Choosing Web Colour Schemes for People with Colour Blindness

Colour blindness is a common impairment, affecting approximately eight percent of males and one percent of females. These individuals see a different range of colours. Colour blindness can express itself in many variations and degrees of severity. Colour perception problems are important considerations when developing web sites to ensure that all users have access to the content and the functionality of sites.

Although there is no one right set of colours that will fit the needs of all individuals with all colour deficits, these guidelines will enable the majority of people with colour blindness to access the web sites.

General Guidelines for Colour

There are four general guidelines to be considered when designing web pages:

• Design in black and white, adding color for emphasis.
• Color should never be the only visual cue for anything.
• Distinguish between features that a user must be able to see in order to use the web page and those that would be nice to see.
• 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).

Sufficient contrast for reading is a key factor when considering accessible colours on web pages. Therefore, particular colour combinations to be avoided are: red-green, green-yellow, and blue-yellow.

Browser-Safe Colours

To ensure cross-platform consistency in colour scheme, it is recommended that web pages be designed only with the 216 common browser-safe colours. Browser-safe colours are also referred to as Web-safe palette, dither-free colours and 6x6x6 colours. Despite the multiple terminology, the colours and hexadecimal codes are the same. Refer to http://www.visibone.com/vaccc/ for the web-safe colours and names.

Resources

• Colour Blind Design


• Colors for the Color Blind


• Color Blind Friendly Web Pages

About the Author

Glenda has her Bachelor of Arts Degree with concentrations in Communications and Psychology from Simon Fraser University. She is a member of the Physical Access Advisory Committee at SFU. She has been a Teaching Assistant at the Neil Squire Foundation, a Canadian non-profit organization that researches, develops and delivers innovative services and technology for individuals with disabilities. She is also skilled in writing accessible HTML code, according to the World Wide Web Consortium's Web Accessibility Initiative and has published works related to these subjects. Glenda has over twenty-five years of direct experience with the disabled community.

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