>When the output pixel depends on neighboring pixels (e.g. I strongly >suspect that bumpmap uses a 3 x 3 neighborhood) the region iterator >does not work very well. Not on its own. However, if you iterate the output region with the pixel region iterator, and use a pixel fetcher like the one in whirlpinch for the input sourcing, and there is at least some weak relationship between input and output locality, the standard tile cache should be enough to obtain decent efficiency. Obviously, the more you know about your data access patterns, the more efficient an access strategy you can develop. Kelly
