Well, let's see. I'm not sure that angles are a meaningful way to think about the shift between pixels that is used to calculate the co-occurrence matrix. If you want the co-occurence matrix to compare pixels with themselves (is that what a 0 degree direction would mean in this context?), then you would set the shift values to x=0 and y=0. If you want it to compare pixels with their neighbor to the upper right (45 degrees?) then you would set the shift values to x=1, y=1. For the neighbor to the right, it would be x=1, y=0 (90 degrees?). For the neighbor to the left, it would be x=-1, y=0. For the neighbor to the lower left, it would be x=-1, y=-1. Does that help at all? - Peg