cmap.x11r2  X11R2 definition of cmaps (generated by cmap -o 0)
depth   linear depth cmap (generated by cmap -c 50 255 -o 1 and
	cmap -c 0 255 -o 1)
nldepth nonlinear(log) depth cmap (generated by cmap -c 0 255 -o 2)
alternating constructed manually (alternating colors of high contrasts)
