| 摘要 |
PROBLEM TO BE SOLVED: To improve the prediction performance of DC/AC coefficients by using a maximum value and a minimum value of DC coefficients of an adjacent block to a current block in a discrete cosine transformation area for the predic tion of current DC coefficients. SOLUTION: In the step 404, a maximtnm value DC max and a minimum value DC min are obtained among quantized DC coefficients DC- A to DC- C in blocks A, B, C adjacent to each other, and in the step 405, an absolute value of a difference between the DC- max and the value DC- min is obtained. In the step 405, the absolute value of the difference is compared with a critical value. When the former is larger, a DC coefficient of a current block is closer to which of the DC- max and the value DC- min is discriminated in the step 408, and a predicted value DC- P of the current block is set to the closer value in the steps 412, 413. When the absolute value of the difference is smaller than the critical value in the step 405, a predicted value DC- P of the current block is set to the DC- C in the step 411. Thus, the prediction performance of DC/AC coefficients is improved. |
