The good news: there’s a new TV technology in town called high dynamic range (HDR) that’s actually really, really good. The bad news: HDR is insanely complicated. Or at least that’s how an over-aggressive and self-obsessed AV industry has managed to make it look.
A combination of fractured development, belated standardization, over-eagerness and using it as a weapon in bitter OLED vs LCD feuding have conspired to make the mere mention of the letters ‘HDR’ enough to cause your average consumer’s eyes to glaze over.
Even today, despite us now being faced with a second generation of ‘HDR-capable’ TVs, the AV world still seems hell bent on piling more confusion and obfuscation around its latest bid to get us all to recycle our TVs again.
So the plan here is to try and cut through all the jargon and bluster and make HDR accessible to anyone. After all, when you strip away the techno-babble the only thing that truly matters about HDR is that it can deliver TV picture quality far beyond anything seen before - so it would be truly sad if consumers decided to shun it just because they didn’t understand it.
What does High Dynamic Range mean in the TV world?
If you’ve got a reasonably recent smartphone you’ve probably already come across the concept of HDR from a photography perspective. However, HDR for still photography is a very different kettle of fish to HDR for video.
When it comes to HDR in still photography, your camera takes multiple exposures of the same shot and combines them together to make the end result look more dynamic. With HDR video you’re actually capturing in the camera and then retaining during the video mastering and delivery stages a much greater brightness range.
The result is pictures that enjoy far more dynamism and contrast, and contain much more of the visible light spectrum and low-light detail our eyes see in the world around us every day.
The difference between standard and high dynamic range images really can be spectacular - you certainly don’t have to have a trained eye or a TV the size of a small country to appreciate it.
So far, so straightforward. However, slightly confusingly the HDR term has also come to be associated with a desire on the part of the AV world to expand the color range of the
The current target for HDR TVs is to go far beyond the color range of the old TV picture standards we’ve been stuck with for decades and reproduce a color range that gets as close as possible to what you see in high quality commercial digital cinemas. So as well as reproducing pictures on your TV that look more like real life, HDR enables you to see films at home that look much more like they were designed to look at the cinema. Though actually, HDR has the built-in potential to go far beyond the current cinema color standard as technological advances permit.
It's not just TVs that can show HDR - some projectors, such as the Sony VW520ES shown here, can also... [+]
What you need to watch HDR
HDR is an end to end technology. The source pictures need to be created containing HDR-friendly color and brightness ranges; the distribution method needs to retain all the extra HDR brightness and color information; and the display device you’re watching HDR on has to be capable of reading and managing the HDR data, as well as - hopefully! - having sufficient brightness and color capabilities to deliver at least some of HDR’s picture quality benefits.
In short, if you want to watch HDR at home you’ll need an HDR-capable TV and at least one HDR-capable source.
What HDR sources are there?
The recently launched Ultra HD Blu-ray format supports HDR, and every disc released to date includes an HDR version of the film it contains.
You can also download HDR movies to compatible Smart TVs or storage devices using the Vidity system. At the time of writing this involves downloading select Fox or Warner Bros titles from fandangonow.com (previously M-Go) to Western Digital storage devices via Samsung TVs, though it’s possible other licensees to the Vidity system will provide alternative solutions at some point.
Please note that only Netflix and Amazon currently offer HDR services outside of North America.
Does all HDR look the same?
No. For starters, film-makers can have very different visions of how dynamic a particular movie should look, in terms of its ‘baseline’ brightness and how far into the darkest and brightest extremes of HDR’s expanded light range its pictures should venture.
The technical capabilities of the cameras being used to capture a film or TV show are also a potential issue.
When it comes to getting HDR out to consumers, there are different types of HDR distribution channels available that work to slightly different standards and in different ways that can also potentially have an impact on the HDR picture you experience.
Finally, there can be potentially big differences in the way different TVs deliver HDR, based on everything from the inherent brightness, contrast and color capabilities of their screens to the types of HDR they support and the quality of their video processing.
Let’s look in more depth at some of these HDR differentiators.
