This document provides guidelines for the use of color in electronic voting systems.  The guidelines are intended to promote usability, such as legibility, as well as accommodate users with visual impairments, such as color vision deficiencies and low vision.

The paper includes guidelines for selecting color sets so that they are legible as both text and background colors and an example of eight colors that meet the guidelines, maintaining a consistent luminance.

Additional details

Use color for a function

• Use color sparingly and for a specific purpose.
• Use color only to categorize the type of information, to identify different types of controls and navigation features,or to provide selection feedback
• Use color only for secondary coding.
• Use color consistent with convention.
• Use color consistently throughout the voting system.

Maintain legibility

•  Luminance contrast must be at least 10:1. (Note that this is more contrast than WCAG AAA, for more universal design.)
• Avoid placing colored text or symbols on a colored background.
• Use only white, yellow, or a light cyan for text on a black background.
• When using color for labeling, use wide lines or blocks of color, not thin lines or colored text.
• Avoid using pastel washes to separate or group blocks of information.
• Present most information as black text and symbols on a white background, like a printed page.

Avoid color chaos. 

• For any given page/display, use no more than four colors used for labeling and categorization.
• Do not use colored text, borders, backgrounds, or patterns for purely decorative purposes.
• Clearly separate colors used for identification from the functional part of the ballot
• Select colors as a functional set.