Now many TVs in the market claim to be “HDR” TVs, but many consumers say that the TVS they buy can not display HDR content. In fact, HDR technology is composed of many different standards. If the TV does not support the corresponding standards, it will either display the wrong color, or it will not play normally. So what are the HDR standards, and how to judge which HDR standards TV supports?
Before we understand this problem, we’d better make it clear what is the difference between HDR and ordinary display technology, and why there are different HDR standards.
HDR is called “high dynamic range”. Compared with the content of standard brightness range (SDR), HDR has more details in the dark and light parts, and will not appear the phenomenon of “dead black” or “dead white”. In addition, when measuring the color performance of HDR content, brightness coordinates are introduced into the traditional two-dimensional gamut index to form a three-dimensional “color space”. The brightness and color information in video content is called “metadata”.
Different display devices not only have different color gamut, but also have different maximum brightness. When playing HDR content, we need to change the color volume according to different devices. One of the core functions of different HDR technologies is to standardize the conversion process.
You should have understood that HDR TV needs not only chip and software support, but also display screen itself. At present, many middle and low-end TVs in the market also use the HDR concept, but only the chip supports HDR decoding, that is, the conversion from 3D to 2D, and the screen itself cannot display HDR content. Such a TV can not be called a real HDR TV.
After getting to the root, let’s sort out several common HDR standards.
Hdr10 is a standard published by the consumer Technology Association of America. Because it is a free standard, it is widely supported. Almost all HDR devices support this format. “HDR” definition on iqiyi, Youku and other video websites also refers to hdr10 standard. The HDR output function of PS4 and ps5 game console is also based on hdr10.
2. Dolby horizon / Dolby horizon IQ
As the name suggests, Dolby horizon is the HDR standard launched by Dolby Laboratories in the United States. Compared with HDR 10, the most important feature is that it adopts the concept of “dynamic metadata”, that is, it can set different conversion information according to different scenes, instead of applying a formula to the whole content to make the picture more realistic.
As it is a standard launched by commercial companies, Dolby vision standard requires terminal manufacturers to pay for authorization. Therefore, not all devices support it, and the supported products usually indicate “support Dolby vision”, which should be distinguished when purchasing.
In addition to some TVs and mobile phones, Microsoft’s Xbox series game console also supports the output of Dolby view. Now more and more movies and HdTV series support Dolby vision. If you have a higher pursuit of image quality, you are still recommended to buy display devices that support Dolby vision.
During the 2020 CES, Dolby horizon’s upgrade technology “Dolby horizon IQ” is released, which can adjust the conversion algorithm through the ambient light sensor to achieve more restored details.
Hdr10 + is the HDR standard launched by Samsung and Amazon. It adopts the “dynamic metadata” format similar to Dolby vision and supports up to 10000 nits of brightness. Like hdr10, hdr10 + is a freely licensed technology standard. In 2017, Samsung, Panasonic and 20th Century Fox established the “HDR 10 + alliance” to fight against Dolby vision. At present, Samsung, TCL, Hisense, Panasonic and other manufacturers have launched HdTV, mobile phone, tablet and other products that support the standard. But up to now, the content supporting the standard is still relatively small.
HLG is a HDR standard launched by BBC and NHK. Its biggest feature is that it does not need metadata, but converts relative values according to the maximum brightness of the display device. HLG adaptive features make it more suitable for radio and television and other occasions with higher requirements for adaptive ability. The 4K channel of CCTV adopts HLG format.
Compared with the above “big brothers”, HDR video was born in March 2021, which is a real freshman. However, the significance of the birth of HDR video is extraordinary – compared with the above several foreign led standards, HDR video is a domestic original HDR standard released by China ultra high definition video industry alliance. At present, domestic chip giant Hisilicon has released chips that support HDR video, and Huawei smart screen has been able to support HDR video standard. I believe that with the promotion of Huawei and other domestic terminal enterprises, China’s HDR standardization road will become wider and wider.