Cynthia A. Brewer, 1996, "Guidelines for Selecting Colors for Diverging Schemes on Maps," Cartographic Journal 33(2): 79-86.
The figures were overly reduced in the publication, so this page also functions as a clarification of the published figures.
Results from research on the consistent use of basic color names, on colors that look the same with impaired color vision, and on changes in color appearance caused by surrounding colors have application in cartography. These results are synthesized to recommend the following pairs of hues for use on thematic maps suited to diverging color schemes: red/blue, orange/blue, orange/purple, and yellow/purple. These recommendations are robust because they may be communicated verbally and require no particular color charts or color measurements for use. These color pairs will aid in producing maps of differences and of changes that can be read accurately by all map users.
This paper combines color principles in a way that leads to simple guidance using everyday color vocabulary. The focus is selection of pairs of hues for use on thematic maps and graphs with diverging color schemes. The guidance is limited, but it will be helpful to map designers working in reflected, projected, and emitted media (such as prints, slides, and computer displays) and to software developers designing useful default schemes for software tools.