I've written some wrappers for some small C libraries for image reading, writing and resizing. They are part of
Sean Barrett's collection which some of you may know. What's nice about them is that they don't have any external dependencies. I don't know how well they behave on corrupt images and things like that, however. They are intended to be used for games where you're in control of you asset pool.
They should work for CHICKEN 4 and 5.
K.