I’d like to replace the blue in the linked image with red. What is the easiest and best-looking way to do this? I had the idea of selecting the gold trim and colorizing the inverse, but that would take way too long to trace all that gold.
I can take suggestions for Paint.NET, GIMP, or Paint Shop Pro 9.
Disclaimer: I’m a Photoshop user, and I know you’re not asking for a solution in that software. I do suspect that apps like GIMP have very similar options with similar results.
Put a completely red layer on top of your image layer. (I used a red that was somewhat lighter and a lot more vivid than the eventual effect I’d like to achieve.) Then change that layer’s blending mode to Screen or Lighten. Play around with the exact opacity to tweak the effect to your liking.