MiniLED is a backlight approach used in some LCD displays. Local dimming can change backlight output across separate screen areas, while a bright object on a dark background may appear surrounded by a halo known as backlight blooming. Its visibility depends on the display and viewing conditions.
1. How LCD vs. OLED Backlighting Works
To understand blooming, we must compare screen structures:
- OLED (Self-emissive): Pixels produce their own light, so an individual pixel can be turned off. Actual image appearance also depends on the panel and viewing conditions.
- LCD: The panel controls light from a backlight to form an image. Backlight layouts and local-dimming features vary by display model.
- MiniLED with local dimming: Uses small backlight LEDs behind an LCD panel; some models group them into separately controlled areas called local-dimming zones. The number and layout vary by product.
2. The Cause of Backlight Blooming
A local-dimming area can cover multiple LCD pixels. When a bright object is smaller than the area used to illuminate it, nearby dark parts of the image may appear brighter. This is one possible contributor to blooming; panel optics and processing also affect the result.
Zone dimensions and the number of pixels affected vary with the display's resolution and backlight design; a browser-rendered pattern cannot reveal those hardware details.
When a small bright object appears on a dark background, a display's local-dimming algorithm may raise the backlight in the area behind it. Light can extend beyond the object's edges, but the amount and shape depend on the display, its settings, content, and viewing conditions.
3. Dimming Algorithm Trade-Offs
Display manufacturers tune local dimming algorithms differently:
- Lower backlight output: May reduce the visible halo in some scenes, with a possible change in highlight brightness. The result depends on the display's controls and algorithm.
- Higher backlight output: Can make bright elements more prominent and may make halos more visible in some scenes. This is not consistent across all models.
Use the online MiniLED Blooming Test to view an adjustable moving pattern. It supports visual comparison only; it does not read or stress-test hardware zones.