Video and displays
Local dimming
A backlight technique that divides an LCD into zones that brighten or darken independently to improve contrast and black levels.
An LCD panel cannot block light completely, so a conventional edge-lit set shows uniform grey where black should be. Local dimming splits the backlight into zones, each driven separately, so a dark region gets a dim backlight while a bright region gets full power.
This is the main reason a good LCD can produce convincing HDR: highlights get high peak brightness while adjacent shadows stay dark. The limitation is blooming, a halo around small bright objects, which shrinks as zone count rises.
Edge-lit sets may have only a handful of zones, full-array sets run from a few dozen to several hundred, and Mini-LED backlights push into the thousands. More zones help most on small bright objects against black, such as subtitles or starfields.