Color blindness is the inability to distinguish one or several chromatic colors, independent of the capacity for distinguishing light and shade. Usually inherited or present at birth, color blindness is caused by an absence of color-sensitive pigment in the cone cells of the retina. About one out of 20 women and one out of 12 men are color blind.
When you are color blind, you cannot distinguish the differences between certain colors, especially red, green, blue, or mixtures of these colors. Caused by an absence of color-sensitive pigment in the cone cells of the retina, most color vision problems are inherited and are present at birth.
Could you be color blind? Take this online version of the Ishihara Color Blindness Test to find out. This test consists of scanned plates, with a number in the center of a circle. If you can see the number, chances are you are not color blind. Please be aware that the colors here are not exactly the same as in the original version. Also, every computer screen has different color settings, therefore the test results might alter between different trials.