The full name of HDR is high-dynamic Range, or High Dynamic Range image technology.The technology, which was first used in photography, turns on HDR during the shooting process, making previously dark scenes brighter and more transparent.Now, HDR technology has been applied in home appliances, intelligent terminals and other aspects.Thanks to nova technology, LED display began to truly experience the advantages brought by HDR technology.
What does HDR do
Take television for example.The brightness range of traditional TV is very limited, far from that of human eyes.The reason is that the traditional television in bright areas of the brightness of the picture does not go up, dark dark.This leads to a poor sense of layering and a lot of detail loss.
HDR is a perfect solution to this problem.Compared with the current mainstream SDR 1080P display technology in the market, HDR has higher pixel load: 3840×2160;Wider gamut: BT2020.The same picture can display more color information, more details of the image texture.At the same time, coupled with more advanced electro-optical conversion technology, the overall improvement of the picture contrast, so that a picture of the full range of the most real look.
HDR color depth
The ultra-high-definition blue light standard specifies a depth of 10 bits, or 1.07 billion colors.
Each color in RGB has a power of two to the tenth, or 1024 levels.RGB three colors are more than 1.07 billion (1024×1024×1024) color collocation.
While the ordinary blue light standard SDR supports 8bit color depth, only 16.77 million colors, which is a huge gap.In other words, with 10bit output, the color is richer and fuller, and the color transition is smoother than with 8bit.
HDR color gamut
Another concept corresponding to color depth is called color gamut.The former represents the number of colors that can be displayed, and the latter the range of colors that can be displayed.
Color range comparison of eyes, HDR and SDR
Currently, the color gamepad covered by civilian LCD/OLED screens is bt.709, which is approximately equal to the 95%NTSC gamepad (72%NTSC=100%sRGB) advertised by mobile phone manufacturers.In recent years, many mobile phones and laptops have started to use daci-p3 gamut, and the gamut standard of HDR is BT.2020.
The color restoration range of bt.709 and bt.2020 is shown in the figure below.The bt.2020 gamut of HDR standard is far more than the existing SDR gamut and can display a richer color range, which plays a key role in enhancing the color level and transition of the whole image.
In the HDR standards that have been published, the corresponding provisions on color depth and color space have been made.The overall improvement of these parameters leads to "better pixel" display
What are the industry standards of HDR
HDR 10
HDR10 is currently the most common HDR standard, and is the mandatory format for ultra-hd blu-ray.The HDR standard supported by most HDR display devices refers to HDR10, which is also supported by nova technologies.
Announced by the consumer technology association of America on August 27, 2015, HDR10 has so far received support and recognition from dell, LG, samsung, sharp, SONY, Vizio and other monitoring and TV manufacturers.SONY's PS4 and X Box One consoles already support the HDR10 standard.
The HDR10 standard sets a series of conditions for image restoration, including the aforementioned 10Bit color depth and bt.2020 color space.In addition, the display must have a brightness of at least 1,000 nits, which is required to claim to be an HDR10.
HLG is the HDR standard for digital broadcasting, or Hybrid log-gamma, developed by the BBC and NHK, a Japanese broadcaster, and launched in May 2015.
When the BBC and NHK developed HLG, they took into account broadcasting's biggest problem, "bandwidth".HLG does not have metadata. It incorporates HDR signals into TV broadcast signals, compatible with current broadcast devices, and does not require licensing fees.Therefore, it is suitable for digital broadcast of cable/satellite TV, or even live broadcast, allowing people to enjoy HDR effects while watching programs at home.
This is a standard for ultra-high-definition blu-ray televisions developed by dolby LABS.Unlike the open source HDR10, only Dolby lab-certified devices can claim to support the Dolby Vision standard.The certification process requires payment to dolby, which is also calculated indirectly into the cost of the equipment.So devices that support the Dolby Vison standard tend to be expensive.
Dolby Vision's standard color depth is further enhanced to 12 bits, and the display needs to be at least 4, 000 niitts bright.
What are the requirements of HDR display screen
Peak brightness of display screen ≥1000 nits
Minimum brightness of display screen ≤0.05 nits
Cover more than 90% of DCI-P3 gamut space
The effect that high brightness brings is not only "dazzling", still can bring richer color.
To understand the display effect, we need to three-dimensional all the quantitative concepts.There is also a chemical reaction between brightness and colour.For example, in the real world, the center of fireworks and firelight is colored, but if the scene is reproduced with a display device with a low brightness range, the color in the center of fireworks and firelight may not be expressed, and will only be a pale scene.This is because each level of brightness contains a different color.
High brightness is only one quadrant of the dynamic range of brightness, while the other is extremely low brightness, which can show a deeper black color.This very high and very low brightness between a good level of control, this is the basic conditions for the implementation of HDR technology.With this limit of brightness and level control, you can express the color in the limit of brightness more accurately.The larger the range of brightness, the more level of brightness, the same color, gray information will be more rich.
LED has the advantage of high brightness range that LCD can't match.In the color gamut range, LED is also wider than LCD.In the past, the biggest bottleneck restricting the application of HDR technology in LED industry is that there is no processing system capable of dealing with the dynamic range of HDR. Now nova, as the leader of LED display industry, takes the lead in developing the control system for dealing with HDR source, perfectly solving the application problem of HDR in LED field.
The future of HDR technology
HDR is not an isolated technology. It specifies the processing requirements of image signal for chip source, hardware decoding and screen display.Therefore, the realization of HDR technology requires the linkage of chip source, hardware decoding equipment and display equipment to form a processing system and achieve the final display quality together!