A common question I run into when designing CCTV systems is “how do we compensate for the all the bright light?” This is generally referring to the sunlight coming through the front door or window area, causing incoming foot traffic to look more like shadows or silhouettes than actual people. This, in turn, is due to the wash out created by sunlight pouring into an area that is not as well lit as the outdoors.
The best solution for this problem is what is known as Wide Dynamic Range or WDR. The WDR function of a camera is a technology that compensates for high contrast of light and shadow situations. This makes it possible to monitor surveillance in interior or exterior settings with dim lighting and high shadows.
Common applications where a Wide Dynamic Range Camera is best utilized include:
- Entrances where sunlight is a factor
- Parking garages
- License plate capture scenarios (balances out headlights)
- Low florescent lighting (cameras are positioned near lights due to low clearance or mounting restraints)
While the WDR feature does cost a little more, it is well worth the extra money in terms of picture quality. Details in the image are maintained as light extremes are balanced, providing a far more accurate and life-like picture.
Back Light Compensation (BLC)
In case it comes up and one is considering a camera with Back Light Compensation (BLC) – remember to keep in mind, it will not be as effective as one with Wide Dynamic Range. It can help balance lighting conditions in order to make out what is in the foreground of the picture. However, the background could remain a bit washed out, which could result in the loss of pertinent information.
Disclaimer: The “W” in WDR has nothing to do with the viewing angle of the camera. I frequently hear: “I want one of your wide-angle cameras – you know – the ones that say WDR”. Albeit some cameras that support WDR may also have a wide-angle viewing lens, the terms are not synonymous.