“Local dimming” is a popular marketing word for LED LCD products. Local dimming, on the surface, appears to be a way to dim only the section of the screen that is needed while leaving the rest of the screen fully illuminated. Improved contrast ratios can be achieved by using this new technology. HDR footage, with its ability to capture the most intense high-contrast details, is an absolute necessity.
As a result, some types of local dimming are more effective than others.
This article is a condensed/expanded version of a portion of the LED LCD backlights discussed. More information can be found in the linked article. If local dimming is all you care about, continue reading!
Local Dimming – What Is It?
Local dimming, as the name suggests, is a feature that allows the illumination of LCD HDR displays to be entirely turned off in specified areas.
To achieve pure blacks, LCD screens use active backlights. Since it’s difficult to hide all of the light emitted by LCD displays, blacks on screens wind up appearing as dark shades of gray rather than genuine black on screens that use LCD technology.
However, it should be evident why local dimming is so crucial when we consider the additional brightness that HDR brings. Basically, by reducing the amount of backlight that is used to depict black, the contrast ratio of the monitor or TV can be improved significantly.
What Constitutes Good Local Dimming?
There are many factors that contribute to how well a display performs at local dimming, including the number of dimming zones the display has (the ability to turn off each individual zone). The more zones there are, the better the local dimming may be.
Local dimming quality can be affected by other factors such as the display’s backlight type, i.e., whether it is a direct/full array or edge lit panel.
There are two types of screens: one with LEDs embedded in its backlight and the other with LEDs strung along its edges, as their names imply. A direct-lit/full array display’s ability to precisely control the backlight makes it a better candidate for local dimming.
Full-array local dimming
This is the whole nine yards, so to speak. In this case, the name refers to an array of LEDs underneath the LCD panel that are all aimed directly at your eyes. The LED backlight may be seen in the mock-up on the right if the front LCD layer is removed.
It would be ideal to be able to individually control each LED, but this is rarely done. Instead, a predetermined number of “zones” is used. These could number in the dozens or hundreds, depending on the television. Unfortunately, the vast majority of LED TV manufacturers refuse to divulge this information.
There is a specific area of the screen that each zone is responsible for. Some objects smaller than the zone (such as stars at night) may appear muted due to local dimming not being applied. A halo or bloom may appear around a lit area of the screen that is brighter than the surrounding area if a nearby zone is not lit. “Blooming” is a frequent term for this type of artifact.
Full-array backlight local dimming offers the best visuals possible on LCD when it is at its peak performance level. TVs from the same manufacturer with one of the other illumination technologies listed below are always more expensive.
Full array local dimming is the greatest way to get the most out of HDR video on an LCD.
Size and pricing are the main drawbacks of this product. Due to the LEDs having to be set back from the screen (the farther away they are, the fewer LEDs are needed to cover the same area), this model has a little more depth.
Most top-of-the-line models from manufacturers are full-array, but this isn’t always the case… Edge-lit TVs have becoming more widespread since they are slimmer and less expensive to build. For this reason it’s imperative that you read the specifications (or our reviews) to see which models are full array before assuming that “local dimming” means anything at all.
Edge-lit local dimming
LED LCDs with edge lighting are the most prevalent. All of the LEDs on an edge-lit LCD TV point toward the center of the screen.
In this instance, “local dimming” becomes a little more loosely defined. The TV can still dim sections of the screen, but as you can see in the image above, those areas are significantly larger than they are when the complete array is used.
Edge-Lit vs Full-Array Local Dimming
The top, bottom, or sides of edge-lighted TVs are lit by a row of LEDs, whereas the back of full-array TVs is lit by a grid of LEDs spread out behind the screen. Despite the fact that edge-lit TVs are lighter and thinner than full-array TVs, they can’t produce as much brightness. The dimming capabilities of full-array TVs are also superior.
Local dimming can produce long streaks of light around bright sections of a picture on edge-lit TVs since the LED lights are all on the side of the screen. Full-array TVs will have more precise dimming zones since they have more LED lights spread out behind the screen, which will reduce the amount of light “blooming” around the brightest things.
Edge Lit vs Full Array Local Dimming 2
Local dimming zones get smaller the more zones a TV has. As a result, the blooming effect is reduced and overall contrast ratio is improved.
Local dimming, in addition to blooming, can produce other issues, such as “black crush.” This occurs when a feature intensifies the darkness of a picture, making it more difficult to see fine details in a dark image.
Should I turn local dimming off?
Due to the default setting of “High,” the lighter colours appear far too bright. As a result, the picture may look a little wonky or out of place at times. Check the picture quality by turning it off and see whether you like it. If it’s done right, it’ll look more authentic.
What is local dimming on a monitor?
Some monitors and most TVs have a feature called “local dimming” that is intended to enhance contrast. When the screen content is analyzed and divided into zones and backlights are adjusted to match the average luminance of each zone, it works.
It can be summarized like this: local dimming accomplishes the following tasks.
Check out our buying guides below if you’re in the market for an HDR gaming monitor, and we’re sure you’ll discover a model that meets your needs and price point.