Does HLG Increase DR When Rendered as Rec 709???

[Mark Romero 2]

Does shooting in HLG increase the dynamic range when your footage is going to be output to Rec 709? Is there a real world benefit when it will be displayed on youtube? This would be shot with a Sony a7 III.

In trying to justify upgrading from the a6500 to the a7 III and part of the appeal is the ability to shoot in HLG. Unfortunately, I still don't know whether shooting in HLG would give any benefit over shooting in S LOG or one of the Sony cinegammas if it is all going to be delivered as a rec 709 file primarily viewed on youtube.

Is outputting as Rec. 2020 and then uploading to youtube just a disaster waiting to happen? (Especially since I don't have an HLG monitor to grade my footage in the first place.)

Any insights are appreciated. Thanks in advance.

[Don Kotlos]

 

33 minutes ago, Mark Romero 2 said:

Does shooting in HLG increase the dynamic range when your footage is going to be output to Rec 709? Is there a real world benefit when it will be displayed on youtube? 

rec709/rec2020 are colorspaces so the dynamic range wouldn't change. Even though you can record in rec709 in the camera, I am not sure how wide the support for HLG with rec709 is. The standard is rec2020 so probably stick with that one. 

33 minutes ago, Mark Romero 2 said:

In trying to justify upgrading from the a6500 to the a7 III and part of the appeal is the ability to shoot in HLG. Unfortunately, I still don't know whether shooting in HLG would give any benefit over shooting in S LOG or one of the Sony cinegammas if it is all going to be delivered as a rec 709 file primarily viewed on youtube.

The benefit of HLG over SLOG for HDR delivery is that you don't have to spend time grading it. You can uploaded from your SD card and it should work. For non HDR delivery I haven't seen any real advantage of HLG with Sony cameras. if anything having to use rec2020 makes color harder to work with. So in the latter case I would stick with Cine/slog gammas with non-rec2020 color spaces. 

33 minutes ago, Mark Romero 2 said:

Is outputting as Rec. 2020 and then uploading to youtube just a disaster waiting to happen? 

Youtube has support for it so you could potentially just upload your videos with minimal to no grading,  but if you really need it then you should definitely find a monitor to see how your footage actually looks  . That will give you the ability to do more extensive color grading as well. 

[jonpais]

re: Sony 8 bit HLG from Paul Leeming's Leeming LUT One Facebook page:

Quote

Sony's 8 bit implementation is not strictly enough bit depth for precision high dynamic range... It's the same problem with S-log3. Not enough bit depth for precision in 8 bit but they put it in anyway as a sales point, even though using it causes big banding issues in post.

It is not possible to grade HDR content without an HDR monitor.

[Luke Mason]

Essentially, HLG gamma is just BT.709 with aggressive highlight roll-off. It's not advisable to do any intensive grading due to this highly non-linear distribution of bits.

If you have used BT.2020 gamut (often combined with HLG gamma as a default). Just map the gamut to BT.709 with some minor adjustment. The dynamic range will remain unchanged after export. After all, HLG is designed to work on both SD TV and HDR TV.

[Mark Romero 2]

@Don Kotlos

@Luke Mason

Just to confirm, you are both saying there is no advantage (in terms of DR) then in shooting HLG in Rec 2020, applying a LUT that converts it to REC 709, and then delivering in standard definition, correct???

Or am I misunderstanding your explanations???

[Don Kotlos]

Yes that is correct.

But again, rec2020 should be the preferred colorspace in most cases with HDR. 

 

[Mark Romero 2]

1 minute ago, Don Kotlos said:

Yes that is correct.

But again, rec2020 should be the preferred colorspace in most cases with HDR. 

 

Thanks.

I am guessing I won't have much need to shoot in HLG / HDR then, but if I do, will try to remember to shoot in rec 2020 gamut.

[jonpais]

@Mark Romero 2 Paul Leeming has a LUT for converting Sony a7 III HLG to rec709 if you’re interested.