Mobile HDR is one of the biggest tech advances for mobile devices. It's something that's been landing on flagship phones since 2017, with most manufacturers, including Apple, Samsung, HTC and Sony getting in on the act. 

It's following a trend that's been tearing through the TV industry over the past few years, but really hit home in the last couple of years. And, in the last 12 months, the move to get more content in HDR to your mobile devices has stepped up. It's still early days for this emerging technology, but it's also hugely interesting and worth paying some attention to.

Here's everything you need to know about the latest step in mobile entertainment.

What is HDR?

HDR stands for high dynamic range and it's been a buzzword in TV for the past couple of years. If you've bought a top tier 4K television recently, it's almost certain that it will also be HDR capable. 

HDR means that the display is able to produce a wider range of colours, bringing greater authenticity, but in many cases it's about brightness and contrast.

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On televisions, HDR is about using the display's peak brightness to give amazing highlights, while still maintaining fidelity in darker areas of a scene. For example, a typical HDR scene is a sunset, where you have searing oranges across the sky, a detailed shadowed foreground and perhaps the blazing sun dipping over the horizon. 

Mobile HDR aims to create the same stunning visuals. In reality, it's about making content look better - specifically movies or games - with increased impact and expanded colours.

We've written a lot about HDR in other devices, so for the nitty gritty, make sure you read up on that feature too. 

What is mobile HDR?

Mobile HDR is specifically about bringing a similar experience from your 55-inch TV to your smartphone or tablet. Again, it's all about using the skills of the display, giving amazing colours and controlling the backlight to give you a better experience.

It has a great deal to do with brightness, because it's the ability of the display to push the brightness in areas that are supposed to be bright that really makes a difference. Many mobile devices have displays that are under-utilised and HDR can make much better use of the display's ability to show content.

The Samsung Galaxy Note 7 attempted to kickstart the mobile HDR movement, but the biggest early hitter was the LG G6. The LG G6 offers HDR10 and Dolby Vision support, just like LG's televisions, so this transition from big screen to small makes sense. The selection of devices is always expanding and you'll find a more complete list below.

There are several different standards for HDR on mobile that you'll hear about: there's HDR10 which is a common standard and there's Dolby Vision, which Dolby is pushing as an enhanced HDR experience. 

Dolby Vision aims to achieve much the same results as HDR10, but can use frame-by-frame metadata to ensure that the display you're watching is showing you the best results. HDR10, by comparison, uses metadata less often, once for an entire show for example, so technically isn't as potent a solution. Whether you'll see the difference or not between the two standards on a small screen is debatable.

Dolby Vision has been slightly rarer, but in 2017 that position seemed to change, with a big push to expand the Dolby Vision ecosystem. Support from Apple with iTunes offering Dolby Vision content, as well as support on the iPhone 8 and iPhone X resulted in a growing user base for this content.

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What is Mobile HDR Premium?

In February 2017, the Ultra HD Alliance announced a new standard for mobile devices, called Mobile HDR Premium. The Ultra HD Alliance is made up of movie producers and technology companies looking to establish a standard for next-gen entertainment. The UHDA is best known for the Ultra HD Premium badging that it applies to televisions - as seen on Samsung, LG and other sets. 

For mobile devices, the Mobile HDR Premium badging means that the device adheres to a particular standard too, designed to ensure that you're getting a great experience from mobile HDR entertainment.

The specifics include:

  • Resolution: 60 pixels/degree
  • Dynamic range: .0005-550nits
  • Colour space: 90 per cent of P3 colour gamut
  • Bit depth: 10

These standards apply to smartphones, tablets and laptop computers, meaning that the Mobile HDR Premium badging could be applied to all those devices which offer HDR content, but not necessarily at 4K resolution.

How does Dolby Vision on mobile work?

The LG G6 was the first mobile device to support Dolby Vision and the message from its implementation on TV has changed slightly. On mobile devices, Dolby Vision is a software solution, rather than hardware-based. On the first run of TVs to support Dolby Vision, you needed the correct hardware to decode the information; now you'll be able to do this with software - something which Dolby seems to be accepting as necessary for the proliferation of its standard. 

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Dolby Vision (or HDR10) doesn't apply to all your content, only the content that's encoded for HDR, like Luke Cage on Netflix, for example. Unlike technologies such as Sony's X-Reality image processing that attempts to improve everything you see on your device, Dolby Vision or HDR only swings into action when you're watching the right content.

