[xsl] converting gif,jpeg,png into wbmp

Hello XSL-list!
I have an XML DTD which allows the use of images in GIF, JPEG and PNG
format.
Now I want to translate the original XML document into WML 1.3
So I have to convert my images into the appropriate format, That means they
should be resized to
a certain width and height and they should be converted into wbmp format.
Does anybody know if there already exists a free converter I can invoke
within XSLT (and where I can get that one)?
Can I use the Bean Scripting Framework or is there another interface/method
to do that?
Thanks for your comments in advance,

   Andreas


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