I remember in GIMP 2.4 editing palette in an indexed image was as easy as changing the foreground color but I’m a little lost in GIMP 2.8 as there is no Dialog menu. So, I played around a little and found out it was in the colors > Map > Set color map > hit Default > scroll to the top > right click the image palette and bring up the palette editor and I figured out I can’t do anything after that. Neither can the palette be edited on click nor can we edit the HTML notations that refer to respective palettes. How can we edit palettes in an indexed image(for this I’m using an indexed image with eight colors).
In GIMP 2.8 for an indexed image you can use the Colormap dialog, which is very simple to activate (see the provided link):
In this dialog the entire palette is shown and you can edit each color by right clicking on it:
Choosing Edit color, a color editor appears:
And the effect is immediate:
Source : Link , Question Author : lind , Answer Author : Paolo Gibellini