LG talk OLED, HDR and the evolution of TV

"The future’s here. The future’s now. The future’s OLED."

by Steve Withers Nov 6, 2015 at 10:33 AM

  • It’s been hailed as the next stage in the evolution of television but OLED’s journey to our living rooms has been slow and often fraught with difficulties.
    However it would seem that the technology is finally beginning to reach the mainstream and we essentially have one company to thank for that - LG. Over the last three years the Korean manufacturer has practically been the only champion of OLED and it looks as though their $1.5 billion gamble is beginning to pay off. OLED is an entirely new category of television, with more in common with plasma than LCD, and LG Display are the dominant manufacturer. You may see OLED TVs from other companies but it’s a safe bet they’ll be using LG panels.

    We have now reviewed five different LG OLED TVs using both Full HD and Ultra HD panels and the company has released nine different models in total, seven of which are 4K resolution. You can buy their OLED TVs in over a thousand retail points across the country and to emphasise the unique attributes of OLED’s self-illuminating properties, LG have just launched a new advertising campaign. This campaign uses quotes from major media outlets including AVForums and will run through Black Friday and into the week before Christmas.
    For three years LG have been the only champion of OLED but it looks as though their $1.5 billion gamble is beginning to pay off.
    LG are also installing OLED screens in airports, expos, sports arenas, shopping malls and museums, in order to increase the technology’s exposure. These various promotional campaigns go hand-in-hand with staff training in stores, so that retailers are fully equipped to answer the inevitable question “what’s the difference between an LED TV and an OLED TV?” LG’s approach is to concentrate on the four key differences of wider viewing angles, much deeper blacks, better colours and an ultra slim design, which the company hopes will differentiate OLED from LED LCD.

    So what does make OLED better than LCD? Well for a start OLED is self-illuminating, which means there’s no backlight. This results in vastly superior blacks and contrast ratios on an OLED panel, something that LCD can only approximate using local dimming which will result in haloing and other artefacts. In addition, to get decent blacks on an LCD TV requires the use of a VA panel and that severely restricts the optimal viewing angle. An OLED screen has a very wide viewing angle with no drop off in colour accuracy or contrast performance. Finally an OLED screen can deliver more consistent colours from dark to bright scenes when compared to an LCD screen because there’s no light leakage from the backlight.
    It has been a challenging year for all brands with 9% less spending on TVs during the first nine months of 2015. However LG have seen their sales actually grow by 6% this year, bucking an industry-wide trend. Despite this it has been good year for Ultra HD 4K across all brands, with over 1 million UHD TVs sold in the UK during 2015, and a quarter of those TVs were made by LG. The company certainly regards OLED as their premium product, combining stylish design with cutting-edge technology to create a market leader. In fact, one out of every five premium TVs sold is an LG OLED.

    This premium approach also reflects a general move towards larger screen sizes and LG will continue to offer 55-, 65- and 77-inch screens. When TVs reach a certain size there is a tendency to hang them on the wall and the thinner the TV the easier it is to wall mount. LG are already developing panels that are less that 3.9mm deep for release next year and have investigated various design themes including a wall paper screen, a picture on glass with a crystal back cover and one that LG call ‘Blade Slim’. In the future, OLED will even offer the option of flexible, roll-up and transparent screens; in fact LG have barely begun to exploit the technology’s full potential.
    Across all brands there have been over 1 million Ultra HD TVs sold in the UK during 2015, and a quarter of those TVs were made by LG.
    In fact it was exploiting the full potential of OLED that was one of the main reasons why LG had invited us to their offices. They wanted to talk about High Dynamic Range (HDR) and how their latest OLED TVs can already support this exciting new technology. On hand was Neil Robinson, the Director of Technology Strategy for the LG Technology Centre of America, who started by explaining how TV is in the middle of a gradual evolutionary process. We have already moved from standard definition to high definition and now we’re moving into a 4K Ultra High Definition world. That move will be accompanied by a number of other changes including a move from 8-bit to 10-bit, wider colour gamuts, higher frame rates and HDR. The idea is to have TV images with both higher resolution and greater expressiveness.

    One of the aspects of this evolution has been the development of High Dynamic Range for TVs, which Neil was quick to stress shouldn’t be confused with the HDR modes found on many cameras. HDR in terms of TVs is a way of utilising the wider dynamic range captured by film and television cameras and delivering that wider dynamic range to viewers to create an experience that better replicates the full range of the human eye. Until recently the standard used for transferring video content was based on decades old CRT technology but now the standards are catching up the the capabilities of modern displays.
    The development of HDR has involved an element of open innovation but mostly has centred partnerships between manufacturers, studios and various professional bodies. Contrary to popular belief, it isn’t just about making images brighter but widening the dynamic range so there’s greater detail in brighter parts of the image and better low level rendering in the darker parts. LG believe that OLED can create a more faithful image and deliver an improved contrast performance with HDR.

    This is because an OLED screen is capable of incredibly low black levels (almost zero), whereas LED TVs are limited by the native contrast ratio of the LCD panel. An OLED can deliver the equivalent of 20 stops on a camera, whilst an LCD panel is limited to about 12 and a much lower native contrast ratio. This can be improved by using local dimming but since they all use zones, they can result in haloing. The only way to avoid that would be to use local dimming at a pixel level, which of course is exactly what OLED is doing.
    HDR is about widening the dynamic range so there’s greater detail in brighter parts of the image and better low level rendering in the darker parts.
    It isn’t just about black levels and contrast ratios when it comes to to HDR and there is clear correlation between the brightness of an image and the colour accuracy. Since an LCD panel uses a backlight, in bright or dark scenes there is a tendency for light to spill through from this backlight, affecting the accuracy of the colours across the dynamic range. As a result, in darker environments LCD TVs can have colours that appear washed out, so once again this is an area where OLED has an inherent advantage.

