Other than that the FFT technique works the same. It produces three individual images for red, green and blue instead of the channels being visible within the original image as in Ps. In PSP go to Image menu | Split Channel | Split to RGB. You can have a channel mixer layer and set it to let just red through. 8bf file loads easily enough into PSP, I cannot figure out how to isolate one channel in exactly the way that it requires. I use PSP-X2 these days and, although the. I know how to do that in Photoshop as it is very obvious there, but not so in PSP. (The FFT software is discussed here.) It hinges on being able to isolate the red colour channel. There is a very nice and free piece of software, developed apparently for forensic purposes, that is useful for that purpose. Over in 'Uncle Jerry's Photo Restoration' group there is some interesting discussion of removing repetitive textural patterns, for instance from mid-1960s portraits.
