DevIL is an image loading/manipulation library, previously known as OpenIL, with a syntax similar in some ways to OpenGL.
It integrates with DirectX, OpenGL, Windows GDI and Allegro, is compatible with most platforms and C compilers (and also has Delphi and Visual Basic support) and is capable of loading almost all common image file types, and saving many of them.
A simple C++ wrapper is included, making it extremely easy to use it in your own C++ programs.
It supports animation, mipmaps and layers among various other features.
www.openil.org