Color blindness test for you

Presented here in black and white so that even
the fully colorblind get a sense of how the
test works. Look for the number represented
by dots of a different color.

Ishihara Test

The Ishihara Color Test is an example of a color perception test for red-green color deficiencies. It was named after its designer, Dr.cShinobu Ishihara, a professor at the University of Tokyo, who first published his tests in 1917.

The test consists of a number of colored plates, called Ishihara plates, each of which contains a circle of dots appearing randomized in color and size. Within the pattern are dots which form a number visible to those with normal color vision and invisible, or difficult to see, for those with a red-green color vision defect. The full test consists of 38 plates, but the existence of a deficiency is usually clear after a few plates. Testing the first 24 plates gives a more accurate diagnosis of the severity of the color vision defect.

Common plates include a circle of dots in shades of green and light blues with a figure differentiated in shades of brown, or a circle of dots in shades of red, orange and yellow with a figure in shades of green; the first testing for protanopia and the second for deuteranopia.

What numbers do you see revealed in the patterns of dots below?

The plates here are a small representative sample of the whole, but will help spot the most common forms of colorblindness. Depending on the color balancing of your monitor, the tests may be somewhat more or less effective (e.g. if your monitor is not rendering the proper colors).

Results For Ishihara Test(above)
Normal Color Vision			Red-Green Color Blind
	Left	Right		Left	Right
Top	25	29	Top	25	Spots
Middle	45	56	Middle	Spots	56
Bottom	6	8	Bottom	Spots	Spots

Credit: Wikipedia, toledo-bend