How should map color schemes be selected so that maps can be interpreted by color-blind map readers?
Some color schemes (eg, red-green) can result in maps that are difficult for color-blind people to read (6). VisCheck is a Web-based tool that people with normal color vision can use to get a sense of how color-blind people see colors (10). Colors for maps should be selected to be consistent with Section 508 of the US Rehabilitation Act, which requires federal agencies to make their electronic and information technology accessible to people with disabilities (11). ColorBrewer (Penn State, University Park, Pennsylvania), a Web-based tool that helps identify and create good color schemes for maps and other graphics, indicates which recommended color schemes work well for people with red-green color blindness (12,13). For users of ArcGIS software, the National Cancer Institute has developed an ArcGIS extension known as ColorTools, which facilitates the preparation of GIS maps using the color schemes recommended in ColorBrewer (12,14).
