Subjective image quality as a function of viewing distance, resolution and picture size

This paper describes two experiments concerning the subjective quality of complex scenes. Slide projections were used as stimuli and they were varied in viewing distance, resolution and picture size. The subjective quality Was judged by a group of twenty subjects by means of categorical scaling. The results of the experiments show that the (angular) resolution expressed in periods per degree and the picture angle spanned by the display, each influence the quality independently. Subjective quality increases with resolution, but saturates at a resolution (6 dB cut-off frequency) of approximately 25 periods per degree. There is also a linear relationship between the subjective quality and the logarithm of the picture angle. In the discussion, these results are compared with those of a number of experiments known from the literature. The results are also interpreted in terms of consequences for High-Definition TV.