A simple algorithm for the reduction of blocking artifacts in images and its implementation

A simple but effective operator for the reduction of blocking artifacts is presented, together with a simple hardware implementation. The method is based on the rational filter approach: the operator is expressed as a ratio between a linear and a polynomial function of the input data. Such filters have been proved to outperform other conventional methods in other applications, such as noise smoothing, thanks to their capability of adapting gradually to the local image characteristics. The filter is capable of biasing its behaviour in order to achieve good performance both in uniform areas, where linear smoothing is needed, and in textured zones, where nonlinear and directional filtering is required. An activity detector is embedded in the expression of the operator itself so that the biasing of the behaviour of the filter is smooth and not based on fixed thresholds. A solution for the hardware implementation of the scheme is presented in detail. Despite the simplifications imposed by the hardware design, the filter retains the same efficiency as the original algorithm.