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<title>Gets the image histogram</title>
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<h1 class="refname">Imagick::getImageHistogram</h1>
<p class="verinfo">(PECL imagick 2.0.0)</p><p class="refpurpose"><span class="refname">Imagick::getImageHistogram</span> — <span class="dc-title">Gets the image histogram</span></p>
</div>
<div class="refsect1 description" id="refsect1-imagick.getimagehistogram-description">
<h3 class="title">Description</h3>
<div class="methodsynopsis dc-description">
<span class="type">array</span> <span class="methodname"><strong>Imagick::getImageHistogram</strong></span>
( <span class="methodparam">void</span>
)</div>
<p class="para rdfs-comment">
Returns the image histogram as an array of ImagickPixel objects.
</p>
</div>
<div class="refsect1 returnvalues" id="refsect1-imagick.getimagehistogram-returnvalues">
<h3 class="title">Return Values</h3>
<p class="para">
Returns the image histogram as an array of ImagickPixel objects.
</p>
</div>
<div class="refsect1 errors" id="refsect1-imagick.getimagehistogram-errors">
<h3 class="title">Errors/Exceptions</h3>
<p class="para">
Throws ImagickException on error.
</p>
</div>
<div class="refsect1 examples" id="refsect1-imagick.getimagehistogram-examples">
<h3 class="title">Examples</h3>
<p class="para">
<div class="example" id="example-3925">
<p><strong>Example #1 Generates <span class="function"><strong>Imagick::getImageHistogram()</strong></span></strong></p>
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br /></span><span style="color: #007700">function </span><span style="color: #0000BB">getColorStatistics</span><span style="color: #007700">(</span><span style="color: #0000BB">$histogramElements</span><span style="color: #007700">, </span><span style="color: #0000BB">$colorChannel</span><span style="color: #007700">) {<br /> </span><span style="color: #0000BB">$colorStatistics </span><span style="color: #007700">= [];<br /><br /> foreach (</span><span style="color: #0000BB">$histogramElements </span><span style="color: #007700">as </span><span style="color: #0000BB">$histogramElement</span><span style="color: #007700">) {<br /> </span><span style="color: #0000BB">$color </span><span style="color: #007700">= </span><span style="color: #0000BB">$histogramElement</span><span style="color: #007700">-></span><span style="color: #0000BB">getColorValue</span><span style="color: #007700">(</span><span style="color: #0000BB">$colorChannel</span><span style="color: #007700">);<br /> </span><span style="color: #0000BB">$color </span><span style="color: #007700">= </span><span style="color: #0000BB">intval</span><span style="color: #007700">(</span><span style="color: #0000BB">$color </span><span style="color: #007700">* </span><span style="color: #0000BB">255</span><span style="color: #007700">);<br /> </span><span style="color: #0000BB">$count </span><span style="color: #007700">= </span><span style="color: #0000BB">$histogramElement</span><span style="color: #007700">-></span><span style="color: #0000BB">getColorCount</span><span style="color: #007700">();<br /><br /> if (</span><span style="color: #0000BB">array_key_exists</span><span style="color: #007700">(</span><span style="color: #0000BB">$color</span><span style="color: #007700">, </span><span style="color: #0000BB">$colorStatistics</span><span style="color: #007700">)) {<br /> </span><span style="color: #0000BB">$colorStatistics</span><span style="color: #007700">[</span><span style="color: #0000BB">$color</span><span style="color: #007700">] += </span><span style="color: #0000BB">$count</span><span style="color: #007700">;<br /> }<br /> else {<br /> </span><span style="color: #0000BB">$colorStatistics</span><span style="color: #007700">[</span><span style="color: #0000BB">$color</span><span style="color: #007700">] = </span><span style="color: #0000BB">$count</span><span style="color: #007700">;<br /> }<br /> }<br /><br /> </span><span style="color: #0000BB">ksort</span><span style="color: #007700">(</span><span style="color: #0000BB">$colorStatistics</span><span style="color: #007700">);<br /> <br /> return </span><span style="color: #0000BB">$colorStatistics</span><span style="color: #007700">;<br />}<br /> <br /><br /><br />function </span><span style="color: #0000BB">getImageHistogram</span><span style="color: #007700">(</span><span style="color: #0000BB">$imagePath</span><span style="color: #007700">) {<br /><br /> </span><span style="color: #0000BB">$backgroundColor </span><span style="color: #007700">= </span><span style="color: #DD0000">'black'</span><span style="color: #007700">;<br /><br /> </span><span style="color: #0000BB">$draw </span><span style="color: #007700">= new \</span><span style="color: #0000BB">ImagickDraw</span><span style="color: #007700">();<br /> </span><span style="color: #0000BB">$draw</span><span style="color: #007700">-></span><span style="color: #0000BB">setStrokeWidth</span><span style="color: #007700">(</span><span style="color: #0000BB">0</span><span style="color: #007700">); </span><span style="color: #FF8000">//make the