Dolby Vision: Bringing High Dynamic Range to TVs
JOHN ARCHER takes a look at a new TV technology that promises to deliver high dynamic range (HDR) to our living rooms.
Famed US audio tech company Dolby is no longer just interested in sound. At this year’s IFA show in Berlin Dolby’s most intriguing story wasn’t its new Atmos multi-channel audio system, but rather something called Dolby Vision.
This startling new video tech takes as its starting point a belief that the picture quality of all today’s TVs are rubbish. Why? Because they don’t have a high enough dynamic range.
What is High Dynamic Range?
Try this. Whip out your smartphone (assuming it’s a fairly modern model) and try taking two photographs of the same subject, preferably one with lots of light contrast. Take one with your phone’s HDR setting active, and then with it deactivated.
You'll be amazed what a phone with a good HDR mode, such as the Samsung Galaxy S5 or iPhone 5S, can produce. A good HDR shot is brighter, more contrast rich and vibrant than a non-HDR shot. You get detailed shadows and bright, searing sunlight in the same picture, whereas a standard photo averages out and looks flatter.
This is, in very broad strokes, what Dolby Vision wants to achieve with TV pictures.
How does Dolby Vision work?
In its fullest expression Dolby Vision is a full end-to-end deal. That means directors must shoot for Dolby Vision, or master their films for Dolby Vision. This requires the P3 digital cinema colour gamut, though Dolby is considering the extreme Rec 2020 format in future.
Next, studios need to encode and package that content correctly. It needs to be delivered the right way, too. That means TVs with decoder chips that can handle 12-bit video and a 20% expansion of the HEVC/H.264 compression codecs. They must be super bright, too, so they can handle the 40x times brightness levels and 1,000 times more contrast of Dolby Vision.
Benefits are evident even if you only satisfy one or two parts of the full end-to-end solution. But for the maximum Dolby Vision impact, source and display need to be in perfect harmony.
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Where can I get Dolby Vision?
Right now, you can't. No current, commercially available TVs are compatible with Dolby Vision. Not even the latest ultra-bright models from Philips, Samsung and Toshiba support it.
Moroever, as AV industry veteran Joe Kane pointed out during an IFA presentation on future AV standards, look behind the scenes of a full-spec Dolby Vision demo and you’ll find refrigeration units and industrial power supplies cooling and feeding the screen.
But Dolby says that Dolby Vision-capable TVs will be appearing in the US before Christmas. That's because it believes mainstream sets can still deliver some of the benefits, just scaled down. It even has a chip for doing just this.
One of the brands working with Dolby (though it’s not yet an official licensee) on Dolby Vision is Philips. In fact, the Dutch brand had a Dolby Vision demo running on its stand at IFA. It used a panel which, while ‘next generation’, wasn't all that far beyond what the brand’s top-end TVs are delivering now.
It showed what Dolby Vision will look like if you buy a certified TV later this year, so we settled down to see whether it's something worth considering.
How good is Dolby Vision?
The demo comprised two screens running side-by-side. Both screens had the same next-gen panels at their heart, but they were setup differently. The one on the left is set to deliver 120 Nits of light output – a level intended to represent the typical brightness levels of current LCD TVs – while the one on the right is running at a high-brightness 1,000 Nits to highlight Dolby Vision’s potential. Dolby Vision clips included extended samples from Oblivion and Star Trek: Into Darkness.
There have to be concerns about any demo that features a TV ‘specially calibrated’ to emulate another type of technology. But Philips has a greater track record for honesty in this department than most, so we’re prepared to take the demo at face value.
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A close-up shot from Star Trek Into Darkness in the background shows the bright area blown out
Dolby Vision retains the detail in this shot, though it perhaps loses some foreground shadow detail.
And, for the most part, we were seriously impressed by what we saw. The brightness of the Dolby Vision screen is truly intense. It drives images out of the screen with an incredible intensity that left all the other TVs on Philips’ stand looking muted by comparison. It's delivered without causing the lightest parts of the picture to look ‘torn out’ or clipped, too.
This high brightness joins the expanded colour range to deliver a colour palette of phenomenal intensity. Pictures look more visceral, vibrant and, for the most part, life-like. They have almost 3D-like intensity and sense of depth.
Occasionally the vastly expanded colour gamut looked a touch unbalanced, but we were really impressed to see how believably the extra colour range translated into skin tones. People just look more alive and vital, a fact which has a bizarrely strong impact on boosting your sense of connection with what you’re watching.
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Here is a scene without Dolby Vision
And now with Dolby Vision. Note the great detail in both dark and bright areas, such as individual sparks in the intensely bright end of the welder.
We were also impressed by the spectacular amount of detail in the image. This was especially true when it came to dark scenes, where shadow detail in the Dolby Vision image was in a whole different stratosphere. This helps dark scenes look deeper and more natural, as well as ensuring they sit more comfortably alongside bright scenes than they do on lower-brightness screens.
Our big fear was that the massive boost in brightness would lead to the destruction of black level response. But this doesn’t appear to be the case.
Philips was brave enough to include some fairly dark footage from a vintage car repair garage on its show reel, and the darkest parts of these shots look decently black. Not truly inky, perhaps, but believable enough – especially given the outstanding levels of shadow detail they contain.
There are issues with Dolby Vision, for sure. We’ve been burned enough times in the past to be innately suspicious of any picture technology that depends on support from the content creation and shipping side.
The potential for different ‘levels’ of Dolby Vision experience could lead to confusion, too. Considerable work is needed to make TVs power efficient enough to support such high brightnesses while remaining legal, though Dolby believes Quantum Dot technology holds the answer here.
Still, there’s no doubt that Dolby Vision has the potential to have a stunningly positive impact on TV picture quality. So for now let’s put practical concerns to one side and declare ourselves fully behind it.
Next, read Curved TVs: The Pros and Cons
