Image manipulation via XSLT extensions

Hello,

"Unfortunately, there is no single graphics file format that meets all needs."  - Bob

Bob is right.  One of the biggest annoyances I have when writing documents is that, when I want to insert a graphic, I must reference and maintain multiple versions of the image file in order to accommodate the various types of output I am producing:

<mediaobject>
  <imageobject role="fo">
    <imagedata format="SVG" fileref="figure.svg"/>
  </imageobject>
  <imageobject role="html">

    <imagedata format="PNG" fileref="figure.png"/>
  </imageobject>
</mediaobject>

Let's say I created a figure in SVG, as in the above example.  This SVG is my original image source, and in a perfect world, it would be all I'd need to carry around.  But, since we can't trust SVGs with our web browsers, I must convert it to PNG and carry around another version of the file for HTML output.

What if I actually could only keep the SVG, and have the stylesheet somehow convert the image to alternate formats as needed?  If I run the HTML stylesheet, it sees an SVG, and calls an external program--say, ImageMagick--to convert the file to a PNG.

This leads me to my question.  I know that with processors like Saxon and Xalan, you can write extensions in Java/JavaScript.  It seems to me that one would be able to write an extension to call ImageMagick as needed.  However, I have absolutely no experience with XSLT extensions, and don't really know where to start.

I do know where to find resources on the subject.  However, I thought I would first post here to see if anyone has done anything similar, or thought about anything like this before.

- Colin