I use .BMP for the texture maps in my models. OK, the files are big, but in zipping they compress spectacularly (since they are only black and white). If I JPEG such a file, oh yes, here come the diffraction-type fringes along the borders between the colors. - Also: I wrote a 2D graphics handling program, and when I put JPG support in, the JPG matter's source code is enormous. GIF support code is much shorter.