Color Blindness and Cartography: Practical Suggestions for Making Readable Maps

Author: Steve Schoenig
Organization: California Department of Food and Agriculture

1220 N Street
Sacramento, CA 95814
USA

Phone: 916-654-0768
Fax: 916-653-2403
sschoenig@cdfa.ca.gov

While most cartographers have general knowledge of the phenomenon of color blindness, there seems to be little incorporation of special graphic and chromatic techniques to widen the audience of people who can successfully use maps and graphics. Color blindness affects over 11 percent of the population. There are a number of genetic mutations that lead to a variety of color blindness syndromes. Color blindness causes an inability to see or discriminate colors that those with "normal" color vision discriminate with ease. Thematic maps, with their many shades of similar colors, often fall in this category. While it is a matter of ethics and practicality how much to accommodate those in our society with physical handicaps, it can be a matter of crucial importance to a cartographer if the recipient of a map can't read it--especially if they are your boss or client.

This presentation will briefly review the biology and major types of color blindness, and then focus on a number of practical guidelines and examples. These techniques are culled from the cartographic literature and from personal experience. They will include use of appropriate, easily distinguished color series, use of embedded symbols and textures, and other relevant cartographic techniques. Input will be solicited from the audience.