10-15-2018, 06:38 AM
OK, got it. It seems your grayscale picture contains 256 colors (Colors>Info>Colorcube analysis). In the GIF format, you can have 256 colors, but... the "transparency" of pixels is indicated by painting pixels in some predefined color and indicating that this color should be made transparent. So if you have a transparent image you only have 255 real colors to work with for the opaque parts.
So, what that cryptic message is telling you is that Gimp cannot find a a free color slot to create that transparent color. The solution is to sllghtly the number of color in the image to make room for the transparent color Colors>Posterize and posterize to 255 colors. Then there is one unused slot in the color map and you can save as a transpatent GIF.
So, what that cryptic message is telling you is that Gimp cannot find a a free color slot to create that transparent color. The solution is to sllghtly the number of color in the image to make room for the transparent color Colors>Posterize and posterize to 255 colors. Then there is one unused slot in the color map and you can save as a transpatent GIF.