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Color Contrast

This article applies to: Web Accessibility

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WCAG AA Contrast Ratios

In order to make PDFs accessible for low vision readers, a certain amount of contrast is required.

  • For normal text WCAG  requires contrast ratios of 4.5:1 (AA) or 7:1 (AAA).
  • For large text WCAG requires contrast ratios of 3:1 (AA) or 4.5:1 (AAA).

Siteimprove will check PDFs on websites for color contrast, however, Adobe Acrobat requires a manual check.

Contrast Checkers

Here are tools that will evaluate contrast ratios:

For PDFs

To check contrast, PDFs must be opened in Chrome using the Color Contrast Analyzer plugin.

You may use additional tools listed below to verify Color Contrast Analyzer results.

Use High Contrast Colors in Acrobat

  1. Under Preferences, select Accessibility.
  2. Select Replace Document Colors.
  3. Select Use High Contrast Colors.
  4. Select Change the color of line art as well as text.
  5. Select OK.


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