Practical application of objective picture quality measurements

Increasing use of compressed video methods in the generation and distribution of television programs has led to a requirement for objective picture quality measurement methods. Although traditional, indirect, signal quality measurements are still required for evaluation of the uncompressed part of the system, they are not adequate for evaluation of the compression-decompression process. Subjective testing methods are complex and time consuming and are only applicable for development purposes. They do not lend themselves to operational monitoring, production line testing or trouble shooting. Considering the variety of video compression methods and growing ease of data interconnection, measurement of resulting video quality must not be limited to a particular compression system. This paper describes the feature-extraction and picture-differencing objective picture quality measurement methods with reference to on-going research developments. Emphasis is placed on application of the human visual system model to picture-differencing as the preferred objective method. System requirements for application of the model are described in conjunction with a practical implementation of a measurement set