Before pointing at an odd pixel, predict what (a) has there, and which input pixels (b) reads. Both routes apply the same 7 × 7 kernel to a 64 × 48 greyscale crop of the photograph: (a) to a copy that keeps every second row and column, (b) to the full image with its taps two pixels apart. Point at any pixel of either output, or of the inputs, to see the pixels each route reads; the zooms underneath show them large.