Decompression of Graphics in MD

I am searching for more algoritms for Decompress Graphics in MD, Since "Half-Byte" is a pixel in MD.

The only way I saw to compress/decompress is in case of a 8x8 (or more little.) use only 2,4 or 8 colors (2^1... 2^2... 2^4), so, only 1,2 or 3 bits are needed to do the compression.

If There's any other way to compress Graphics, I would like to know.