Science popularization: What do HDR and WDR in cameras mean respectively| Love to play computer games - 上海419贵族宝贝-上海后花园1314-上海品茶网-阿拉爱上海

With people's pursuit of mobile photography, more and more manufacturers now let cameras natively support HDR effect, but do you know the concept of HDR? What does the newly emerging WDR mean? Here is a simple science popularization.

HDR

HDR (High Dynamic Range, It will give priority to the dark details and make the picture excessively bright. The resulting photos are either overexposed or underexposed and cannot record extremely bright or dark details at the same time. For HDR processed photos, both highlights and dark parts can be displayed even when the light and dark contrast is strong, and the picture will not be too bright or the dark parts will not be black. It can make photos more layered.

The following editor uses iPhone 5 as an example:

HDR is not enabled because there is a sun in the sky, and the high light source causes the loss of sky details.

When HDR is turned on, the sky details will be supplemented.

HDR is not turned on.

Turn on HDR.

However, different mobile phones have different HDR effects, some of which play well, and some of which are ugly after being opened. This depends on the situation. The HDR effect of iPhone 5 is the best among all the mobile phones I have used.

Hardware HDR

In the past, HDR effects used in mobile phones were basically synthesized by software. The principle is that when HDR is used for shooting, the camera will take an overexposed photo, an underexposed photo and a normal exposure photo, and then combine the three photos to get an HDR photo. Therefore, when taking HDR photos with mobile phones, the imaging time is longer than that of ordinary photos, and the requirements for the hand stability of the photographer are higher. After a period of development, hardware HDR technology finally appeared. Hardware HDR does not need software synthesis, and it can even display the display effect after HDR directly on the screen. The principle is to precisely control the exposure time of each row of pixels separately, so as to achieve native high dynamic range rendering at the sensor level. Currently, OPPO Find5 and Sony are the only mobile phones on the market Xperia Z supports hardware HDR.

WDR

WDR (Wide Dynamic Range) is translated as wide dynamic range. A wide dynamic range simply means that the particularly bright and dark parts of the scene can be seen clearly at the same time. The wide dynamic range is the ratio of the brightest brightness signal value that can be resolved to the darkest brightness signal value that can be resolved.

From the perspective of use purpose, HDR and WDR are designed to balance overexposure or underexposure, so that photos can get more levels and clearer images. At present, the most common mobile phones equipped with WDR technology in the market are the Bovo F-16, Moto MT917 and Meizu MX2. But it also needs to rely on software synthesis, rather than hardware support. It can only be shown after shooting. It cannot be shown directly on the screen. In addition, it does not support using WDR when shooting.

Bovo F-16 WDR demo effect:

WDR effect is not turned on.

Turn on the WDR effect. After turning on the WDR effect, the dark parts that were originally photographed can also be displayed. However, the WDR effect of Bovo is not good, the noise increases more, and the picture is slightly distorted.

Meizu MX2 WDR proof effect:

WDR is not turned on.

When WDR effect is turned on, the details of dark places can also be displayed.

HDR and WDR are both used in shooting scenes with strong light and dark contrast and backlit portraits. Under the backlit portraits, the originally dark portraits will be clearly displayed, and the background will not be exposed too much.

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