Subjective assessment of impairments in television pictures

It is appropriate to use an opinion rating method to assess the effect on broadcast television pictures of the impairments that can arise in transmission from studio to receiver. Of the available techniques, a procedure in which lay observers rate picture quality has proved successful over a number of years, and has been standardized for use at the Post Office Research Station. Mathematical models are fitted to the raw data to analyse opinion distributions and to relate mean opinion level to the objective magnitude of the impairment. Results for some 8 different kinds of impairment have been published so far, and summarized in terms of sets of objective magnitude values at a series of mark points based on a scale of summable subjective impairment units termed IMPS.