| 摘要 |
<p>PURPOSE: To effectively detect block distortion by obtaining respective differences among plural picture elements in symmetrical relation holding a boundary between the blocks of (n)×(n) picture elements, comparing the distribution values of the entire differences in vertical and horizontal directions and judging discontinuity. CONSTITUTION: An inverse DCT circuit 1 performs inverse DCT to inputted compressed image data, the data for one field are tentatively fetched in a memory 2 and the presence/absence of the block distortion generation of 8×8 picture elements are detected. Thus, 4 picture elements×8 lines at vertical and horizontal symmetrical positions holding a block boundary there between are defined as reference picture elements and the differences of the respective adjacent picture elements are detected by difference detection circuit 3 to 5. Difference value distributions obtained by distribution detection circuits 6 to 8 from the differences are compared by a comparator circuit 9 and whether or not the block distortion is generated is judged from the distribution state of discontinuous components. When the block distortion is judged, the circuit 9 turns on a post-filter 10 and the entire block is filtered. Thus, the block distortion is effectively detected and treated.</p> |
