| 摘要 |
PURPOSE:To obtain a restored image with high image quality and smooth gradation changes without lowering a code compression rate by averaging and eliminating differences in gradation between blocks at a region where one-gradation averaging blocks are consecutive. CONSTITUTION:An input halftone image signal 1 is inputted to a block averaging processing section 2 in the unit of blocks at the coder side, divided into resolution information and gradation information, they are inputted to coding sections 3, 4 corresponding to them respectively and codes. Both the coded signals are converted into a serial coding signal 6 by a mixing section 5 and then outputted. On the other hand, an input coding signal 7 is inputted to a separation section 8, divided into coded signals of resolution and gradation information at the decoding signal, and decoded respectively by decoding sections 9, 10. Further, a signal representing whether the gradation information is a one-gradation averaging block or two-gradation averaging block is generated in the decoding section 10, and the said signal and the gradation information signal of the preceding block latched once at each block are inputted simultaneously to a decision section 12.
|
