Attached Link: http://en.wikipedia.org/wiki/Gamut

I did some work on Colour TV technologies in the '70s, and if you want to make your head spin I can recommend looking up articles about colour gamut or the CIE colour triangle. To generalise, computer monitors can represent more colours than any printing process; yet neither technology can show all the colours that the human eye can perceive (the missing colours are mostly shades of green).