Different types of HDR
As if HDR wasn't already complicated enough, the AV industry has in its infinite wisdom introduced a whole raft of different HDR formats, all with their own particular benefits. There are four, in particular, that you really need to know about: HDR10, Dolby Vision, HDR10+ and HLG.
I'll explain each of these below - but bear in mind that currently no TVs out there that support all four. While most modern TVs support HDR10 and HLG, some brands (Sony, LG, Vizio) support Dolby Vision but not HDR10+, while other brands (Samsung, Panasonic) support HDR10+ but not Dolby Vision. This is about to change, though, with Philips (Europe), Panasonic and TCL all launching TVs that support all four formats in 2019.
Open Standard HDR/HDR10
Pretty much any TV that claims to be HDR capable will support the open HDR standard (commonly abbreviated to HDR10) developed by the Society of Motion Picture and Television Engineers. This standard also has to be supported on Ultra HD Blu-rays that use HDR, and the expectation is that the vast majority of streaming services that offer HDR will also support the open HDR standard.
Certainly that’s the case with Netflix and Amazon, though VUDU initially threw a spanner in the works by only offering HDR on its platform using the Dolby Vision system (though it has recently pledged to support HDR10 too).
Dolby Vision
Dolby Vision has, as you can probably guess, been developed by Dolby Laboratories. It differs from the open HDR standard in a number of ways, but the main four are a) that any delivery system or display hardware that wants to support it has to pay a license fee to Dolby; b) that any Dolby Vision hardware needs a dedicated Dolby Vision decoder chip or licensed software iteration inside; c) that color is mastered to 12 bits rather than open HDR’s 10 bits; and d) that it adds an extra ‘layer’ of information to the main HDR picture data which optimizes the way pictures look on a scene by scene basis for whichever Dolby Vision-capable TV they’re being watched on.
The need for a dedicated Dolby Vision chip (or a processing system powerful enough to run Dolby Vision in software) in Ultra HD Blu-ray players or TVs/projectors that want to support it means that unlike open HDR it’s not nearly so widely available. At the time of writing the only Dolby Vision Ultra HD Blu-ray players are the Oppo 203, Oppo 205 and LG UP970, while the only TV manufacturers that support it are LG, Vizio, Sony (via a recent software update to TVs equipped with its X1 Extreme processing chip), TCL, Loewe (on its OLED TVs) and Philips (US).
Dolby Vision also requires special mastering of films and TV shows, and at the time of writing the only studios which have released a small number of Dolby Vision titles are Disney, Lionsgate, Sony Pictures, Universal and Warner Bros.
As I’ve already mentioned, meanwhile, VUDU initially exclusively supported Dolby Vision for its HDR movie streams - though it has since shifted away from that position.
Netflix and Amazon now both offer Dolby Vision streams alongside HDR streams for people with Dolby Vision-capable TVs, though the extent of this support is pretty limited at the time of writing.
I review Dolby Vision on Ultra HD Blu-ray in this separate article.
HDR10+
HDR10+ has been developed chiefly by Samsung, and is designed to offer similar advantages to Dolby Vision but from a licence-free, open standard format.
As with Dolby Vision, its main trick is that it introduces dynamic metadata , for scene by scene image optimization. However, it leaves a little more freedom for different TVs to add their own processing to the signal than the more proscriptive Dolby Vision approach.
At the time of writing HDR10+ is supported by Samsung, Panasonic, TCL, Oppo and Philips (Europe) on the hardware front, and Amazon Video, 20th Century Fox, IMAX Enhanced, Warner Bros and Universal on the software front. Though only Amazon Video and Fox have actually already provided HDR10+ content. All Amazon Video HDR content is available in HDR10+, while a handful of recent Fox 4K Blu-ray releases support the format.
HLG
Short for Hybrid Log Gamma (!), HLG has been developed by the BBC and Japan's NHK broadcaster. As you might expect from this heritage, HLG is designed to make HDR easier to implement in broadcast situations. One of its most important tricks given the broadcast bandwidth issues usually associated with broadcast situations is its ability to carry standard dynamic range and HDR images in the same 'package', to support legacy TVs.
