>image:</dt>
<dd>The image.</dd>
<dt>threshold:</dt>
<dd>define the threshold values, <red>{<green>,<blue>,<opacity>}{%}.</dd>
</dl>
</div>
</div>
<div class="section" id="convolveimage">
<h1><a class="toc-backref" href="#id58">ConvolveImage</a></h1>
<div class="section" id="id13">
<h2>Synopsis</h2>
<pre class="literal-block">
<a class="reference external" href="../api/types.html#image">Image</a> *ConvolveImage( const <a class="reference external" href="../api/types.html#image">Image</a> *image, const unsigned int order,
const double *kernel, <a class="reference external" href="../api/types.html#exceptioninfo">ExceptionInfo</a> *exception );
</pre>
</div>
<div class="section" id="id14">
<h2>Description</h2>
<p>ConvolveImage() applies a custom convolution kernel to the image.</p>
<p>The format of the ConvolveImage method is:</p>
<pre class="literal-block">
<a class="reference external" href="../api/types.html#image">Image</a> *ConvolveImage( const <a class="reference external" href="../api/types.html#image">Image</a> *image, const unsigned int order,
const double *kernel, <a class="reference external" href="../api/types.html#exceptioninfo">ExceptionInfo</a> *exception );
</pre>
<dl class="docutils">
<dt>image:</dt>
<dd>The image.</dd>
<dt>order:</dt>
<dd>The number of columns and rows in the filter kernel.</dd>
<dt>kernel:</dt>
<dd>An array of double representing the convolution kernel.</dd>
<dt>exception:</dt>
<dd>Return any errors or warnings in this structure.</dd>
</dl>
</div>
</div>
<div class="section" id="despeckleimage">
<h1><a class="toc-backref" href="#id59">DespeckleImage</a></h1>
<div class="section" id="id15">
<h2>Synopsis</h2>
<pre class="literal-block">
<a class="reference external" href="../api/types.html#image">Image</a> *DespeckleImage( const <a class="reference external" href="../api/types.html#image">Image</a> *image, <a class="reference external" href="../api/types.html#exceptioninfo">ExceptionInfo</a> *exception );
</pre>
</div>
<div class="section" id="id16">
<h2>Description</h2>
<p>Despeckle() reduces the speckle noise in an image while preserving the
edges of the original image.</p>
<p>The format of the DespeckleImage method is:</p>
<pre class="literal-block">
<a class="reference external" href="../api/types.html#image">Image</a> *DespeckleImage( const <a class="reference external" href="../api/types.html#image">Image</a> *image, <a class="reference external" href="../api/types.html#exceptioninfo">ExceptionInfo</a> *exception );
</pre>
<p>A description of each parameter follows:</p>
<dl class="docutils">
<dt>image:</dt>
<dd>The image.</dd>
<dt>exception:</dt>
<dd>Return any errors or warnings in this structure.</dd>
</dl>
</div>
</div>
<div class="section" id="edgeimage">
<h1><a class="toc-backref" href="#id60">EdgeImage</a></h1>
<div class="section" id="id17">
<h2>Synopsis</h2>
<pre class="literal-block">
<a class="reference external" href="../api/types.html#image">Image</a> *EdgeImage( const <a class="reference external" href="../api/types.html#image">Image</a> *image, const double radius,
<a class="reference external" href="../api/types.html#exceptioninfo">ExceptionInfo</a> *exception );
</pre>
</div>
<div class="section" id="id18">
<h2>Description</h2>
<p>EdgeImage() finds edges in an image. Radius defines the radius of the
convolution filter. Use a radius of 0 and Edge() selects a suitable
radius for you.</p>
<p>The format of the EdgeImage method is:</p>
<pre class="literal-block">
<a class="reference external" href="../api/types.html#image">Image</a> *EdgeImage( const <a class="reference external" href="../api/types.html#image">Image</a> *image, const double radius,
<a class="reference external" href="../api/types.html#exceptioninfo">ExceptionInfo</a> *exception );
</pre>
<dl class="docutils">
<dt>image:</dt>
<dd>The image.</dd>
<dt>radius:</dt>
<dd>the radius of the pixel neighborhood.</dd>
<dt>exception:</dt>
<dd>Return any errors or warnings in this structure.</dd>
</dl>
</div>
</div>
<div class="section" id="embossimage">
<h1><a class="toc-backref" href="#id61">EmbossImage</a></h1>
<div class="section" id="id19">
<h2>Synopsis</h2>
<pre class="literal-block">
<a class="reference external" href="../api/types.html#image">Image</a> *EmbossImage( const <a class="reference external" href="../api/types.html#image">Image</a> *image, const double radius, const double sigma,
<a class="reference external" href="../api/types.html#exceptioninfo">ExceptionInfo</a> *exception );
</pre>
</div>
<div class="section" id="id20">
<h2>Description</h2>
<p>EmbossImage() returns a grayscale image with a three-dimensional effect.
