How to remap image's colors but without changing the actual palette?

I mean for stuff that can be reliably done with changing the palette, but without rearranging it, just remapping color references in the image. Any quick way to do this other than pixel hunting and running around with bucket fill tool?

So you mean replacing pixel A by pixel B?

  1. Activate pipette tool and hold Hold Alt Gr (=Ctrl + Alt) click on a pixel to replace it with the current foreground/background color
  2. Define a gradient with the colors you want to use (destination colors) and use menu Colors/Remap/Frame(s) to Gradient.

I do this a lot and the method I use is:
-on you brush change the background color to the destination color
-on you brush change the foreground color to the source color

  • go to menu colors - swap FG<>BG - Image/animation