HDR

When we watch any video, on TV or online, one of the most important factor is the contrast ratio, like how dark or bright the video can get, and the colour accuracy, like how clearly the video screen resembles real life.

HDR, or high dynamic range escalating the range of both contrast and colour; for instance, the bright side of the image gets brighter, so the image has more depth. HDR videos are highly in demand as it is one of the biggest 4K features. HDR videos simply contain more data to describe more steps in between the extremes.

There are currently three different formats of HDR available as of now:

HDR10

HDR10 was introduced in 2015 by a US-based consumer electronic association, the Consumer Electronic Association. The HDR10 standard transmits fixed metadata to the video stream, containing encoded information about colour calibration settings necessary for achieving a lifelike image. It is the baseline of HDR technology for 4K Ultra HD Blu-ray. Most streaming platforms have opted for HDR10. The biggest drawback of the format is that it only supports static HDR.

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Dolby Vision

Dolby has created its own version of HDR in 2017, and it has escalated HDR10 by providing a more dynamic version. It is used by streaming platforms like Netflix and iTunes. This is a proprietary technology, but while companies have to pay Dolby to use it, Dolby in turn provides resources and tools to adopters so that Dolby Vision content is optimised for their devices or platforms.

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HLG

Hybrid Log Gamma was introduced by the British BBC and Japan's NHK. This format of HDR is not as dynamic as the other available formats, but what makes it special is that it is the only significant format that is backwards compatible with SDR TVs. This is only possible because, unlike other formats, this doesn’t use metadata but uses the same gamma curve as SDR. The only difference is that HLG adds an extra logarithmic curve with extra brightness on top of the signals.

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