    Another key area where OLED has a clear advantage with HDR is in terms of viewing angles. Although an LCD TV has a higher peak brightness, this drops off significantly when viewing off-axis. Once the viewer moves away from the centre of an LCD screen, the luminance drops off significantly, as does the contrast performance. The same is true for both the contrast ratio and colour accuracy, once you move off-axis with an LCD TV, so ultimately it's only the person in the sweet spot that gets the full effect of HDR. That isn’t the case with OLED, which means the entire family can enjoy the benefits of HDR.
    Neil pointed out that whilst HDR was primarily about dynamic range, it was also directly related to colour and specifically colour volume. As with Ultra HD in general, the various HDR formats all use the Rec.2020 coordinates for signalling colour but they don’t currently extend all the way to the limits of the standard. At present the Wider Colour Gamuts (WCG) have been limited to the DCI/P3 colour gamut within the Rec.2020 container but they could theoretically extend much further. There have been various new WCG display technologies, including Quantum Dot, OLED and Laser Projection, but different displays may not look the same even when calibrated to the same CIE x, y coordinates. Displays are designed to stimulate human vision in different ways to replicate D65, which is shown in the graph above and represents daylight in Western Europe.

    However, two different people can look at a WCG display and see completely different colours, with very wide colour gamuts actually looking objectionable. The industry has discovered that previous standards weren't as accurate as previously thought and the closer you get to Rec.2020, which is shown by the single three wavelengths in the graph above, the greater the variations between individual viewers and the bigger the problem. WCG is certainly a step forward but there are still significant challenges and just trying to reproduce Rec.2020 isn’t necessarily the best approach. What is actually needed is a new standard for Rec.2020 reproduction in displays, that uses wider tolerances to avoid these problems. In other words, rather than using three individual wavelengths for red, green and blue, the standard should use a wider range of wavelengths that better replicates the measurements for D65.
    The development of HDR has resulted in a number of different versions and LG currently support two specific types - HDR 10 and BBC Hybrid Log Gamma.
    The development of HDR has resulted in a number of different versions and although LG have been trialling all of them, they currently support two specific types of HDR. The current EG960, EG920 and EF950 models all support HDR 10, which is what is currently used by Amazon Instant and will probably be used by Netflix. HDR 10 is also the most likely version of HDR to be initially used on 4K Ultra HD Blu-ray, although that format also includes both Dolby Vision and Philips HDR in its specifications. The other form of HDR that LG OLEDs will support is BBC Hybrid Log Gamma, which the company has been assisting the BBC in its development.

    One of the reasons LG has been in partnership with BBC is because the broadcaster realises the difference between LCD and OLED, which means it needs both types of TV for HDR testing. The BBC is a publicly funded body, so it needs to find an HDR solution that is compatible with both SDR and HDR TVs, whilst also being used with Full HD if necessary. Although, like most of those involved in Ultra HD, LG would rather HDR was used exclusively with the new higher resolution formats as a way of distinguishing them from what has gone before.
    BBC Hybrid Log Gamma is currently being tested for any delivery or compression issues and we saw test footage of a firework display and also the Americas Cup, which the BBC covered in HDR in conjunction with BT Sport. It certainly looked very impressive, with deep blacks, brighter peaks and more detail in the lighter and darker parts of the image. The BBC footage certainly showed the potential of HDR in conjunction with either Full HD or Ultra HD broadcasting. There were also videos being shown in HDR 10 that LG had specially commissioned and these looked spectacular. It was the same footage that impressed us so much when we reviewed the EF950 and whilst we appreciate that this kind of demo footage is designed to show off the content as effectively as possible, it still revealed the real potential of HDR as a way of creating images with greater impact.

    We also saw the Amazon TV series Mozart in the Jungle, which is available in HDR 10. It was a live video stream and the results looked very good on the EG960, not as in-your-face as the demo footage but more realistic and cinematic. When an LG OLED TV detects the HDR metadata it automatically switches to HDR and then returns to your previous setting when the HDR content has finished. We saw this when testing the EF950 and it works really well, making things as easy as possible for viewers. The EG960 can currently only display HDR content from streaming services but the EG920 and EF950 have HDMI 2.0a inputs, which means they can detect the HDR metadata over HDMI. LG said that since many of the standards were still being decided, they were looking at possibly retro-fitting HDMI 2.0 inputs to pass HDR metadata; which would be good news for owners of TVs like the EG960.

    Watch our video report

    As far as LG’s current plans are concerned, although we won’t see the same OLED price drops that were announced for the US because it’s a very different market, we will see competitive promotions in the run-up to Black Friday and Christmas. After that the new line-up will be announced at CES in January, before probably going on sale around March or April time. After that there will be the European Championships, closely followed by the Olympics before the whole cycle starts again. The manufacturer also acknowledged that they were aware of the vignetting and are looking at ways of eliminating it on future generations of OLED panels. So although the technology is already delivering some of the best TV images we've ever seen, there's still room for iterative improvements and further evolution.

    It’s a common misconception to think that evolution involves the survival of the fittest. What it actually involves is the survival of the best adapted and it certainly looks as though OLED is well adapted to survive the seismic changes in the TV industry over the next few years. We did say that OLED was the future of TV and we still believe that to be true but now we’re more excited than ever to see the latest evolution of OLED in 2016.

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