Method of, and apparatus for, modifying luminance levels of a black and white video signal

摘要

A method of modifying luminance levels of a black and white video signal is provided. The signal is fed to a voltage controlled amplifier and to first and second clipper amplifiers. Each clipper amplifier has an adjustable gain and an adjustable clip level, which are set to desired levels. The outputs of the clipper amplifiers are fed to a summation amplifier in which they are summed to produce a control signal. The control signal is fed to the voltage controlled amplifier, to vary its gain, and thus to compress one band of luminance levels whilst expanding another band of luminance levels.