| 摘要 |
PURPOSE:To decide an image area on real-time basis by deciding whether the image area is a pattern image part or variable density image part on the basis of data obtained by shifting binary-coded data by several picture elements in a main scanning or subscanning direction. CONSTITUTION:Image data read by a readout part is processed into a digital signal (b), which is applied to a binary-coding circuit 161. The binary-ciding circuit 161 converts a pattern area into a binary signal with a threshold level lower than that of a simple binary-ciding circuit and supplies the binary-coded data (g) to an Y-directional shift processing circuit 162. The Y-directional shift processing circuit 162 shifts the binary-coded data by 8 picture elements and ANDs the shifted data (h) with the input data (g) to generate processing data (j). The shift data (h), on the other hand, is processed similarly by an X- directional shift processing circuit 163 to obtain processing data (k) and those data (j) and (k) are applied to a mixer 164 to obtain a switching signal (f) as an image area decision result.
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