Troubleshooting - User Verification - Color Contrast

Product

Simplified Editor (Web-based CL PDF)

Advanced Editor (Web-based CL PDF)

CommonLook PDF Desktop Version

Feature

Color

Document Element

Contrast

Issue

There is insufficient contrast between background and foreground text/images, making it difficult for people to easily see the content. Depending on the standard(s) selected in the verification phase, this can trigger a "User Verification" checkpoint alongside Use of Color. 

Symptom 

Text or images are hard to read against their background — for example, foreground text or an image sitting on a background color it does not contrast well against.

To check color contrast we suggest using a color contrast analyser, such as WebAIM:  Contrast Checker.

Causes

Foreground and background colors were chosen without checking whether the resulting contrast is sufficient for the content to be easily seen.

Affected Users

People who are significantly visually impaired, and anyone with low vision who has difficulty distinguishing foreground content from its background. 

Accessibility Guidelines

WCAG 1.4.3 Contrast (Minimum)

1.4.11 Non-Text Contrast (as applicable to the flagged content) 

Resolution Steps

Contrast issues cannot be solved the same way Use of Color issues can. Placing content in a Span tag with appropriate Actual Text only changes what is read aloud to someone listening to the document via assistive technology — it does nothing for someone who is looking at the document visually, so the document remains out of compliance. The best solution is to return to the source document, fix the contrast issue there, and regenerate the PDF from the corrected source. 

Verification

Measure the contrast ratio between the corrected foreground and background colors and confirm it meets the applicable threshold. Visually confirm the content is easy to see against its background.

Related Articles

Troubleshooting - User Verification - Use of Color