| 摘要 |
<p>PURPOSE:To improve the quantity of a reproduced picture by comparing a threshold level and an orthogonal transform coefficient different from a block in the case of a luminance signal and a chrominance signal in response to the quantization characteristic in the unit of blocks and quantizing the orthogonal transform coefficient or zero depending on the quantity. CONSTITUTION:A significant/nonsignificant error block discrimination circuit 16 calculates a quantization step width (g) and a succeeding threshold level Th as a function Yc as to whether the block is a luminance signal or the color difference signal at first; Th=f(g, yc). In the case of Cij<=Th, where Cij is the orthogonal transform coefficient of the block, it is discriminated as a nonsignificant error block, and when the equation is not satisfied, it is discriminated as a significant error block. In the case of discrimination as the nonsignificant error block, a coefficient quantization circuit 7a quantizes zero. In the case of the discrimination of the significant error block, an orthogonal transform circuit 6 calculates the coefficient, which is quantized. Thus, coding of noise is reduced and the quality of the reproduced picture is improved.</p> |