We convolve the image with a Gaussian operator of the given radius and
standard deviation (sigma). For reasonable results, radius should be
larger than sigma. Use a radius of 0 and Emboss() selects a suitable
radius for you.</p>
<p>The format of the EmbossImage method is:</p>
<pre class="literal-block">
<a class="reference external" href="../api/types.html#image">Image</a> *EmbossImage( const <a class="reference external" href="../api/types.html#image">Image</a> *image, const double radius, const double sigma,
<a class="reference external" href="../api/types.html#exceptioninfo">ExceptionInfo</a> *exception );
</pre>
<dl class="docutils">
<dt>image:</dt>
<dd>The image.</dd>
<dt>radius:</dt>
<dd>the radius of the pixel neighborhood.</dd>
<dt>sigma:</dt>
<dd>The standard deviation of the Gaussian, in pixels.</dd>
<dt>exception:</dt>
<dd>Return any errors or warnings in this structure.</dd>
</dl>
</div>
</div>
<div class="section" id="enhanceimage">
<h1><a class="toc-backref" href="#id62">EnhanceImage</a></h1>
<div class="section" id="id21">
<h2>Synopsis</h2>
<pre class="literal-block">
<a class="reference external" href="../api/types.html#image">Image</a> *EnhanceImage( const <a class="reference external" href="../api/types.html#image">Image</a> *image, <a class="reference external" href="../api/types.html#exceptioninfo">ExceptionInfo</a> *exception );
</pre>
</div>
<div class="section" id="id22">
<h2>Description</h2>
<p>EnhanceImage() applies a digital filter to the image color channels that
improves the quality of a noisy image. The opacity channel is preserved
but is otherwise ignored.</p>
<p>The format of the EnhanceImage method is:</p>
<pre class="literal-block">
<a class="reference external" href="../api/types.html#image">Image</a> *EnhanceImage( const <a class="reference external" href="../api/types.html#image">Image</a> *image, <a class="reference external" href="../api/types.html#exceptioninfo">ExceptionInfo</a> *exception );
</pre>
<p>A description of each parameter follows:</p>
<dl class="docutils">
<dt>image:</dt>
<dd>The image.</dd>
<dt>exception:</dt>
<dd>Return any errors or warnings in this structure.</dd>
</dl>
</div>
</div>
<div class="section" id="gaussianblurimage">
<h1><a class="toc-backref" href="#id63">GaussianBlurImage</a></h1>
<div class="section" id="id23">
<h2>Synopsis</h2>
<pre class="literal-block">
<a class="reference external" href="../api/types.html#image">Image</a> *GaussianBlurImage( const <a class="reference external" href="../api/types.html#image">Image</a> *image, const double radius, const double sigma,
<a class="reference external" href="../api/types.html#exceptioninfo">ExceptionInfo</a> *exception );
</pre>
</div>
<div class="section" id="id24">
<h2>Description</h2>
<p>GaussianBlurImage() blurs an image. We convolve the image with a
Gaussian operator of the given radius and standard deviation (sigma).
