title: colorTransform equivalent color matrix
body: <p>I'm trying to convert a simple <a href="http://en.wikipedia.org/wiki/FXG" rel="nofollow">FXG</a> to SVG.
  The conversion is pretty much straightforward, but I'm encountering a color manipulation problem.</p>
  
  <p>The FXG have a base shades of gray path, and I apply a different color transformation on subsequent use of this path for other shapes.<br>
  Here the FXG color transformation (equivalent to <a href="http://help.adobe.com/en_US/FlashPlatform/reference/actionscript/3/flash/geom/ColorTransform.html" rel="nofollow">colorTransform</a>) :</p>
  
  <pre><code>&lt;ColorTransform redOffset="-255" blueOffset="25" greenOffset="56"/&gt;
  </code></pre>
  
  <p>How can I convert this color transformation (even the negative offset) to something SVG understand ? I only need the color offset changes, no multiplier or alpha.<br>
  I think it could be achieved with &lt;feColorMatrix&gt; (look like this SVG filter work like the AS3 ColorMatrixFilter) but I can't find how.</p>
  
  <p>So, the real general question is how I could convert those color offset changes to a color matrix filter ?</p>