functions for simulating color blindness?

I'm trying to enhance kmag to add 'color blindness simulation' modes, 
and am looking for a simulation algorithm that I can implement in a way 
that is GPL-compatible. Anyone know of one?

I found http://www.nofunc.com/Color_Blindness_Library/, but the 
licensing looks like it will be a problem.

(Why kmag? Because using an existing screen-grabber gives me a framework 
where I can drop in just the color-manipulating code without having to 
write any front-end stuff... plus kmag seems like a good place that will 
make it easy for me to fiddle, and might even be suitable for accepting 
such code "for real".)

-- 
Matthew
"I always thought the KDE coders were simply very intelligent AI's... 
since I've never seen one in person before :)" -- Troy Unrau