Ensure that foreground and background color combinations provide sufficient contrast
when viewed by someone having color deficits or when viewed on a black and white screen.
[Priority 2 for images, Priority 3 for text].
To test whether color contrast is sufficient to be read by people with color deficiencies
or by those with low resolution monitors, print pages on a black and white printer (with
backgrounds and colors appearing in grayscale). Try taking the printout and copying it for
two or three generations to see how it degrades. This will show you where you need to add
redundant cues (example: hyperlinks are usually underlined on Web pages), or whether the
cues are two small or indistinct to hold up well.
Also, try setting up a color scheme in your browser that only uses black, white, and the
four browser-safe grays and see how your page holds up.
It is recommended that you use style sheets to specify text and background colors so that
users can override color choices with their own style sheets.
For more information about colors and contrasts, refer to LIGHTHOUSE. Rationale:
When foreground and background colors are too close to the same hue or brightness, they
may not provide sufficient contrast when viewed using monochrome displays or by people who
have difficulty seeing certain colors. |
