I found this interesting article on www.handsonbuildergrower.blogspot.com :
Color Matching by the Color Blind
Color matching is an important aspect of the printing industry and something I got pretty good at after 8 years in the industry. Generally, when a color is not right it needs one of five colors to make it right - red, blue, yellow, black, or white/clear. 15 years later, I still describe colors as having more of one primary color and less of another (I have never been good at naming all the crayon colors).Sometimes when we were stumped, we would ask our color-blind associate to help us. He could only see color as gray, but he could tell if one gray was darker (denser) than another and that would help us make the adjustments that to color that the rest of us couldn't see.
This was a surprise to me, that a color blind person could help match colors. When I asked around about it, I was told that color blind people were used to look at aerial photos during World War II. They did not see the camoflage. They could pick out hidden artillery or tanks that others wouldn't see.
Think about that the next time you are picking out numbers from the colored dots at the eye doctors office.