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<title>Apply a 3x3 convolution matrix, using coefficient and offset</title>
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</div><hr /><div id="function.imageconvolution" class="refentry">
<div class="refnamediv">
<h1 class="refname">imageconvolution</h1>
<p class="verinfo">(PHP 5 >= 5.1.0)</p><p class="refpurpose"><span class="refname">imageconvolution</span> — <span class="dc-title">Apply a 3x3 convolution matrix, using coefficient and offset</span></p>
</div>
<div class="refsect1 description" id="refsect1-function.imageconvolution-description">
<h3 class="title">Description</h3>
<div class="methodsynopsis dc-description">
<span class="type">bool</span> <span class="methodname"><strong>imageconvolution</strong></span>
( <span class="methodparam"><span class="type">resource</span> <code class="parameter">$image</code></span>
, <span class="methodparam"><span class="type">array</span> <code class="parameter">$matrix</code></span>
, <span class="methodparam"><span class="type">float</span> <code class="parameter">$div</code></span>
, <span class="methodparam"><span class="type">float</span> <code class="parameter">$offset</code></span>
)</div>
<p class="para rdfs-comment">
Applies a convolution matrix on the image, using the given coefficient and
offset.
</p>
</div>
<div class="refsect1 parameters" id="refsect1-function.imageconvolution-parameters">
<h3 class="title">Parameters</h3>
<p class="para">
<dl>
<dt>
<span class="term"><em><code class="parameter">
image</code></em></span><dd>
<p class="para">An image resource, returned by one of the image creation functions,
such as <span class="function"><a href="function.imagecreatetruecolor.html" class="function">imagecreatetruecolor()</a></span>.</p></dd>
</dt>
<dt>
<span class="term"><em><code class="parameter">matrix</code></em></span>
<dd>
<p class="para">
A 3x3 matrix: an array of three arrays of three floats.
</p>
</dd>
</dt>
<dt>
<span class="term"><em><code class="parameter">div</code></em></span>
<dd>
<p class="para">
The divisor of the result of the convolution, used for normalization.
</p>
</dd>
</dt>
<dt>
<span class="term"><em><code class="parameter">offset</code></em></span>
<dd>
<p class="para">
Color offset.
</p>
</dd>
</dt>
</dl>
</p>
</div>
<div class="refsect1 returnvalues" id="refsect1-function.imageconvolution-returnvalues">
<h3 class="title">Return Values</h3>
<p class="para">
Returns <strong><code>TRUE</code></strong> on success or <strong><code>FALSE</code></strong> on failure.
</p>
</div>
<div class="refsect1 examples" id="refsect1-function.imageconvolution-examples">
<h3 class="title">Examples</h3>
<p class="para">
<div class="example" id="example-3200">
<p><strong>Example #1 Embossing the PHP.net logo</strong></p>
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br />$image </span><span style="color: #007700">= </span><span style="color: #0000BB">imagecreatefromgif</span><span style="color: #007700">(</span><span style="color: #DD0000">'http://www.php.net/images/php.gif'</span><span style="color: #007700">);<br /><br /></span><span style="color: #0000BB">$emboss </span><span style="color: #007700">= array(array(</span><span style="color: #0000BB">2</span><span style="color: #007700">, </span><span style="color: #0000BB">0</span><span style="color: #007700">, </span><span style="color: #0000BB">0</span><span style="color: #007700">), array(</span><span style="color: #0000BB">0</span><span style="color: #007700">, -</span><span style="color: #0000BB">1</span><span style="color: #007700">, </span><span style="color: #0000BB">0</span><span style="color: #007700">), array(</span><span style="color: #0000BB">0</span><span style="color: #007700">, </span><span style="color: #0000BB">0</span><span style="color: #007700">, -</span><span style="color: #0000BB">1</span><span style="color: #007700">));<br /></span><span style="color: #0000BB">imageconvolution</span><span style="color: #007700">(</span><span style="color: #0000BB">$image</span><span style="color: #007700">, </span><span style="color: #0000BB">$emboss</span><span style="color: #007700">, </span><span style="color: #0000BB">1</span><span style="color: #007700">, </span><span style="color: #0000BB">127</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 /></span><span style="color: #0000BB">imagepng</span><span style="color: #007700">(</span><span style="color: #0000BB">$image</span><span style="color: #007700">, </span><span style="color: #0000BB">null</span><span style="color: #007700">, </span><span style="color: #0000BB">9</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
</div>
<div class="example-contents"><p>The above example will output:</p></div>
