HLG, short for Hybrid Log-Gamma, is an HDR format developed jointly by broadcasters for live and traditional television transmission. Unlike HDR10, HDR10+ or Dolby Vision, HLG does not rely on separate metadata sent alongside the picture to describe brightness.
Instead, HLG builds its extended brightness range directly into the video signal in a way that remains compatible with older standard dynamic range televisions, which will simply display a reasonable, though not HDR, picture from the same signal. This makes HLG well suited to live broadcast, where there is no time to author scene by scene metadata, and to reception paths such as satellite, cable or terrestrial television where metadata support can be inconsistent.
Viewers mainly encounter HLG through certain live sports and event broadcasts in HDR, rather than through streaming services or discs, which more commonly use HDR10 based formats. Our guide to antenna and reception covers how broadcast HDR fits into over the air and cable television more broadly.
