02-13-2019, 10:50 AM
When you image is color-indexed this is stated in the image title bar:
In color-indexed images (GIF, and some PNG), pixels colors are indexed into a 256-colors "color map". Any color you try to add to the image is shoe-horned into the closest color in the color map. A quick fix is to change the image to RGB (Image>Mode>RGB) but if you go back to indexed mode (implicit if you export as GIF...) the image is reduced to 256 colors again.
In color-indexed images (GIF, and some PNG), pixels colors are indexed into a 256-colors "color map". Any color you try to add to the image is shoe-horned into the closest color in the color map. A quick fix is to change the image to RGB (Image>Mode>RGB) but if you go back to indexed mode (implicit if you export as GIF...) the image is reduced to 256 colors again.