With this in mind, you can't turn it off or on: it just works, taking the content you're watching and using the metadata to control the backlight of your device to give you the best colour, great contrast and those characteristic dazzling highlights.

You'll find markers in apps like Netflix showing you that something is in HDR. On the iPhone X, for example, Netflix will show you Stranger Things in Dolby Vision and all you have to do it hit play.

What about variable bitrate services?

One thing that's helped services like Netflix and Amazon Video offer a great services is using variable bitrate. This means that the stream of data is scaled, so on a slow connection you get less data and watch at a lower resolution - without the video stopping or buffering. This also allows almost instant starting of videos too. 

We asked Dolby what happened to Dolby Vision content in a variable bitrate situation and the reply was that it very much came down to the content provider. Technically, HDR and resolution aren't intrinsically linked, so you can have that HDR effect even if you're not watching the highest quality stream. 

One thing is clear though: you don't want to be jumping from HDR to non-HDR, because the colours will be changing and that doesn't make for a good viewing experience.

What about auto-dimming on your display?

This is something of a potential problem for HDR on mobile devices. The TV in your front room probably doesn't change its brightness. It's likely you set it to your preference and then it stays at that level. However, mobile devices use auto-brightness to change the display to suit the environment - it's darker in dark conditions, brighter in bright conditions. 

This will have an impact on how HDR content is displayed. Talking to Dolby, the company confirmed that it takes into account these sorts of hardware factors with the aim of always delivering the best visual experience when watching Dolby Vision content. 

But you can mess with it. If you turn auto-brightness off and turn the display brightness all the way down, then you get a fairly dull result. The long and short of it is that you're best leaving your device on auto-brightness to get the best effect that's balanced for the environment that you're in.

What devices support mobile HDR?

There have been several big announcements for mobile HDR support in the last year, including several new phones launched at Mobile World Congress 2018. The following devices have all confirmed that they support mobile HDR:

What does mobile HDR content look like?

We've been fortunate enough to see HDR working on several phones in the last 12 months, with Netflix offering HDR on some devices. We also saw the LG G6 playing a Dolby Vision demo at launch of that device. Plus, with the launch of the iPhone X, we've now seen a lot more of it.

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If you've seen HDR content on TV, then you know what to expect: colour are richer, there's better contrast and brighter highlights. HDR makes everything look better and this is certainly an exciting evolution: if you watch Netflix on your tablet or smartphone in bed, it's going to look better.

However, the size of the display means that the effect isn't as profound. While HDR looks better than not-HDR on your mobile device, you don't get that punch-in-your-face wow effect that you will on a huge TV - the bigger screen just makes for a bigger experience. 

What HDR content is available?

This is where technology often falls over, when there's no actual content to support the abilities of the devices.

In the case of HDR and Dolby Vision, it's really only Netflix and Amazon Video streaming HDR content to your TV. Both services confirmed that they are offering HDR content to mobile devices and if you have a compatible phone, the Netflix is a good source of HDR entertainment. Netflix has followed this through, and is regularly updating its list of compatible devices.

Currently, only the LG G6 and the new Apple devices are Dolby Vision compatible.

For Apple users there's the added advantage that iTunes movies are available in Dolby Vision and HDR too. This is really a play to boost Apple TV, but for those watching on the latest Apple devices, you'll benefit there too.

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YouTube also offers HDR content and we'd expect this to be enabled on mobile devices at some time in the future and this is likely to be one of the best sources of free HDR content. The only barrier, perhaps, is creation, as currently there are few consumer devices that can capture HDR video - the Panasonic Lumix GH5 is one such camera.

That could be changing soon, however, as Sony became the first manufacturer to announce a smartphone capable of recording 4K HDR video on a handset: care of its Xperia XZ2 launched at MWC 2018. Others could follow suit.

Can my old phone support mobile HDR?

This is a good question. Technically, if the display is good enough, then there could be some scope to enabling viewing of HDR content on existing devices. When talking to Dolby, we were told that Dolby Vision isn't restricted to a specific set of specifications and that the aim was to make the display work to its maximum potential.

As Dolby Vision on mobile devices is a software solution, it's really down to the manufacturer to work with Dolby to enable support. For a manufacturer this is likely to involve licensing fees, so we suspect that some won't take the Dolby path for this reason.

However, with manufacturers wanting to sell you new devices, it's unlikely they will move to support HDR in older devices.