| 摘要 |
PURPOSE:To execute highly efficient encoding processing by repeating a dither matrix in each prescribed lines, and using the correlation of picture signals between scanning lines. CONSTITUTION:A picture on a reading original 1 is converged on a CCD line sensor in each line by a lens system 2, decomposed into picture elements then converted into a serial picture signal AV. The signal AV is supplied to an automtic background density control (ABC) circuit 4 and converted into a level signal based upon the backgroud density in accordance with respective picture elements. An output signal CV from the circuit 4 is supplied to an A/D converter 5 and converted into a digital picture signal DV consisting of four bits corresponding to the level and the signal DV is inputted to a comparator 6. A threshold generator 7 generates a threshold signal DT corresponding to a dither matrix MD and supplied the signal DT to a reference input terminal of the comparator 6. The comparator 6 encodes the DV into a binary value on the basis of the DT and supplies the binary signal SB to a line buffer 8 and an MR encoder 9.
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