HLG strategy - simultaneous grading with SDR or two passes ?

Hi,

Looking for the best workflow for grading HDR HLG - Rec2020 and SDR - Rec709 version, I’ve found accross the web contradictory strategy for doing this.
As HLG as meant to be backward compatible with SDR, on one side I’ve found some people who grade HLG with simultaneous monitoring HLG and SDR. But in that case the resulting SDR is not as good as as graded direct to SDR.
On the other side other people are grading HLG alone and after doing a second pass for SDR only.

And you, what is your approach ?
Does HLG need to be monitored also on SDR and adjusted for SDR ? Or could we simply work for HLG without taking care of SDR even if SDR version should follow not too far ?

Best,
Christophe

HLG by default won't look good on SDR monitor- it will be to dark. There may be other "look" issues also.

i've used the stereo approach with SDR in one eye and HDR in the other, each eye fed to the matching mon/proj

works really well

i'd not be comfortable doing one grade for both displays

I had a conversation with a colorist working on some major HDR shows the other day, and I was surprised to learn he's doing the Dolby Vision HDR pass AND the SDR pass simultaneously, in 3 days. He finds when the HDR pass looks good, he's able to come up with a very good SDR image using the Dolby CMU.

I know of other people who have done the SDR pass first and then brought in the Dolby CMU and done a tone-mapped HDR version which then gets tweaked shot-buy-shot. There are pros and cons to each approach.

I suspect there will be quite a bit of HDR news at NAB in a few weeks.

HLG is supposed to be compatible with SDR monitoring, so double monitoring is a must.
Not comparable with HDR10 grading recommendations.
I grade with my reference set to SDR and my calibrated client display set to HLG.

But honestly, I don't see any benefit in the backward compatibility. The SDR version always looks dull because HLG and SDR are display refered standards and the upper part of the brightness is simply ignored from SDR displays.
Then the SDR display must be set to Rec.2020.
All this doesn't really make sense, sothat it's best to create two versions. This is also what I tell my clients.

Hi all,
Thanks for all your feedbacks.

About the starting point for a second pass for SDR-Rec709 version I did several tests with internal tools : LUT (Hybrid Log Gamma to gamma 2.4), Color Space Transform (as OFX or via Resolve Color Management) but finally the simplest look te be the better : only a Color Space Transform on Color Space : Rec2020 to Rec709. And then mostly highlight and contrast adjustements.

Any thoughs ?

Best,
Christophe

Sounds right- you do fixed math where it's 100% defined (Rec.2020 to Rec.709) and then it's human choice for highlights adjustment. For me this should be always better than any automated/fixed math way.