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

Experiments on real-time operation of various frame repeating and replenishment systems were performed with a low-resolution TV system described in a companion paper. 1 The head-and-shoulder view of a person was used as the picture source as might be used in a visual communication system. As is well-known, the lower bound on the number of presentations per second in a television system is set by the flicker requirements. No systematic study of motion in TV pictures has been possible in the past because the flicker requirements dictate that for a screen luminance of, say, 85 cd/m 2 (25 fL), something of the order of 60 presentations must be presented every second to alleviate the flicker problem. The presentation requirements for producing smooth perceived motion for most of the common types of movements are much less than this. In the past, suitable means have not been available for the study of the lower bound on the picture rate necessary for the satisfactory rendition of motion in television systems. With the availability of large-capacity, high-speed ultrasonic delay lines,2 it is now possible to store, in digital form, large quantities of information. Delay lines with a total storage capacity of 25 kilobits and an input-output rate of approximately 1.5 megabits/second are readily available now. Using eight assemblies of lines and a picture format of 160 samples per line, 160 lines per frame sequentially scanned at 60 frames per second, allows storage of one complete picture frame encoded as 8-digit P C M at a sampling rate of 1.536 MHz.