What exactly is meant by "Fourier techniques" for edge detection? I'm trying to work on an edge detection assignment for a Fourier Analysis class. I've nailed every bit of it up to this point, but now the assignment is wanting me to do edge detection via "Fourier techniques." No amount of looking around on the internet has given me any clue as to what this could be. I already had to do edge detection via convolution techniques, so my first instinct, which was to FFT the image, multiply it by the filter, and convert back is redundant (by the convolution theorem). Any thoughts on this? Thanks so much for your help!