| 摘要 |
PURPOSE:To obtain the result of processing with most excellent gradation to a data not including edge information and with high resolution to a character or a line drawing including the edge information by using plural threshold matrixes having different threshold arrangement patterns so as to switch the arrangement pattern in response to the presence of edge information. CONSTITUTION:A threshold table used at each unit area of gradation processing consists of plural kinds of tables having different arrangement patterns and whether or not the edge information is included in an input data is discriminated at each unit area of gradation processing and the type of utilized arrangement pattern is switched in response to the presence of the edge information. That is, the 1st processing system is provided with an 8X8 averaging circuit 150 and a density pattern processing circuit 153. The gradation processing by the density pattern method is applied in this processing system. An edge emphasis circuit 152 in the 2nd gradation processing system is a 2-dimension space filter and amplifies the density change of the data of the area to emphasize the edge when the input data has a density level change, that is, when edge information exists.
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