Local dimming allows LED’s to darken the areas of the screen that require it without also darkening the brighter areas, which is why the user is able to achieve a better contrast ratio. Due to the fact that LED’s (regular and mini) are backlight dependent for image creation, they are unable to achieve a high contrast as some light always slips through resulting in the blacks becoming greyish.

Display Technologies like MicroLED or OLED are the complete opposite. These technologies are able to produce their own light and so are capable of completely shutting off individual pixels meaning true black can be achieved right next to white, which in turn means that such technologies are capable of achieving infinite contrast ratio.

Here Local Dimming comes into play, it helps regular LED’s to achieve a higher contrast ratio and compete with the likes of OLED’s. The following is a list of advantages and disadvantages of using LED local Dimming.

Advantages

Improved contrast: Local dimming can enhance the contrast of an image by selectively dimming the backlight in darker areas of the screen. This results in deeper black levels and brighter highlights, making images appear more lifelike and vibrant.
Reduced blooming: Blooming is a visual artifact that occurs when a bright object on the screen spills over into adjacent dark areas. Local dimming can help reduce this effect by selectively dimming the backlight around the bright object, creating a more natural-looking image.
Energy efficiency: Local dimming can be more energy-efficient than a traditional LCD display because it only uses backlighting in the areas that need it, reducing overall power consumption.
Wide viewing angles: Local dimming can help improve the viewing experience from wide angles, as it helps maintain a consistent level of contrast across the screen.

Disadvantages

Haloing: Haloing is a visual artifact that occurs when the dimming zones are not precise enough, causing a visible halo around bright objects on the screen. This can be distracting and can reduce the overall image quality.
Limited dimming zones: The number of dimming zones on a display can vary, and a display with fewer dimming zones may not be able to provide the same level of contrast improvement as a display with more dimming zones.
Potential for color inaccuracies: Local dimming can affect the color accuracy of an image, particularly in the areas where the backlight is dimmed. This can result in color shifts or inconsistencies.
Cost: Displays with local dimming tend to be more expensive than traditional LCD displays, which may be a drawback for some buyers.

In short

Overall, local dimming can be a useful feature for improving the image quality of an LED LCD display, but it may also come with some drawbacks. When considering a display with local dimming, it’s important to weigh the pros and cons and determine whether the feature is worth the additional cost.