The TV industry never stands still, with new technologies every year to improve TVs and convince you that now's the time to upgrade.

Over the past few years we've seen the move from CRT to thin TVs, we've seen the rise and fall of plasma, we've witnessed the ascent of HD, Full HD and Ultra HD, we've seen dalliance with 3D and the debate around curved or flat. Joining this race is HDR, the latest technology that's among the acronym-laden features on new TVs.

HDR hit the big time last year, throwing up more HDR formats, more HDR devices and more HDR choices. And there's no let-up of action in HDR in 2018 with some stunning new TVs from Samsung. Sony, Panasonic, Phlips and more.

What is HDR?

HDR stands for high dynamic range. The abbreviation will be familiar because it's a term also used in photography, with HDR on some cameras and many smartphones: it's a feature on the iPhone, for example.

It's the same thing, because on televisions, just as in photography, the aim is to recreate an image that's closer to that seen by the human eye, or to better recreate the vision of the original storyteller. That often means balancing out light and dark areas or the range of colours, and not losing, for example, shadow detail because of a bright sky.

When it comes to TVs, this is handled in a couple of areas. The first is contrast, dealing specifically with the relationship between light and dark, and colour, with HDR offering a wider range of colours, particularly in challenging situations like sunsets.

The results delivered by HDR should mean more sumptuous colours, bringing more realism and depth, and added "pop". HDR aims to be a visual treat, which it very much is. HDR preserves the gradation from dark to light in ways that SDR (standard dynamic range) cannot. That results in fidelity in the darkness, as well as that very bright point of light, with both being rendered with lots of detail and colour.

The "original storyteller" aspect is also important, as HDR is very much being pitched as bringing the director's vision to your TV, much like Hi-Res music claims to be bringing the artist to your ears. In the case of HDR, this could extend beyond the realistic into more radically styled visuals. In previous standards, including those used on Blu-ray, it just wasn't possible to achieve the same results.

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What are the HDR tech specs?

HDR uses new panel technology deliver this wider colour range and contrast, and it's very much about brightness and illumination. To view HDR content, you need to have a TV that's compatible with HDR, it's as simple as that.

HDR-capable sets are suped-up televisions. Many HDR sets have a backlight system that can output about 1,000 nits peak brightness or greater, whereas standard HDTVs typically only output 100 nits, which is the level that Blu-ray and standard TV content is specified to.

Nits refers to the brightness, although this isn't used uniformly when watching HDR content - this only refers to brightness in particular places, those highlights in a scene. Using an increased brightness range and a wider colour gamut, HDR can recreate visuals that weren't previously possible.

However this isn't about absolute brightness, it's about the range, so although you'll see some LCD manufacturers talking about 1000 nit brightness, others, like OLED manufacturers, might be offering 800 nits. Because both offer the wide range, they both have that ability to carry the HDR badge.

When it comes to colour standards, HD TVs offer an 8-bit video specification known as Rec. 709, or BT.709. HDR steps up to 10- or 12-bit Rec. 2020, or BT.2020, which represents 60 times more colour combinations with smoother shade gradations. Those numbers don't really mean anything in themselves, they're just the standard defined by the ITU (International Telecommunications Union) but you'll often hear TV manufacturers saying that they conform to BT.2020, for example.

To help complicate things, HDR was initially introduced with Ultra HD (4K). HDR is included in the Ultra HD Blu-ray spec, and the UHD Alliance has created a certification called Ultra HD Premium, which confirms that a device (e.g.: TV or Blu-ray player) meets particular standards for Ultra HD and HDR.

In 2017 things have changed slightly, with Sony introducing a line of televisions that support HDR, but aren't 4K. They're designed to be smaller, so the resolution doesn't matter, but still offer that HDR punch - and this is the same approach that's taken with mobile HDR - which we talk about below.

Things don't stop there however. Aside from those ITU specifications for devices, there are a number of standards for HDR content that are being talked about: HDR10 and Dolby Vision are the more established technologies and HLG and and Advanced HDR by Technicolor are emerging technologies, while HDR10+ wants to turn the whole thing on its head. More recently, Vesa DisplayHDR has emerged as a standard specifically aimed at the PC monitor market.

That might all sound confusing, but as a "consumer" there are only a few things you really need to look out for.

