| 摘要 |
PURPOSE:To prevent a shade-off of a picture and an unnatural change of a color and to reproduce a clear picture by changing sequentially a threshold level to make binary following a change in the picture signal output, and further, installing a limited value at the threshold level. CONSTITUTION:A picture signal from a terminal 6 is inputted through an amplifier 7 and a sample holding circuit 5 to an A/D converter 8. At an adder and divider circuit 13, the signal from a white output peak and black output peak detecting circuits 11 and 12 is calculated, and the obtained value is outputted to the limiter circuit 14. The value is the one to show a threshold level, and at the circuit 14 the limited value is installed for the threshold level and the controlling is executed so that the level may be within the limited value. The signal to show the threshold level from the circuit 14 is inputted to a comparing circuit 15, and compared with the picture signal from a converter 8. Consequently, the picture signal is made binary to the white output and the black output by the threshold level, and removed from the output terminal 16 as a binary output waveform.
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