Optimized sampling and bit rates of digital NTSC picture codes based on subjective evaluation of reproduced pictures

This paper describes optimized digital NTSC picture coding in which circuit and system configurations are simplified by lowering the sampling frequency and quantizing level. The sampling frequency and quantizing level are determined based on the subjective evaluation of the reproduced picture quality. In accordance with the result of the subjective evaluation, the digital NTSC picture containing one third of the information as compared with that of the normal digital NTSC picture was found to be satisfactory. Although the digital NTSC picture coding system normally uses a sampling frequency of 4× fsc (fsc: the color subcarrier frequency of the NTSC system) with a quantizing level of 8 bits, the subjective evaluation leads to the result of a sampling frequency of 2.28× fsc with a quantizing level of 5 bits