Also, if I render on a white background to use as a 2D cut-and-paste, if I JPG it, much of the white background near the image becomes that annoying few units darker than proper white (red=green=blue=255) and the 2D graphics program has trouble telling what is background and what is image. One way round that is to put along with the picture another picture which is white for background and black for image and, GIF-code it. - I remember handling a JPG'ed photo of an alien in a wood from a Gerry Anderson UFO site: when I came to extracting the alien, the alien's spacesuit is red, the forest is mostly green:: easy:: except that along the edge of the alien, the JPG process had made an annoyingly wide border of intermediate fawn and russet pixels, and I had to put into my 2D graphics program a special border-sharpening facility.