What HDMI cable do I need for HDR?

In terms of cables, there's nothing special you need from your cable. If you're watching Ultra HD Blu-ray, then an 18Gbps or High Speed HDMI cable is recommended, but unless you have really old HDMI cables, you probably have that covered already. It doesn't have to be an expensive cable either, the Amazon Basics ones work just fine.

The only really HDMI implication on HDR comes from the sockets themselves (and you either have them or don't have them, you can't upgrade the hardware on your devices. But this is a consideration when it comes to HDR passthrough on AV receivers or soundbars.

You'll need HDMI 2.0a for HDR to be part of the signal that makes it to your TV. If you have an old soundbar or receiver that offers 4K passthrough using HDMI 1.4, the HDR part won't make it to your TV. It might be that you have to use optical or ARC to get the sound back to your audio device and go straight from source to TV for anything you want HDR on.

If you have an Ultra HD Blu-ray player, you'll likely find it has two HDMI connections on the rear so you can route video to the TV and audio your sound system directly.

What is HDR10?

HDR10 is also referred to as "generic" HDR, which is a slightly derogatory term, but HDR10 really refers to the baseline specifications for HDR content.

HDR10 is a 10-bit video stream and if you have HDR-compatible devices, it will support HDR10. This is included in the specification defined by the Blu-ray Disc Association for those Ultra HD Blu-rays we've just mentioned, and it's HDR10 support that's included in the Ultra HD Premium certification we've talked about.

One of the things that HDR10 does is tell the display the content is being viewed on how bright things should be. The aim is the carry that information from the original studio monitor through to your living room.

HDR10 is also the HDR standard that the Xbox One S and PS4 Pro offers, and with an HDR firmware update for all previous PS4 models, it's likely to be HDR10 that's the standard used for gaming too, as well as being supported on an increasing number of mobile devices.

Technically, it uses static metadata, i.e., it only tells the display those values once and then that applies to the whole movie.

What is Dolby Vision?

Things can never be simple, especially not in home entertainment, so there's an alternative HDR standard and it's called Dolby Vision.

One of the things that makes Dolby Vision different is that it's designed as an end-to-end HDR process. So from capture through processing and into production, Dolby Vision is designed to preserve information that was originally captured and pass it on. It does this using metadata that's then read by the Dolby Vision decoder in the TV you're watching. The aim is to give you an HDR experience that's closer to the original by supplying more information - it's dynamic metadata.

It tells the display device how bright it should be, but rather than provide one value as HDR10 does, it can do this for every frame. The idea is that it allows creators to ensure that what you're seeing is what they intended.

Support for Dolby Vision has been announced by many studios - Universal, Sony Pictures, Warner Bros and Lionsgate for example - as well as streaming services - like Vudu, Amazon Video and Netflix - and it's also aiming to come to games and mobile applications too. You can now also buy Dolby Vision encoded Ultra HD Blu-ray discs.

It can deliver 12-bit colour depth (68 billion colours) and supports backlight systems four times more powerful than standard HDR TV sets, so Dolby Vision has been designed as future-proof, surpassing the current specifications for "generic" HDR10, even if there's nothing you can currently buy that fulfils that potential.

But a Dolby Vision decoder doesn't just support Dolby Vision HDR content, it will also handle HDR10, so if you have a Dolby Vision compatible device and you're not watching Dolby Vision HDR content, there shouldn't be a problem. However, if you don't have the Dolby Vision decoder, you can't take advantage of Dolby's system.

That also applies to other devices like Chromecast Ultra or Apple TV 4K: these devices support Dolby Vision, but your TV will have to support it too. The same applies to new Ultra HD Blu-ray players - if your TV doesn't support Dolby Vision, you'll be watching HDR10 instead.

Things have evolved through 2017 on the Dolby Vision front. Originally Dolby said that you needed to have a hardware decoder in your TV, but things have softened slightly, with Sony confirming updates to support Dolby Vision on TVs that previously didn't, allowing DV support as a software solution rather than hardware.

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What is HDR10+?

A year ago, Samsung announced a new open standard for HDR called HDR10+ and is using it on its 2018 TVs.

As the name suggests, it's very much related to HDR10 that we've talked about above, but it makes a move to combat that dynamic metadata available from Dolby Vision. The HDR10+ group has grown in support with Panasonic joining and bringing some Hollywood connections with it - the most recent being Warner Brothers.

