Friday, February 09, 2007

Ensuring Accessibility for People With Color-Deficient Vision

Research behind selecting colors for website accessiblility ...

"This article is Part IV of my series “Color Theory for Digital Displays.” It describes how you can use color in applications and on Web pages to ensure that they are accessible to people who have color-deficient vision.

If you do not consider the needs of people with color-deficient vision when choosing color schemes for applications and Web pages, those you create may be difficult to use or even indecipherable for about one in twelve users.

... To ensure that the content and functionality on Web pages are accessible to and usable by people with color-deficient vision, do the following:

Maximize contrasts in hue, value, and chroma.
Maximizing contrast in all three of these dimensions of color ensures the readability of text and the decipherability of images and other visual elements.

For numerous examples of hue, value, and chroma contrast, in “Color Theory for Digital Displays: A Quick Reference: Part I,” see the section Color Contrast; in “Color Theory for Digital Displays: A Quick Reference: Part II,” see the sections Contrast Effects, Color Dominance, and Color Balance, and in “Applying Color Theory to Digital Displays,” see Ensuring the Readability of Text Through Contrast.

Use dichromatic color schemes.
Using color schemes that are similar to the ten dichromatic color schemes shown in Table 2 for essential elements on Web pages and their backgrounds ensures adequate figure-to-ground contrast for readability by dichromats.

Use analogous color schemes with care.
When using analogous hues for essential elements on Web pages, maximize their value contrasts. Many analogous hues have similar inherent values, so this generally requires limiting the number of analogous hues to three—as shown in the example, which combines the analogous hues carnation pink (#FF99CC), violet (#9933FF), and navy blue (#000066). Additional analogous hues are always useful for non-essential, purely decorative elements."    (Continued via UXmatters)    [Usability Resources]

Analogous Hues - Usability, User Interface Design

Analogous Hues


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