| 摘要 |
PURPOSE:To achieve a binary processing faithful to an original, by limiting the width of a picture signal obtained in matching with the width of an original and determining a threshold value level for quantization through normalization of a picture signal level. CONSTITUTION:A picture signal of a scanning means 1 is amplified 2, and a signal is clamped to zero via an FET 4. Further, it is amplified 5 and applied to a comparator 12 and given to a transistor (TR)9. On the other hand, an original scanning width detection circuit 17 receives a signal corresponding to the start point of an original, stops the generation of a DC voltage, and generates a DC voltage again when a prescribed number corresponding to the width of an original is counted by counting the pulses of a timing pulse generating circuit 18. Thus, TRs 19 and 20 are conductive at a period other than the period corresponding to the width of the original, and an amplifier 5 is in AGC operation only for the period corresponding to the width of the original and a reference voltage in following to the average level of an output of the amplifier is given to a comparator 12. Thus, a signal VIDEO to be quantized is obtained. |