For reasonable results, the radius should be larger than sigma. Use a
radius of 0 and GaussianBlurImage() selects a suitable radius for you</p>
<p>The format of the GaussianBlurImage method is:</p>
<pre class="literal-block">
<a class="reference external" href="../api/types.html#image">Image</a> *GaussianBlurImage( const <a class="reference external" href="../api/types.html#image">Image</a> *image, const double radius, const double sigma,
<a class="reference external" href="../api/types.html#exceptioninfo">ExceptionInfo</a> *exception );
</pre>
<dl class="docutils">
<dt>blur_image:</dt>
<dd>Method GaussianBlurImage returns a pointer to the image
after it is blur. A null image is returned if there is a memory
shortage.</dd>
<dt>image:</dt>
<dd>Image to blur.</dd>
<dt>radius:</dt>
<dd>the radius of the Gaussian, in pixels, not counting the center
pixel.</dd>
<dt>sigma:</dt>
<dd>the standard deviation of the Gaussian, in pixels.</dd>
<dt>exception:</dt>
<dd>Return any errors or warnings in this structure.</dd>
</dl>
</div>
</div>
<div class="section" id="gaussianblurimagechannel">
<h1><a class="toc-backref" href="#id64">GaussianBlurImageChannel</a></h1>
<div class="section" id="id25">
<h2>Synopsis</h2>
<pre class="literal-block">
<a class="reference external" href="../api/types.html#image">Image</a> *GaussianBlurImageChannel( const <a class="reference external" href="../api/types.html#image">Image</a> *image, const <a class="reference external" href="../api/types.html#channeltype">ChannelType</a> channel,
const double radius, const double sigma,
<a class="reference external" href="../api/types.html#exceptioninfo">ExceptionInfo</a> *exception );
</pre>
</div>
<div class="section" id="id26">
<h2>Description</h2>
<p>GaussianBlurImageChannel() blurs an image channel. We convolve the image
with a Gaussian operator of the given radius and standard deviation
(sigma). For reasonable results, the radius should be larger than sigma.
Use a radius of 0 and GaussianBlurImage() selects a suitable radius for
you.</p>
<p>The format of the GaussianBlurImageChannel method is:</p>
<pre class="literal-block">
<a class="reference external" href="../api/types.html#image">Image</a> *GaussianBlurImageChannel( const <a class="reference external" href="../api/types.html#image">Image</a> *image, const <a class="reference external" href="../api/types.html#channeltype">ChannelType</a> channel,
const double radius, const double sigma,
<a class="reference external" href="../api/types.html#exceptioninfo">ExceptionInfo</a> *exception );
</pre>
<dl class="docutils">
<dt>blur_image:</dt>
<dd>Method GaussianBlurImage returns a pointer to the image
after it is blur. A null image is returned if there is a memory
shortage.</dd>
<dt>image:</dt>
<dd>Image to blur.</dd>
<dt>channel:</dt>
<dd>Channel to blur in image.</dd>
<dt>radius:</dt>
<dd>the radius of the Gaussian, in pixels, not counting the center
pixel.</dd>
<dt>sigma:</dt>
<dd>the standard deviation of the Gaussian, in pixels.</dd>
<dt>exception:</dt>
<dd>Return any errors or warnings in this structure.</dd>
</dl>
</div>
</div>
<div class="section" id="medianfilterimage">
<h1><a class="toc-backref" href="#id65">MedianFilterImage</a></h1>
<div class="section" id="id27">
<h2>Synopsis</h2>
<pre class="literal-block">
<a class="reference external" href="../api/types.html#image">Image</a> *MedianFilterImage( const <a class="reference external" href="../api/types.html#image">Image</a> *image, const double radius,
<a class="reference external" href="../api/types.html#exceptioninfo">ExceptionInfo</a> *exception );
</pre>
</div>
<div class="section" id="id28">
<h2>Description</h2>
<p>MedianFilterImage() applies a digital filter that improves the quality
of a noisy image. Each pixel is replaced by the median in a set of
neighboring pixels as defined by radius.</p>
<p>The algorithm was contributed by Mike Edmonds and implements an insertion
