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. 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.