| 摘要 |
PURPOSE:To evaluate block distortion quantitatively by calculating a reference image based on original image data and decoded image data and calculating an evaluation value of an elimination filter based on the calculated reference image and its block distortion reduction processed image. CONSTITUTION:Since a picture element value changes stepwise at each block adjacent position, a differentiated value is much deviated from a mean value Mm. A differentiated value of a reference image is obtained by adding a normalized difference of the mean value Mm to the differentiated value. In this case, the differentiated value of the reference image is much deviated from a mean value Mn and a decoded image whose edge is not lost is obtained. Thus, even when a change in the picture elements at the adjacent position of blocks of the decoded image is the same, information of a discontinuous position or a flat position is obtained depending on a change in the position in the original image. Thus, the image is not affected by distortion other than block distortion such as mosquito noise. |
