I wrote this program for coloring any map with only 4 colors. Input for it is an bitmap file with 24 bit colors (must gray/scale). Output is a bitmap which is colored with maximum 4 colors.

Generate a 3D point plot of L=(x,y,z) using the values in the vector c to determine the color of each point. If c is empty, then z (column 3 of L) is used to color the plot. The data points are sorted so that plot3 is only called once for each