I would like to create an image from a map, where each country is colored in a different color, where the frontiers are in black, and in which each color except black is fully transparent, while not losing the RGB information.
My tools are The Gimp or anything installable on Linux, and small scale programming (if I need to fully understand the png format, I won't succeed).
My current image is perfect, except for the transparency information. My current experiments with GIMP have always resulted in RGB information being lost when exporting the image to png or gif.
Any pointers? Thanks a lot.