sort for selecting median color-channel values. For more on this algorithm
see "Skip Lists: A probabilistic Alternative to Balanced Trees" by William
Pugh in the June 1990 of Communications of the ACM.</p>
<p>The format of the MedianFilterImage method is:</p>
<pre class="literal-block">
<a class="reference external" href="../api/types.html#image">Image</a> *MedianFilterImage( const <a class="reference external" href="../api/types.html#image">Image</a> *image, const double radius,
<a class="reference external" href="../api/types.html#exceptioninfo">ExceptionInfo</a> *exception );
</pre>
<dl class="docutils">
<dt>image:</dt>
<dd>The image.</dd>
<dt>radius:</dt>
<dd>The radius of the pixel neighborhood.</dd>
<dt>exception:</dt>
<dd>Return any errors or warnings in this structure.</dd>
</dl>
</div>
</div>
<div class="section" id="motionblurimage">
<h1><a class="toc-backref" href="#id66">MotionBlurImage</a></h1>
<div class="section" id="id29">
<h2>Synopsis</h2>
<pre class="literal-block">
<a class="reference external" href="../api/types.html#image">Image</a> *MotionBlurImage( const <a class="reference external" href="../api/types.html#image">Image</a> *image, const double radius, const double sigma,
const double angle, <a class="reference external" href="../api/types.html#exceptioninfo">ExceptionInfo</a> *exception );
</pre>
</div>
<div class="section" id="id30">
<h2>Description</h2>
<p>MotionBlurImage() simulates motion blur. We convolve the image with a
Gaussian operator of the given radius and standard deviation (sigma).
For reasonable results, radius should be larger than sigma. Use a
radius of 0 and MotionBlurImage() selects a suitable radius for you.
Angle gives the angle of the blurring motion (direction object appears
to be coming from).</p>
<p>Andrew Protano contributed this effect.</p>
<p>The format of the MotionBlurImage method is:</p>
<pre class="literal-block">
<a class="reference external" href="../api/types.html#image">Image</a> *MotionBlurImage( const <a class="reference external" href="../api/types.html#image">Image</a> *image, const double radius, const double sigma,
const double angle, <a class="reference external" href="../api/types.html#exceptioninfo">ExceptionInfo</a> *exception );
</pre>
<dl class="docutils">
<dt>image:</dt>
<dd>The image.</dd>
<dt>radius:</dt>
<dd>The radius of the Gaussian, in pixels, not counting
the center pixel.</dd>
<dt>sigma:</dt>
<dd>The standard deviation of the Gaussian, in pixels.</dd>
<dt>angle:</dt>
<dd>Apply the effect along this angle.</dd>
<dt>exception:</dt>
<dd>Return any errors or warnings in this structure.</dd>
</dl>
</div>
</div>
<div class="section" id="randomchannelthresholdimage">
<h1><a class="toc-backref" href="#id67">RandomChannelThresholdImage</a></h1>
<div class="section" id="id31">
<h2>Synopsis</h2>
<pre class="literal-block">
unsigned int RandomChannelThresholdImage( <a class="reference external" href="../api/types.html#image">Image</a> *image, const char *channel,
const char *thresholds,
<a class="reference external" href="../api/types.html#exceptioninfo">ExceptionInfo</a> *exception );
</pre>
</div>
<div class="section" id="id32">
<h2>Description</h2>
<p>RandomChannelThresholdImage() changes the value of individual pixels based
on the intensity of each pixel compared to a random threshold. The result
is a low-contrast, two color image.</p>
<p>The format of the RandomChannelThresholdImage method is:</p>
<pre class="literal-block">
unsigned int RandomChannelThresholdImage( <a class="reference external" href="../api/types.html#image">Image</a> *image, const char *channel,
const char *thresholds,
<a class="reference external" href="../api/types.html#exceptioninfo">ExceptionInfo</a> *exception );
</pre>
<dl class="docutils">
<dt>image:</dt>
<dd>The image.</dd>
<dt>channel:</dt>
<dd>The channel or channels to be thresholded.</dd>
<dt>thresholds:</dt>
<dd>a geometry string containing LOWxHIGH thresholds.
