Automatic shutter control adds further flexibility to camera by controlling the quality of light. Light sources consist of several different wavelenghts of light. Sunlight, for example, is an almost pure form of white light; each wavelength is present in roughly equal amounts.
However, in other types of light (flouresent, household light bulbs, sodium vapor streetlights, etc)., wavelengths are unequally represented. These differences can be extreme, resulting in significantly degraded image quality.
While the human eye is able to compensate for many of these differences, a color camera needs specialized circuitry. Automatic shutters compensate for changes in light quality. Thus, an outdoor camera with automatic shutter control can produce accurate images of activity in a parking lot in daylight, as well as under artificial illumination.
Shuttering is a function of the camera. Basic cameras sample, or "look" at an image at a rate of 60 times per second, a shutter speed of 1/60. Digital signal processing technology in the camera has been enhanced so that this circuit can now analyze the video signal and, if needed, change the sampling rate of the image up to 100,000 times per second. This allows darker images to be digitally sampled more, utilizies existing light, and produces better pictures.
