GLIP-Lib is an OpenGL image processing library written in C++. It features all the necessary tools to quickly build texture filters and pipelines and operate them on the GPU.
MDSTk is a collection of 2D/3D image processing tools aimed at medical images. It contains routines for volume data processing (3D filtering, segmentation, etc.) as well as fast low-level vector graphics library for surface and tetrahedral meshing.
MDSTk has been forked by 3Dim Laboratory s.r.o. to provide better support and further push its development forward. Please check VPL (Voxel Processing Library) project available on Bitbucket (https://bitbucket.org/3dimlab/vpl).