Development of a perceptual distortion meter for digital video

Digital image compression techniques introduce complex, time-varying distortions in coded video. There is an enormous interest in developing a reliable methodology to assess the level of distortion. The RACE project MOSAIC developed a new technique of continuous assessment (Single Stimulus Continuous Quality Evaluation, referred to as SSCQE) which has recently been incorporated in Rec. ITU-R BT.500. In this approach, viewers give a vote of quality against time according to the temporal variation in the video impairment. Under certain circumstances, it is desirable to be able to replace the human subjects with a mathematical model which produces an output approximating to the trace of continuous quality that would be obtained using the SSCQE method. In this paper, the initial stages of development of such a distortion metering tool are described. This meter takes into consideration both the psychophysical and psychological aspects of the viewers during the process of judging the quality of decoded MPEG-2 video. An overview of this new model is first discussed, followed by a brief introduction of each element in the model. Finally, some preliminary results are presented and discussed.