High Dynamic Range (HDR) is a technology that most photographers are familiar with, but it's comparatively new in the TV world. Without it, viewers of video can lose details in areas that are particularly dark or washed out in very bright parts of an image.
What HDR does is allow those details to be captured and viewed on compatible screens, in a manner that is much more representative of what our eyes process in real life. It also results in a broader color palette, so it's not just that the image is brighter or that you are seeing details that were obscured. The images themselves are more vibrant and there is more contrast in the picture.
I'm told the introduction of HDR has had a far more positive impact on consumers' impression of the TV experience than the additional resolution provided by 4K/UltraHD screens. As such, the introduction of HDR could help substantially accelerate the adoption of UHD TVs.
HDR has been included in the UHD Blu-ray specification and is being added into a number of other components of the value chain. But there is a need for further standardization because compatibility is required across device manufacturers, producers and distributors of video content.
International Telecommunication Union (ITU) announced that it is building on its superior color fidelity for UHD TV Recommendation (BT.2020) by adding the ITU-R HDR-TV Recommendation BT.2100. This will enable programmers to leverage HDR display technology, "giving TV producers the ability to reveal texture and subtle colors that are usually lost with existing Standard Dynamic Range TV," the ITU said.
The ITU has offered two HDR options for producers: The Perceptual Quantization (PQ) specification, which delivers "a very wide range of brightness levels using a transfer function that is finely tuned to match the human visual system;" and the Hybrid Log-Gamma (HLG) specification, "allowing a degree of compatibility with legacy displays by more closely matching the previously established television transfer curves." The Recommendation also describes a simple conversion process between the two.
The ITU is the United Nations agency responsible for information and communication technologies. It works with 193 UN member states, and includes 700 private sector entities and academic institutions.
— Aditya Kishore, Practice Leader, Video Transformation, Telco Transformation