In emulating Kodak Infrared Ektachrome (EIR) film (a.k.a. Aerochrome) with images from a full-spectrum-modified digital camera, I want to subtract the blue channel from the red and green channel, then re-map the blue channel to red, red to green, and green to blue. (This is called "IRG to RBG transform".)
Digital infrared enthusiasts typically do this via the Photoshop "channel mixer," but that is tedious and slow in a GUI. I'd like to batch-process it.
Is this the sort of thing ImageMagick can do?
If so, can you provide a lead as to how it would be accomplished? It is not obvious from the documentation — I can see how to swap colour channels around, but not how to subtract one channel from another.
If not, is there some other open-source command-line program that could do this?
Thank you for any leads offered!