Automatic Gain Control
A feature of cameras that enhances videos of low lights to maintain the output video signal strength. This has the effect of making the picture brighter, however, it may also add more noise to the picture, as it is amplifying all aspects of the video signal. AGC is a critical, though often overlooked, factor in a low light surveillance video. It is generally only noticed when the negative side effects of aggressive gain levels are seen, namely noise/snow on the screen.