Accessibility Testing in PDF

Color Contrast

According to the National Eye Institute (NEI), a division of the U.S. National Institutes of Health, color blindness affects approximately 1 in 12 men and 1 in 200 women. Ensure that the color contrast of the content in the document is suitable. The WCAG guidelines require a color contrast ratio of 4.5:1 for normal text, 3:1 for large text (18-point or 14-point bold). You can use different tools to check the color contrast between the background and foreground.

WebAIM

WebAIM provides a free color contrast checker tool. Learn how to use the color contrast checkers on the accessible content page.

Accessibility Checker

Adobe Acrobat includes a built-in accessibility checker that can automatically flag many common issues in a PDF. However, automated checking alone is not enough. You still need to perform manual checks for things that tools cannot accurately assess, such as:

• Click on Accessibility in the tool list. If you do not see it in the tool list, search for the tool or click the More Tools option in the tool list.
  
• The following list will appear. Click on the Accessibility Check.
  
• A new window will appear, enabling you to edit the settings for the accessibility check. Check the "Create accessibility report" checkbox to generate a report. Update the category to match the document. Once you have selected the settings, click on Start Checking.
  
  
• On the left side, a panel will appear, displaying all accessibility issues related to the document. Click on the arrows to expand the issues.
  
• Resolve any failed issues by right-clicking on them and selecting 'Fix'. A window will appear showing how to fix the problem. Some issues will require manual checks, such as tab order, reading order, and color contrast. Once you have performed the manual check, we recommend right-clicking on the issue and selecting Pass.
  

Automated Checkers
These are helpful for baseline testing, but manual review by people—including those with experience in assistive technology—is essential to catch issues that tools cannot reliably detect. However, automated checking alone is not enough. You still need to perform manual checks for things that tools cannot accurately assess, such as:

• Reading order – Ensuring the content flows logically for screen readers
• Tab order – Verifying that keyboard navigation follows the correct sequence
• Color contrast – Confirming sufficient contrast between text and background
• Alt text quality – Checking that alternative text is meaningful, not just present
• Semantic structure – Making sure headings, lists, tables, and form fields are tagged correctly
• Form field accessibility – Verifying labels, instructions, and keyboard access