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Lumens Class: How to Think of Tolerance and Dynamic Range

17:05, December 30, 2019 Source: China Digital Audiovisual Network Font [ Big Middle Small ]

[Digital Audiovisual Network News] Watching the sunrise at the seaside was originally a romantic thing, but such a romantic scene can hardly be recorded with a camera. This is not because the camera is not good enough, but because our eyes are so good that even the most tolerant camera cannot have the same imaging effect as the human eye, which may even have a dynamic range of up to one million.

Camera

What ... what are latitude and dynamic range? Isn't a good camera just a high-aperture large aperture? The answer is no. Today I will bring you to know latitude and dynamic range.

The concepts of latitude and dynamic range appear more in the discussion of professional photography, because the degree of camera latitude will directly affect the imaging effect. You think people take good photos because of the expensive camera, but if you don't have excellent tolerance, everything is just clouds.

How beautiful are the photos? The latitude can also decide

Before science popularization, let's enjoy two photos:


The scene of a call by the window taken in the above two photos. The second one is straight out of the original film, and the first is a post-processed photo that is output after adjusting the dark part and highlights in LightRoom.

The biggest difference between the two photos is the exposure of highlights and shadows. The highlights overflowed outside the original film window, and details of people who were not exposed to sunlight were unclear. After the post-processing, the highlights and shadows are more exposed to the real state that the human eye sees, and the look and feel of the picture has also been qualitatively improved.

With proof comparison, the meaning of tolerance is very easy to understand. Scientifically, tolerance is the ability of a camera to record the brightest and darkest details and levels. In the same environment, photos taken with the same shutter speed, ISO, and aperture have rich details in highlights and shadows, and a higher tolerance.

Corresponding to latitude is also the concept of "dynamic range" and "light ratio". Dynamic range represents the lightest to darkest range of a photo. The larger the dynamic range, the higher the latitude, which is proportional to each other. Light ratio is used to describe the contrast between light and dark of the shooting scene.

Next, I will show you about wide dynamics

Wide dynamic, short for WDR in English, stands for Wide Dynamic Range, which means wide dynamic range. To put it simply, even the parts that are not bright in the scene and the particularly dark instability can be seen clearly at the same time. The wide dynamic range is the ratio of the brightest luminance signal value that the image can distinguish to the darkest bright signal value that it can resolve.

WDR is not a shooting technique in the strict sense, and it is implemented by a hardware DSP algorithm. Of course, it also needs the support of high-speed photosensitive elements. The principle is actually very simple, for example: for a scene, your shutter is set to 1/16 second, WDR will record 3 images at 1/256 second, 1/64 second, 1/16 second, and then use To compose a frame, the bright part is retained with the details of the bright parts, and the dark part is retained with the details of the dark parts.

WDR before and after comparison


The picture above is a normal photo. We can see that the sky is a bit white, and the buildings in the close range are not rich because they are dark.


Photos after WDR. Because of the WDR, the sky is rich in color, the foreground is brightened, and the color is much richer.

So what is the implementation process of WDR? Let's look at the picture to understand


In the bright area, take a picture of "Shutter 1/16". For the normal area, get a "Shutter 1/64". In the dark area, take a picture of "Shutter 1/256". The end result is a photo with rich details in every aspect, so the contrast is naturally reduced.

final effect


Because WDR is powerful, all major brands of cameras have this feature. The difference is that because of the different processing methods of different brands, there are DSP hardware processing and software software. The software processing method is called HDR (High-Dynamic Range in English). In terms of WDR, both dynamic and static are applicable, while HDR is mainly static

How high is the tolerance?

There is no standard answer as to how much tolerance a digital camera has. After all, with the development of CMOS technology, high-quality CMOS will definitely have higher and higher tolerances. Camera manufacturers, smartphones, and camera manufacturers It will also use the power of algorithms to make the photos taken by the camera have a higher dynamic range.

To understand the benefits of high latitude, let's take a look at the following aerial photos:


This panoramic photo was taken by a drone at sunset. After processing the WDR highlights and shadows and stitching the 4 photos together, it looks very good, but the original image looks like this:


It is precisely because of its good tolerance that after WDR processing, the details of the building and the tree's backlighting surface under the screen are restored. At the same time, the exposure of the highlight overflow area around the sun is controlled within a reasonable range. . Of course, the shooting effect of backlit scenes has a lot to do with the quality of the lens, so a professional-grade camera with a better lens can easily take a high-quality picture in such a scene.

In summary, in the digital age, latitude limits the limit of the dynamic range of a picture that can be output by a single picture taken by a camera, and it also affects the difficulty of controlling picture exposure. I believe that if you have high requirements for the quality of your photos, the higher the camera's tolerance, the better.

About Lumens

Lumens, founded in 1998, is headquartered in Hsinchu, Taiwan, known as the "Taiwan Silicon Valley". It is an important member of the global EMS leader "Heshuo Group". It has a history of intensive cultivation for more than 20 years. "Fine" features become a shining star in the group!

Lumens has strong product development, technical research and market expansion capabilities. One third of the more than 400 employees worldwide are scientific and technical personnel. Its R & D capabilities cover optics, hardware, and product planning. Independently developed products such as high-definition physical exhibition stands, rear projection DLP movements, high-definition conference cameras, and smart recorder-players have been successfully marketed in more than 40 countries worldwide, and each product line ranks among the top 3 in the world. The forthcoming video signal multimedia terminal processing center will build a complete Lumens video product ecosystem, and is committed to transforming product solutions into product solutions, with a view to creating a better future with upstream and downstream partners in the rapidly changing technology field and market development. future!

Lumens has branches or service centers all over the world, including the United States, China, Asia, and Europe. Each branch and service center radiates around the world with the Taiwan headquarters as the core. Lumens' strategic global layout is committed to providing customers with integrated service solutions from high-quality products to extremely friendly interfaces, which completely and effectively meet the different needs of customers in different regions.

(Edit: bingjiling)

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