Highlights eliminator for low light level TV - compares grey level before and after highlight using delayed video signal

摘要

A circuit for use with low light level television systems is used for preventing disturbance from highlights and amplifier valve-induced scintillations, which detects parts of the picture with amplitudes greater than that appropriate to the relevant information to be transmitted and reduces them to a preset value giving proper contrast; a video signal with a specific delay is fed to a scanning circuit with adjustable grey level setting to derive a reference level for the immediately previous level, and the undelayed signal is fed to a comparator with adjustable threshold to scan the level after the particular signal.