| 摘要 |
PURPOSE:To read a transmitted picture high in tone reproduction of primary colors by providing a conversion means which makes the ratio of change of slice level of picture output level read by an image pickup device change in logarithmic ratio, and thereby binary coding a picture quality signal by slice level that changes in said logarithmic ratio. CONSTITUTION:Outputs of a sub-scanning counter 4 and a main scanning counter 5 is supplied to the table memory (ROM)9 of an half tone reading controlling section 3 of a facsimile device, and dither map information from the ROM9 is applied to a slice signal generating circuit 10. A slice signal analog converted in Log(n) ratio upward and downward making middle point of LSB and MSB of the ROM9 a standard is outputted. This slice signal is amplified by an amplifier 11 and added to the input of one side of a comparator 8, and compared with a picture signal read by an image pickup device inputted to the another side of the comparator 8. The picture signal is binary-coded by the slice signal of Log(n) ratio from the circuit 10, and a transmitted picture high in tone reproduction of primary colors is read out.
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