Preprocessing of MPEG-2 Video Sequences Using Rational Filters

摘要

In this paper the preprocessing of MPEG-2 video sequences is considered with reference to the characteristics of the human visual system (HVS). In fact, since image details which are not perceptually relevant can be smoothed without affecting the visual quality, more efficient compressions of video sequences can be achieved, especially at low bitrates. The main perceptual assumption is that the sensibility of HVS is a decreasing function of the velocity of the moving objects in the scene. Therefore, the degree of smoothing depends on the amount of motion in the video sequence. Moreover, in order to preserve the spatial details, a nonlinear filtering procedure based on the so-called rational filters is required. The technique presented is based on the block partitions used in the conventional MPEG-2 coders. Extensions to the object or region partitions used in MPEG-4 coders can be also devised. Finally, the implementation issues are considered and an evaluation of the computational load required by the preprocessing method is given. As a conclusion, it has been shown that the current DSP technology can easily support the proposed algorithm.