If the string contains 2x2, 3x3, 4x4, 5x5, 6x6, or 7x7, then
an ordered dither of order 2, 3, 4, 5, 6, or 7 will be performed
instead.</dd>
<dt>exception:</dt>
<dd>Return any errors or warnings in this structure.</dd>
</dl>
</div>
</div>
<div class="section" id="reducenoiseimage">
<h1><a class="toc-backref" href="#id68">ReduceNoiseImage</a></h1>
<div class="section" id="id33">
<h2>Synopsis</h2>
<pre class="literal-block">
<a class="reference external" href="../api/types.html#image">Image</a> *ReduceNoiseImage( const <a class="reference external" href="../api/types.html#image">Image</a> *image, const double radius,
<a class="reference external" href="../api/types.html#exceptioninfo">ExceptionInfo</a> *exception );
</pre>
</div>
<div class="section" id="id34">
<h2>Description</h2>
<p>ReduceNoiseImage() smooths the contours of an image while still preserving
edge information. The algorithm works by replacing each pixel with its
neighbor closest in value. A neighbor is defined by radius. Use a radius
of 0 and ReduceNoise() selects a suitable radius for you.</p>
<p>The format of the ReduceNoiseImage method is:</p>
<pre class="literal-block">
<a class="reference external" href="../api/types.html#image">Image</a> *ReduceNoiseImage( const <a class="reference external" href="../api/types.html#image">Image</a> *image, const double radius,
<a class="reference external" href="../api/types.html#exceptioninfo">ExceptionInfo</a> *exception );
</pre>
<dl class="docutils">
<dt>image:</dt>
<dd>The image.</dd>
<dt>radius:</dt>
<dd>The radius of the pixel neighborhood.</dd>
<dt>exception:</dt>
<dd>Return any errors or warnings in this structure.</dd>
</dl>
</div>
</div>
<div class="section" id="shadeimage">
<h1><a class="toc-backref" href="#id69">ShadeImage</a></h1>
<div class="section" id="id35">
<h2>Synopsis</h2>
<pre class="literal-block">
<a class="reference external" href="../api/types.html#image">Image</a> *ShadeImage( const <a class="reference external" href="../api/types.html#image">Image</a> *image, const unsigned int gray, double azimuth,
double elevation, <a class="reference external" href="../api/types.html#exceptioninfo">ExceptionInfo</a> *exception );
</pre>
</div>
<div class="section" id="id36">
<h2>Description</h2>
<p>ShadeImage() shines a distant light on an image to create a
three-dimensional effect. You control the positioning of the light with
azimuth and elevation; azimuth is measured in degrees off the x axis
and elevation is measured in pixels above the Z axis.</p>
<p>The format of the ShadeImage method is:</p>
<pre class="literal-block">
<a class="reference external" href="../api/types.html#image">Image</a> *ShadeImage( const <a class="reference external" href="../api/types.html#image">Image</a> *image, const unsigned int gray, double azimuth,
double elevation, <a class="reference external" href="../api/types.html#exceptioninfo">ExceptionInfo</a> *exception );
</pre>
<dl class="docutils">
<dt>image:</dt>
<dd>The image.</dd>
<dt>gray:</dt>
<dd>A value other than zero shades the intensity of each pixel.</dd>
<dt>azimuth, elevation:</dt>
<dd>Define the light source direction.</dd>
<dt>exception:</dt>
<dd>Return any errors or warnings in this structure.</dd>
</dl>
</div>
</div>
<div class="section" id="sharpenimage">
<h1><a class="toc-backref" href="#id70">SharpenImage</a></h1>
<div class="section" id="id37">
<h2>Synopsis</h2>
<pre class="literal-block">
<a class="reference external" href="../api/types.html#image">Image</a> *SharpenImage( const <a class="reference external" href="../api/types.html#image">Image</a> *image, const double radius, const double sigma,
<a class="reference external" href="../api/types.html#exceptioninfo">ExceptionInfo</a> *exception );
</pre>
</div>
<div class="section" id="id38">
<h2>Description</h2>
<p>SharpenImage() sharpens an image. We convolve the image with a
Gaussian operator of the given radius and standard deviation (sigma).
