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We need Immersive TV, not just 4K

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Sony advertises its UHD televisions

There was a reminder at the recent SES Ultra HD Conference that some of the new technologies that are being investigated for UHD can also be applied to HDTV with potentially striking effect. Dr Giles Wilson, Head of TV Compression at Ericsson pointed out that if you take 10-bit, high dynamic range (HDR) and 60Hz (frame rate) and apply these to HD “it still provides a massive leap forward in the viewing experience…and there are circumstances where there is not enough bandwidth to offer UHD and you might want better HD.”

And in a blog last July Ericsson said: “‘Enhanced HD’ offers an interesting alternative, with a better experience irrespective of screen size. It is possible that enhanced HD quality may prove at least as significant as 4K in the longer term.”

This fits with the Ericsson message that what we really want is to deliver better television that consumers are prepared to pay for – so we should not lose sight of how, for example, high dynamic range can be used separately to 4K resolution with a normal TV, tablet or mobile phone, and how multiscreen services could also take advantage of enhanced colours and higher frame rates.

Focusing on the UHD opportunity, Wilson made it clear, as other speakers had before him at the SES Astra conference in London, that 4K resolution is just the starting point if you want a genuinely next generation TV experience. “We have been looking for the true value in UHD, in how we perceive television and what it takes to deliver a truly immersive experience,” he began.

Immersive TV is the goal for Wilson, when we move away from looking at a picture inside a box and feel like we are sitting inside the scene on the television – something that is altogether more realistic. His company has shown demonstrations of what this looks like in practice for sports, when you get a real ‘in the stadium’ perspective that is not just about more picture detail but a much more comprehensive view of your surroundings as well as the on-field action.

Wilson added to the chorus of approval for HDR as a complement to 4K resolution and one of the additional layers that makes up a true UHD experience. “For us, HDR is the thing that has probably the biggest impact on immersion. HDR gives a big boost in contrast that also results in a big boost in detail; it contributes significantly to the level of detail you can see.”

As Ericsson has explained previously, dynamic range describes the range a viewer sees between the darkest and lightest images. Humans have a huge perceptual dynamic range and so do many modern cameras, but traditionally televisions do not come close to matching these ranges. 

It now looks like HDR is going to become an important feature in high-end televisions although, as Wilson noted, it comes at a price. “20% of the cost of a television today is the back-lighting and with HDR you need more back-light so it starts off expensive. We have to figure out a way to get those costs down.” Nevertheless, with HDR televisions in the marketplace, content producers can start filling the natural dynamic range, and that will make images more realistic.

Wilson also highlighted the importance of bit-depth and the requirement for at least 10-bit data precision if you want to get away from the obvious step-changes in luma seen with 8-bit viewing and so avoid the rings and contours “that make something look like a TV picture rather than a real scene”. Once again, the focus is on realism.

Closely related to both bit-depth and dynamic range, the colour gamut is another variable that must be thrown into the mix. Current SD and HD televisions only show part of the colour gamut that humans can see and with true UHD televisions producers will be able to exploit a wider colour gamut, or colour space. But if you want to do that, it points towards 10-bit or 12-bit depth, Wilson argues.

Wilson pointed out that there is no bandwidth penalty for using 10-bit compared to 8-bit. “It is absolutely free in terms of bandwidth, yet it makes a significant difference in terms of the quality delivered to the consumer if you go to 10-bit,” he declared.

Higher frame rates (50/60 fps is probably enough, Wilson reckons) is another must-have if you want an immersive, truly next-generation TV experience rather than just a 4K resolution upgrade. Wilson shares the view that the general 4K experience today, with 30Hz (frames per second), 8-bit depth and standard dynamic range is sub-standard.

“We are not big fans of ‘UHD Lite’; we want truly immersive television. What we see today is in danger of damaging the UHD brand,” he warned. “Done right, UHD is truly compelling and a definite winner but we are not quite there yet.”

More reading:

Sky UK Aiming For UHD Utopia, Not A Half-Hearted UHD Lite


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