The Plotutils Package

Appendix B: Specifying Colors by Name

Many of the plotting utilities allow colors to be specified by name. For example, graph supports the `--frame-color' option. The other graphics programs support the `--pen-color' option, and they all, including graph support the `--bg-color' option. The libplot library, on which the graphics programs are based, includes the pencolorname, fillcolorname, and bgcolorname functions.

In any of these contexts, 665 distinct color names are recognized, including obscure ones like "dark magenta", "forest green", and "olive drab". Color names are case-insensitive, and spaces are ignored. So, for example, "RosyBrown" is equivalent to "rosy brown", and "DarkGoldenrod3" to "dark goldenrod 3".

The file `colors.txt', which is distributed along with the GNU plotting utilities, lists the available color names. On most systems it is installed in `/usr/share/libplot' or `/usr/local/share/libplot'. The color names are essentially those recognized by recent releases of the X Window System, which on most machines are listed in the file `/usr/lib/X11/rgb.txt'. However, for every color name containing the string "gray", a version containing "grey" has been included. For example, both "dark slate gray 4" and "dark slate grey 4" are recognized color names.