The Scene and Light
The scene refers to the objects or area to be observed and the total environment in which they exist.

A scene often contains different colors, surfaces and materials that reflect varying levels of light. To select proper equipment, it is necessary to determine the minimum lighting level (day or night) that will arrive from the scene to the camera lens. The "available" light will affect everything from picture clarity to focus (see figure 1).

A scene or target area can be illuminated by natural or artificial light sources. Natural sources include the sun, the moon and stars. Artificial sources include incandescent, sodium, fluorescent, infrared, and other man-made lights. An axiom in CCTV security applications is: The better the light, the better the picture.

Figure 1: Cameras respond the amount of light reflected from the scene.

Color vs. Black & White
Color cameras generally require a higher level of lighting than their monochrome
(black & white) counterparts.

Color produces a more natural, richer image than black & white and may keep the operators' interest for longer periods of time. It also makes it easier to detect subjects. For example, with a color system a viewer can easily distinguish a red car from a green one, while on a black & white system both cars would appear a similar shade of gray. In retail applications, a color system can help security personnel identify shoplifters and their clothing more easily and convincingly. Color accuracy is extremely important in gambling casinos, where hundreds of dollars can ride on the ability to recognize the difference between a maroon chip and a red one.

While the use of color cameras is growing, black & white cameras continue to offer some distinct advantages. Black & white cameras are better suited for extremely low light situations.

The ability to capture good quality images in low light situations increases the cost of both black & white and color cameras. Before purchasing cameras, organizations should consider the crossover point between lighting costs and camera costs. It's possible that low-light cameras (which are expensive) will cost less than paying to increase the lighting in a parking lot.