Grading HLG BT2020

Get answers to your questions about color grading, editing and finishing with DaVinci Resolve.
  • Author
  • Message
Offline
User avatar

Yogendra Singh

  • Posts: 235
  • Joined: Sun Apr 30, 2017 5:51 pm
  • Location: Chandigarh

Grading HLG BT2020

PostMon Aug 20, 2018 7:18 pm

Guys,
Is there anyway I can utilise the full dynamic range of HLG format shot on a7III in BT2020. The possible color space transformation tips if you can give that would be great. TIA
https://www.instagram.com/weddings_by_yogendra/

Resolve Studio 18.0.1
Fusion Studio 16.2.1
Offline

Andrew Kolakowski

  • Posts: 9209
  • Joined: Tue Sep 11, 2012 10:20 am
  • Location: Poland

Re: Grading HLG BT2020

PostMon Aug 20, 2018 7:43 pm

There is no special approach needed. You just grade from source to HLG calibrated screen. That's it.
Offline
User avatar

Yogendra Singh

  • Posts: 235
  • Joined: Sun Apr 30, 2017 5:51 pm
  • Location: Chandigarh

Re: Grading HLG BT2020

PostMon Aug 20, 2018 8:04 pm

Andrew Kolakowski wrote:There is no special approach needed. You just grade from source to HLG calibrated screen. That's it.

So can it be made to view on a normal TV without clipping details?
Last edited by Yogendra Singh on Tue Aug 21, 2018 1:15 am, edited 1 time in total.
https://www.instagram.com/weddings_by_yogendra/

Resolve Studio 18.0.1
Fusion Studio 16.2.1
Offline

Andrew Kolakowski

  • Posts: 9209
  • Joined: Tue Sep 11, 2012 10:20 am
  • Location: Poland

Re: Grading HLG BT2020

PostMon Aug 20, 2018 11:30 pm

Don't understand your question.
You said you want to grade to HLG HDR.
If you have no HDR TV then forget about HDR and work in Rec.709.

If you then want HLG convert to Rec.709 then you can. Just adjust it. HLG will look dull (bit dark) on SDR screen without any processing.
Offline
User avatar

Yogendra Singh

  • Posts: 235
  • Joined: Sun Apr 30, 2017 5:51 pm
  • Location: Chandigarh

Re: Grading HLG BT2020

PostTue Aug 21, 2018 1:53 am

Yes, I would like to convert it to rec 709 so that it can run on normal LED TVs with its complete dynamic range.
https://www.instagram.com/weddings_by_yogendra/

Resolve Studio 18.0.1
Fusion Studio 16.2.1
Offline

Dermot Shane

  • Posts: 2720
  • Joined: Tue Nov 11, 2014 6:48 pm
  • Location: Vancouver, Canada

Re: Grading HLG BT2020

PostTue Aug 21, 2018 3:20 am

709's dynamic range and gamut are both far smaller than a modern camera can capture, or that negitive film could capture decades ago

there is tone mapping to convert HDR to SDR, to my mind, best thought of as a starting place for creative choices, not a final destnation
Online
User avatar

Cary Knoop

  • Posts: 1437
  • Joined: Sun Mar 12, 2017 6:35 pm
  • Location: Newark, CA USA

Re: Grading HLG BT2020

PostTue Aug 21, 2018 4:09 am

You could set up an HLG to Rec709 workflow like this:

settings-hlg.jpg
settings-hlg.jpg (69.72 KiB) Viewed 20942 times


The timeline gamma above is a log format, it is not essential to the result but depends on how you want the controls to work, you could for instance also use Rec709.

After this, you should map the wider dynamic range onto Rec709, Resolve also has tone mapping functionality but it is an auto mode, better to do it by hand to see what looks give based on the type of footage, exposure etc.
Offline

Andrew Kolakowski

  • Posts: 9209
  • Joined: Tue Sep 11, 2012 10:20 am
  • Location: Poland

Re: Grading HLG BT2020

PostTue Aug 21, 2018 9:35 am

This is more for case when you already have HLG master and want to do Rec.709 one.

If you're starting from scratch with Sony source files you don't do such a thing. You either set Resolve for HLG or Rec.709. If you don't have HLG decent monitoring then your only option is Rec.709.

