HLG
Also known as: Hybrid Log-Gamma, HLG HDR
Hybrid Log-Gamma, an HDR transfer curve that looks acceptable on standard screens and shows extra highlight range on HDR displays without needing metadata.
Updated
What it means
HLG was developed by broadcasters as a practical way to send HDR video. Its curve behaves like a normal gamma in the darker and middle tones and like a log curve in the highlights. A standard screen shows a reasonable picture, while an HDR screen uses the extra highlight data to show brighter skies and specular reflections.
Unlike HDR10, HLG does not rely on metadata describing the scene brightness, which makes it simpler for live production and for cameras. Many drones, phones and some action cameras offer an HLG recording mode, usually in the Rec. 2020 color space and 10-bit depth.
It is sometimes treated as a lighter alternative to log profiles: more range than standard, less work than full log.
How it works in practice
If you plan to deliver HDR, HLG footage can go to supported platforms with fairly little grading, as long as the export keeps the HLG tags. If you plan to deliver standard video, you convert HLG to Rec. 709, either with your editor color management or with a conversion LUT.
Expose HLG carefully. Highlights have room, but skin and midtones should still sit where they look right, and 10-bit recording helps avoid banding in skies.
Previewing on an HDR-capable screen during editing avoids surprises, because a standard monitor cannot show what the highlights will look like.
What to watch out for
HLG footage viewed in a non-HDR app without conversion can look flat or slightly gray, and some editors misread it, applying the wrong curve. Check that your software recognizes the clip as HLG before you start grading.
Mixing HLG and standard clips in one timeline without color management creates mismatched brightness and color. Convert everything to one target first, then do the shot matching on top of that common base.
Some platforms and devices still handle HDR inconsistently, so a standard export is often the safer choice for wide sharing, with an HDR version kept for screens that can show it.
How RawClip handles it
RawClip does not convert HDR. For the most predictable highlight, convert HLG clips to a standard Rec. 709 look before upload, then the AI picks the best moments from them for your highlight.