Tom - Show me a 12bit colour display. I assume you mean 10 bit.
Your best bet for getting an understanding is to read the CinC tutorial I posted a link to earlier very carefully.
What causes a lot of confusion in most cases in this area is that when we are using a PC monitor we are working in 3 x 8 bit colour spaces visually. The extra bit resolution available underneath is essentially fractions of these 8 bits and can not be seen visually. PP can be used to make these fractions visible. This is why some say working in 8bit throws information away because these fractions are being truncated in some way. Taking a simple example 12bit has 16 times the resolution of 8 bit so each of the bits in 8bit has 1/16 bits "underneath". This is why working spaces generally have higher bit depths than output formats / colour spaces. There is another aspect as well.
Say some one is working in 8bits 0 to 255 and and pushes something up to 256 - it's gone and can't be restored because it's outside the scope of the number range. If the number range is larger it can be bought back again.
People also work in ProPhoto for printing. In this case they are working on colours that they can not visually see so have to take care of that some other way. Your instructors comment doesn't make any sense at all This describes prophoto
![Smile](https://cdn.cambridgeincolour.com/forums/images/smilies2/smile.png)
and shows that in practice speaking literally people can not generate all of the output colours that it contains as some are imaginary.
http://en.wikipedia.org/wiki/ProPhoto_RGB_color_space
John
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