What is Mini-LED Blooming & How Local Dimming Works

Unlike OLED where every single pixel is its own independent light source (8.3 million zones on 4K), Mini-LED displays use thousands of tiny LEDs grouped into hundreds or thousands of "local dimming zones" behind an LCD panel.

A typical high-end Mini-LED monitor features 576, 1152, or 2304 zones.

On a 4K panel with 1152 zones, each individual backlight zone is responsible for lighting over 7,200 individual screen pixels!

When a tiny bright object (such as a mouse cursor, a star in space, or white subtitle text) sits on a black background, the entire zone behind it must illuminate at high brightness. Because the zone is larger than the object, excess light bleeds into the adjacent black pixels, producing an optical halo known as blooming.

• Launch the ScreenCheck Blooming / Halo Test: Drag the bright highlight across black to see how backlight zones turn on and off in real time.

• Launch the Starfield Test: Tiny moving stars challenge the local dimming algorithm to balance peak brightness against dark space clipping.

• Launch the Subtitle Blooming Test: Evaluate light bleed into 2.39:1 letterbox bars.