The Integrating Vision Toolkit (IVT) is a powerful and fast C++ computer vision library with an easy-to-use object-oriented architecture. It offers its own multi-platform GUI toolkit. OpenCV is integrated optionally. Website: http://ivt.sourceforge.net
AVSLib is an extension library to the Avisynth non-linear video editor, offering a rich set of new features: filters (animation, editing, runtime and more), array containers & operators, debugging tools, math & string functions and many more.