Color: Perception: Color Blindness

Color blindness is used in colloquial terms to refer to the difficulty in telling colors apart but a more correct term would be color vision defect. Color blindness is a misnomer because only a small percentage of people are unable to see any color. Color vision is important in many everyday tasks, such a driving a car (does that traffic light mean "stop" or "go"?).
http://www.uic.edu/com/eye/LearningAboutVision/EyeFacts/ColorBlindness.shtml 

Online Resources
Ishihara Test: http://www.toledo-bend.com/colorblind/Ishihara.asp
Colors for the Color Blind: http://www.toledo-bend.com/colorblind/index.asp


Video: Online Color Vision Test
http://youtu.be/yEIM4jmK1F0