What is WDR? Exposure strength in CCTV system

The main problem that affects the quality of video surveillance is uneven light. As a result, some parts of the frame may be overexposed or, on the contrary, remain darkened. But image distortion is an unacceptable error when controlling objects. In this article, you will learn what WDR in a CCTV camera is.

WDR and CCTV exposure. What are they?

WDR is used in almost every surveillance camera. This is because the conventional matrix does not cope with its task under the conditions of uneven light.

The function uses a unique matrix with double scanning. As a result, the two pictures are folded so that you can see the details of the dark and light areas on the screen.

You should remember that you will need an appropriate processor capable of processing the image for such a strengthened matrix.

Algorithm of work

If you look deeper, the function works according to the following algorithm:

  • the first image is recorded with a minimum shutter speed, due to which the flare does not occur;
  • the following shots are taken at the maximum exposure. At this time, the sensor captures the darkest parts of the image;
  • in the end, the resulting images are combined, thereby improving the quality and detail of the entire frame.

Thanks to the technology, the video surveillance exposure creates images where you can easily see people’s faces, license plates, etc.

Difference between WDR and BLC

At first glance, it may seem that these two technologies are similar. But if you dig deeper, then:

  • WDR delivers a wide dynamic range with an enhanced matrix. This allows you to distinguish between objects in different shooting conditions;
  • BLC automatically adjusts the electronic shutter; that is why excess lighting is not compensated for the entire frame but in the only part required.

Setting and measuring the WDR level

The strength of the exposure of the frame has a significant impact on the quality of the shot. It is not enough to install the cameras; you need to position them correctly, taking into account the peculiarities of the local geometry of the premises or street.

Devices with WDR are configured based on the strength of the light contrast. Some models already automatically include several levels: low, medium, and high.

WDR is measured in decibels and is expressed by the ratio between the most exposed part of the image and the darkest part.

Alternative solution

If you need an analysis of what is happening in addition to the usual shooting, then connect cameras with a reinforced matrix and WDR to the Faceter service.

Built-in video analytics will help you:

More information about the video surveillance functionality can be found here.


WDR technology is used in almost all cameras since the problem of flare, or insufficient lighting is relevant. The function helps to balance the lighting level, producing a high-contrast image without glare or dark parts.

But WDR is not the only option for upgrading video surveillance. Cameras can be connected to the intelligent service Faceter and get a “smart” assistant in business and at home.

Александр Вебер

Alexander Weber

Specialist in video surveillance, video analytics, cloud storage systems. Consultant on the integration of video surveillance systems and tools in various business sectors. Over 10 years of industry experience.

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