What HDR10+ does is use dynamic metadata (basically more information) to tell the display how bright it should be. This is something that all HDR standards do, but as we've already discussed, HDR10 has static information, whereas Dolby Vision can set the brightness for each frame, making it more accurate. Now HDR10+ will be able to deliver metadata frame by frame if needed, or scene by scene as needed by the content, so the brightness remains accurate throughout.

Here's the business angle: Dolby Vision is a proprietary format that involves paying a license fee so the introduction of HDR10+ as an open standard is likely to be a move to introduce a comparable format that doesn't need that license. Often that means it's popularly adopted because it's free to use. 

Amazon Video partnered on the announcement of HDR10+ and content started appearing in December 2017 and in 2018 the message is very much that more HDR10+ content is on the way.

Finally, HDR10+ really aims to boost the performance of cheaper TVs. We've seen HDR10+ demos on mid-range HDR sets that don't have the peak brightness of flagship models and the difference between HDR10 and HDR10+ is remarkable. This is a technology to watch, it's going to be big.

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What is HLG?

HLG stands for hybrid log gamma, which is a system for HDR developed by the BBC and NHK. The aim of HLG is to recreate that HDR standard for broadcast, rather than streaming or via optical disc as is the case with HDR10 and Dolby Vision. Because broadcast is less consistent than those other delivery systems, the aim of HLG is to create an HDR system not dependent on metadata.

Ultimately, if HLG is adopted for broadcast, it could reproduce the HDR effect without needing special equipment to receive it or process it, which should allow a good deal of backwards compatibility, as well as being cost effective for TV production companies, as they won't have to upgrade all their equipment.

HLG is very much in the testing stages still, and if you want to know more, we have a dedicated feature on it.

The BBC also has tried  HLG content available via BBC iPlayer. Starting with the stream of Blue Planet II in 4K HDR it then moved onto the Royal Wedding, Wimbledon and the World Cup in 2018.

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What is Vesa DisplayHDR?

Moving along from TV watching, Vesa announced in late-2017 that it was introducing another standard for HDR. The justification was that as Vesa saw it, there was no consistent standard to certify devices in the PC industry. With many monitors touting HDR support, this is designed as a transparent approach to create a comparable standard across monitors from different manufacturers. This applies to both external monitors and built-in, i.e., laptops.

There are three levels to the Vesa DisplayHDR standard:

  • DisplayHDR 400 - entry-level, 8-bit, global dimming, 400cd/m2 brightness, colour boost over SDR
  • DisplayHDR 600 - enthusiast level, 10-bit, local dimming, 600cd/m2 brightness, colour boost over DisplayHDR 400
  • DisplayHDR 1000 - professional level, 10-bit, local dimming with 2x contrast increase over DisplayHDR 600, 1000cd/m2 brightness

A lot of manufacturers have signed up and we've already seen the first certified monitor announced about the standard: the Samsung CHG90 QLED gaming monitor has attained the DisplayHDR 600 standard.

Which TVs support HDR?

You need a HDR-compatible TV to see HDR content. Vizio, Sony, Samsung, Panasonic, PhilipsLG, TCL, Hisense, and practically every other TV manufacturer you can think of now have HDR-compatible TV sets.

Most flagship and top-tier Ultra HD (4K) televisions launched in 2016 support HDR in some form, and HDR is supported across both LCD and OLED televisions, as we've discussed.

Samsung, LG, Philips and Panasonic offer Ultra HD Premium televisions supporting HDR10. Sony is also supporting HDR10, but has opted not to use the Ultra HD Premium badge, instead using the 4K HDR brand instead, or 4K HDR Premium for its best TVs.

Dolby Vision support is getting wider. Dolby Vision is often linked to 12-bit OLED panels, so is much more likely to be supported on OLED TVs - although not all manufacturers using LG's panels also support Dolby Vision. Panasonic, for example, is backing HDR10+ rather than DV.

There are also 2015 models that support the HDR10 standard, so if you bought a flagship or high-end 4K television in 2015, you probably have some form of HDR support.

