Does anyone know of any reference material on writing advanced embossing algorithms? I want to write an emboss filter of the likes of Flaming Pear's Boss Emboss. If you haven't seen it, you can download a demo version at:
[Actually, they have a bunch of great filters that I would like to somewhat emulate: Boss Emboss, Aetherize, and Kyoto Color, in particular. They are Photoshop filters that can run under Gimp using the PSPI plug-in (even on 32 bit Linux with Wine).]
I know that you can do basic embossing with convolution matrices, and that's useful, but I want the big daddy of them all. I don't care what language the reference materials are written in if they are programming examples, as well I don't care if it's pure mathematics. I'm just having a hard time finding anything substantial.