I really don't understand what Yogendra is trying to do.
He wants to get most of the source as HLG Rec.2020, but then he is talking about watching it on SDR monitor.
If you want perfect solution you simply need to do 2 masters HDR and SDR one.
Offline

Martin Heffels

  • Posts: 29
  • Joined: Mon Apr 03, 2017 6:46 am

Re: Grading HLG BT2020

PostTue Aug 21, 2018 10:16 am

Andrew Kolakowski wrote:I really don't understand what Yogendra is trying to do.
He wants to get most of the source as HLG Rec.2020, but then he is talking about watching it on SDR monitor.


HLG is being experimented with as an alternative to S-Log/S-Log2/S-Log3, because it isn't as squeezed in the bitrate, and allows lower ISO.

I played around with it a bit, grading it down to Rec.709, and I find the end-result a bit more pleasing than with S-Log. For instance the skies stay blue, while on S-Log I find it has this odd Sony cyan-look.
I haven't found the ideal recipe yet, but I use ACES with an output transform to Rec.709 and set ACES Input Transform of the individual clips to Rec.2020 (Camera), and go from there.
Offline

Andrew Kolakowski

  • Posts: 9209
  • Joined: Tue Sep 11, 2012 10:20 am
  • Location: Poland

Re: Grading HLG BT2020

PostTue Aug 21, 2018 10:36 am

Well, now I understand original question properly :D
Oh well- still can't read English sometime.

Source is HLG Rec.2020 and destination just SDR. Is there a special approach? You just grade it to look which you like. You may use ACES or mentioned Cary's method. I don't know what gives you better start, you need to experiment. You definitely can get good result without any clipping. You will have to make artistic decision how data is spread in highlights, bu this is nothing special. Rec.709 is forcing you to squeeze all source data, but because source has much more data you can make those artistic decision ( this is why you want to shot in HLG or SLOG- to have more data to play with).
Funny enough, but according to Alister Chapman you should not use HLG as source for grading. It meant to be "final" signal, like Rec.709 for SDR is:
http://www.xdcam-user.com/2017/07/what- ... -used-for/

I assume when you start adjusting HLG for HDR output then you will quickly see that there is not much data to play with (like with REc.709 for SDR), but when you going down to SDR maybe it's good data to work with (alternative to SLOG). I've seen few people saying this.
Online
User avatar

Cary Knoop

  • Posts: 1437
  • Joined: Sun Mar 12, 2017 6:35 pm
  • Location: Newark, CA USA

Re: Grading HLG BT2020

PostTue Aug 21, 2018 2:36 pm

Andrew Kolakowski wrote:You may use ACES or mentioned Cary's method.

Unfortunately, you cannot currently use ACES with Resolve because Resolve has not updated to ACES 1.1.

Something that is rather puzzling to me since Blackmagic had plenty of time to put in ACES 1.1 for Release 15.
Offline

Andrew Kolakowski

  • Posts: 9209
  • Joined: Tue Sep 11, 2012 10:20 am
  • Location: Poland

Re: Grading HLG BT2020

PostTue Aug 21, 2018 3:24 pm

Also- Resolver doesn't have any ACES Input Device Transform for HLG shot content at all.
Whole ACES is nice on paper, in reality it's still problematic mainly due to IDTs, which apparently is key element.
Online
User avatar

Cary Knoop

  • Posts: 1437
  • Joined: Sun Mar 12, 2017 6:35 pm
  • Location: Newark, CA USA

Re: Grading HLG BT2020

PostTue Aug 21, 2018 3:28 pm

Andrew Kolakowski wrote:Also- Resolver doesn't have any ACES Input Device Transform for HLG shot content at all.

It will be in ACES 1.1.

HDR has improved in 1.1 (read: HDR in ACES 1.0 was not all that).
Offline

Alex Potemkin

  • Posts: 207
  • Joined: Tue Nov 01, 2016 9:27 pm
  • Location: Queens, NY

Re: Grading HLG BT2020

PostWed Jan 29, 2020 2:48 am

Cary Knoop wrote:You could set up an HLG to Rec709 workflow like this:

settings-hlg.jpg


The timeline gamma above is a log format, it is not essential to the result but depends on how you want the controls to work, you could for instance also use Rec709.

After this, you should map the wider dynamic range onto Rec709, Resolve also has tone mapping functionality but it is an auto mode, better to do it by hand to see what looks give based on the type of footage, exposure etc.


Hello Cary!

I have a strange problem with HLG.
What I need is to grade HLG (and have more dynamic range) to rec 709.

My settings for color management is exactly the same as on your screenshot.
But it doesn't work.

