| 摘要 |
PURPOSE:To avoid execution of the coding to a duplicated information without losing the continuity of gradation components by coding binary components by a binary coding part and the gradation components by a halftone gradation part respectively. CONSTITUTION:On the coding-side, an input halftone image signal 1 of 2<m>- gradation is separated into a binary component signal 3 and a gradation component signal 5 by a separating part 2 in accordance with a conversion function table aforementioned, and the signals 3 and 5 are temporarily stored respectively in a page memory for binary components 4 and a page memory for gradation components 6. The binary coding part 8 is actuated by an action switching signal 7 to code a binary component output signal from the page memory 7. An this resulting coded data 10 of the binary components is outputted 13 through a selector 12. Thereafter, based on a request signal from the restoring-side, the signal 7 actuates the halftone coding part 9. Thus the gradation component signal from the page memory 6 is coded, and the resulting coded data 11 of the gradation components is outputted 13 through the selector 12.
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