Quality Rating of Television Images

Two methods of evaluating impairments in television images are described. Both employ observers and, therefore, yield subjective evaluations. The first is an extension of Baldwin's in which observers vote a preference between pictures with different impairments; one of the pictures is optically projected somewhat out of focus and is used as a reference. In the second method, the impairment is rated by observers in terms of pre-worded comments which are numbered and form a rating scale. Both methods permit an evaluation in terms of liminal increments as computed from the distribution of votes of the observers. These methods have been used to evaluate the impairing effects of echoes and noise in television pictures, and also to relate picture sharpness to other quality parameters.