| 摘要 |
<p>PROBLEM TO BE SOLVED: To enhance image quality by achieving highly precise prediction even when the signal value changes in the prediction direction.SOLUTION: An image decoder includes intra-prediction means for, when the coding mode according to the coding block is an intra-coding mode, generating a prediction image by performing intra-frame prediction processing for each block becoming the unit of prediction processing of a coding block. When the intra-prediction parameters indicate horizontal direction prediction processing, the coordinate of an upper left pixel in the block is an origin (0, 0), and the coordinate of a pixel for which a prediction value is to be calculated is (x, y), the intra-prediction means adds, to the luminance value of a pixel at coordinate (-1, y) adjoining to the left of the block, a value proportional to a value obtained by subtracting the luminance value of a pixel at coordinate (-1, -1) from the luminance value of a pixel at coordinate (x, -1) adjoining the block from above; then sets the calculated value to a prediction value for the pixel at coordinate (x, y).</p> |
