A SIMPLE ALGORITHM FOR THE REDUCTION OF BLOCKING ARTIFACTS IN IMAGES AND ITS IMPLEMENTATION

In this paper a simple but effective operator for the reduction of blo cking artifacts is presented, together with a simple hardware implemen tation. The method is based on the Rational Filter approach: the opera tor is expressed as a ratio between a linear and a polynomial function of the input data. Such filters proved to outperform other convention al methods in other applications, such as noise smoothing [1], thanks to their capability of adapting gradually to the local image character istics. The filter is capable of biasing its behaviour in order to ach ieve good performance both in uniform areas, where linear smoothing is needed, and in textured zones; where nonlinear and directional filter ing is required. A detector of activity is embedded in the expression of the operator itself so that the biasing of the behaviour of the fil ter is smooth and not based on fixed thresholds. A solution for the ha rdware implementation of the scheme is presented in detail. Despite th e simplifications imposed by the hardware design, the filter retains t he same efficiency as the original algorithm.