TOOLS: Testing for Color Blindness Accessibility

Types of color blindness. Eye color perception. Vector illustration on isolated background.

According to the National Eye Institute, there are three main kinds of color blindness, based on photopigment defects in the three different kinds of cones that respond to blue, green, and red light. Red-green color blindness is the most common, followed by blue-yellow color blindness. A complete absence of color vision —total color blindness – is rare.

Most Common: Red-Green Color Blindness

The most common types of hereditary color blindness are due to the loss or limited function of red cone (known as protan) or green cone (deutran) photopigments. This kind of color blindness is commonly referred to as red-green color blindness.

Protanopia: In males with protanopia, there are no working red cone cells. Red appears as black. Certain shades of orange, yellow, and green all appear as yellow. Protanopia is an X-linked disorder that is estimated to affect 1 percent of males.

Deuteranopia: In males with deuteranopia, there are no working green cone cells. They tend to see reds as brownish-yellow and greens as beige. Deuteranopia is an X-linked disorder that affects about 1 percent of males.

Photoshop Testing Resource

Adobe Photoshop allows you to view protanopia and deuteranopia versions of your images. With the image to be tested open in Photoshop, select View → Proof Setup > Color Blindness – Protanopia-type to activate the Protanopia test. Select View → Proof Setup > Color Blindness – Deuteranopia-type to activate the Deuteranopia test.

Photoshop menu open to View → Proof Setup to test an image for color blindness

Make Use of  This Excellent Online Tool

Take the Corblindor Coblis (Color Blind Simulator) for a spin to see how an individual with a color vision handicap will visually interpret your images.

As all the calculations are made on your local machine, no images are uploaded to the server. Therefore you can use images as big as you like, there are no restrictions. Be aware, there are some issues for the “Lens feature” on Edge and Internet Explorer. All others should support everything just fine.

Screenshot of Corblindor Coblis (Color Blind Simulator)

Additional Resource:

Read Alex O’Neal’s excellent article Beautiful, accessible traffic light colors

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