A 3-D nonlinear recursive digital filter for video image processing

The authors introduce a recursive 3-D nonlinear digital filter that is capable of performing noise suppression without degrading important image information such as edges in space or time. It also has the property of unnoticeable bandwidth reduction immediately after a scene change, which makes the filter an attractive preprocessor to many interframe compression algorithms. The filter consists of a nonlinear 2-D spatial subfilter and a 1-D temporal filter. In order to achieve the required computational speed and increase the flexibility of the filter, all of the linear shift-invariant filter modules are of the infinite impulse response (IIR) type