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Hard Color Blind Test

Eleven low-contrast plates for people who passed the normal test and want to know how fine their color vision is. Mild color weakness often shows up only here, but screen settings matter more too, so turn off night mode and blue light filters first.

Before you start

  • Turn off night mode, Night Shift, blue light filters and dark-reader extensions. They change the colors and spoil the result.
  • Set your screen to normal brightness and look at it straight on, in ordinary room light.
  • Give each plate about 3 seconds. If you can’t see a number, pick “I can’t see a number” rather than guessing.
  • Wear your glasses if you normally do, but not colored or blue-blocking lenses.
Plate of

What number do you see?

Your answers

These plates are generated on the spot from cone science (Viénot, Brettel & Mollon, 1999); they are not copies of printed Ishihara plates. Want to know what color blind people see? Try the Color Blind Simulator.

About the Color Blind Test

The color blind test shows dot plates with a number hidden in them, like the plates an eye doctor uses, but generated fresh each time from cone science rather than copied. Each plate is built from two colors that look different to normal eyes but the same to people missing one cone type, so which plates you miss shows whether your red (protan), green (deutan) or blue (tritan) cones are affected, and the faint plates show how strong it is. There is also a red-green test, a blue-yellow test and a hard test with fainter plates.

How to use it

  1. 1 Turn off night mode and blue light filters, and set normal screen brightness.
  2. 2 Look at each plate for about 3 seconds and pick the number you see.
  3. 3 If you can’t see a number, choose “I can’t see a number” instead of guessing.
  4. 4 Read your result for red, green and blue cones, and look back over every plate.

Frequently asked questions

Is it normal to miss plates in the hard test?

Yes, the last plates are close to the limit of what a normal screen and normal eyes can show. Missing one or two of the faintest plates is common; missing several of the same color group points to a mild deficiency.

How accurate is an online color blind test?

It is a good screening test, but not a diagnosis. Screens differ in color and brightness, so a faint plate can be easier or harder on your screen than it should be. If the test suggests color blindness, an eye doctor can confirm it with printed plates or an anomaloscope.

What are the types of color blindness?

Red-green color blindness is by far the most common. It comes in protan (red cones) and deutan (green cones) types, each either mild (protanomaly, deuteranomaly) or strong (protanopia, deuteranopia). Blue-yellow (tritan) color blindness is rare, and seeing no color at all (achromatopsia) is very rare.

Is this the Ishihara test?

No. The Ishihara test is a printed book of plates. This test uses the same idea, a number made of dots among dots of a confusing color, but every plate is generated on the spot so you get new numbers each time.

Can color blindness be cured?

Inherited color blindness can’t be cured. Special tinted glasses can make some colors stand out more for some people, but they don’t restore normal color vision, and they can make this test harder to read.

Why is color blindness more common in men?

The genes for the red and green cones sit on the X chromosome. Men have one X chromosome, so one faulty copy is enough, while women need two. That is why about 1 in 12 men but only about 1 in 200 women are red-green color blind.