Impairment metrics for digital video and their role in objective quality assessment

In this paper we discuss work on quantification of video impairments resulting from MPEG compression, their role, and their scope of application for objective quality assessment. Three impairment metrics, blocking artifact level, ringing artifact level, and corner outlier artifact level have been used to create a combined impairment metric. The relevance of this metric to develop an objective quality assessment has been investigated, as well as the issues facing the creation of a no-reference quality metric. The main issues are overall metric completeness, and performance of the individual metric components. The impairment metrics that we have studied appear to be key components for future no-reference type of objective quality metrics. Impairment metrics are also of great importance because they allow closing the detect-measure-correct loop that is necessary to improve image quality in real time. Applications of single-ended quality metrics include multimedia home terminals, STBs, digital TV, and low bit-rate video applications such as IP videotelephony and video streaming over IP.