Greetings, I am attempting to implement an algorithm in which I am multiplying an f(x,y) times a (p^2 + q^2) in which (x,y) and (p, q) are real-space and "Fourier-space pixel coordinates", respectively, of the same 2D image. I have the image and its Fast Hartley Transform but can't really get beyond that. f(x,y) gives me the grayscale value of the point of course. p and q will identify a point in the FHT image but if I just use p and q as values, I'm getting an integer mask that has nothing to do with the image. I don't think of Fourier space pixels as mapping 1 to 1 onto real space pixels so it doesn't seem to me that I'm looking for a corresponding Fourier space pixel for the real space pixel. That wouldn't work in k space anyway. Any tips on this puzzle would be greatly appreciated. Thanks, ECB