The acronym WDR stands for "Wide Dynamic Range"; a WDR is a feature in security cameras which is used for capturing images of objects surrounded by a strong back light while still keeping the background visible. WDR enables capturing and displaying both bright and dark areas in the same frame, in a way that details can appear in both areas (incorporates techniques for handling a wide range of lighting conditions in a scene).
WDR cameras are usually used in surveillance systemswhich allow cameras to filter the intense backlight surrounding subjects and thus enhance the ability to distinguish features and shapes on the subject. When shooting a scene that includes great differences in brightness with a conventional digital camera, detail is lost in bright areas because of saturation and is lost in dark areas due to low light. Dynamic range of a digital camera sensor is typically 7~8EV, where EV (Exposure Value) is a unit of exposure. This technology uses a high-speed image sensor to capture images so quickly that the ultra-short time difference virtually eliminates displacement. Wide Dynamic Range gives the camera the ability to capture shadow and highlight detail at the same time without artifacts. It is measured by "deep black" and crisp white while retaining image detail. It is also measured by subtlety of gradations. Pixim-powered cameras are the only cameras with >100dB.
As mentioned, WDR cameras are used in surveillance due to their abilities to capture more details.Thus, the wider the dynamic range, the better a digital imaging system will be able to accurately capture the varying light intensities of a scene. By varying the combination of barrier voltage and integration time, as well as applying different techniques to widen the dynamic range, developers can exercise more accurate control of image quality across a broad range of imaging applications.
The mechanism of WDR camera is that the camera fits two CCDs, the first one is high speed CCD and the other is low speed. The two CCDs scan the same image twice, instead of doing a one-time scan like typical cameras. The first CCD scans the images in normal light condition. After that, the camera scans in the second time basing on high speed to get the image with strong light background. The image processor then combines the two images, in order to provide a balanced image, which shows the indoors and outdoors clearly. On the other hand, a WDR camera takes two- scene images for every video frame. The first image is taken to optimize the camera's ability monitor the dimly- lit areas, and the second image is adjusted to accommodate the bright light. These two images are then combined together in the camera's DSP on the fly, so they can produce an image that is recorded clearly.
As you can see, there are a lot of advantages for WDR camera, the thing that distinguishes it from other surveillance cameras. It's a new technology but it has recently expanded in a tremendous way because of its ability of observing every detail in various environmental conditions i.e.light conditions, which is considered an important feature to a lot of users.
