High performance image library

Hi!
Previously I've been using ImageMagick for image processing, but now I need something that is more performance-oriented.

I need to be able to:
* analyze a stored JPG/GIF/PNG image per pixel
* compress to JPG/GIF/PNG
* store processed image

Do you have any tips for me? Thanks in advance!

I usually use ImageMagick, but I think DevIL (formerly OpenIL) might be pretty good: http://openil.sourceforge.net/
Not sure how performance oriented it is, but you can use it in conjunction with OpenGL which is performance oriented.