lines be as thin as possible<br /><br /> </span><span style="color: #0000BB">$imagick </span><span style="color: #007700">= new \</span><span style="color: #0000BB">Imagick</span><span style="color: #007700">();<br /> </span><span style="color: #0000BB">$imagick</span><span style="color: #007700">-></span><span style="color: #0000BB">newImage</span><span style="color: #007700">(</span><span style="color: #0000BB">500</span><span style="color: #007700">, </span><span style="color: #0000BB">500</span><span style="color: #007700">, </span><span style="color: #0000BB">$backgroundColor</span><span style="color: #007700">);<br /> </span><span style="color: #0000BB">$imagick</span><span style="color: #007700">-></span><span style="color: #0000BB">setImageFormat</span><span style="color: #007700">(</span><span style="color: #DD0000">"png"</span><span style="color: #007700">);<br /> </span><span style="color: #0000BB">$imagick</span><span style="color: #007700">-></span><span style="color: #0000BB">drawImage</span><span style="color: #007700">(</span><span style="color: #0000BB">$draw</span><span style="color: #007700">);<br /><br /> </span><span style="color: #0000BB">$histogramWidth </span><span style="color: #007700">= </span><span style="color: #0000BB">256</span><span style="color: #007700">;<br /> </span><span style="color: #0000BB">$histogramHeight </span><span style="color: #007700">= </span><span style="color: #0000BB">100</span><span style="color: #007700">; </span><span style="color: #FF8000">// the height for each RGB segment<br /><br /> </span><span style="color: #0000BB">$imagick </span><span style="color: #007700">= new \</span><span style="color: #0000BB">Imagick</span><span style="color: #007700">(</span><span style="color: #0000BB">realpath</span><span style="color: #007700">(</span><span style="color: #0000BB">$imagePath</span><span style="color: #007700">));<br /> </span><span style="color: #FF8000">//Resize the image to be small, otherwise PHP tends to run out of memory<br /> //This might lead to bad results for images that are pathologically 'pixelly'<br /> </span><span style="color: #0000BB">$imagick</span><span style="color: #007700">-></span><span style="color: #0000BB">adaptiveResizeImage</span><span style="color: #007700">(</span><span style="color: #0000BB">200</span><span style="color: #007700">, </span><span style="color: #0000BB">200</span><span style="color: #007700">, </span><span style="color: #0000BB">true</span><span style="color: #007700">);<br /> </span><span style="color: #0000BB">$histogramElements </span><span style="color: #007700">= </span><span style="color: #0000BB">$imagick</span><span style="color: #007700">-></span><span style="color: #0000BB">getImageHistogram</span><span style="color: #007700">();<br /><br /> </span><span style="color: #0000BB">$histogram </span><span style="color: #007700">= new \</span><span style="color: #0000BB">Imagick</span><span style="color: #007700">();<br /> </span><span style="color: #0000BB">$histogram</span><span style="color: #007700">-></span><span style="color: #0000BB">newpseudoimage</span><span style="color: #007700">(</span><span style="color: #0000BB">$histogramWidth</span><span style="color: #007700">, </span><span style="color: #0000BB">$histogramHeight </span><span style="color: #007700">* </span><span style="color: #0000BB">3</span><span style="color: #007700">, </span><span style="color: #DD0000">'xc:black'</span><span style="color: #007700">);<br /> </span><span style="color: #0000BB">$histogram</span><span style="color: #007700">-></span><span style="color: #0000BB">setImageFormat</span><span style="color: #007700">(</span><span style="color: #DD0000">'png'</span><span style="color: #007700">);<br /><br /> </span><span style="color: #0000BB">$getMax </span><span style="color: #007700">= function (</span><span style="color: #0000BB">$carry</span><span style="color: #007700">, </span><span style="color: #0000BB">$item</span><span style="color: #007700">) {<br /> if (</span><span style="color: #0000BB">$item </span><span style="color: #007700">> </span><span style="color: #0000BB">$carry</span><span style="color: #007700">) {<br /> return </span><span style="color: #0000BB">$item</span><span style="color: #007700">;<br /> }<br /> return </span><span style="color: #0000BB">$carry</span><span style="color: #007700">;<br /> };<br /><br /> </span><span style="color: #0000BB">$colorValues </span><span style="color: #007700">= [<br /> </span><span style="color: #DD0000">'red' </span><span style="color: #007700">=> </span><span style="color: #0000BB">getColorStatistics</span><span style="color: #007700">(</span><span style="color: #0000BB">$histogramElements</span><span style="color: #007700">, \</span><span style="color: #0000BB">Imagick</span><span style="color: #007700">::</span><span style="color: #0000BB">COLOR_RED</span><span style="color: #007700">),<br /> </span><span style="color: #DD0000">'lime' </span><span style="color: #007700">=> </span><span style="color: #0000BB">getColorStatistics</span><span style="color: #007700">(</span><span style="color: #0000BB">$histogramElements</span><span style="color: #007700">, \</span><span style="color: #0000BB">Imagick</span><span style="color: #007700">::</span><span style="color: #0000BB">COLOR_GREEN</span><span style="color: #007700">),<br /> </span><span style="color: #DD0000">'blue' </span><span style="color: #007700">=> </span><span style="color: #0000BB">getColorStatistics</span><span style="color: #007700">(</span><span style="color: #0000BB">$histogramElements</span><span style="color: #007700">, \</span><span style="color: #0000BB">Imagick</span><span style="color: #007700">::</span><span style="color: #0000BB">COLOR_BLUE</span><span style="color: #007700">),<br /> ];<br /><br /> </span><span style="color: #0000BB">$max </span><span style="color: #007700">= </span><span style="color: #0000BB">array_reduce</span><span style="color: #007700">(</span><span style="color: #0000BB">$colorValues</span><span style="color: #007700">[</span><span style="color: #DD0000">'red'</span><span style="color: #007700">] , </span><span style="color: #0000BB">$getMax</span><span style="color: #007700">, </span><span style="color: #0000BB">0</span><span style="color: #007700">);<br /> </span><span style="color: #0000BB">$max </span><span style="color: #007700">= </span><span style="color: #0000BB">array_reduce</span><span style="color: #007700">(</span><span style="color: #0000BB">$colorValues</span><span style="color: #007700">[</span><span style="color: #DD0000">'lime'</span><span style="color: #007700">] , </span><span style="color: #0000BB">$getMax</span><span style="color: #007700">, </span><span style="color: #0000BB">$max</span><span style="color: #007700">);<br /> </span><span style="color: #0000BB">$max </span><span style="color: #007700">= </span><span style="color: #0000BB">array_reduce</span><span style="color: #007700">(</span><span style="color: #0000BB">$colorValues</span><span style="color: #007700">[</span><span style="color: #DD0000">'blue'</span><span style="color: #007700">] , </span><span style="color: #0000BB">$getMax</span><span style="color: #007700">, </span><span style="color: #0000BB">$max</span><span style="color: #007700">);<br /><br /> </span><span style="color: #0000BB">$scale </span><span style="color: #007700">= </span><span style="color: #0000BB">$histogramHeight </span><span style="color: #007700">/ </span><span style="color: #0000BB">$max</span><span style="color: #007700">;<br /><br /> </span><span style="color: #0000BB">$count </span><span style="color: #007700">= </span><span style="color: #0000BB">0</span><span style="color: #007700">;<br /> foreach (</span><span style="color: #0000BB">$colorValues </span><span style="color: #007700">as </span><span style="color: #0000BB">$color </span><span style="color: #007700">=> </span><span style="color: #0000BB">$values</span><span style="color: #007700">) {<br /> </span><span style="color: #0000BB">$draw</span><span style="color: #007700">-></span><span style="color: #0000BB">setstrokecolor</span><span style="color: #007700">(</span><span style="color: #0000BB">$color</span><span style="color: #007700">);<br /><br /> </span><span style="color: #0000BB">$offset </span><span style="color: #007700">= (</span><span style="color: #0000BB">$count </span><span style="color: #007700">+ </span><span style="color: #0000BB">1</span><span style="color: #007700">) * </span><span style="color: #0000BB">$histogramHeight</span><span style="color: #007700">;<br /><br /> foreach (</span><span style="color: #0000BB">$values </span><span style="color: #007700">as </span><span style="color: #0000BB">$index </span><span style="color: #007700">=> </span><span style="color: #0000BB">$value</span><span style="color: #007700">) {<br /> </span><span style="color: #0000BB">$draw</span><span style="color: #007700">-></span><span style="color: #0000BB">line</span><span style="color: #007700">(</span><span style="color: #0000BB">$index</span><span style="color: #007700">, </span><span style="color: #0000BB">$offset</span><span style="color: #007700">, </span><span style="color: #0000BB">$index</span><span style="color: #007700">, </span><span style="color: #0000BB">$offset </span><span style="color: #007700">- (</span><span style="color: #0000BB">$value </span><span style="color: #007700">* </span><span style="color: #0000BB">$scale</span><span style="color: #007700">));<br /> }<br /> </span><span style="color: #0000BB">$count</span><span style="color: #007700">++;<br /> }<br /><br /> </span><span style="color: #0000BB">$histogram</span><span style="color: #007700">-></span><span style="color: #0000BB">drawImage</span><span style="color: #007700">(</span><span style="color: #0000BB">$draw</span><span style="color: #007700">);<br /> <br /> </span><span style="color: #0000BB">header</span><span style="color: #007700">( </span><span style="color: #DD0000">"Content-Type: image/png" </span><span style="color: #007700">);<br /> echo </span><span style="color: #0000BB">$histogram</span><span style="color: #007700">;<br />}<br /><br /></span><span style="color: #0000BB">?></span>
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