Primary Colors: RGB vs. Red-Yellow-Blue

[Crazy Jerome]

This conversation reminds me that I've lived through the computer conversions from the first desktops, to 8 bit, to 16 bit, to 32 bit, and now 64 bit. But now I can't remember if it was 16 or 32 that finally gave us more possibilities in color than the human eye could discern. I want to say 32 bit, the actual limit requiring the addressing space in what would be around 24 to 27 bit (depending upon who you asked at the time). I do remember that there was some discussion about the incredible waste of storage space that would happen, storing all those undistinguishable colors, each MB being precious.

CJ - so old he can't remember when he got things he couldn't see.

 

[Fast Learner]

I'm not aware of any systems that use more than 32 bits to store a pixel's color -- 64 bit processing is popular now, but the colors themselves are, as far as I know, stored in 24 or 32 bits, depending on whether they include transparency information.

8 red bits (256 levels) * 8 green bits * 8 blue bits = 16,777,216 possible colors, 24 bit color. For most colors this is beyond what humans can perceive.

Add 8 bits of transparency information (256 levels) = 4,294,967,296 possible color values, though still 16.7 million colors, for 32 bit color value storage.

64 bit color would allow for 16 red bits (65,536 values) * 16 green bits * 16 blue bits for roughly 281,474,976,700,000 colors; 281 trillion is certainly more than the human eye can detect and more than most (all?) instruments can detect. Plus 16 transparency bits (which actually would be nice) for roughly 18,446,744,070,000,000,000 combinations, 18 quintillion, which is just nutty.

 

[Umbran]

8 red bits (256 levels) * 8 green bits * 8 blue bits = 16,777,216 possible colors, 24 bit color. For most colors this is beyond what humans can perceive.

Yes and no. That's 16 million + colors, but they're all within a range of chromaticity, an area of color space, if you will. There are going to be colors outside that space that the red, green, and blue base you're working from simply *cannot* add up to make, ever.

The difference to many will seem negligible, I expect. It may be functionally as good as anyone ever needs.

 

[Fast Learner]

Right, that's why I said "for most colors": it doesn't include colors outside of that gamut. Fortunately most of the colors we can perceive are within the RGB gamut.