Caveat: I'm not a graphic designer and may be misusing some terminology. Please bear with me. :-)
I'm attempting to add color to some greyscale icons (i.e. all three channels are identical). I want to map the colors such that the brightest grey becomes one specific color, the darkest grey becomes another specific color, and all the greys in between are translated into colors along the "gradient" between those two specific colors.
I've never used GIMP in this manner before and, while it looks like I should be able to use the Colors > Curves tool for this, I can't figure out the specifics even after reading the docs and Googling around a bit.
Perhaps someone who actually knows what they're doing can offer me some advice? ;-)
As per leugim's suggestion, I ended up going with the Gradient Map tool, but there turned out to be two caveats:
- It appears to map the full range of possible Values (0.0 through 1.0), not just what's being used in the image. This was easy enough to work around by using the Curves tool to "stretch" my images' Value ranges such that the darkest color became (0, 0, 0) and the brightest color became (255, 255, 255).
- It doesn't seem to be exact? The colors I used in my gradient were (7, 7, 11) and (70, 58, 96), but the colors in the final image were (6, 6, 10) and (69, 59, 95). Mind you, no one's holding a colorimeter to my work, so this is plenty close enough! Just thought it a bit odd.