HLG Update

[chris319]

I received this information from an "informed source":

an update to BT.2408 is in the pipeline. It makes it clear that the 75% HLG signal level for HDR Reference White is the primary anchor point in live production.  It goes on to say that the 18% grey card reference is likely to change when typical camera painting (or colour grading) controls are applied.

Also worth a mention is that we've found operational staff find it too confusing to have both a 75% and 73% reference levels for different whites. So even a 90% reflectance chart is usually lined-up at 75% HLG.

I don't think anyone is actually using PQ in professional TV acquisition, and its a moot point as to whether those cameras that do support it actually  implement the PQ reference OETF.