If color alone is used to convey information, users who cannot differentiate between certain colors and users with devices that have non-color or non-visual displays will not receive the information. When foreground and background colors are too close to the same hue or luminosity, the colors may not provide sufficient contrast when viewed using monochrome displays or by people with color blindness.
- A state agency must ensure that all information conveyed with color alone is also available without color.
- A state agency must ensure that foreground and background color combinations provide strong contrast.
Example: An air quality report that uses a red bar to indicate an alert level must also include that information in text.
- Do a manual check by printing the web page on a black and white printer to verify that text and images are visible and that the meaning is conveyed without requiring the use of color.
- Use a color contrast analyzer to determine if the color contrast is adequate.