TV technology is constantly progressing, and right now everyone is talking about 4K resolution - also known as ultra-high-definition. But what exactly is 4K? And how can you get it? Read on to find out.
What is 4K?
The term '4K' refers to the image quality of a video. Specifically, it means that the video has a resolution of around 4000 x 2000 pixels. What we call 'full HD' right now is 1920 x 1080 pixels - so 4K is about four times the definition of high definition itself. And that means an incredibly crisp, clear picture, where barely a detail is lost.
While 1080p (or full HD) is what we currently think of as the standard HD resolution, there's a push to make 4K the standard by 2017. It doesn't look like that'll actually happen, but we're on our way.
Technically speaking, 4K is only supposed to be used when we're talking about cinema. In the movie world, it means a film has been shot and projected at a resolution of exactly 4096 x 2160 pixels. However, it's getting used more and more to refer to ultra-high-definition television on our home TV sets - also known as UHD, UHDTV, or UHD-1 - and it looks like the term will stick.
Okay, so what's ultra-high-definition?
Ultra-high-definition is the highest resolution picture you can get on a home TV right now. It's an umbrella term that can be applied to anything with an aspect ratio of 16:9 and a resolution of 3840 x 2160 pixels or above. So in a nutshell: it's very very very high definition telly.
Two different resolutions of UHD can be found in consumer TVs. The first is only a little different from the traditional 4K, at 3840 x 2160 pixels. The second is FUHD (full ultra high definition), also known as 8K or Super Hi-Vision, with a whopping 7680 x 4320 pixels - that's 16 times the resolution of full HD.
8K might eventually be a successor to 4K, but it doesn't look very likely in the next few years. For a start, you can only really see the difference on screens that are larger than 84 inches wide - so it's not exactly commercially viable. At the moment, its main uses are for really big screens like cinemas and really, really big screens like fulldomes in planetariums. Some filmmakers also shoot in 8K so they can either crop or 'downsample' it to 4K and get a sharper, richer image that they wouldn't be able to get with a 4K camera alone.
How can I watch things in ultra HD / 4K?
The good news is, it's totally possible to watch TV and movies in 4K or UHD right now. Most TV manufacturers have 4K tellies available, and the majority will set you back around £500-£1000. You'll then need a 4K-capable set top box for your TV, or a 4K-capable graphics card if you're streaming via a computer.
Now let's look at where you can find ultra-HD shows and movies to watch.
- Sky Q has a ton of 4K stuff to watch on its 4K-ready Silver box, including Premier League Games, movies, and documentaries.
- BT TV offers the BT Sport Ultra HD channel, and other drips and drabs of 4K content.
- has been streaming House of Cards, Breaking Bad, and 'some nature documentaries' in 4K since 2014.
- Amazon started shooting its full-length original series in 4K for its Prime Instant Video service.
- YouTube and Vimeo both support a maximum upload resolution of 4096 x 3071, so there are bound to be some videos to watch on there too.
- Virgin Media will release a 4K-ready TiVo box pretty soon. Watch this space...
Oh, and bear in mind that streaming or downloading 4K video uses a lot of data - you'll want a nice fast broadband connection, ideally fibre optic broadband and preferably with no download limit.
A short history of 4K
The first 4K devices can be traced back to ye olde days of 2001, when IBM introduced a UHDTV production monitor. Over the next decade there was a flurry of trials and prototypes of the tech, mostly from Japanese broadcaster NHK. The corporation led the way in research, by building cameras and trialling transmission - first over fibre optic cables, then wirelessly in 2007. The next year saw the first ever public live 4K transmission, from London to Amsterdam. The projection of 4K films in cinemas finally began in 2011, though Sony had been making capable projectors since 2004.
2012 was a big year for ultra HD. Good old NHK announced the development of an 8K sensor in February, and LG released the world's first 3D, 4K-ready home TV set, which went on sale in the US for a perfectly affordable $19,000. And in the summer, some events at the Olympics were broadcast in UHD on huge 15m-wide screens in UK city centres.
January 2013 saw the transmission of the first 4K Ultra HD channel, from French company Eutelsat. HOT BIRD, named after Eutelsat's satellites, was broadcast across parts of Europe and the Middle East. Over the next few months, there were announcements left, right and centre about upcoming 4K-capable tech: PlayStation 4, Xbox One, chips for smartphones, Blu-ray discs, YouTube videos… the list goes on.
In 2014 the FIFA World Cup was shot entirely in Ultra HD, and in November a Linkin Park concert was broadcast live in UHD too, for some reason. Then in 2015, satellite operator SES got ready to launch Europe's first free-to-air UHD channel, and BT announced the impending broadcast of BT Sport Ultra HD. 2015 was also the year that Sony launched the world's first smartphone with a 4K display - the Sony Xperia Z5. And finally, in 2016, we saw the start of 4K content from Sky and Virgin Media too.