gillan, my (Mac) version above works as it should in Poser with all angles of light - that's why I just named it "right". I think it also is the correct up/down orientation - according to the manual, black means "down", white means "up". It looks the other way round in the olive .bum file, but if you apply it to a Poser object, the lights are correct. Your "red inversion" indeed repairs the .bum file to a valid ("non Escher") map, but I if I'm right it is inverted (look at my first sample in post 6). So I think the correct way to fix it is probably to invert the green channel. Is this bug really in every PC Poser? I can hardly believe this...