Low-Resolution TV: Subjective Effects of Frame Repetition and Picture Replenishment

Abstract

Using the experimental television facility described in a companion paper, frame repeating and point-by-point selective replenishment of picture elements have been accomplished in real time. On the basis of initial experiments, using the head-and-shoulder view of a person as the picture source, such as is likely to be encountered in a visual communication system, the following tentative conclusions have been reached: (i) The motion rendition with a 15 new pictures/second frame repeating system, while not flawless, is reasonably good. (ii) Selectively replenishing one-quarter of the picture points per frame gives a better continuity of motion but results in objectionable patterns. (iii) Picture quality greatly depends on the pattern of picture replenishment. Of the five replenishment patterns tested, two result in pictures which are significantly better than the other three. (iv) In informal viewings, opinion has been so divided that no preference has been established between simple 15 new pictures/second frame repeating and the more satisfying schemes for picture replenishment. (v) The frame repeating and replenishment systems produce gross impairment during zooming and panning; consequently, these systems in their present form are unlikely to be useful for broadcast television. The impairments observed in these systems are subjective and not yet predictable. This emphasizes the importance of subjective testing of systems in real time.