True meanings behind 4K, HDR, Dolby Atmos and Ultra HD revealed – and why OLED TVs look so good


BUYING a new TV can be confusing, especially when you don’t know all of the jargon.

Here’s a quick guide to some of the most common terms you’ll see on a television spec sheet, and what they mean.


An OLED television is great, if you can afford oneCredit: Getty

What is 4K?

Imagine a grid of 4 x 3 squares – 12 in total.

If someone asked you to paint each one a different color to create a picture, it’d be hard to show anything detailed.

But if that grid was 400 x 300 squares, or 1,200 in total, you’d find it a lot easier to paint a detailed picture.

That’s how TV pixels work, but they’re significantly more dense.

A High Definition TV would have 1,280 pixels across and 720 pixels vertically, coming in at 921,600 pixels in total. This is known as its “resolution”.

Move to Full HD and you’re looking at a resolution of 1,920 x 1,080 pixels, or 2,073,000 pixels in total.

And 4K has 3,840 x 2,160 pixels for a display total of 8,294,400 pixels.

A 4K TV has around four times the number of pixels of a Full HD TV.

What is Ultra HD?

Ultra HD is, for all intents and purposes to the average consumer, the same as 4K.

And the terms Ultra HD and UHD are also interchangeable.

UHD is generally used for marketing, whereas 4K is a strict descriptor of resolution.

You’ll likely find either – and often both – on a 4K TV set.

And you’ll also find them used to describe pieces of content, video games, and other media devices (like an Amazon Fire TV Stick).

What is HDR?

HDR stands for High Dynamic Range.

It’s a term used to describe a piece of content that you might be watching.

But it’s also stamped on TVs to show that they can play HDR content in its true HDR form.

HDR content has improved contrast (brighter whites and darker blacks), and a wider range of colors.

There are several types of HDR that have their own standards, so you might see branding like HDR10, HDR10+, and Dolby Vision.

HDR content is now very common: you’ll find plenty on Netflix or Amazon Video, for instance.

What is Dolby Atmos?

Unlike the other items on this list, Dolby Atmos is specifically for audio – not video.

It’s a surround sound technology that adds “height” channels in to regular surround sound that typically delivers audio on a flat plane.

Atmos was originally released for cinemas, but you can now buy Dolby Atmos speakers systems.

You’ll see Dolby Atmos stamped on certain pieces of content that support that kind of audio.

Dolby has its own visual standard too: Dolby Vision, which – as mentioned earlier – is a standard for HDR video.

What is OLED?

Traditionally, a modern TV would have a LCD – or liquid crystal display – screen.

That means your display is made up of lots of tiny crystals.

These crystals are then illuminated by a giant backlight at the back of the television.

They light up and you see an image. Television!

OLED screens are different: the name stands for organic light-emitting diode.

An OLED screen is made up of diodes with organic compounds that emit light when an electric current is passed through them.

So it completely removes the need for a backlight, because the pixels on your display light up on their own.

This has several advantages.

For one, they have the potential to be far more power-efficient because you’re not constantly running a backlight.

The lack of backlighting also means that your OLED display can be much thinner.

But the real advantage of an OLED display is that you can get a much better picture.

With a normal LED-backlit LCD display, you’ll never see true black – because the panel is illuminated.

But on an OLED screen, individual pixels can be completely turned off.

They can also be dimmed significantly.

So you’re seeing much more accurate blacks during dark scenes in a TV show or movie.

This makes OLED screens great for viewing HDR content, where contrast is improved.

OLED TVs started out as extremely expensive.

But the price has been steadily dropping, and OLED screens are now much more affordable.