A brightness limitation system is employed in a television circuit to
prevent the black reference voltage level and the video signal from
entering a minimum signal clipping zone, to provide precise correction
signal, limiting the brightness, to maintain a constant black reference
voltage level, and maintain a video signal with dynamic amplitude. The
brightness limitation circuit detects a minimum signal level amongst the
black reference signals from each color channel and compares the minimum
signal with a fixed voltage level to generate a brightness feedback
signal. The brightness feedback signal is then used to modify the black
reference signal level for each color channel.