What is 4K TV and Ultra HD?

Everything you need to know about 4K and UHD

With 4K TVs now arriving in numbers and at increasingly affordable prices it’s no longer just a technology for the tech-minded early adopter market. So we thought we’d have a crack at answering some of the most commonly asked 4K-realated question to save you a load of time and effort.

Q: What exactly is 4K?

A: 4K – also known as UHD (more on this in the next answer!) – is a picture technology that quadruples the number of pixels found in a full HD picture. These pixels are usually arranged in a 3,840 x 2,160 configuration, compared with the 1920×1080 you get in a full HD TV.

Q: What is the difference between 4K and Ultra HD?

A: While 4K is the most commonly used name for content and screens that use 3,840 x 2,160 pixels, some brands prefer the term Ultra HD – or UHD for short. While confusing, there is actually some logic to the new UHD term. That’s because it provides a way of distinguishing between the 3,840 x 2,160 resolution adopted by 16:9-ratio TVs and the slightly different 4096×2160 resolution first introduced in digital cinemas (and actually employed by Sony’s domestic 4K projector range). However, 4K is used so widely to describe 3,840 x 2,160 displays and content now that the roots of the technical distinction between the 4K and UHD terms have been all but lost outside of the projection world. In other words, for most people the two terms have become interchangeable.

Q: Is 4K actually any good?

A: While 4K has its detractors, we’re big fans. The extra resolution of 4K images adds more detail, more depth and more colour resolution to the picture, resulting in images that look incredibly life-like – more like looking through a window than watching TV. 4K is especially effective on very large screens – so ideally you’ll go for a 65-inch set or even bigger. That said, we’d argue that 4K resolution clearly improves picture quality at pretty much any screen size. An interesting point about 4K that may help you appreciate its importance to image quality is the fact that 4K is considered by the film-making community as being able to reproduce in pixel form the sort of resolution and ‘finish’ you get with 35mm film. Though that hasn’t stopped some films studios from starting to remaster film prints in 8K! So far as we’re concerned the only problems with 4K from a picture quality perspective are likely to be caused by video compression applied to its distribution, motivated by the difficulties involved in distributing the huge quantities of data associated with 4K masters.

Q: Do I need to sit nearer my TV to benefit from 4K?

A: To get the best from 4K, it is recommended that you sit closer to your screen than is recommended with HD TVs. This is partly so you can most clearly appreciate the extra resolution, but also because it makes the 4K image fill more of your field of view, making for a more immersive experience. There are also ‘scientific’ charts in circulation suggesting that you need to sit extremely close to 4K TVs in order to appreciate the extra resolution at all. However, while we’d agree that you get the most impact from 4K if you sit close to it, we reject the notion that you get no benefit at all from more distant viewing positions. You still perceive more depth, colours still look more smoothly rendered, and objects within the picture still look more solid and three-dimensional.

Q: Is a 4K TV all I need to start watching 4K?

A: No. While your 4K TV will use processing to upscale HD and even standard definition pictures to its 4K pixel count, if you want to watch 4K at its best you will also need a native 4K source. Which brings us neatly to our next Q&A…

Q: What broadband speed do you need to stream 4K?

A: Taking Netflix for example, you’ll need a minimum of 15Mbps. And your speeds need to remain consistently at or above that figure. As soon as you drop lower – due to high contention rates at peak usage times, say – the picture will slip back into HD mode. To try and cover itself for this eventuality, Netflix actually says on its website that you need 25Mbps minimum. But we’ve confirmed with Netflix that a consistent 15Mbps is enough. Compression techniques improve all the time, so it’s possible you may in the future need slightly lower broadband speed to experience 4K on Netflix or other rival 4K streaming platforms. But bear in mind that high levels of compression inevitably negatively affect picture quality, so if you’re serious about 4K a fast broadband connection is a must.

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