What is wide dynamic range (WDR)? Why must backlight scenes be turned on?

Problem Scenario

When the camera is facing a glass curtain wall, gate or garage entrance, the background is extremely bright and the foreground characters are dark. Ordinary cameras can only choose one of the two: Either the background is normal and the characters are black; or the characters are clear and the background is white. This is a typical strong backlight.

The principle of wide dynamic range

Wide Dynamic Range makes two exposures of different lengths for the same scene (one short exposure retains the details of the highlights, A long exposure preserves details in the dark), which is then synthesized by the image processor to present both the bright and dark parts at the same time. The synthesized dynamic range is expressed in dB:

• Digital wide dynamic range (DWDR): Algorithm simulation, about 60~80dB, limited effect.
• Real wide dynamic range (WDR): Hardware double exposure, about 100~120dB, the effect is obvious.
• Super wide dynamic range: Some high-end models can reach more than 140dB.

Typical scenarios that must be enabled

Debugging points

• Wide dynamic range will slightly reduce the frame rate and clarity of dynamic images. Non-backlit scenes can be turned off for better image quality.
• After turning it on, readjust the metering area so that the key target (face/license plate) is located in the metering center.
• When using with fill light, be careful to avoid new overexposure caused by fill light.
• Do not enable backlight compensation (BLC) and backlight compensation at the same time. The algorithm goals of the two are different, and enabling them at the same time may be counterproductive.