HDR10 vs HLG: what's the difference for capture and streaming?

HDR10 and HLG are both high dynamic range (HDR) formats: each carries a wider range of brightness and colour than standard dynamic range (SDR). The short answer is that HLG suits live broadcast and HDR10 suits recorded and on-demand content. They differ in how the picture is described to the display, and that decides where each one fits.

HDR10 uses the PQ (perceptual quantiser) curve together with static metadata: one description of the content's brightness range and mastering display, set once for the whole programme. The display uses that metadata to map the picture to its own capabilities. This suits recorded and on-demand content, such as streaming services and finished productions, where the file and its metadata travel together.

HLG (Hybrid Log-Gamma) was developed by the BBC and NHK for broadcast. It carries no separate metadata, and it is designed to be backward-compatible: an SDR display fed an HLG signal shows an acceptable picture, whereas an HDR10 signal on an SDR display generally looks dull and washed out. That is why HLG is the practical choice for live broadcast, where one signal has to serve every viewer's screen and nobody knows in advance what those screens are.

Rule of thumb: for live broadcast, or anywhere the signal might reach an SDR display, choose HLG. For recorded or on-demand content where every stage of the chain handles HDR metadata, choose HDR10.