PICTURE GENERATING UNIT OF SCANNING TYPE

摘要

A scanning device such as an IR camera generates horizontal and vertical scanning signals to direct a detector over a viewing field. The detector then emits information signals in accordance with the amplitude of a property, such as temperature, at points within the viewing field. The information signals are fed via a video channel to a display device to give a visual indication of the temperature distribution of the viewing field. In addition a selective device through the agency of the scanning signals controllably selects a portion of the viewing field for detailed study. The selective device feeds signals to the display device to visually demarcate the selected area and also selects the information signals in that area for amplitude measurement. The measure of the amplitude is converted to a form suitable to control the black level of information signals passing through the video channel.