For reasonable results, radius should be larger than sigma. Use a
radius of 0 and SharpenImage() selects a suitable radius for you.</p>
<p>The format of the SharpenImage method is:</p>
<pre class="literal-block">
<a class="reference external" href="../api/types.html#image">Image</a> *SharpenImage( const <a class="reference external" href="../api/types.html#image">Image</a> *image, const double radius, const double sigma,
<a class="reference external" href="../api/types.html#exceptioninfo">ExceptionInfo</a> *exception );
</pre>
<dl class="docutils">
<dt>image:</dt>
<dd>The image.</dd>
<dt>radius:</dt>
<dd>The radius of the Gaussian, in pixels, not counting the center
pixel.</dd>
<dt>sigma:</dt>
<dd>The standard deviation of the Laplacian, in pixels.</dd>
<dt>exception:</dt>
<dd>Return any errors or warnings in this structure.</dd>
</dl>
</div>
</div>
<div class="section" id="sharpenimagechannel">
<h1><a class="toc-backref" href="#id71">SharpenImageChannel</a></h1>
<div class="section" id="id39">
<h2>Synopsis</h2>
<pre class="literal-block">
<a class="reference external" href="../api/types.html#image">Image</a> *SharpenImageChannel( const <a class="reference external" href="../api/types.html#image">Image</a> *image, const <a class="reference external" href="../api/types.html#channeltype">ChannelType</a> channel,
const double radius, const double sigma,
<a class="reference external" href="../api/types.html#exceptioninfo">ExceptionInfo</a> *exception );
</pre>
</div>
<div class="section" id="id40">
<h2>Description</h2>
<p>SharpenImageChannel() sharpens an image channel. We convolve the image
channel with a Gaussian operator of the given radius and standard
deviation (sigma). For reasonable results, radius should be larger than
sigma. Use a radius of 0 and SharpenImageChannel() selects a suitable
radius for you.</p>
<p>The format of the SharpenImageChannel method is:</p>
<pre class="literal-block">
<a class="reference external" href="../api/types.html#image">Image</a> *SharpenImageChannel( const <a class="reference external" href="../api/types.html#image">Image</a> *image, const <a class="reference external" href="../api/types.html#channeltype">ChannelType</a> channel,
const double radius, const double sigma,
<a class="reference external" href="../api/types.html#exceptioninfo">ExceptionInfo</a> *exception );
</pre>
<dl class="docutils">
<dt>image:</dt>
<dd>The image.</dd>
<dt>channel:</dt>
<dd>The channel to sharpen.</dd>
<dt>radius:</dt>
<dd>The radius of the Gaussian, in pixels, not counting the center
pixel.</dd>
<dt>sigma:</dt>
<dd>The standard deviation of the Laplacian, in pixels.</dd>
<dt>exception:</dt>
<dd>Return any errors or warnings in this structure.</dd>
</dl>
</div>
</div>
<div class="section" id="spreadimage">
<h1><a class="toc-backref" href="#id72">SpreadImage</a></h1>
<div class="section" id="id41">
<h2>Synopsis</h2>
<pre class="literal-block">
