And if you are working in HDR, you really, really need to read the whole thing ... carefully. Perhaps several times.
Francis also shared some tips that I'll also share verbatim ...
"Lumetri tools are agnostic of color space. Under the hood they are just working on RGB code values
Previously there was an HDR mode in Lumetri, but it was removed when we added color management. Premiere used to handle HDR by extending Rec709 with overrange data. The previous HDR grading tools operated on this overrange area and that approach is no longer appropriate for proper color management because you now can work in the HDR media space directly.
Contrast is not centered around 50nits – it’s centered around 50IRE. In SDR that does work out to 50nits, but in HLG and PQ it’s just in the middle of the range.
I recommend using the 10bit scope for most HDR work. The HDR scope is log scale and mostly useful for checking nits
Color wheels are lift, gamma, gain. So yes, each will affect the entire range to a certain degree. It’s worth noting that there is a highlight and shadow rolloff to help protect against hard clipping.
Exposure, highlight, shadows – yes, these work fine in HDR. The White control works pretty much like pure gain – you can increase exposure without the rolloff."
And some further tips ... on Macs, you need to use the "Extended Dynamic range monitoring" option, but on PCs, not really. But on both, you need to be using the Display Color Management option. Due to the calibration work on my system, I prefer to have that off in Rec.709 work. But it's needed for HDR work.
The scopes take a bit of working with to understand.As Francis notes, for normal working, stick to "10 bit" settings on the scope range settings in the lower right of the Scopes panel.
From checking values, the area right about 78 IRE on the left side scale seems to be about where the "HDR graphics white 203" value actually ... sits. So in the 10 bit scale, for HLG work, the brightest your gradated content should be placed at is between 75/80 IRE. The area above that should be reserved for your specular brights without details.
Whites is probably the best control for setting your peak speculars ... and use the Highlights tool to set the "graphics white" area to that 75/80 area. You can check by setting the Scopes scale to HDR, but yea, working there is a total pain. That log scale is nearly useless. But you can see where your values ended up.
Get very used to working one tool against another ... for instance, the Basic tab Shadow control versus the Wheels tab Shadow, which is actually (in colorist terms) a Lift tool, when setting the bottom values of shadows versus black point. This is where having a control surface you can map REALLY comes in handy, as you can map it so that you can be working both the Basic tab Shadow and color wheels Shadow/Luma slider at the same time.
In this case, you can pull the Basic tab Shadow control down while lifting the Color Wheels shadow slider to pull your shadows down (compress the shadows with the Basic tab Shadows) while keeping the black point up (with the color wheel's Shadow tool). Using the Color Wheels shadow luma slider seems to set black point seems better for most purposes than using the Basic tab Blacks control for this.
And of course, pulling the speculars above 80IRE with the Basic tab Whites tool, while pulling your gradated content to 75 or below with simulataneous movement of the Highlights control. Another example of tool against tool to target a specific response.
User interface or workspaces