HDR10 can be used for broadcasting too in theory, and Dolby has developed a Dolby Vision system that can support live broadcasting. It seems at that moment, though, as if HLG will become comfortably the most widely used format for broadcast HDR.
Why TVs don’t all look the same with HDR
The differences in how effectively TVs reproduce HDR can be pretty extreme for a number of reasons, making choosing the right TV the single hardest part of the HDR story from a consumer’s point of view.
At the heart of the problem is the fact that so many different picture factors go into creating HDR images that it’s really difficult for current TV technologies to nail all of them at once.
Some screens can deliver more of the new color range associated with HDR, for instance, while others do better at delivering more of the extra brightness and/or contrast associated with HDR’s expanded luminance capabilities. Some TVs and TV technologies are better than others at controlling how locally HDR’s extreme brightness peaks are reproduced, and some do better than others at ‘remapping’ the full range of color and brightness range information an HDR source may contain to the usually relatively limited capabilities of their screens.
So how do I figure out which TVs are the best for HDR?
The AV industry has tried to help here by coming up with a series of recommended TV specifications for HDR playback. These include minimum color, brightness, resolution and contrast requirements, and any TV (or Ultra HD Blu-ray player and Ultra HD Blu-ray disc, actually) that hits or surpasses the full array of recommendations can earn an ‘Ultra HD Premium’ badge to use on its marketing materials and packaging. For more details on this, check out this separate story.
This is the logo TVs, Ultra HD Blu-ray players and UHD Blu-ray discs can earn if they pass the Ultra... [+]
Well intentioned though the Ultra HD Premium logo may be, though, there are problems with it. First, it hasn’t been adopted right across the AV industry. The thing is, TVs have to be tested by the Ultra HD Alliance that’s behind the Ultra HD Premium logo before they can wear the badge. Yet some brands don’t want to go through that process or, for internal marketing reasons, they don’t want to use the Ultra HD Premium branding.
This means there are TVs out there - such as Sony’s XD930 and XD940 models - that are apparently capable of earning the Ultra HD Premium badge but which have chosen not to pursue it.
The other issue with the Ultra HD Premium logo is that to some extent it’s just a numbers game. By which I mean that because there are so many interconnected picture quality traits associated with delivering HDR convincingly, it doesn’t necessarily follow that a TV sporting the Ultra HD Premium badge will always deliver a truly stellar HDR performance, even if it looks on paper like it should.
Particularly problematic for LCD TVs, for instance, is light pollution. Since LCD TVs rely on external lighting systems rather than each pixel producing its own light independently, the appearance of bright objects against dark backgrounds in an HDR picture can cause distracting problems like streaks of light running right down the screen or glowing halos around the bright object. For more on this, see my recent reviews of the Samsung UN55KS9500, Sony 65X930D and Panasonic 50DX750.
With this LCD problem in mind, LG’s OLED TVs, where every pixel produces its own light, look like better bets for HDR. Yet OLED screens are not currently capable of hitting the same brightness peaks that LCD ones can, meaning they can find it harder to remap HDR’s most extreme brightness peaks effectively to their screen capabilities.
Sony has decided to use its own 4K HDR logo to signify a high level of HDR performance from its TVs... [+]
So when all’s said and done, really my advice to anyone wanting to pick the right HDR TV for them is to read a selection of reviews from trusted sources. Or, if you’re confident you know what you’re looking for, to get dark room demos of a selection of shortlisted models.
Is there an HDR format war?
When HDR first launched, I wouldn't have said there was a format war. All you had then was the HDR10 industry standard format, and Dolby Vision. As HDR10 is basically the industry standard, it's supported by pretty much every HDR-capable display and source. Dolby Vision is a value-added HDR option that accompanies rather than replaces HDR10 on almost all hardware and sources.
There were some initial ‘complications’ - such as VUDU’s initial decision to only offer support for the Dolby Vision flavor of HDR, and the way Vizio's Dolby Vision TVs initially only supported Dolby Vision without HDR10. Both these situations, though, have now been addressed with added HDR10 support.
The only remaining issue is that some brands refuse to pay Dolby the necessary licence fee to add Dolby Vision to their products. Which means that if Dolby Vision matters to you, you'll have to buy a brand of TV that supports it.
