Implementing LCD AA over transparent background

Belleve Invis

Given that subpixel R, G and B have different coverage, it requires six-channels to represent the full blending mechanism (RGB, and three corresponding alphas). However, can the three alpha channels be compressed into one channel, so that the three alphas can be fitted in 8 bits?

Simon Cozens

Sure. Alpha blend RR0000Ar with 00GG00Ag and 0000BBAb.