Re:No one can. (Score 2)

Tell you what. Take about 5 or 6 images of the same size 32 bit RGBA, keep them fairly simple. Now mathematically blend them together in various ways, such as multiplying, adding, etc. Now look at the result. This causes an effect known as "banding" pretty easily.

Take those same graphics and convert each channel to a float between 0 and 1 and do your blends like that, clamping at 1.0 and 0.0 if necessary. When you convert back to 32 bit color, the image will probably not show the artifacts found in the simply blended version. You can achieve the same results by using a higher precision framebuffer in a 3D card, be it 64 or 128 as some people are suggesting.

While the human eye is only capible of seeing about 10 million colors (I think that's the right number?), 16.7 million plus an alpha channel isn't enough when you do too many blends simply because each blend lowers your precision.