It's important to note that although Ultra HD Blu-ray includes HDR specification, straight forward Ultra HD TV doesn't: there are a lot of 4K/Ultra HD televisions that have no HDR support, either because they are older or cheaper TVs.

This isn't something that can be fixed with software either - if the panel isn't capable enough, it can't display the colours or the brightness, regardless of the resolution, until technologies like HLG become mainstream.

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What HDR content is out now?

Ultra HD Blu-ray

Ultra HD Blu-ray is obviously one of the big avenues that's going to supply UHD and HDR content. As we've mentioned, HDR is part of the Ultra HD Blu-ray specification, so movies appearing on this new format can offer HDR.

Sadly, the PS4 Pro doesn't offer an Ultra HD Blu-ray player, so there will be no support for those discs in the new console, but streaming services will be supported. The Xbox One S and One X do support Ultra HD Blu-ray.

YouTube HDR

YouTube announced support for HDR on 7 November 2016. That means Google's video service is not only a source of 4K and 360-degree video, but now also HDR. This should help give HDR a lot of exposure as there will be a free source of HDR content, but again, you need to have a display that supports it.

Netflix

Netflix has announced support for HDR content and the company has said that it's supporting both Dolby Vision and normal HDR formats. It started showing this content with Marco Polo and a wide range of content has followed in HDR. HDR Netflix is available through the Xbox One S and the PS4 Pro.

Amazon

Amazon announced in July 2015 that HDR content was available through its video service. It now offers episodes of its original series in HDR at no additional cost to paid Prime subscribers, such as Mozart in the Jungle or Bosch. You can also access Amazon in HDR on Roku Ultra and Roku Premiere+, or the Roku Streaming Stick+ devices.

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Apple iTunes

When Apple launched the Apple TV 4K it also also announced that it was upgrading a lot of movies purchased from iTunes - for no additional cost. iTunes also offers the widest variety of Dolby Vision content available to stream, meaning that rentals and digital ownership gets a real boost. It's also a lot better value for money in many instances than rival streaming services. Of course, you'll have to play this this using Apple TV 4K.

Vudu

Vudu supports Dolby Vision as we've already mentioned, so there's support for some Vudu content in HDR using Dolby Vision. However, this is only supported on some Visio models. For more information on Vudu HDR support, see the help pages.

Google Chromecast Ultra and Play Movies

Chromecast is worth a mention, because if you have a TV that supports HDR, you'll be able to use the Chromecast Ultra to watch HDR content from a number of sources, including Play Movies, YouTube or Netflix. Unlike other set-top boxes, Chromecast will rely on you controlling it from your phone, whereafter if should head off and collect the best quality content it can from the service you selected. However, if you have an HDR TV, you might already have a TV app for the service you're looking to cast.

Roku

Roku has a number of different players, but in the UK it's the Roku Streaming Stick+ that supports HDR, as long as you have access to HDR content through the services it offers.  In the US, the Roku Streaming Stick+ and Roku Ultra both support HDR, again, on the proviso that you have access to HDR content on the services supported by Roku. 

HDR Gaming

Microsoft was the first off the bat with an announcement about HDR gaming, with titles like Forza Horizon 3 delivering wonderfully vibrant gaming experiences, enriched with HDR graphics. You'll need an Xbox One S or later to take advantage of that.

With the Xbox One X, Microsoft announced an "enhanced" list of games. Inclusion on the enhanced list means that the developer has done more to boost the title specifically for Xbox One X and one of those enhancements might be HDR - look for HDR labelling alongside the game.

PlayStation on the other hand, although a little later to announce HDR gaming, seems to be making the bigger splash. Sony announced that all PS4 models would receive a firmware update to enable HDR, as well as that being a major feature of PS4 Pro. Sony has also confirmed a big line-up of HDR games.

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HDR on smartphones

One fairly untapped device for viewing HDR content is the smartphone. When Samsung launched the ill-fated Galaxy Note 7, one of the features it introduced was "Mobile HDR". The Note 7 didn't survive, but the new champion for mobile HDR was the LG G6, launched in early 2017. LG's flagship smartphone supported both HDR10 and Dolby Vision.

Following early launches, the mobile HDR dam burst and a huge number of other flagship devices now support the standard. 

We've written a lot more about Mobile HDR here: What is Mobile HDR? Dolby Vision, HDR10 and Mobile HDR Premium explained