HDR is the next step for video quality but standards must converge
by David Souhami (Innovation & Product Marketing Director, SoftAtHome)
The broadcast and TV industries have been focusing heavily on 4K for at least two years now and hyping it as the next big thing for video quality. Yet it has not yet delivered on its promise for several reasons, including insufficient capacity in the transport infrastructure, lack of enough compelling 4K content and the time taken to deploy compatible products.
But there is also a more fundamental debate, one that has stoked fears 4K could turn out to be a repeat of the 3D disappointment that just preceded it, where lack of consumer interest caused the movement to fizzle out. Proponents of this view point out that 4K only yields a noticeable improvement in quality over HD either when people replace their TVs with screens about twice the size in their living rooms, or else they start viewing their existing screens from half the distance. There are of course a few with the money to buy huge 96 inch screens and equally there are some who are prepared to sit nearer to enjoy a better experience, just as there are those who like to sit on the front rows of cinemas. 4K detractors maintain this is a small number, little greater than those switched on to 3D viewing with dedicated eyewear.
Now a different technology has come forward that looks like inspiring consumers much more — although that could have the effect of postponing the march to 4K itself — and that is HDR (High Dynamic Range). This is already having a huge and disruptive impact on the TV business and causing some major vendors to revise their strategies substantially.
At SoftAtHome, our CTO explained what HDR is a while back in this blog. We also believe that HDR really does deliver a significant improvement in viewing experience, irrespective of screen size or viewing distance, by boosting contrast and colour depth. This applies equally to HD or 4K content and has the advantage that consumers have already been persuaded that it really works through their experiences taking photos with their smartphones. Even though the latter uses different technology to replicate on the image the high range of luminosity experienced by the human eye, the principle and effect are much the same.
Viewers subjectively “see more detail” in a HDR image, even if the number of pixels is identical. This is because the human visual system is more efficient and perceives more information when there is greater contrast.
With HDR now becoming more widely accepted as the next big step forward for video quality with or without 4K, major vendors are placing their stakes in the ground. Ericsson has for example been one of the most forthright, having come out at the recent Connected TV Summit in London with the assertion that we may not need 4K at all and that so called Enhanced HD with the addition just of HDR will be sufficient to give consumers a substantial improvement in experience.
HDR could become bogged down by conflicts between different players in the ecosystem driven by vested interests as well as genuine differences in opinion over which is the best way of boosting dynamic range cost effectively. Key players include broadcasters, notably the BBC and NHK, as well as vendors like Philips, Technicolor and Dolby, as well as Ericsson. Some TV set makers like Sony have announced HDR support for their high-end ranges, aiming to cope with whichever standard emerges through future software updates.
There are a number of different standards groups promoting different implementations, including the Blu-ray Disc Association, the UHD Alliance, SMPTE, ITU, MPEG, DIGITALEUROPE, and the EBU. The various proposals all have pros and cons, with some versions being better suited for live broadcasting while others are better for VoD for example.
There is hope of some consensus emerging at least as far as HDR is concerned through a new industry body called the Ultra HD Forum, set up in June 2015 by leading vendors including arch-rivals Ericsson and Harmonic, which as infrastructure providers have a common interest in an agreed standard for HDR delivery. The Ultra HD Forum aims to pave the way for end-to-end UHD delivery focusing on interoperability, including dealing with the HDR issues described here. The UHD Alliance is another industry body driven by Samsung, Dolby and the Hollywood studios that is heavily focussed on HDR from a standards perspective, but also from a narration point of view. Giving filmmakers the ability to work on HDR on parts of the video adds a new dimension to the story telling.
Another worry for HDR proponents is the extra power required as higher contrast requires more light at greater brightness. Our TV’s could therefore consume more power, reversing current trends. Sceptics also worry that just as there was only so much 3D you could see before getting a headache; HDR could have a similar effect.
The next generation of immersive television is coming although the industry will remain in a state of flux in the short term. We are confident that a clear HDR standard will emerge and will be excited to show some HDR magic at IBC this year.
Originally published at www.broadbandtvnews.com on August 1, 2015.
