VIDEO SYSTEM WITH FEEDBACK CONTROLLED WHITE STRETCH PROCESSING AND BRIGHTNESS COMPENSATION

摘要

A non-linear (e.g., "white stretch") processor and a brightness control processor are coupled in cascade between an input for receiving a video input signal to be processed and an output for providing a processed video output signal. A control signal for controlling the transfer characteristics of the non-linear processor is provided by an amplifier having a first input coupled to receive an average picture level (APL) indicating signal derived from the processed video output signal and having a second input coupled to receive a reference level signal supplied thereto. A brightness control signal is applied to a control input of the brightness control processor for controlling the brightness level of the processed video output signal. Circuit means are provided for deriving at least a portion of the reference level signal for the amplifier from the brightness control signal supplied to the brightness control processor thereby reducing a tendency for variations in the brightness control signal to alter the transfer characteristics of the non-linear processor.