This paper from the VIS Group Stuttgart describes the acceleration of so-called morphological operators using graphics hardware and OpenGL. As the problem is mainly memory bandwidth bound, a solution based on graphics hardware can significantly reduce computation time in the filtering step, as graphics hardware typically has much broader and faster memory paths. When using fixed-point graphics hardware for mathematical computations, accuracy can be a problem. However, morphological operators map well onto the graphics pipeline, resulting in no loss of accuracy. See also the project page for more about hardware-based filtering. (Accelerating Morphological Analysis with Graphics Hardware. Matthias Hopf and Thomas Ertl. Workshop on Vision, Modelling, and Visualization 2000. pp 337-345)