Local dimming: everything you need to know

local dimming
LCD televisions do not produce light themselves. Rather, it is the work of backlighting, lighting that creates the image you see.

This is in contrast to older television sets (no pun intended). This is evident both in the fact that the images are now much sharper and in the fact that the black tones of the screen can sometimes look quite gray.

What is local dimming?

Local dimming is a function and a way to make the display on an LCD television much more realistic. In particular, it brings the dark shades of gray closer to their true black level. Everything looks much richer, the whole picture is accented perfectly and darker pictures and scenes look much more realistic.

This is achieved by dimming the backlight “locally” wherever the black tones are displayed. “Local dimming on TV” improves the contrast ratio (in other words higher) so that the parts that do not need to be dimmed are not affected.

Of course, this problem does not occur with OLED and MicroLED displays, especially with the best 75-80 inch displays. This is because, unlike backlighting, OLEDs use self-emitting pixels. These pixels go dark or light up individually, which means that the black is really black and otherwise.

Even for those who own an LCD TV, local dimming is a dynamic “solution” to the problem.

Local full array dimming

The best 4K televisions will find that they support FALD or full array local dimming. You also see it as direct backlighting or direct dimming with direct lighting.

This is generally understood to be the superior type of local dimming, as well as the most expensive and physically heavy type, with the LEDs all over the backlight.

If we understand FALD, we can easily understand the other types as well as the local dimming zones. The full array provides many small local dimming zones in the form of lights – hundreds of them – all dimmed individually. This leads to a highly precise and very well executed dimming, in which both brightness and darkness work 100%.

Of course, the use of FALD also means that more space is required (hence the “violent” explanation).

The local dimming zones

The zones mentioned above are essentially groupings of these LED arrays.

It is the local dimming zones that determine how effectively or exactly your television uses local dimming. Smaller zones help reduce blood flow to areas where it is not needed, while larger zones (which would of course be less) take up larger parts of the visual area, allowing a lot of light to pass over where it is not That shouldn’t mean that local dimming isn’t fully effective – maybe until it’s counterproductive.

However, the reactivity of the zones is also important. In some cases, you may notice a delay in which zones light up and darken after the “scene” no longer requires the specific situation and a small ghost image remains in your eyes for a split second or longer.

While many small lights (ie hundreds of zones) are used in full array local dimming, the other shapes are not as sharp.

Local dimming with edge and backlighting

Local dimming with edge lighting only uses LEDs on the edges of the screen (e.g. top and bottom), and from there the lighting is managed for the entire screen.

This is perhaps the most common form of dimming, which is also very common on smartphones. Although this allows the products to remain “slim” and light, the edges at which the LEDs try to illuminate the LEDs light up, and clearly both edges must reach the center of the screen.

Local dimming of the backlit television is closer to the entire array in relation to the LEDs distributed across the screen, but uses only a limited number of lamps – usually with only four to 12 zones, the brightness of which varies at the same time. This leads to deeper black tones, but also dims areas that may need brighter light.

UHD dimming VS Local dimming

After all, we also have a “newer” technology. UHD dimming is a form of local dimming that is developed and used exclusively by Samsung for its QDOT televisions (quantum dot TVs).

UHD dimming focuses on the strength of the contrast ratio and uses both a wider range of finer dimming zones and powerful algorithms that produce a much more refined level of local TV dimming.

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