Posted by Jester Lapse

How to open color map
~First, index you image. Do this by going to the image tab, scroll down to mode, then click indexed.
~Second, open up your color map. Do this by going to the windows tab, scroll down to dockable dialogs, then click color map.

This tool allows you to see all the colors you are using in your picture. It also allows you to change colors easily.