Lesson 2.2: Color

Appropriate color use also plays a major role in creating accessible digital resources. Because colors are used commonly to convey meaning, and many people have disabilities related to color vision, we will review some facts about color vision and how to ensure any information conveyed through color is accessible.

Color Vision Disabilities

Consider the following information about color vision disabilities:

  • About 4% of the population has low vision and 0.6% is blind
  • Between 7% and 12% of men have some form of color-vision deficiency (color blindness); less than 1% of women do
  • Low-vision conditions increase with age, and half of people over the age of 50 have some type of low-vision condition
  • Over the age of 40, many people will find that they need reading glasses or bifocals to clearly see small objects or text, a condition called presbyopia caused by the natural aging process
  • Color-vision deficiencies, also called color-blindness, are mostly inherited but can also be caused by side effects of medication and age-related low-vision conditions

Types of color-vision deficiencies include:

  • Deuteranopia: reduced sensitivity to green light
  • Protanopia: reduced sensitivity to red light
  • Tritanopia: reduced sensitivity to blue light
  • Achromatopsia: inability to perceive any color (rare)

Because so many people are potentially affected by inaccessible color usage, it is especially important to ensure color usage is appropriate. Inaccessible colors can cause eye strain and make it difficult even for people without disabilities to read text.

Choosing Accessible Color

Watch the following video to see how you can incorporate accessible color into your course materials.

Google Doc: Making Accessible Color Choices Video Transcript

Color can be used to depict information with clarity, but certain best practices should be followed to ensure effective and inclusive use of color. In particular, anywhere color is used to depict information, there should be a full explanation of the significance of the colors used.

Best practices include:

  • Ensuring that colors are not your only method of conveying important information
  • Providing good color contrast between text and its background
  • Avoiding the meaningful use of red, green, or colors that are rich in red or green hues, because they can be difficult to distinguish for people with deuteranopia or protanopia
  • Avoiding the use of black text on red background or red text on black background (some colorblind people cannot see lower color wave frequencies that are associated with red, so red appears black)
  • Taking advantage of any of the multiple online programs that can check the color of your documents for potential accessibility issues, such as the Color Contrast Analyzer Chrome Extension (opens in a new tab)

In today’s instructional practice, color use within course materials is ubiquitous. These best practices concerning color use enable faculty to make informed decisions about color use.


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Additional Resources

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