In digital imaging, high dynamic range (HDR) refers to technology capable of either capturing or reproducing a particularly wide range of brightness values relative to the "standard" of that particular technology.
When viewed on a low dynamic range (LDR) screen, brightness values are clipped (clamped) between 0.0, or black, and 1.0, or white. HDR displays are able to exceed the 1.0 "top" value for very bright lights to create effects such as light bloom.
Most consumer HDR displays use more modern display technologies (OLED, LED local dimming, etc.) that reduces or eliminates light bleed when the display is showing black pixels. This expands the brightness range further by more closely approximating a "true" black color. The precise definition of HDR reproduction often depends on the technologies in use; the definition of "HDR" for an OLED display encompasses significantly broader ranges of contrast than does an LED display.
Numerous HDR video formats exist, including Dolby Vision, HDR10, HDR10+, and HLG.