Good post-production learning materials?
I'm continuously working to improve my skills with the camera, but I'd like to start learning about the theory of post-production. I don't really want a "Photoshop for Dummies" guide since 1) I use GIMP since I'm almost entirely Linux, 2) I can figure out HOW to do most things on my own and 3) the how to use X program books are a dime a dozen. I just don't understand WHY to apply certain effects or how to tell when you should/shouldn't apply them. Does anybody have any good book/website/any reading recommendations that address this?