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Glossary: Backlight Compensation

Backlight Compensation is a term which describes the mechanism by which an IP camera can compensate for backlight by enhancing automatic exposure control on the camera.

Take, for instance, this scene. A person walks into a dimly lit room with a flashlight or torch and shines this light directly into the camera. Normally, because to the camera this light source is bright (high illumination), the camera would reduce its exposure in order to compensate – the scene has become significantly brighter. This has the effect of reducing the brightness of the overall scene potentially making the portions of the picture you’re interested in too dark.

Two images of a man in front of a window - one with no details the other a figure can be seen

Backlight compensation tries to ignore small areas of high illumination so ensuring that the larger portion of the scene remain bright. The areas of interest would have the same exposure regardless of the torch beam shining into the camera. Without backlight compensation the image surrounding the flashlight (i.e. the intruder) would be too dark to be of any use and identification of the intruder would not be possible. (In the above example images the sunlight behind the subject substitutes for the flashlight in our example).

Many IP cameras compensate automatically in this way. Some provide manual control or even no backlight compensation at all.

Published on July 2nd, 2008 by Kevin Bowyer

2 Responses to “Glossary: Backlight Compensation”

  1. James Drinkwater says:

    IR (Infrared light) is a source of illumination used in low-light conditions. Infrared light is not visible to the naked eye but can be captured by cameras without an infrared-cut filter.

    Backlight compensation doesn't use any additional light. It uses the light already present.

  2. mohamed ahmed attia says:

    diffrence between blc&ir