Originally Posted by jsr
I started out from the description, what you showed me, but let's just say, this is true. It would be still impossible to store the alpha, because such thing like '1-bit alpha' is not exists! In this entire thread, everybody confuses transparency with translucency and the alpha layer is the latter one. On 1-bit, you can only store transparency (0 = transparent, 1 = opaque); to have a real alpha layer, you'll need at least two bits, then at least, you'll have two translucent state.
Do you have an idea how this image
would look like with an '1-bit alpha'? Like this!
Well, don't forget about dither (hires and shires can make this quite well).
I'm not pushing for Alpha - just saying how things looks from HW perspective.
just made short comparison for Wu and Spatial Color Quantization.
Original 24 bit
Spatial Color Quantization (15 colors LUT)