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<h2>Canny Edge Detector</h2>
<p><strong>What You&rsquo;re Seeing:<br />
</strong>The edge detector searches for edges between regions of different brightness in the image. It draws a black line for each edge it finds.</p>
<p><strong>How It Works:<br />
</strong>Edge detectors treat changes in brightness between adjacent pixels in an image beyond a certain threshold as edges. The Canny Edge Detector is more sophisticated in that it uses two thresholds. If a pixel is not adjacent to an existing edge, it uses a higher threshold; if a pixel is adjacent to an existing edge, it uses a lower threshold. The high threshold keeps down the number of excess edges to a minimum, while the lower threshold continues existing edges, even if they get slightly fuzzy.</p>
<p><strong>What It&rsquo;s Used For:<br />
</strong>Edge detection is often the first step in object segmentation, that is, breaking up an image into segments that represent different objects in the image.</p>
<p><strong>Try and Notice:<br />
</strong>Experiment with objects different levels of contrast. What&rsquo;s the minimum difference in brightness needed between to areas to find an edge?<br />
Just for for fun, Play A-Ha&rsquo;s song &ldquo;Take on Me&rdquo; in the background while this demo runs, and pretend you&rsquo;re in the music video for the song.</p>
<p><strong>Learn More:<br />
</strong><a href="http://en.wikipedia.org/wiki/Canny_edge_detector">Canny edge detector</a> on Wikipedia</p>
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