Automatic sensitivity control in television systems

This paper discusses a way to resolve the contradiction between a tendency to maximize the optical-signal intensity range of objects and the limited dynamic range of photodetectors. Methods of controlling the sensitivity of television systems are analyzed, taking into account how they affect the spatial, temporal, noise, and other image-quality criteria. Diagrams from automatic-control theory are adapted to sensitivity-control systems, and a flowchart is proposed for an automatic sensitivity-control system that uses five methods with a specified sequence of priorities. A method is proposed that makes it possible to expand the working illuminance range in Pregius-series photodetectors (Sony) to 200 dB-i.e., by more than 40 dB-by controlling the accumulation time and the analog and digital amplification in combination. (c) 2019 Optical Society of America