What is local dimming?

Ever heard of local dimming? We introduce you to this important LED TV tech and explain why it’s so important.

11 Apr 2018

When you’re choosing a new TV there is so much spec you have to consider – screen size, resolution, UHD, HDR, smart or not – the options are mind boggling. You may not even think to check out its local dimming.

But if you overlook its local dimming capabilities you could be missing a trick. Here’s why…

What is local dimming?

What is local dimming?

On most modern LED TVs, tiny LED lights shine through the LCD screen to give pixels their colour. But sometimes that light bleeds through where it shouldn’t, creating a halo around the dark areas of the screen. This is where local dimming comes in.

It can turn off individual areas of pixels so that blacks stay truer and whites are brighter. Perfect for when you’re watching movies or dark, brooding TV series.

There are 3 main types of local dimming – edge-lit, back-lit and full-array – and you’ll need to consider which is right for you.


Edge-lit local dimming

Most TVs with local dimming are edge-lit. As the name suggests, the LED lights sit around the edges of the screen instead of behind it.

They need fewer LEDs than back-lit or full-array models – so they’re thinner and more energy-efficient to run.

Sounds great, but there is a downside. Being so slim can worsen the screen uniformity – so colour and contrast levels may not be distributed evenly.

Back-lit local dimming

Back-lit local dimming

You guessed it – here the LED light is positioned behind the screen. Although just to confuse matters it may sometimes be called “global dimming” – same thing, just a different name.

Found on lower end TVs the LEDs act as one single light – so the entire image will get dark with darker scenes and light with lighter ones.


Full-array local dimming

The crème-de-la-crème of local dimming – again the lights sit behind the screen but this time they are zoned. So certain zones are dimmed and lightened as required for ultimate picture quality.

Full-array gets the best out of a 4K HDR (high dynamic range) TVs by giving even greater contrast of colours.

The downside? It appears on the top models so is more expensive. And the nature of the tech makes the screen deeper and TV heavier. This can make wall mounting trickier – but not impossible.

Which should I go for?

So, which should I go for?

It’s pricier but a full-array TV generally offers a more impressive picture.

But TV manufacturers are improving edge-lit displays – incorporating more local dimming zones so you get a similar effect while keeping the slim design.

If you’re looking for high picture quality at an affordable price and in a slim, lightweight design – then edge-lit TV is probably the right choice for you.


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