Video brightness control circuit

Details Video brightness control circuit Video brightness control circuit

1981-02-02

1984-12-18

Chin, Tommy P.

Facsimile and static presentation processing

Facsimile

Specific signal processing circuitry

358 32, 358164, H04N 568

Patent

active

044893493

ABSTRACT:
A control circuit for controlling the relative brightness of a video signal includes an average picture level (APL) detector to measure the average brightness of the video signal and a brightness control circuit responsive to the detected average brightness to provide an output video signal wherein the picture areas containing most of the picture information are corrected to give greater contrast. In the output signal, portions corresponding to the black and peak white levels of the incoming video signals are provided substantially at the black and peak white levels, respectively, while the average brightness level of the output video signal is provided at an optimum level, such as 50%. The brightness control circuit can include a variable gamma correction circuit in which the value of gamma is automatically determined by a control signal provided from the APL detector.

REFERENCES:
patent: 2255691 (1941-09-01), Wilson
patent: 3619496 (1971-11-01), Lichtenstein
patent: 3752905 (1973-08-01), Schneider
patent: 3873767 (1975-03-01), Okada
patent: 3980822 (1976-09-01), Suzuki
patent: 4044375 (1977-08-01), Norman
patent: 4091419 (1978-05-01), Rhee
patent: 4298885 (1981-11-01), Okada

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