<a class="reference external" href="../api/types.html#image">Image</a> *SpreadImage( const <a class="reference external" href="../api/types.html#image">Image</a> *image, const unsigned int radius,
<a class="reference external" href="../api/types.html#exceptioninfo">ExceptionInfo</a> *exception );
</pre>
</div>
<div class="section" id="id42">
<h2>Description</h2>
<p>SpreadImage() is a special effects method that randomly displaces each
pixel in a block defined by the radius parameter.</p>
<p>The format of the SpreadImage method is:</p>
<pre class="literal-block">
<a class="reference external" href="../api/types.html#image">Image</a> *SpreadImage( const <a class="reference external" href="../api/types.html#image">Image</a> *image, const unsigned int radius,
<a class="reference external" href="../api/types.html#exceptioninfo">ExceptionInfo</a> *exception );
</pre>
<dl class="docutils">
<dt>image:</dt>
<dd>The image.</dd>
<dt>radius:</dt>
<dd>Choose a random pixel in a neighborhood of this extent.</dd>
<dt>exception:</dt>
<dd>Return any errors or warnings in this structure.</dd>
</dl>
</div>
</div>
<div class="section" id="thresholdimage">
<h1><a class="toc-backref" href="#id73">ThresholdImage</a></h1>
<div class="section" id="id43">
<h2>Synopsis</h2>
<pre class="literal-block">
MagickPassFail ThresholdImage( <a class="reference external" href="../api/types.html#image">Image</a> *image, const double threshold );
</pre>
</div>
<div class="section" id="id44">
<h2>Description</h2>
<p>ThresholdImage() changes the value of individual pixels based on
the intensity of each pixel compared to a specified threshold. Values
greater than the threshold are set to the maximum quantum value, and
values equal to or below the threshold are set to the minimum quantum
value. The result is a high-contrast, two color image.</p>
<p>The format of the ThresholdImage method is:</p>
<pre class="literal-block">
MagickPassFail ThresholdImage( <a class="reference external" href="../api/types.html#image">Image</a> *image, const double threshold );
</pre>
<p>A description of each parameter follows:</p>
<dl class="docutils">
<dt>image:</dt>
<dd>The image.</dd>
<dt>threshold:</dt>
<dd>Define the threshold value</dd>
</dl>
</div>
</div>
<div class="section" id="unsharpmaskimage">
<h1><a class="toc-backref" href="#id74">UnsharpMaskImage</a></h1>
<div class="section" id="id45">
<h2>Synopsis</h2>
<pre class="literal-block">
<a class="reference external" href="../api/types.html#image">Image</a> *UnsharpMaskImage( const <a class="reference external" href="../api/types.html#image">Image</a> *image, const double radius, const double sigma,
const double amount, const double threshold,
<a class="reference external" href="../api/types.html#exceptioninfo">ExceptionInfo</a> *exception );
</pre>
</div>
<div class="section" id="id46">
<h2>Description</h2>
<p>UnsharpMaskImage() sharpens an image. We convolve the image with a
Gaussian operator of the given radius and standard deviation (sigma).
