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I think you will have to give a bit more information for us poor only-use-gimp people.
Could be:
1. Exporting as a gif which contains transparency, the 'color' of the mask depends on the background colour set in Gimp at the time. This is the same image exported when bg = black and bg = white (as shown by the thumbnails viewed in XnViewMP)
screenshot https://i.imgur.com/bvYpQ3U.jpg
2. Do you mean editing the gif colour map? To do that first change the color mode to indexed: File -> Mode -> Indexed then then open Windows -> Dockable dialogues -> ColorMap (disabled for RGB images)
screenshot https://i.imgur.com/zr9ybdK.jpg
3. or something else
I think you will have to give a bit more information for us poor only-use-gimp people.
Could be:
1. Exporting as a gif which contains transparency, the 'color' of the mask depends on the background colour set in Gimp at the time. This is the same image exported when bg = black and bg = white (as shown by the thumbnails viewed in XnViewMP)
screenshot https://i.imgur.com/bvYpQ3U.jpg
2. Do you mean editing the gif colour map? To do that first change the color mode to indexed: File -> Mode -> Indexed then then open Windows -> Dockable dialogues -> ColorMap (disabled for RGB images)
screenshot https://i.imgur.com/zr9ybdK.jpg
3. or something else