The imaging principle of video surveillance is to convert the information contained in the light into an image signal that can be judged by the human eye. Thus, light is a “necessity” for video surveillance. If the ambient light is low or no light, the video surveillance system will become a display. In this regard, the current industry mainly uses four imaging technologies to achieve night vision monitoring.
When the illumination is low, the camera receives the near-infrared light field of 0.75-1000 m in the natural illumination environment by switching the infrared filter, and enhances the video processing algorithm to let the camera read the image information carried by the received near-infrared light domain. . A kind of photoresistor is placed on the front end of the camera. When the ambient illumination reaches the switching illuminance value set by the camera, the camera automatically switches the infrared filter; and then relies on the algorithm to process the low-illumination video. The most typical low-illumination image processing algorithm It is the automatic gain function, which automatically increases the brightness of the picture as the ambient illumination decreases.