What is HLG HDR, and do you need it in your new TV?

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If you’ve been shopping for a TV recently, you’ve probably noticed that nearly any TV over a certain size offers 4K Ultra HD resolution — that’s almost a given. But what about High Dynamic Range (HDR), the cool, new thing when it comes to TVs? It offers up darker blacks, brighter highlights, and generally richer, more vivid color. But unlike 4K, which is a standard resolution you can easily measure, there are multiple different kinds of HDR, and you don’t always get access to all of them with a given TV. The TV you get might support HDR10, but not Dolby Vision, for example.

The latest format you’re probably beginning to hear about Hybrid Log Gamma (HLG). Why do we need yet another HDR standard? As we’ll explore in this article, HLG offers a more flexible approach than other standards, and it is the HDR format of choice for broadcast media.

What is Hybrid Log Gamma?

Hybrid Log Gamma aims to solve two problems that exist with other HDR technologies. First, existing HDR solutions like Dolby Vision and HDR10 aren’t suitable for broadcast signals, for reasons we’ll explain later. Second, no other existing HDR technologies are easily backward compatible, meaning that not only are owners of older TVs out of luck, but content needs to be produced in both HDR and non-HDR varieties.

History

Hybrid Log Gamma began in 2014 as a collaboration between the BBC and Japanese broadcaster NHK, which is no stranger to pushing new broadcast technologies. Both were intent on creating a new broadcast-friendly HDR solution. Looking to avoid the same sort of troubles that we saw in the early days of HDTV, when some networks would have SD and HD versions on different channels, the two broadcasters were looking to create a more all-in-one solution.

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