There's potential for extra data in the situation where the two colour attributes are the same. Possibly have a second compliment palette where
if A==B {
colourA:=pallette[A];
colourB:=compliment[A];
}
That allows for an extra set of colour pairs, to help out in unusual cases. You don't gain ability to set the bottom right pixel of each cell to the compliment colour, so even though it gives you another 16 colours to play with you get some interesting restrictions rewarding clever use.
There's potential for extra data in the situation where the two colour attributes are the same. Possibly have a second compliment palette where
That allows for an extra set of colour pairs, to help out in unusual cases. You don't gain ability to set the bottom right pixel of each cell to the compliment colour, so even though it gives you another 16 colours to play with you get some interesting restrictions rewarding clever use.