GRAPHIC SCALING AND VALIDITY OF JAPANESE DESCRIPTIVE TERMS USED IN SUBJECTIVE-EVALUATION TESTS

This article describes the perceived intervals between the official Japanese descriptive terms for subjective-evaluation tests of picture quality, which correspond to the English descriptive terms recommended by the CCIR. The perceived intervals in both the five-grade quality scale and the five-grade impairment scale are examined, using the graphic-scaling method. The results indicate that they are almost uniform. Next, the validity of the results derived is examined. HDTV picture qualities are evaluated under various random-noise levels, using the EBU method. The perceived intervals, concerning the Japanese five-grade impairment scale, are obtained by applying the method of successive categories to the evaluated results. Consequently, it is verified that the results from the EBU method correspond to those from the graphic-scaling method.