10 Bit Per Channel Color - What's the Point?

[TheArTcher]

Studies have shown that the human eye can perceive anywhere from 1 million to 10 million colors.( A small percentage of women can see 100 million colors.)

So 8 bit per channel color gets you 16 million possible colors. Why would you need 10 bits? I realize that most monitors aren't capable of displaying all of the colors the human eye can see, but I think that is a separate issue, isn't it?

I did some research on the web but I didn't find anything definitive. Anyone know what the real story is?

 

[ChrisK15]

I've read that humans can see that many hues, as in, only color changes, instead of brightness changes. Even if humans could only see 256 levels of brightness, that would mean over 1 billion different shades of color, and since we can see way more than that, 10 bit would make sense if it was large gamut.

 

[Benny]

16 million sounds like a lot but 8bit channels actually means that you are limited to 256 steps of brightness of an individual color.

Even on current displays these steps can easily be seen, limiting precision wished for in graphic and needed in medical applications.

With monitors moving to a higher dynamic range and gamut the individual step will become larger and even more apparent, even to the average user.

Far a small test, take a look at the site http://www.drycreekphoto.com/Learn/Calibration/monitor_black.htm
First turn up the brightness as far as possible, and try to spot the color changes.
Then turn the brightness all down, I'm confident you will still be able to spot them. (unless you're on a 6bit TN)
If your monitor brightness can be adjusted down to 1/4 of the maximum you've just seen the "small" steps a 10bit panel would produce set to full brightness.