If the ILBM is not HAM or HALFBRITE, then after parsing and uncompacting if necessary, you will have N planes of pixel data. Color register used for each pixel is specified by looking at each pixel thru the planes. For instance, if you have 5 planes, and the bit for a particular pixel is set in planes 0 and 3: PLANE 4 3 2 1 0 PIXEL 0 1 0 0 1 then that pixel uses color register binary 01001 = 9. The RGB value for each color register is stored in the CMAP chunk of the ILBM, starting with register 0, with each register's RGB value stored as one byte of R, one byte G, and one byte of B, with each component left justified in the byte. (ie. Amiga R, G, and B components are each stored in the high nibble of a byte) But, if the picture is HAM or HALFBRITE, it is interpreted differently. Hopefully, if the picture is HAM or HALFBRITE, the package that saved it properly saved a CAMG chunk (look at a hex dump of your file with ASCII interpretation - you will see the chunks - they all start with a 4-ASCII-char chunk ID). If the picture is 6 planes deep and has no CAMG chunk, it is probably HAM. If you see a CAMG chunk, the `CAMG' is followed by the 32-bit chunk length, and then the 32-bit Amiga view mode flags. HAM pictures will have the 0x800 bit set in CAMG chunk ViewModes. HALBRITE pictures will have the 0x80 bit set. See the graphics library chapters or the Amiga Hardware Reference Manual for more information on HAM and HALFBRITE modes.