Web Development
Web Developer Guidelines
Visual Design Recommendations

Checkpoint 9.2 - Core

Where colour has been used to convey information, the information is also available through context or markup

WCAG 1.0 Priority 1

WCAG Guideline 2. Don't rely on color alone.

Not everyone can easily perceive differences in colour and they would find it difficult to understand information which is conveyed by colour alone. For example, the colour red is used to mark mandatory fields in a form. While this is accessible to a sighted user, colour-blind or unsighted users can't distinguish between the colours and, therefore, won't be able to make the correct choice. The use of an asterisk to indicate mandatory fields immediately improves the accessibility of this page.

Additionally, users find it hard to perceive colours if they work with overhead projectors, poor quality or monochrome display screens.

Requirement

Ensure that all information conveyed with colour is also available without colour. When choosing colours be aware of the various forms of colour blindness and choose the individual colours appropriately.

Checking Tool

Proof-read the page to ensure that colour alone hasn't been used to deliver information

Ensure the page is usable when viewed in grey-scale.

  • Internet Explorer - AIS toolbar: Colour > Greyscale
  • Firefox - Web Developer's Toolbar: Disable > Disable Page Colors

Information Source

The original source of this information is located on the W3C web site  (www.w3.org/TR/WCAG10-TECHS/#tech-color-convey)

 

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