The television industry never stands still, with manufacturers introducing new technologies every year to improve their TVs and convince you that now is 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.
It looks like 2016 is the year of HDR, so we're here to bring you some clarity and demystify this new technology.
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 Blu-ray, this just wasn't possible.
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. Although HDR has been talked about for a few years, there are now a set of standards for it, aiming to ensure that you're getting some sort of parity in HDR delivery across different devices.
HDR-capable sets are suped-up 4K televisions. Many HDR sets have a backlight system that can output about 1,000 nits peak brightness, 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) and you'll often hear TV manufacturers saying that they conform to BT.2020, for example.
To help complicate things, HDR is being bundled together 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.
Things don't stop there however. Aside from those ITU specifications for devices, there are two standards for HDR content that are being talked about: HDR10 and Dolby Vision.
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.
What is Dolby Vision?
But 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. The aim is to give you an HDR experience that's closer to the original by supplying more information.
It also tells the display device how bright it should be, but rather than provide one value as HDR10 does, it does 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 some studios - Universal and Sony Pictures for example - as well as streaming services - like Vudu and Netflix - and it's also aiming to come to games and mobile applications too. Dolby Vision is now available on Amazon Video for compatible TVs in the US, with LG's OLED TVs offering support.
It delivers 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 current buy that fulfils that full 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 the new Chromecast Ultra: the Google streaming dongle supports Dolby Vision, but your TV will have to support it too.
With HDR content being fairly new, we're yet to see exactly how the HDR10 vs Dolby Vision battle will unfold. Dolby's argument is that it's a technically superior HDR offering, but how wide the support runs, how that limits your buying choices and how much of a real difference it will make compared to HDR10 really remains to be seen.
Which TVs support HDR?
Most flagship and top-tier Ultra HD (4K) televisions in 2016 support HDR in some form, and HDR is supported across both LCD and OLED televisions, as we've discussed.
LG has made a lot of noise about Dolby Vision, with all 2016 4K OLED televisions supporting Dolby Vision and those are the sets you're going to see in the UK. In the US you'll find some Visio TVs support Dolby Vision.
Samsung and Panasonic both offer Ultra HD Premium televisions supporting HDR10 in 2016. Sony is also supporting HDR10, but has opted not to use the Ultra HD Premium badge, instead using the 4K HDR brand instead. Philips also has HDR compatible TVs, but doesn't carry the Ultra HD Premium badge, so there's a lot of variation at present.
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 "normal" 4K/Ultra HD televisions that have no HDR support. 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.
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 - The Martian or Kingsmen, for example, offer HDR.
There are currently four Ultra HD Blu-ray players from Samsung, Panasonic and the Xbox One S and none support Dolby Vision. Dolby says it is working with the Blu-ray Disc Association and that Dolby Vision will work within normal formats, but we're waiting to see exactly how it will be delivered in physical media.
Sadly, the PS4 Pro won'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.
YouTube announced support for HDR on 7 November. That means Google's TV 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.
YouTube has confirmed that Samsung's 2016 SUHD and UHD televisions will soon offer support, as well as the new Chromecast Ultra. This will, naturally, mean that you can plug it into any HDR-compatible display to watch YouTube content in HDR.
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 (available in Dolby Vision on LG OLED TVs), and a wide range of content has followed in HDR, like Luge Cage and Narcos. You need a television that supports both HDR and Netflix.
HDR Netflix is available through the Xbox One S and the PS4 Pro, with an app update later in 2016.
For Dolby Vision, only LG and Visio are currently compatible, but for regular HDR streaming, LG, Sony, Samsung, Sharp and Panasonic are compatible. However, your TV will most likely need a software update to support Netflix in HDR - we've yet to see any live content appear, although we know that Sony has started support, we've seen it on Panasonic and Samsung TVs too.
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.
Again, like Netflix, you'll need a compatible television, with Amazon saying that some Samsung and LG sets are compatible. Content is labelled as HDR.
Amazon also announced in June 2016 that Dolby Vision content was available, including its original series Bosch, and available on a range of paid-for movies.
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 and YouTube.
Unlike other set-top boxes, Chromecast will rely on you controlling it from your phone, whereafter if should head off an collect the best quality content it can from the service you selected. Chromecast Ultra is yet to launch, but could be a cheap way of bringing 4K HDR content to your TV.
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 to take advantage of that, and so far there have only been two HDR titles released: Forza and Gears of War 4.
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 the new PS4 Pro. Sony has also confirmed a big line-up of HDR games.
The PS4 HDR update landed in mid-September alongside the launch of the new slim PS4 model; the PS4 Pro launched on 10 November and Sony has already lined up a range of compatible HDR titles, such as Uncharted 4.
HDR gaming is likely to be hitting the big time towards the end of 2016 and into 2017.
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". This didn't really come to fruition as the device was pulled from sale, but mobile HDR looks to be of greater interest now that YouTube supports HDR.
For a mobile device, it will still have to adhere to those rules about the range of brightness that it will support. For the Samsung Galaxy Note 7, the maximum brightness of 800 nits on its OLED panel would make this possible in theory.
Mobile HDR support was destined to come from Amazon Video, but we suspect that if Mobile HDR takes off, the YouTube will be at the forefront and Netflix is likely to jump onboard too.
It's very early days for HDR on smartphones, so watch this space.