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<title>Set the interpolation method</title>
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<h1 class="refname">imagesetinterpolation</h1>
<p class="verinfo">(PHP 5 >= 5.5.0)</p><p class="refpurpose"><span class="refname">imagesetinterpolation</span> — <span class="dc-title">Set the interpolation method</span></p>
</div>
<div class="refsect1 description" id="refsect1-function.imagesetinterpolation-description">
<h3 class="title">Description</h3>
<div class="methodsynopsis dc-description">
<span class="type">bool</span> <span class="methodname"><strong>imagesetinterpolation</strong></span>
( <span class="methodparam"><span class="type">resource</span> <code class="parameter">$image</code></span>
[, <span class="methodparam"><span class="type">int</span> <code class="parameter">$method</code><span class="initializer"> = IMG_BILINEAR_FIXED</span></span>
] )</div>
<p class="para rdfs-comment">
Sets the interpolation method, setting an interpolation method affects the rendering
of various functions in GD, such as the <span class="function"><a href="function.imagerotate.html" class="function">imagerotate()</a></span> function.
</p>
</div>
<div class="refsect1 parameters" id="refsect1-function.imagesetinterpolation-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">method</code></em></span>
<dd>
<p class="para">
The interpolation method, which can be one of the following:
<ul class="itemizedlist">
<li class="listitem">
<span class="simpara">
<strong><code>IMG_BELL</code></strong>: Bell filter.
</span>
</li>
<li class="listitem">
<span class="simpara">
<strong><code>IMG_BESSEL</code></strong>: Bessel filter.
</span>
</li>
<li class="listitem">
<span class="simpara">
<strong><code>IMG_BICUBIC</code></strong>: Bicubic interpolation.
</span>
</li>
<li class="listitem">
<span class="simpara">
<strong><code>IMG_BICUBIC_FIXED</code></strong>: Fixed point implementation of the bicubic interpolation.
</span>
</li>
<li class="listitem">
<span class="simpara">
<strong><code>IMG_BILINEAR_FIXED</code></strong>: Fixed point implementation of the bilinear interpolation (<em>default (also on image creation)</em>).
</span>
</li>
<li class="listitem">
<span class="simpara">
<strong><code>IMG_BLACKMAN</code></strong>: Blackman window function.
</span>
</li>
<li class="listitem">
<span class="simpara">
<strong><code>IMG_BOX</code></strong>: Box blur filter.
</span>
</li>
<li class="listitem">
<span class="simpara">
<strong><code>IMG_BSPLINE</code></strong>: Spline interpolation.
</span>
</li>
<li class="listitem">
<span class="simpara">
<strong><code>IMG_CATMULLROM</code></strong>: Cubic Hermite spline interpolation.
</span>
</li>
<li class="listitem">
<span class="simpara">
<strong><code>IMG_GAUSSIAN</code></strong>: Gaussian function.
</span>
</li>
<li class="listitem">
<span class="simpara">
<strong><code>IMG_GENERALIZED_CUBIC</code></strong>: Generalized cubic spline fractal interpolation.
</span>
</li>
<li class="listitem">
<span class="simpara">
<strong><code>IMG_HERMITE</code></strong>: Hermite interpolation.
</span>
</li>
<li class="listitem">
<span class="simpara">
<strong><code>IMG_HAMMING</code></strong>: Hamming filter.
</span>
</li>
<li class="listitem">
<span class="simpara">
<strong><code>IMG_HANNING</code></strong>: Hanning filter.
</span>
</li>
<li class="listitem">
<span class="simpara">
<strong><code>IMG_MITCHELL</code></strong>: Mitchell filter.
</span>
</li>
<li class="listitem">
<span class="simpara">
<strong><code>IMG_POWER</code></strong>: Power interpolation.
</span>
</li>
<li class="listitem">
<span class="simpara">
<strong><code>IMG_QUADRATIC</code></strong>: Inverse quadratic interpolation.
</span>
</li>
<li class="listitem">
<span class="simpara">
<strong><code>IMG_SINC</code></strong>: Sinc function.
</span>
</li>
<li class="listitem">
<span class="simpara">
<strong><code>IMG_NEAREST_NEIGHBOUR</code></strong>: Nearest neighbour interpolation.
</span>
</li>
<li class="listitem">
<span class="simpara">
<strong><code>IMG_WEIGHTED4</code></strong>: Weighting filter.
</span>
</li>
<li class="listitem">
<span class="simpara">
<strong><code>IMG_TRIANGLE</code></strong>: Triangle interpolation.
</span>
</li>
</ul>
</p>
</dd>
</dt>
</dl>
</p>
</div>
<div class="refsect1 returnvalues" id="refsect1-function.imagesetinterpolation-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.imagesetinterpolation-examples">
<h3 class="title">Examples</h3>
<p class="para">
<div class="example" id="example-3275">
<p><strong>Example #1 <span class="function"><strong>imagesetinterpolation()</strong></span> example</strong></p>
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br /></span><span style="color: #FF8000">// Load an image<br /></span><span style="color: #0000BB">$im </span><span style="color: #007700">= </span><span style="color: #0000BB">imagecreate</span><span style="color: #007700">(</span><span style="color: #0000BB">500</span><span style="color: #007700">, </span><span style="color: #0000BB">500</span><span style="color: #007700">);<br /><br /></span><span style="color: #FF8000">// By default interpolation is IMG_BILINEAR_FIXED, switch <br />// to use the 'Mitchell' filter:<br /></span><span style="color: #0000BB">imagesetinterpolation</span><span style="color: #007700">(</span><span style="color: #0000BB">$im</span><span style="color: #007700">, </span><span style="color: #0000BB">IMG_MITCHELL</span><span style="color: #007700">);<br /><br /></span><span style="color: #FF8000">// Continue to work with $im ...<br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
</div>
</div>
</p>
</div>
<div class="refsect1 notes" id="refsect1-function.imagesetinterpolation-notes">
<h3 class="title">Notes</h3>
<p class="para">
Changing the interpolation method affects the following functions
when rendering:
<ul class="itemizedlist">
<li class="listitem">
<span class="simpara">
<span class="function"><a href="function.imageaffine.html" class="function">imageaffine()</a></span>
</span>
</li>
<li class="listitem">
<span class="simpara">
<span class="function"><a href="function.imagerotate.html" class="function">imagerotate()</a></span>
</span>
</li>
<li class="listitem">
<span class="simpara">
<span class="function"><a href="function.imagescale.html" class="function">imagescale()</a></span>
</span>
</li>
</ul>
</p>
</div>
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