| 摘要 |
PURPOSE:To improve a compression ratio and to prevent the occurrence of the artifact of a restored image by applying nonreversible and reversible compressions to overlapped areas including the boundary of an interesting area in an image. CONSTITUTION:It is assumed that an area with a prescribed width, which includes the boundary of the interesting area, is an overlap area and an area inner from the outer boundary of the overlap area and the outside from said boundary are a 1st area and a 2nd area, respectively. A compressor 7 reversibly compresses the 1st area, and a compressor 8 nonreversibly compresses the 2nd area. A control circuit 12 selects the reversible or nonreversible compression. Since the reversible compression is applied to the 1st area and the nonreversible compression to the 2nd area, the compression ratio can be improved. Since the reversible and nonreversible compressions are applied to the 1st and 2nd areas including the overlap areas, the occurrence of the artifact of the restored image can be prevented. |
