Compression used in Windows DIB can be RLE4 or RLE8. RLE8 is run-length encoding used for a 256 colors bitmap (8 bits-per-pixel) and RLE4 is run-length encoding used for a 16 colors bitmap (4 bits-per-pixel). Formats are using two modes: Encode and absolute. Both can occur anywhere in the bitmap.Oops, I had forgotten about the RLE compression support in BMP, though it's limited to 256 colors. I guess it might work as an alternative to GIF.