Content is presented with sufficient contrast to its background.

As with photography, contrast makes the content represented more readable.

Objectives

• Enable good readability of content.
• Limit mental load during consultation.
• Improve accessibility of content to disabled people.

Implementation

Ensure a minimum contrast ratio of 3:1 between text and background, as measured by the WCAG2.0 algorithm

Control

• Either upstream (when designing the digital book): Identify content whose contrast/brightness difference with their background is potentially insufficient; Use a tool such as Color Contrast Analyzer to calculate the contrast ratio: click on Brightness and note the color of the foreground then that of the background in the dedicated fields; Check that the contrast ratio recorded is greater than or equal to 3:1
• Either downstream: Use ACE and its error reporting. If necessary, check the “Errors” tab and search for “color-contrast”. Follow the procedure described above.

Validation

• Needs to be human verified.