Recommend me an image editing library

[Naureg]

I'd imagine there's a bunch of them around, but considering I've never used one I'd like to use one with these properties:

Easy to begin with
Good resources to read up on
Editing individual pixels of an image without any hassle (e.g something extremely simplistic like EditPixel(int r, int g, int b))
Fast as hell, minor performance differences in the libs may end up becoming several minutes in my resulting program.

Thanks :D

[Moschops]

You want easy and fast; those are generally conflicting considerations (ease of use for the user means the code has to handle the edge cases and safety for you), so a bit more information would be helpful. What kinds of images do you want to work with, what operations do you envisage doing, do you care about the size of the final executable or how long it takes to build?