A Method of Coding Television Signals Based on Edge Detection

There is an increasing trend in the communication field to utilize the physiological and psychological properties of the ultimate receiver -- the human observer. Some of these properties were applied many years ago in establishing television transmission standards -- for example, visual acuity and flicker-fusion frequency thresholds. The development of information theory made this trend even more apparent, particularly in Shannon's first coding problem, where he posed the question of finding an optimum code for a continuous information source when the fidelity criterion of the receiver was given. Unfortunately the fidelity criteria of human observers are not known. This lack of knowledge is particularly apparent in visual processes, even though in this field the challenge of possible channel-capacity saving is tempting. From a theoretical standpoint, the solution of the first coding problem must be postponed until enough psychological data are collected. But, from a practical point of view, it is possible to overcome this barrier. Instead of searching for human fidelity criteria, we can proceed in the following simpler way. First, we take the present television pictures of toll quality as a stand1001