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Dynamic Range quick overview
CCTV security cameras have many obstacles to overcome to provide accurate, high resolution images, the first and foremost being LIGHT. How sensors react to varying lighting conditions can be the difference between capturing the suspect or being left with just a shadow.
Wide dynamic range is essential for capturing image detail at all light levels. Today's surveillance cameras are plagued by dynamic range problems in a typical 24 hour day, due to severe reflections, glare, car headlights, and direct sunlight.
The brightness of a wide dynamic scene has very different levels. A very typical example is a camera that observes an inside scene with a window in the background. A camera equipped with Wide Dynamic Range (WDR) can display very bright as well as dark areas in one scene without missing important details.
What is Dynamic Range really?
Dynamic range is the difference between, or ratio, of the largest and smallest possible values of a measureable quantity, such as sound and light. In the case of cameras, dynamic range is the ratio of the lightest and darkest elements that are capable of being displayed on an image. In photography, photographers use different exposure ranges and luminosity ranges in order to create a more realistic photograph. Photographers will take several pictures of the same image at different exposure ranges and combine them together in order to create fantastic and visually appealing photos. This same concept is applied to CCTV Cameras and has created the technology known as Wide Dynamic Range.
How exactly does WDR (Wide Dynamic Range) affect cameras?
Wide Dynamic Range is a technology utilized by security cameras in order to balance out images that have a large dynamic range. An example of this situation would be if an indoor security camera were pointing towards a window or building entrance. During daytime, the image produced by the camera would be extremely washed out due to the high brightness of the incoming light. This effect is commonly seen in restaurants, stores, offices, and other buildings that have large windows or entrances.
In order to solve this problem, CCTVs have been using Back Light Compensation (BLC) to help compensate for high brightness situations. However, Wide Dynamic Range technology has recently become the most popular solution to washed out images. WDR cameras are fitted with two Charge-Coupled Devices (CCD), one high speed, and the other low speed which are designed to take multiple scans of the same image in order to provide a clear and balanced image.
The two CCDs take 2 scans of the same image instead of only one scan like typical cameras. The first CCD scans the images in normal light conditions while the second CCD scans the image at high speed in order to get an image with a strong light in the background. The image processor in the CCDs will then process and combine the two images to provide one clear and balanced image which shows both the indoors and outdoors clearly.
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