| 摘要 |
PURPOSE:To facilitate an easy control, by securing an automatic control of the white compression characteristics by means of a small-sized computer. CONSTITUTION:A differential signal is detected through the error detecting circuit 2 between the video signal 1 to be controlled and the reference level A for start point of white compression that is produced by a small-size computer 5 and converted into an analog signal through a D/A converter 6. The detection output receives a sample holding at two areas by the sample holding circuit 3 and with sampling pulses P1 and P2 supplied from the computer 5 and then converted into a digital signal by the A/D converter 4 to be supplied to the computer 5. The computer 5 calculates such control signal with which a coincidence is obtained between the differential signals sampled at the two areas. Then the control signal 10 is supplied to the white compression control circuit via the D/A converter 8. Based on this, the video signal 1 is controlled at the white compression control circuit. |
