The scheme guidelines are limited to the use of color to directly represent data that occur at locations in the graphic where colors occur. The types of thematic maps to which these guidelines apply are choropleth maps (for example, census tracts filled with colors representing the percentage of the population from an ethnic group), filled isoline maps (for example, color bands that mark set ranges of terrain elevation), and qualitative areal-extent maps (for example, different colors for different types of vegetation). My hope is that these guidelines and the associated terminology will also guide the work of people grappling with data visualization challenges in diverse disciplines such as physics, medicine, psychology, and graphic arts.
A disorderly jumble of colors produces a map that is little more than a spatially arranged look-up table. The goal of this WWW resource is to help you do better than that by using color with skill. This resource provides a generalized set of color schemes and example maps.
Also online: ColorBrewer, a tool for selecting specific color schemes in RGB, CMYK, Hex, Lab, and HSV
These guidelines are described in greater detail in two of my publications, and much of the text here is quoted from these papers:
Cynthia A. Brewer, 1994, "Color Use Guidelines for Mapping and Visualization," Chapter 7 (pp. 123-147) in Visualization in Modern Cartography, edited by A.M. MacEachren and D.R.F. Taylor, Elsevier Science, Tarrytown, NY.
Cynthia A. Brewer, 1994, "Guidelines for Use of the Perceptual Dimensions of Color for Mapping and Visualization," Color Hard Copy and Graphic Arts III, edited by J. Bares, Proceedings of the International Society for Optical Engineering (SPIE), San Jose, February 1994, Vol. 2171, pp. 54-63.