Ramp edges are generated by defocusing step edges with a 3 x3 equally weighted averaging filter. The underlying ideal texture is transformed by distorting the primitive at each node to make a realistic texture. Neighborhoods in the collection, however, are not required to be square. The usual way of handling the problem theoretically is to assume the image is wrapped around a torus. They avoid much uf the problem of 7ero scatter by considering only cells containing a 2 x 2 block nf pixels.
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