A full featured cross-platform image library
Developer's Image Library (DevIL) is a cross-platform image library utilizing a simple syntax to load, save, convert, manipulate, filter and display a variety of images with ease.
FLENS (Flexible Library for Efficient Numerical Solutions) is a C++ library for scientific computing. It can be considered as a very convenient and --- at the same time --- extremely efficient interface for BLAS and LAPACK. But it is much more than this
Libquadratic provides methods for automatic numerical integration with various backends, strategies, error approximation models and mappings with special emphasis on line-integrals in the complex plane. Language bindings are currently in C++.