<div class="mediaobject">
<div class="imageobject">
<img src="images/21009b70229598c6a80eef8b45bf282b-imageconvolution_emboss.png" alt="Output of example : Embossing the PHP.net logo" width="120" height="67" />
</div>
</div>
</div>
<div class="example" id="example-3201">
<p><strong>Example #2 Gaussian blur</strong></p>
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br />$image </span><span style="color: #007700">= </span><span style="color: #0000BB">imagecreatetruecolor</span><span style="color: #007700">(</span><span style="color: #0000BB">180</span><span style="color: #007700">,</span><span style="color: #0000BB">40</span><span style="color: #007700">);<br /><br /></span><span style="color: #FF8000">// Writes the text and apply a gaussian blur on the image<br /></span><span style="color: #0000BB">imagestring</span><span style="color: #007700">(</span><span style="color: #0000BB">$image</span><span style="color: #007700">, </span><span style="color: #0000BB">5</span><span style="color: #007700">, </span><span style="color: #0000BB">10</span><span style="color: #007700">, </span><span style="color: #0000BB">8</span><span style="color: #007700">, </span><span style="color: #DD0000">'Gaussian Blur Text'</span><span style="color: #007700">, </span><span style="color: #0000BB">0x00ff00</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">$gaussian </span><span style="color: #007700">= array(array(</span><span style="color: #0000BB">1.0</span><span style="color: #007700">, </span><span style="color: #0000BB">2.0</span><span style="color: #007700">, </span><span style="color: #0000BB">1.0</span><span style="color: #007700">), array(</span><span style="color: #0000BB">2.0</span><span style="color: #007700">, </span><span style="color: #0000BB">4.0</span><span style="color: #007700">, </span><span style="color: #0000BB">2.0</span><span style="color: #007700">), array(</span><span style="color: #0000BB">1.0</span><span style="color: #007700">, </span><span style="color: #0000BB">2.0</span><span style="color: #007700">, </span><span style="color: #0000BB">1.0</span><span style="color: #007700">));<br /></span><span style="color: #0000BB">imageconvolution</span><span style="color: #007700">(</span><span style="color: #0000BB">$image</span><span style="color: #007700">, </span><span style="color: #0000BB">$gaussian</span><span style="color: #007700">, </span><span style="color: #0000BB">16</span><span style="color: #007700">, </span><span style="color: #0000BB">0</span><span style="color: #007700">);<br /><br /></span><span style="color: #FF8000">// Rewrites the text for comparison<br /></span><span style="color: #0000BB">imagestring</span><span style="color: #007700">(</span><span style="color: #0000BB">$image</span><span style="color: #007700">, </span><span style="color: #0000BB">5</span><span style="color: #007700">, </span><span style="color: #0000BB">10</span><span style="color: #007700">, </span><span style="color: #0000BB">18</span><span style="color: #007700">, </span><span style="color: #DD0000">'Gaussian Blur Text'</span><span style="color: #007700">, </span><span style="color: #0000BB">0x00ff00</span><span style="color: #007700">);<br /><br /></span><span style="color: #0000BB">header</span><span style="color: #007700">(</span><span style="color: #DD0000">'Content-Type: image/png'</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">imagepng</span><span style="color: #007700">(</span><span style="color: #0000BB">$image</span><span style="color: #007700">, </span><span style="color: #0000BB">null</span><span style="color: #007700">, </span><span style="color: #0000BB">9</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
</div>
<div class="example-contents"><p>The above example will output:</p></div>
<div class="mediaobject">
<div class="imageobject">
<img src="images/21009b70229598c6a80eef8b45bf282b-imageconvolution_gaussian.png" alt="Output of example : Gaussian blur" width="180" height="40" />
</div>
</div>
</div>
</p>
</div>
<div class="refsect1 notes" id="refsect1-function.imageconvolution-notes">
<h3 class="title">Notes</h3>
<blockquote class="note"><p><strong class="note">Note</strong>: <span class="simpara">This function is only available if
PHP is compiled with the bundled version of the GD library.</span></p></blockquote>
</div>
<div class="refsect1 seealso" id="refsect1-function.imageconvolution-seealso">
<h3 class="title">See Also</h3>
<p class="para">
<ul class="simplelist">
<li class="member"> <span class="function"><a href="function.imagefilter.html" class="function" rel="rdfs-seeAlso">imagefilter()</a> - Applies a filter to an image</span></li>
</ul>
</p>
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