How do I select a high-contrast color set for a map?
Obviously, black & white are the highest contrast. I also want 2 sets of colors, so that regions on the map can be colored with good contrast. For instance, one region might be red, another blue, and another green. Simultaneously, each of those regions may contain sub-regions that are cyan, yellow, and magenta. I could just pick dark versions of the 1st set and light versions of the 2nd set, but would like about 6 colors in each set. Also, simply picking colors that are numerically far apart doesn't lead to good visual contrast.
Any suggestions? (Colors are for on-screen display)
ColorBrewer is an amazing tool that does just that.
It's aimed at cartographers, support up to 12 colors, and has some nice options as well (such as the ability to generate colorblind-safe color sets)