| 摘要 |
<p>PURPOSE:To perform quantization processing correctly by providing a quantization table and an inverse number table separately, and finding an inverse number after performing bit shift when threshold data is shifted to an LSB side by a scale factor. CONSTITUTION:The threshold data of quantization matrix outputted from the quantization table 1 is multiplied by a coefficient 2 at a bit shift circuit 2, and the inverse number of it is inputted to a multiplier 3. At the bit shift circuit 2, the threshold data is shifted to the LSB side by a barrel shifter 20 when the scale factor S shows a negative value, and when the scale factor S shows a positive value, after the inverse number is found at an inverse number table, it is shifted to the LSB side by a barrel shifter 23. When the scale factor S shows the negative value, the output of the barrel shifter 20 is selected by a switching circuit 21, and the output of the inverse number table 22 is selected by a switching circuit 24. Also, when it shows the positive value, input threshold data is selected, and the output of the barrel shifter 23 is selected.</p> |
