What is HDR?
HDR (High Dynamic Range) is an image which has a wide range between bright and dark areas (dynamic range).It is technology that faithfully reproduces the reality, like the sparkles or details in the darkness that could not be expressed in the conventional SDR (Standard Dynamic Range), and the rich natural colours.The international standard of HDR is regulated by ITU-R (International Telecommunication Union Radio Communication Division) BT.2100,and has evolved in many respects from the conventional full HD standard ITU-R BT709.
HDR technology can reduce crushed shadows and blown out highlights, expanding the images expressiveness.
Q: Why in HDR do you see the parts you could not see in SDR?
A: In HDR, the four elements that create the beauty of the image are dramatically improved!
Four Elements to create High Image Quality
There are four major factors that influence the image quality.
The HDR standard HDR 10 faithfully reproduces the reality by achieving High Resolution, High Brightness, Wide Colour Gamut and High Gradation compared to conventional SDR, combined with a wide dynamic range.
① The Resolution is different! (Fine-grained image)
Resolution is expressed by the number of pixels. As the pixel count increases, the number of pixels that can be drawn on the same area increases,improving the details of the image that can be expressed.Current Hi-Vision 2K is 1920×1080, 4K is 3840×2160, 8K is 7680×4320.As the number of pixels increase, the image detail increases.
② The Brightness is different! (Brightness of image)
Brightness refers to the range of brightness that can be expressed. Generally, the range of brightness (dynamic range) that the human eye can perceive is said to be 1012, but in conventional SDR it could only display up to the range of 103. However, by spreading the dynamic range with HDR, it has become possible to capture the brightness of 105, that is 100 times more than the conventional SDR. You can also display the details of the sparkles and dark shadows at the same time.
③ The Colour Gamut is different! (Colour range that can be expressed)
The colour gamut indicates the range of colors that can be expressed. The colour gamut of BT.2020, which is a standard adopted for UHD Blu-ray Disc or 4K/8K broadcasting,covers wider colour range than BT.709 used in conventional full high vision broadcasting. It is possible to express colors richly, such as the natural gradation of the sky and the sea, contrast of the deep red roses and the fresh green trees, which were difficult to reproduce in the past.
④ Bit depth (gradation) is different! (Fine reproduction of Colour, Gradation)
Bit depth represents the number of colors a pixel can display. The higher the bit depth, the more colors can be displayed, and the gradation becomes smoother. You can enjoy vivid colours and fine natural gradations.With 8bit display approximately 16,77 million colours can be reproduced, approx. 1,07 billion colours with 10bit, and in the case of 12bit display, approx. 68,7 billion colours can be reproduced.
Summary of HDR
In HDR, the four elements of high image quality are dramatically improved over conventional SDR,so it is possible to reproduce a wide range of information like the image below.
