Specifications

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Camera elements
There are a number of camera elements that have an impact on image quality and
eld of view and are, therefore, important to understand when choosing a network
camera. The elements include the light sensitivity of a camera, the type of lens, type of
image sensor and scanning technique, as well as image processing functionalities, all
of which are discussed in this chapter. Some guidelines on installation considerations
are also provided at the end.
3.1 Light sensitivity
A network camera’s light sensitivity is often specied in terms of lux, which corresponds to a
level of illuminance in which a camera produces an acceptable image. The lower the lux speci-
cation, the better light sensitivity the camera has. Normally, at least 200 lux is needed to
illuminate an object so that a good quality image can be obtained. In general, the more light on
the subject, the better the image. With too little light, focusing will be dicult and the image
will be noisy and/or dark. To capture good quality images in low light or dark conditions, a day
and night camera that takes advantage of near-infrared light is required. For more on day and
night cameras, see Chapter 2.
Dierent light conditions oer dierent illuminance. Many natural scenes have fairly complex
illumination, with both shadows and highlights that give dierent lux readings in dierent parts
of a scene. It is important, therefore, to keep in mind that one lux reading does not indicate the
light condition for a scene as a whole.
Table 3.1a Examples of dierent levels of illuminance.
CAMERA ELEMENTS - CHAPTER 3
Illuminance Lighting condition
100,000 lux Strong sunlight
10,000 lux Full daylight
500 lux Oce light
100 lux Poorly lit room