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<a accesskey="3" href="page.php?w=Mach_bands&amp;p=2">3.Next</a>
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<p><b>Mach bands</b> is an <a href="page.php?w=optical_illusion">optical illusion</a> named after the physicist <a href="page.php?w=Ernst_Mach">Ernst Mach</a>. It exaggerates the <a href="page.php?w=contrast_%28vision%29">contrast</a> between edges of the slightly differing shades of gray, as soon as they contact one another, by triggering edge-detection in the human visual system. The Mach band illusion is sometimes called the <b>Chevreul</b> illusion.</p>

<p><big>Explanation</big></p>
<p>The Mach bands effect is due to the <a href="page.php?w=Unsharp_masking">spatial high-boost filtering</a></p><p>
<a accesskey="3" href="page.php?w=Mach_bands&amp;p=2">3.Next</a>
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