Local dimming on a TV is a feature that improves the contrast ratio and black levels by selectively dimming the backlight in specific areas of the screen. This allows for deeper blacks in dark scenes and brighter whites in bright scenes, enhancing the overall picture quality.
How Local Dimming Works
Essentially, local dimming divides the TV's backlight into zones. The TV analyzes the image being displayed and dims the backlight in zones that are showing dark content while keeping the backlight bright in zones displaying bright content. This contrast enhancement is particularly noticeable in scenes with both bright and dark elements.
Types of Local Dimming
There are three main types of local dimming technology:
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Edge-lit Local Dimming: The LEDs are located along the edges of the TV screen. This is generally the least effective type of local dimming, as it can be difficult to control the light accurately across the entire screen, often resulting in light bleed or "haloing" around bright objects.
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Back-lit Local Dimming: LEDs are positioned directly behind the LCD panel, but the number of dimming zones is limited. This offers better performance than edge-lit local dimming, allowing for more precise control of the backlight, although it may still exhibit some blooming.
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Full-Array Local Dimming (FALD): This is the most advanced and effective type of local dimming. LEDs are arranged in an array behind the entire screen, with numerous independently controlled zones. The increased number of zones allows for highly precise dimming, resulting in significantly improved contrast, deeper blacks, and minimal blooming. TVs with FALD generally offer the best picture quality, especially in dark viewing environments.
Benefits of Local Dimming
- Improved Contrast Ratio: Deeper blacks and brighter whites lead to a more dynamic and realistic image.
- Enhanced Black Levels: Dark scenes appear richer and more detailed.
- Reduced Light Bleed/Blooming: Though not entirely eliminated (especially in less advanced implementations), local dimming minimizes unwanted light around bright objects on a dark background.
- Better Picture Quality: Overall, local dimming significantly improves the viewing experience.
Considerations
- The effectiveness of local dimming depends on the number of dimming zones. More zones generally result in better performance.
- Different TVs implement local dimming differently, so performance can vary between models, even with the same type of local dimming technology.
- Haloing or blooming can still occur, particularly with edge-lit or back-lit local dimming. This artifact manifests as a glow around bright objects on dark backgrounds.
In summary, local dimming enhances your viewing experience by improving contrast and black levels through controlled backlight dimming. Full-array local dimming is the most effective technology for achieving the best results.