For reasonable results, radius should be larger than sigma. Use a radius
of 0 and UnsharpMaskImage() selects a suitable radius for you.</p>
<p>The format of the UnsharpMaskImage method is:</p>
<pre class="literal-block">
<a class="reference external" href="../api/types.html#image">Image</a> *UnsharpMaskImage( const <a class="reference external" href="../api/types.html#image">Image</a> *image, const double radius, const double sigma,
const double amount, const double threshold,
<a class="reference external" href="../api/types.html#exceptioninfo">ExceptionInfo</a> *exception );
</pre>
<dl class="docutils">
<dt>image:</dt>
<dd>The image.</dd>
<dt>radius:</dt>
<dd>The radius of the Gaussian, in pixels, not counting the center
pixel.</dd>
<dt>sigma:</dt>
<dd>The standard deviation of the Gaussian, in pixels.</dd>
<dt>amount:</dt>
<dd>The percentage of the difference between the original and the
blur image that is added back into the original.</dd>
<dt>threshold:</dt>
<dd>The threshold in pixels needed to apply the diffence amount.</dd>
<dt>exception:</dt>
<dd>Return any errors or warnings in this structure.</dd>
</dl>
</div>
</div>
<div class="section" id="unsharpmaskimagechannel">
<h1><a class="toc-backref" href="#id75">UnsharpMaskImageChannel</a></h1>
<div class="section" id="id47">
<h2>Synopsis</h2>
<pre class="literal-block">
<a class="reference external" href="../api/types.html#image">Image</a> *UnsharpMaskImageChannel( const <a class="reference external" href="../api/types.html#image">Image</a> *image, const <a class="reference external" href="../api/types.html#channeltype">ChannelType</a> channel,
const double radius, const double sigma, const double amount,
const double threshold, <a class="reference external" href="../api/types.html#exceptioninfo">ExceptionInfo</a> *exception );
</pre>
</div>
<div class="section" id="id48">
<h2>Description</h2>
<p>UnsharpMaskImageChannel() sharpens an image channel. We convolve the
image channel with a Gaussian operator of the given radius and standard
deviation (sigma). For reasonable results, radius should be larger than
sigma. Use a radius of 0 and UnsharpMaskImage() selects a suitable
radius for you.</p>
<p>The format of the UnsharpMaskImageChannel method is:</p>
<pre class="literal-block">
<a class="reference external" href="../api/types.html#image">Image</a> *UnsharpMaskImageChannel( const <a class="reference external" href="../api/types.html#image">Image</a> *image, const <a class="reference external" href="../api/types.html#channeltype">ChannelType</a> channel,
const double radius, const double sigma, const double amount,
const double threshold, <a class="reference external" href="../api/types.html#exceptioninfo">ExceptionInfo</a> *exception );
</pre>
<dl class="docutils">
<dt>image:</dt>
<dd>The image.</dd>
<dt>channel:</dt>
<dd>The channel to sharpen.</dd>
<dt>radius:</dt>
<dd>The radius of the Gaussian, in pixels, not counting the center
pixel.</dd>
<dt>sigma:</dt>
<dd>The standard deviation of the Gaussian, in pixels.</dd>
<dt>amount:</dt>
<dd>The percentage of the difference between the original and the
blur image that is added back into the original.</dd>
<dt>threshold:</dt>
<dd>The threshold in pixels needed to apply the diffence amount.</dd>
<dt>exception:</dt>
<dd>Return any errors or warnings in this structure.</dd>
</dl>
</div>
</div>
<div class="section" id="whitethresholdimage">
<h1><a class="toc-backref" href="#id76">WhiteThresholdImage</a></h1>
<div class="section" id="id49">
<h2>Synopsis</h2>
<pre class="literal-block">
MagickPassFail WhiteThresholdImage( <a class="reference external" href="../api/types.html#image">Image</a> *image, const char *thresholds );
</pre>
</div>
<div class="section" id="id50">
<h2>Description</h2>
<p>WhiteThresholdImage() adjusts the levels of image channels such that
values above a specified threshold are set to the maximum value (white)
while the remaining pixels are unchanged.</p>
<p>The format of the WhiteThresholdImage method is:</p>
<pre class="literal-block">
MagickPassFail WhiteThresholdImage( <a class="reference external" href="../api/types.html#image">Image</a> *image, const char *thresholds );
</pre>
<p>A description of each parameter follows:</p>
<dl class="docutils">
<dt>image:</dt>
<dd>The image.</dd>
<dt>thresholds:</dt>
<dd>Channel thresholds which are specified as a comma delimited
list containing the thresholds for red, green, blue, and opacity. If
the list contains a percent symbol (%) then all values are treated as
a percentage of MaxRGB.</dd>
</dl>
</div>
</div>
</div>
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