Quote Originally Posted by NecroDOME
Most videocards are limited to a texture size of 4096x4096.
Note that I have all this running, except for the false color bit. GF8 cards have 8192*8192, GF7 cards 4096*4096. Trick is that I pick the videocard we ship, usually so that it is just right for the job.

Since till now, the bottleneck is pretty much texture uploading, not shader performance, generally the speed is about the same across the same family of GPU (as long as not embedded). E.g. one can't really notice a difference between a 7300 and 7800

Texture lookups to convert color are easy to do in a shader. Currently I don't have an example, but I can help you if you have an OpenGL app that can render with shaders.
Thanks, I'll keep that in mind for when I'm a bit further.