The Camellia library is an open source and cross-platform image processing library, written in plain C. It includes a lot of speed-optimized imaging functions (filtering, morpho, labeling, motion detection, warping, color conversion, project/backproject)
IMGH (IMaGe library in C++ Header files) is a simple, light-weight, and
cross-platform image processing library, that supports simple
editing and drawing, multiple pixel formats (pointers and float).
Designed for developers and researchers.