In Depth: 4K TV resolution: what you need to know

4K TV: what you need to know

TV is gearing up for another revolution in picture quality.

Today's 1920 x 1080 resolution Full HD TVs present us with an image of around 2 million pixels. But a new generation of screens are coming that deliver an 8 million pixel image.

These so called 4K Quad HD, or Super HD, displays, have a resolution of 3840 x 2160 (give or take), and can offer unprecedented picture clarity.

But their introduction will prove complex in the extreme. Introducing a 4K TV isn't like adding LED backlighting to an LCD. It's about orchestrating a seismic shift in the broadcast and entertainment infrastructure, not to mention rewriting the consumer electronics handbook.

4K basics

So why would you want a 4K display?

High def already comes in a variety of flavours, from 1280 x 720 upwards. All offer more picture information than the standard definition formats that came before. The more pixels that make up an image, the more detail you see and the smoother curved and diagonal lines become.

A high pixel count also allows images to go larger before they break up. 4K is already making big inroads into the world of digital cinema.

Of course, perceived picture resolution is as much about viewing distance as resolution. What's the real difference between 720p and 1080p? The answer is about 2 metres. Increase the pixel density and you can sit closer without the pixel grid becoming obvious.

Some engineers dispute that you can see a difference between 2K and 4K on any screen less than 100inches. Go larger and the subtle nuances that make up a 4K picture become easier to appreciate.

4K ON THE WALL: The Sony VPL-VW1000ES home cinema projector is the first true consumer 4K device – yours for £18k

The first genuine 4K consumer product to hit the streets is the Sony VPL-VW1000ES, a home cinema projector that borrows technologies originally developed for the brand's digital cinema projectors. Indeed, the VPL-VW1000ES conforms to the DCI (Digital Cinema Initiative) specification.

NO CONTENT: The Sony VPL-VW1000ES offers a single HDMI input for 4K, but there's no native 4K video content available

Not to be confused with JVC's DLA-X70R and DLA-X90R '4K branded' projectors, which actually deliver a Full HD picture but use pixel-shifting panel technology to produce a more texture image, the Sony VPL-VW1000ES has a native 4k (4096 x 2160) 8.8 million pixel SXRD panel, to deliver true super-high resolution.

The VPL-VW1000ES can accept 4K content over HDMI and display it natively, as well as upconvert any incoming source. Just as well as there's no commercial 4K native content available.

Toshiba first with 4K TV

When it comes to TVs, Toshiba appears to be first at the gate. The soon to be released 55Z2 TV has a 4K 3840 x 2160 pixel resolution screen, and uses a heavyweight multi-core CEVO Engine processor to upscale Full HD sources to its Quad HD panel. Sony, Samsung, Panasonic and LG also have 4K display technology waiting in the wings, but their commercialisation plans are less clear.

The Toshiba 55Z2 is an autostereocopic 3D screen. With no glasses required, it utilises the extra resolution offered by the 4K panel to create nine 3D views filtered through a directional 'lenticular lenslet.'

4K displays and auto-3D technology go hand in hand for many manufacturers who are looking to attribute some practical benefit to super high resolution screens.

A lack of native 4K content is certain to impede the introduction of 4K TV in the early years. But there are huge strides that need to be taken before 4K screens become usable for super high resolution telly-gazing.

Tapping into 4K content

The good news is that there is 4K content available in the vaults of the Hollywood majors. Increasingly movies are mastered at 4K resolution, both for commercial distribution and restoration projects. Hollywood has also begun shooting movies in 4K and beyond.

Peter Jackson's upcoming 3D production of The Hobbit, for example, is being shot on RED Epic digital cameras, capable of 5K resolution.

BEYOND 4K: Hollywood is already moving beyond 4K. Director Peter Jackson is shooting The Hobbit on RED Epic digital cameras, capable of 5K resolution

Quite whether studio bosses actually want this level of picture quality in the hands of consumers remains to be seen. The Blu-ray disc specification currently does not support 4K, although it's not a stretch to imagine at some point the format will accommodate it, via highly-efficient codecs and/or greater storage capacity. Naturally 4K Blu-ray discs would also require a new generation of BD hardware.

At present there is no way to get native 4k video into the likes of the Sony VPL-VW1000ES or Toshiba 55Z2. While the latest HDMI cable specification is compatible with a 4K bitstream, there is no industry standard for the output of a 4K video signal over HDMI from a playback device. So while modern HDMI cables are fat enough to take the signal, there's no way of pouring it in.

A new standard needed

Sony's projector marketing manager Tak Nakane says his engineers are currently developing a converter box able to accept native 4K via a bank of four HDMI/SDI inputs. This convertor would then output the 4K signal via a single HDMI to the projector.

CONVERT IT: Sony's Tak Nakane says his team is working on a converter box able to deliver 4K via a single HDMI output

Currently the only devices to offer 4K play-out are ultra high resolution PC graphics cards, which typically use a quartet of SDI or HDMI outputs to deliver 8MP of video.

Explains Nakane: "For 4K native content to be used, the HDMI specification must be modified to allow a super high resolution player to output 4K. There is no other solution available at the moment."

4K GRAPHICS: With no 4K over single HDMI output standard, graphic cards like this Konga 3G resort to four SDI or HDMI outputs to deliver the 8MP image

The picture's brighter for digital photographers though. A firmware update planned for the PS3 will allow it to display digital still images at 4K resolution over HDMI. Strange as it may seem, the first enthusiasts to benefit from the technology look likely to be photographers and not cineasts.