Light sources and closed-circuit television

Closed-circuit television is often used for security purposes or for traffic control. The ultimate quality of the screen image depends on a number of factors; the camera (optics, camera sensor and video processor) and the lighting quality of the scene being the most obvious. The monitor is not considered in this paper, because its performance is standardised. Though entirely logical, it is less well known that the spectral distribution of the light source also has a significant influence on the quality of monochrome pictures. This has sometimes resulted in unexpectedly poor picture quality. In this paper the influence of the spectral distribution is discussed in relation to the other elements in the CCTV chain and guidance is given for the practical design of lighting systems for CCTV.