Hybrid Log-Gamma, usually abbreviated HLG, is an HDR system developed for television production and distribution. Its transfer characteristics combine different behaviour across the signal range, supporting an HDR presentation without relying on the same static mastering metadata model used by HDR10. HLG is often discussed in live broadcast workflows, where predictable production and distribution matter. A device still needs to recognise and handle the signal correctly. HLG compatibility should be checked explicitly rather than inferred from a general HDR logo or from support for a different HDR format.
HLG and PQ
HLG and PQ are different transfer systems, not alternative names for the same brightness mapping.
A broadcast-oriented approach
HLG describes a relationship between scene information, encoded values and display presentation that differs from PQ-based systems. The final appearance depends partly on the display environment and system interpretation. Its design supports practical television workflows, but this does not make every HLG programme interchangeable with SDR or remove the need for correct colour signalling throughout the playback path.
Compatibility needs qualification
HLG is sometimes described as backwards compatible because of how its signal is designed. That phrase should not be read as a promise of an accurate image on every older television or every unrecognising player. Colour interpretation, signal conversion and display behaviour still matter. A stream can decode successfully yet look wrong if another stage treats it as ordinary SDR.
Inspect a live programme carefully
When an HDR sports feed looks different from an HDR film, check the actual formats before adjusting the panel globally. The film may use HDR10 or Dolby Vision while the live feed uses HLG. Confirm the input mode during that feed, then compare another known HLG source if available. Different production choices can remain visible even when both paths work correctly.
An illustrative example
A television recognises an HLG sports broadcast, but an older connected player outputs the same programme as unconverted SDR. The second picture appears incorrect despite uninterrupted playback. The useful check is the signal’s transfer handling across that route, rather than whether enough network bandwidth is available.
Practical actions
- Check explicit HLG support for the active output route.
- Read the display mode while the live feed plays.
- Avoid applying a global correction based on one misread source.