Using color and pattern

Important Information about Techniques

See Understanding Techniques for WCAG Success Criteria for important information about the usage of these informative techniques and how they relate to the normative WCAG 2.1 success criteria. The Applicability section explains the scope of the technique, and the presence of techniques for a specific technology does not imply that the technology can be used in all situations to create content that meets WCAG 2.1.

Applicability

All technologies that support images.

This technique relates to Success Criterion 1.4.1: Use of Color (Sufficient).

Description

The objective of this technique is to ensure that when color differences are used to convey information within non-text content, patterns are included to convey the same information in a manner that does not depend on color.

Examples

Example 1

A real estate site provides a bar chart of average housing prices in several regions of the United States. The bar for each region is displayed with a different solid color and a different pattern. The legend uses the same colors and patterns to identify each bar.

Example 2

An on-line map of a transportation system displays each route in a different color. The stops on each route are marked with a distinctive icon such as a diamond, square, or circle to help differentiate each route.

Example 3

A flow chart describes a set of iterative steps to complete a process. It uses dashed, arrowed lines with a green background to point to the next step in the process when the specified condition passes. It uses dotted arrowed lines with a red background to point to the next step in the process when the specified condition fails.

Example 4

The content includes an interactive game. The game pieces for the 4 players are distinguished from one another using both color and pattern.

Tests

Procedure

For each image within the Web page that use color differences to convey information:

  1. Check that all information that is conveyed using color is also conveyed using patterns that do not rely on color.

Expected Results

  • Check #1 is true.