I4	Use the i4 color table in indexed mode.				Image > Mode > Indexed Color... Set Palette to "Exact" and set Forced to "Custom..." and load the I4 color table.
IA4	Use the i4 color table in indexed mode with transparency.	Same as above except you check the "Transparency" checkbox below the Forced dropdown this time.
I8 	Use grayscale mode. (do not use alpha as it will be removed)	Image > Mode > Grayscale
IA8	?
IA16	Use grayscale mode.						Image > Mode > Grayscale
RGB5A1	?
RGBA32	Use RGB mode.							Image > Mode > RGB Color