Appearing in some of the science fiction novels of US mathematician and computer scientist Vernor Vinge is something called ‘active wallpaper’. All walls are covered with it. If you want to change décor, you set it to a different colour, or pattern. If you want to watch the news, you have a section of it act as a TV screen. Why, the picture can even follow you around the house if you like.

The key to this would be robust, flexible, high resolution, cheap and energy efficient displays. This complete combination remains a long way off, but two steps in its direction are appearing on our retailers’ shelves this year: 4K TVs and OLED TVs.

4K

We talked about 4K in these pages a few months ago, but let’s briefly recap. While 4K in theory means 4,096 pixels across, in the consumer context it has come to mean 3,840 pixels across by 2,160 tall, or double Full HD in both dimensions. This has been labelled variously UDTV or UHDTV, the latter for Ultra High Definition TV, although these tags actually include both those displays and those with even higher resolutions.

Of course, 4K display devices actually appeared on the Australian market last year in the form of JVC and Sony projectors, and Sony and LG TVs. Technically the JVC projectors can’t be called UHDTV, though, because this standard requires them to be able to accept 4K video signals. The JVC projectors merely upscale internally.

The value of 4K, as of today, is somewhat limited due to the dearth of content. But, even so, such devices as the Sony VPL-VW1000ES 4K projector show that smaller pixels, and more of them, are generally better.

This is true for two reasons.

First, they make for a smoother picture. Even Full HD content can be jagged along high contrast diagonal lines. Interpolated pixels can be produced which smooth those out.

Second, they allow video processing that we would generally regard as something to be avoided, such as image sharpening. All such video processes produce artefacts that can sometimes be even worse than the defects that the process is intended to remove, such as traditional edge enhancement. With the Sony 4K projector, the artefacts are so small as to be practically invisible, while the improved detail they provide is readily apparent.

So far all 4K displays have been huge: front projectors or 84-inch (213cm) TVs. But smaller sizes – 55 inches or thereabouts – at far more affordable prices are likely to appear this year. Of course the smaller the screen, the less value in the higher resolution, so we’ll reserve judgement on these until we get our hands on them.

As for content, the International Eutelsat programming provider (which mostly serves Europe, the Middle East and North Africa) has just commenced broadcasting 4K content from its satellite system. It can be done. We can expect 4K camcorders to become readily available this year, as well.

No clear standard exists yet for disc-based 4K content delivery. Multi-layer Blu-ray disc variants clearly have the capacity to carry this content, but it simply won’t happen until a sizeable consortium of content producers and equipment makers agree to standards.

OLED

Organic light-emitting diode (OLED) displays are not primarily about resolution, but will also be appearing this year in TV form with their own special virtues.

First, though, the ‘organic’ in the title has nothing to do with life, but refers to ‘organic chemistry’, which deals with certain classes of carbonbased molecules.

The two main consumer display technologies differ in marked ways. Plasma displays produce light at the pixel level, but are complicated devices. Each pixel is formed by three tiny glass cells, each of which has electrodes, a special gas and phosphor coating. The good thing about light being produced at the pixel level is that each pixel should be able to be switched off when black. Unfortunately plasma cells aren’t very linear when running at extremely low levels, so ramping smoothly down to and up from black is difficult to achieve. In practice, plasma displays use a fair amount of energy.

LCD TVs have far less complicated construction, but the pixels do not produce their own light: they merely filter light produced from a backlight. That limits the thinness of the panel – although with suitable edge lighting some remarkably thin panels have been produced. Samsung had one model out a couple of years ago that was just 8mm thick over most of the panel.

OLEDs combine these virtues. They produce their own light, yet are simple in construction and tiny. Because of the absence of a backlight the panels can be extremely thin.

A few years ago Sony had a tiny OLED TV out, more or less as a novelty item. An expensive novelty item (it was nearly $7,000 for a 29cm TV). Much of the screen was only 3mm thick, although structurally it required greater thickness in places of up to 10mm.

Indeed, OLED displays can be flexible. Some prospective models appearing on consumer electronics shows aren’t flexible, as such, but are curved concave with a view to delivering a more cinematic experience (a silly claim, actually, and pretty unworkable in the home because such a screen would have only one person in the optimal viewing position).

The OLED pixels can be very small – that 29cm TV had a resolution of 960 by 540 pixels.

They will lend themselves nicely to 4K displays. And they have effectively no borders around pixels, so they provide a smooth picture even at very close viewing distances. They are energy efficient because when a pixel is supposed to be black, it can just be turned off completely, saving power. Unlike plasma, though, they ramp smoothly all the way down to black. However, they appear to use somewhat more power than LCDs when all the colours are operating to produce large areas of white.

Still, perhaps the most extraordinary thing about that early Sony TV was the depth of the black levels it produced. I turned off all the lights in the room, yet the TV showing a full black video panel was totally black, producing no light output whatsoever. As I wrote at the time: ‘Sony quotes a contrast ratio of a million to one, but I think that is misleading. A ratio in which the divisor is zero has no answer.’

OLEDs are still more expensive to produce than LCD displays, so they’ll be premium items on their appearance this year (although nowhere near as premium as that little Sony TV!)

There remain questions about their longevity and possible colour shift. Different organic chemicals are selected to provide different wavelengths of generated light and, thus, different colours, so OLEDs are used which natively produce blue, red and green light. The blue ones have tended to lose efficiency faster than the others, so it is possible that after some years of watching the colour may shift in a red/green direction. But they are being improved all the time, and the longevity is already in the many thousands of hours.

CONCLUSION

I do like the science fiction fantasy of having totally configurable display material anywhere you like, thanks to cheap and flexible displays. The reality so far is that while OLEDs are potentially flexible, in TV terms a flat and rigid panel is what is required.

But what we can expect is continuing increases in picture quality thanks to improved black levels and higher resolution, in more attractive TV sets due to the ability to produce very thin panels.