What is local dimming?

If you’re in the market for a new TV, you may have come across the term local dimming. 

Keep reading to learn everything you need to know about local dimming, including what it is, how it works and all about the three main types of local dimming. 

What is local dimming? 

Local dimming is a display technology that improves the contrast ratio on LED and mini LED TVs. The technology works by dimming individual areas of LEDs to ensure that no light bleeds through the darker parts of a scene. It also makes blacks appear deeper and highlights look brighter. 

There are three types of local dimming – edge-lit local dimming, backlit local dimming and full-array local dimming. 

If a TV is labelled as having edge-lit local dimming this means that the LEDs are placed around the perimeter of the screen. This allows the TV to remain very thin but can cause issues with screen uniformity as there are no lights in the centre of the display. 

Backlit local dimming means there are 4 to 12 zones that are lit up from behind. Think of it like a more sparse version of full-array local dimming. 

Finally, there’s full-array local dimming. This method involves hundreds of small zones that are lit up with LEDs arranged uniformly behind the display. This creates a more contrasted effect with deeper blacks and brighter whites, making full-array local dimming well-suited to 4K HDR TVs. This technique does, however, require the TV to be a bit thicker to accommodate all of the LEDs and is generally the most expensive of the three. 

If a TV has global dimming listed as a feature, this means that there is no local dimming as the entire screen is dimmed at the same time. This means that the contrast on these screens won’t be as deep. 

OLED TVs don’t need local dimming because they produce their own light. This means that the pixels on these displays can be completely switched off to create true blacks and higher contrast ratios.