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How Important is Local Dimming on a TV?

How Important is Local Dimming on a TV?

The TV has come a long way since its invention in 1927.

It transitioned from black and white to color, lost weight considerably, and the display got bigger and bigger with no signs of stopping. The TV is one piece of technology we don’t appreciate enough.

Only the massive TVs that we will never be able to afford tend to grab our attention. The TV we already own or could realistically purchase gets snubbed.

The most significant changes to a TV have been in its display. The TV display has undoubtedly become more prominent and colorful over the years, but we should not ignore the little modifications.

Fancy features like HDR and 3D have undoubtedly made a splash. Still, the less fancy or more technical sounding terms such as “local dimming” have also made watching TV an overall pleasant experience.

But what is “local dimming”? What does it achieve, and how important is it to a TV? Read on as we dive deep to answer the questions and more.

What is Local Dimming?

Local dimming is a screen technology that helps a display put out blacks better or achieve a better contrast ratio. It’s a hardware feature usually found in LCD HDR TVs. 

Local dimming employs backlighting behind the LCD, which adapts to the image shown.

The feature makes the dark portions of a scene darker, enhancing the overall image quality. The dimming functionality comes in particularly handy when watching HDR content.

a man watching TV at home in dark room

Local Dimming Types

Local dimming is mainly categorized as full-array local dimming (FALD) and edge-lit local dimming.

Full-array local dimming denotes a complete spread of individual LEDs lighting up the LCD panel from behind.

These lights are not individually controlled but in zones. Based on the TV model, the number of lights per zone could be a few dozens or more. The exact number is usually not known.   

The various zones take care of the lighting for specific screen portions. If an object shown on screen is smaller (for instance, night-time stars), the dimming effect won’t be apparent.

And if a particular zone is not lit and the one adjacent to it is on, a halo effect could be seen around an object. These artifacts are referred to as “blooming.”

At its best, full-array local dimming is the best representation of the display technique.

Edge-lit dimming is local dimming on panels with LED lights across their edges, projecting light toward the screen’s center and not straight at the viewer.

Because there are fewer lights or the positioning of the lights is not standard, the dimming effect isn’t the best, particularly compared to FALD.

Based on the TV, the LEDs could be along the screen’s four sides, on just two sides (right and left, top and bottom), or just one side (usually top or bottom).

At times, the local dimming is almost invisible, or large portions of the screen could dim simultaneously.

When it works, the picture shows noticeable improvements. But the effect still cannot be compared to full-array dimming. Edge-lit dimming is more common of the two dimming techniques since it’s less expensive to make and incorporate.

Some TVs implement neither full-array nor edge-lit but “global dimming.” When global dimming is enabled, the entire picture gets darker during dark scenes or fully illuminates with bright scenes.

dark scene on the TV mounted on the wall and woman's feet on the mattress in the bedroom

Unsurprisingly, it’s the least effective dimming effect and is usually not considered actual local dimming.

Local Dimming is Not Perfect

Not all TVs have local dimming, and not all those with dimming functions perform excellently. The real-world output depends on the number of dimming zones and the panel backlighting. The more the number of dimming zones, the better or more precise the dimming will be.

The more premium TVs tend to handle local dimming better than the mid-rangers.  When not implemented well, local dimming may worsen picture quality.

Common concerns include:

  • a trail light following bright moving objects
  • black crush or the loss of information in the dark portions of a scene
  • unintended dimming or bright portions not looking as bright (a rare occurrence), and
  • uniformity concerns or fluctuating brightness levels across the screen.

How well local dimming works also depends on the dimming level. The backlight can emit less or more light with specific dimming settings.  

A low dimming setting dims the backlight less, which means you don’t get the best contrast levels. A higher setting shall dim the lights more but could cause blooming issues.

It’s recommended to try the various settings out before settling on one.

How Important is Local Dimming on a TV?

Local dimming helps LCD panels display blacks close to OLED quality.

Unlike OLED displays, LCD panels are not self-lit. An LCD needs external backlighting to illuminate its pixels and show the picture on the screen.

The LCD screen does a pretty good job of filtering the light. However, it cannot prevent all light from trespassing. As a result, blacks do not look black enough. They are usually dark grey.

Local dimming helps ameliorate things considerably, targeting the dark areas of a screen and dimming the backlight.

The result is darker dark portions, with the bright bits remaining untouched or as bright as they must be.

In short, the contrast between light and dark objects increases significantly, all thanks to local dimming.

couple watching a romantic movie in dark room

Is Local Dimming Worth It?

Yes, local dimming is worth it if it’s implemented well in the TV and you’ve chosen the proper settings.

If you like the dark portions to be appropriately dark and bright areas to be lit correctly in a scene, grab an OLED TV.

a LG Signature OLED TV on display at the exhibition

The next best option is an LCD or QLED TV with local dimming. The dimming feature comes very close to OLED.

But because local dimming doesn’t turn off LED lights individually but in zones, it cannot fully achieve what OLED can accomplish.

Should the Local Dimming Be On or Off for Gaming?

a man playing video game on TV at home

Local dimming plays true to its character during gaming. However, some TVs could have issues rendering visuals in gaming mode with local dimming enabled.

Likely issues are excessive blooming, bright objects in a scene not standing out as much, and no real improvements in dark backgrounds.

But even when there are no issues, there’s not much of a positive impact when gaming with local dimming turned on.

It’s, therefore, recommended to turn off local dimming during gaming. But because dimming performance varies across panels, try out the feature on your TV and see if you like it.

If there are noticeable changes you like or the dimming function enhances your gameplay, let it remain.

FAQs

Do OLEDs Have Local Dimming?

a Sony OLED Bravia TV on display at the exhibition

OLEDs do not have or don’t need local dimming as they achieve the same effect with their self-emitting pixels.

An OLED panel usually performs better since the dimming functionality is built into the display and per pixel. That means zero blooming and inky blacks, among other positives.  

Conclusion

You can change a scene’s contrast and brightness level on your TV individually. But those alterations apply holistically.

On the other hand, local dimming targets individual LED backlights or specific portions of a scene, resulting in a much better contrast ratio.

Local dimming is, therefore, important to have in a TV. 

But the dimming feature is not perfect. It could be implemented haphazardly in some TVs, causing users to turn off the feature altogether. 

Luckily, the glaring concerns are not typical and are usually among the lower-end models. Most TVs do a great job with dimming; even edge-lit panels look good when they work correctly. 

But, if you’re out shopping, choose a TV with full-array local dimming. It is more expensive than edge-lit dimming but is worth the extra spend.

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