I know nothing about Linux, beyond what it is. Regarding GIMP, this app allows for custom scripts to do special functions. Our vice admin, RobA has made many custom scripts for all kinds of specialty mapping needs. Find one of his posts and look at his Sig, many of his custom scripts are linked there. There's an automatic forester, a city building random placer, a random dungeon tile creator, and many others. I dabble with GIMP, but as mentioned in my previous post, I primarily use Xara Xtreme Pro 4.0 which is vector app, like Inkscape (though not free) so I can't help you as much regarding these specific apps - still there are many in the community who can. Just look around.

GP