4K. Ultra HD. UHD.
These terms have been quickly adopted and are thrown around with wild abandon. Not only are high-end TVs offering 4K UHD resolutions, both Sony’s PlayStation 4 Pro and Microsoft’s Xbox One X are trumpeting their ability to run games at 4K resolutions, Netflix offers some 4K content, Apple TV has started listing shows in 4K, and even the Sony Xperia XZ Premium boasts the fact it has a 5.5-inch 4K screen.
But what is 4K, and how does it differ from Ultra HD and Full HD?
What is 4K?
At its most basic, 4K and Ultra HD are four times the resolution of Full HD. A standard Full HD screen will have a resolution of 1,920 x 1,080 (a total of 2,073,600 pixels). Ultra HD and 4K screens have a resolution of 3,840 x 2,160 (a total of 8,294,400 pixels). The more pixels there are, the more detail the picture contains.
4K TVs all tend to come in larger sizes than their Full HD counterparts to help make the difference between the two more noticeable, but even at the same size, you can see the benefits of a 4K image over a Full HD one. Side-by-side, a Full HD image will typically look flatter and softer, while a 4K picture brings out more detail and improved colour grading, making the picture sharper and vibrant.
The terms 4K and Ultra HD aren’t just about resolution, though. The technology allows for higher frame rates and better colour replication to give a more true-to-life image. 4K and Ultra HD TVs support 10- and 12-bit colour, over Full HD’s 8-bit capabilities. This means a wider range of colours are available on a 4K screen and therefore pictures appear more vibrant.
A bump in frame rate capabilities to 60 frames-per-second also means smoother action scenes and a sharper picture for frantic shows such as a football game or rugby match. Current TV is broadcast at 25fps – with films being shown at 24fps – so the bump in frame rate is certainly noticeable and can look somewhat unnatural at first, but it’s definitely an improvement.
What is 4K HDR?
4K HDR is yet another variable to factor in when understanding 4K, Ultra HD TVs and content. Not all 4K Ultra HD TVs actually come with HDR capabilities, which is why it’s worth holding out for newer, HDR-enabled sets to come down in price.
HDR, or High Dynamic Range, is all about the contrast ratio of a picture. It describes the range between the darkest and lightest shades in an image. Think of it like the HDR mode on your phone’s camera, with it enabled, photos appear more detailed with subtle shadows and bright areas all appearing clearly without impacting the rest of the image. 4K HDR is the same, but for video, and it’s absolutely stunning in motion.
Technically speaking, you can’t get HDR on Full HD panels – although you will see some retailers marketing their Full HD screens as such, it simply means they’ve used some contrast technology to emulate the effect. By picking up a 4K Ultra HD TV you’ll be able to snap up HDR technology if the TV you’ve bought supports it.
Where can you watch 4K footage?
An increasing number of services are offering 4K content, with Netflix and YouTube being the standard-bearers for the service. If you’re so inclined, you can additionally get 4K Blu-ray players – or just an Xbox One S – to watch Blu-ray films and shows in 4K. Both Sony’s PS4 Pro and the upcoming Xbox One X from Microsoft support 4K for video content and certain games – with a library that’s growing by the day.
All of these services support HDR, but you’ll have to ensure you’ve bought a HDR-capable Blu-ray player and a Blu-ray disc that’s encoded for HDR. Many PS4 Pro games also need an update to display in HDR and the standard PS4 and Xbox One S both output in HDR, even for games running at Full HD.