The improved gray scale and the coarse-fine PCM systems, two new digital TV bandwidth reduction techniques

Two new digital television bandwidth-reduction techniques are presented with experimental results. Each provides twice the efficiency of a conventional pulse code modulation (PCM) system with similar picture fidelity, and each is simple and feasible for present-day spacecraft Implementation. The Improved Gray Scale PCM system effectively eliminates, by an averaging process, the gray scale contouring effect encountered in low-bit digital TV systems. The Coarse-Fine PCM system is somewhat more complex, but provides a higher fidelity reproduction of the original picture. The basic principles of operation of these two new data-compression techniques are given along with comparative pictorial results.