Video processor gamma control1/10/2023 ![]() A feedback loop 20 is coupled from the output of amplifier 12 to a gain-control input 22 of amplifier 10 for maintaining the gain for the combination of amplifiers 10 and 12 and nonlinear stage 14 substantially constant. A video signal 16 is supplied from, e.g., an image pickup tube of a television camera and associated signal processing circuitry (not shown) to the input of amplifier 10 via a signal combining circuit 18 and a gamma corrected video signal 19 is supplied at the output of amplifier 12. 1 comprises first and second serially coupled gain-controlled amplifiers 10 and 12, respectively, and a non-linear signal translating stage 14 coupled between the output of amplifier 10 and the input of amplifier 12. Accordingly, it is desirable to adjust the gamma of the video signal prior to transmission in such a manner that the signal received and reproduced in a television receiver has an undistorted contrast range. A measure of the nonlinearity is the exponent of the power law function which describes the nonlinear transfer characteristic. For example, if a video signal varying linearly in amplitude is applied to a conventional picture tube in a television receiver, it is likely to result in a picture having a contrast range which is undesirably distorted in accordance with the nonlinear electrical-to-optical conversion characteristic (gamma) of the picture tube.
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