Example
This filter selects only the high luminance areas of a source graphic, blurs the contents and composites the blurred content on top of the original.
<svg width="800px" height="600px">
<defs>
<filter id="highlightblur" color-interpolation-filters="sRGB">
<feColorMatrix type="luminanceToAlpha" in="SourceGraphic" result="lumMap"/>
<feComponentTransfer in="lumMap" result="highlightMask">
<feFuncA type="discrete" tableValues="0 0 0 0 0 0 0 1"/>
</feComponentTransfer>
<feComposite operator="in" in="SourceGraphic" in2="highlightMask" result="highlights"/>
<feGaussianBlur in="highlights" stdDeviation="3" result="highBlur"/>
<feComposite operator="over" in="highBlur" in2="SourceGraphic" result="final"/>
</filter>
</defs>
<image filter="url(#highlightblur)" x="0" y="-40" width="780" height="600" preserveAspectRatio="true" xlink:href="http://i554.photobucket.com/albums/jj424/allbowerpower/Christmas%202009/ChristmasTablesetting016b.jpg"
/>
</svg>
