Providing Alternatives to Color Coding to Convey Meaning
This section explains how to design applications according to the following WCAG 2.0 standard:
1.4.1 - Use of Color: Color is not used as the only visual means of conveying information, indicating an action, prompting a response, or distinguishing a visual element.
Do not use color as your only way to convey information. Include a redundant clue so that people who are color-blind or visually impaired are aware that a field or process is special or different. For example, do not change the background or text color to red to indicate an error. Another common mistake is to use an icon that changes color based on status but is otherwise the same. Color-blind users cannot distinguish between certain colors, nor can screen readers. In addition, if a user prints a page on a black and white printer, color-dependent items on the page become indistinguishable.
When showing status, you have two options:
Use a display-only text field with the label Status to indicate status.
Use icons that have different colors and different shapes to represent the different status values.
The following incorrect example shows status icons that are differentiated only by color:
The following correct example shows status icons that have both different colors and different shapes:
Note: When using icons, be sure to assign alternative text labels to the icons.
For consistency, use the following icons to indicate status:
Field or Control
PS_STATUS_OK_ICN: OK, normal, good
PS_STATUS_CAUTION_ICN: Warning, caution, at risk
PS_STATUS_ERROR_ICN: Error, critical
PS_STATUS_UNCHANGED_ICN: No status, status unchanged
PS_STATUS_TREND_UP_ICN: Trend up
PS_STATUS_TREND_STABLE_ICN: Trend unchanged
Note: In addition, do not use flickering, moving, blinking, scrolling, or auto-updating objects to indicate status.