Biomes from terrain

[rich2005]

Back to reducing the number of colours.

Seach enough and there is often a Gimp script/plugin to implement a procedure.

This one which uses the index method but returns the image to RGB mode.

I found the discussion for the script here, it was originally from gimpusers.com:
http://gimp.1065349.n5.nabble.com/Reduce...d8887.html

In use, same image as before, looks like: 



The script is attached, if you want to try it, un-zip, copy to your Gimp profile
In windows C:\Users\your-name\.gimp-2.8\scripts
In linux ~/.gimp-2.8/scripts
Only given it a very brief try, it is old, 2008, bound to be some snags.
I still advice a small gaussian blur before (depending on image)