| 摘要 |
PURPOSE:To realize a binary coding process in accordance with contents of pictures without subjecting a black or white picture to a dither process and to improve the compression efficiency, by deciding the black or white picture in consideration of the maximum and minimum values of the density in addition to the density gradient which is a conventional image area deciding ciriterion. CONSTITUTION:Formerly, the output of a binary coding process is selectively switched to either one of binary coding process outputs by means of a dither binary coding circuit 3 and fixed slice binary coding circuit 4 by the output of a comparator 7. However, only when the maximum value is larger than a fixed value A and, at the same time, the minimum value is smaller than another fixed value C, namely, when oututs of ''1'' level are respectively generated from comparators 6 and 8 in addition to the output of the comparator 7, the output, binary picture data, of the dither binary coding circuit 3 is selected by a multiplexer 10 at the time when the output of an AND gate circuit 9 becomes ''1''. The 11 of the figure is an MH decoder which encodes and the 13 is a page memory which stores encoded data, and then, the 14 is the transmitting section of FAX, etc.
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