Unseen Colors

While 7 men in 100 have some form of colorblindness, only 1 woman in 1,000 suffers from it.
The most common form of color blindness is a red-green deficiency.



Example of an Ishihara color test plate. The numeral "74" should be clearly visible to viewers with normal color vision. Viewers with dichromacy or anomalous trichromacy may read it as "21", and viewers with achromatopsia may see nothing.