Vizio has a number of TVs - including this Reference Series model - that support Dolby Vision. (Pic:... [+]
The unveiling of the new HDR10+ format last year, though, completely changed things. For me, HDR10+ versus Dolby Vision can be considered a format war. After all, at the time of writing there are no TVs out there that support both formats, even though some film studios and streaming services support one format but not the other.
In other words, you cannot watch every film you buy on 4K Blu-ray or every stream you watch from a particular streaming service in its absolute best picture quality. You can't watch Dolby Vision on HDR10+-capable TVs, or HDR10+ on Dolby Vision-capable TVs.
Panasonic has at least unveiled a 4K Blu-ray player, the UB820, that will play both Dolby Vision and HDR10+. And all sources and screens will support the fall-back, less impressive HDR10 system. But until TVs start to support both Dolby Vision and HDR10+ too, you're essentially being forced to choose one dynamic HDR format over the other. Which sounds like a format war to me.
The Sony 65X930D recently received a firmware update that lets it handle the HLG broadcast format.... [+]
Do you need faster broadband to stream HDR?
Only slightly. One of the best things about HDR is that unlike 4K/UHD resolution, it adds relatively little data to a video stream. Amazon actually claims that HDR adds no significant data bandwidth requirements to its streams, while Netflix claims HDR adds between 10 and 20 per cent extra streaming bandwidth. So given that Netflix claims you should have at least 25Mbps of broadband speed for stable Ultra HD streaming, you’re looking at needing around 30Mbps for stable UHD HDR streams.
What happens if you watch standard dynamic range video on an HDR TV?
Many HDR-capable TVs - especially the relatively high-end ones - feature ‘remastering’ systems capable of expanding the colour and brightness range of standard dynamic range sources to ‘fill’ the HDR-friendly capabilities of their screen. This is a very difficult thing to achieve successfully, though; unless a TV’s processing systems are exceptional you may see such issues as color balance problems, unnatural color tones, bleached whites, forced and detail-light dark scenes, plus exaggerated video noise.
I’m not saying you should deactivate an HDR TV’s SDR-to-HDR conversion systems by default; some TVs really can do a better job of upconverting SDR than you might think. If, however, you find yourself feeling acutely aware of any of the SDR upconverting issues listed above then it’s worth at least experimenting with turning all or some of the upconversion circuitry off.
What’s next for HDR?
With content mastering standards for HDR largely set and appearing to contain many years worth of future proofing, I’d expect the main areas of improvement/change for HDR to take in place in the TV hardware world.
We can probably expect a ‘nit race’, for starters, where TVs push for ever higher levels of brightness with which to unlock more of the potential contained in the HDR video sources, most of which are mastered to much higher brightness standards than anything that can be achieved by today’s TVs.
LCD TVs like Samsung's UN55KS9500 are strong when it comes to the brightness part of HDR. (Pic:... [+]
Alongside this push for more brightness will (hopefully) come more advanced ways of controlling how locally light appears on the screen. This may extend to more brands adopting OLED technology - though as discussed earlier, OLED has its own brightness challenges to overcome.
There will also be a push by the TV makers to expand the color range their TVs can achieve. At the moment the focus is on screens reaching 100% of the color range used in digital cinemas, but the HDR format includes the potential to extend way beyond that if film makers want to go there.
Also likely to undergo a period of change is the way films and, especially, TV shows are shot, as their makers start to experiment with the new story-telling options HDR makes possible.
Further reading
If you’re feeling brave enough to take your HDR knowledge to a level where phrases like Electro-Optical Transfer Function, Perceptual Quantizer, Rec.2020, DCI-P3, HDR10 Media Profile and SMPTE ST 2084 abound, I consider this article by Yoeri Geutskens to be pretty much definitive (at least up to the date it was written).
I’d also recommend the following reviews of the latest HDR-capable TVs:
Here, too, is a review of the first Ultra HD Blu-ray player, the Samsung UBD-K8500.
Finally, to give you some idea of just how good HDR can be, here’s a review of The Revenant on Ultra HD Blu-ray.
