According to the online dictionary, being color blind is described as the following;
1.Ophthalmology . pertaining to or affected with color blindness.
2.Photography . (of an emulsion) sensitive only to blue, violet, and ultraviolet rays.
3.showing or characterized by freedom from racial bias.
Focusing on the opthalmolgoy, color blind is describe to be Color blindness or color vision deficiency is the
inability or decreased ability to see color, or perceive color differences, under lighting conditions when color
vision is not normally impaired.
check this out for a better understanding; http://colorvisiontesting.com/
To be 'color blind' it not so literal. It doesn't mean they can't see any color at all, like a black and white movie.
It means that they have trouble seeing the difference between certain colors. It is not a serious problem!
Although we use many colors as symbols within society, people who are color blind are capable to do normal stuff, even drive. Most color-blind people can't tell the difference between red or green, but they can learn to respond to the way the traffic signal lights up — the red light is generally on top and green is on the bottom.
What makes this phenomenon possible is When your cones don't work properly, or you don't have the right combination, your brain doesn't get the right message about which colors you're seeing. To someone who's color blind, a green leaf might look tan or gray. Color blindness is always inheridited and passed down through genes.
Eye doctors test for color blindness by showing a picture made up of different colored dots, like the one above. Someone who can't see the picture or number within the dots may be color blind.
Here is a youtube video for example;http://www.youtube.com/watch?v=j-1r0iXUAlc&feature=related