| 摘要 |
<p>PURPOSE:To prevent deterioration of picture quality and obtain high efficiency of encoding by making forecast error encoding (DPCM) for each of luminance signal and color difference signal of picture signals and quantizing obtained differential signals giving priority to those components that give large influence to human visual valuation. CONSTITUTION:Y, I, Q signals are converted to differential signals eY, eI, eQ by a forecasting device 1. A quantizer 2 treats signals eY, eI, eQ as three-dimensional vector signals, and when quantizing, selects those nearest to vector E=(eY, eI, eQ) out of plural quantizing representative values arranged on only basic axes of three-dimensional vector coordinate. As quantizing characteristic, for instance, five values are allotted to eY axis, and three values of quantizing representative value qn(n=0-8) are allotted to eI and eQ axes respectively. In this quantizing characteristic, there is follow-up characteristic similar to normal scalar quantizing for signals that formed maximum change out of luminance signal or two color difference signal. However, in the case where two signals or three signals change largely, following-up becomes slow. However, deterioration of picture quality is hardly detected due to color difference error or luminance error masking. As mentioned above, quantizing is made utilizing man's visual characteristic.</p> |