I have the setup with two displays, one with GUI and another connected via DeckLink MiniMonitor 4K.
I calibrated both GUI and DeckLink-connected monitor properly (for Rec 709 color space for sure); when I applying 3D LUT for GUI, I got exactly the same look in the viewer as on the monitor. I use GUI without 3D LUT therefore to have more control of how my grade may look on uncalibrated system (I work for stock videography, so I don't have a real client nor any particular technical requirements). I use QuickTime Viewer for preview; it don't have any color management and can't use the system CMS.

So, what is my problem?

1. When I use the setup explained above, with DaVinci's color management settings as on your screenshot (which is an expected setting for this task as far as I understand) I can easily get the colors I want on the calibrated display. But after export, the final clips look terrible, with a strong color cast, lake of contrast, and oversaturated colors with lost details. It is more similar to clips' look in a color viewer without 3D LUT but worse, it is not even close match.
2. When I turning off all luts in color management, both for viewer and monitor, I can have something "acceptable" on the screen, but after render the clips appear very different anyway (and again, with flat dull colors but harsh gradients and oversaturated colors and missed details).
3. But if I set color management to "DaVinci YRGB" with Timeline color space Rec 708 Gamma 2.4, the things are changing totally. I can grade clips what I want (I use 3D LUT Creator to set a proper color space conversion, then I polishing grade in DaVinci) and after render, I have clips with perfect colors matching closely the screen.

Another funny thing is: when I grading in HLG, the difference in colors in the not-calibrated GUI color viewer and on the calibrated external monitor is HUGE and way over the real difference between two displays, with perfect colors on the monitor but dull and oversaturated colors in the GUI, and resulting clips don't match GUI nor monitor looks, even they are closer to the GUI as I explained in p.1. But when I grading in REC709, the looks on the calibrated monitor and in the not-calibrated GUI are different for sure, but this is a "real difference" between two displays (some differences in color tone, brightness, and saturation which are totally understandable), and the final clips going pretty close to the GUI but same time you may consider them as "close enough to the monitor to be good".

I can't explain this. Help me to understand, please!
Alex Potemkin
http://yourphoto.nyc
http://yourphoto.biz
http://getty.yourphoto.biz
http://istock.yourphoto.biz
http://alexpotemkin.com
Online
User avatar

Cary Knoop

  • Posts: 1437
  • Joined: Sun Mar 12, 2017 6:35 pm
  • Location: Newark, CA USA

Re: Grading HLG BT2020

PostWed Jan 29, 2020 4:45 am

Alex Potemkin wrote:I have a strange problem with HLG.
What I need is to grade HLG (and have more dynamic range) to rec 709.

My settings for color management is exactly the same as on your screenshot.
But it doesn't work.

I use 3D LUT Creator to set a proper color space conversion

I am not sure why you want to use the 3d LUT for color space conversion. The only time you want to use the 3D LUT is if you have a monitor that cannot be calibrated internally.

As long as the output color space is set to Rec709/2.4 you are grading in Rec709, not HLG.
Offline

Alex Potemkin

  • Posts: 207
  • Joined: Tue Nov 01, 2016 9:27 pm
  • Location: Queens, NY

Re: Grading HLG BT2020

PostTue Feb 04, 2020 2:40 pm

Cary Knoop wrote:
Alex Potemkin wrote:I have a strange problem with HLG.
What I need is to grade HLG (and have more dynamic range) to rec 709.

My settings for color management is exactly the same as on your screenshot.
But it doesn't work.

I use 3D LUT Creator to set a proper color space conversion

I am not sure why you want to use the 3d LUT for color space conversion. The only time you want to use the 3D LUT is if you have a monitor that cannot be calibrated internally.

As long as the output color space is set to Rec709/2.4 you are grading in Rec709, not HLG.


I mentioned "3D LUT Creator", not "3d LUT". This is brilliant software that provides a full control over conversion, with many creative possibilities and high accuracy.

Anyway, my problem with DaVinci native grading of HLG is solved: viewtopic.php?f=21&t=101253&start=200#p589831

Strange but the problem was with the output gamma 2.4; set it to Rec.709 and everything is back to normal.
Alex Potemkin
http://yourphoto.nyc
http://yourphoto.biz
http://getty.yourphoto.biz
http://istock.yourphoto.biz
http://alexpotemkin.com
Offline

Paul Anderegg

  • Posts: 16
  • Joined: Sun Aug 04, 2013 2:24 am

Re: Grading HLG BT2020

PostSat Feb 08, 2020 10:36 pm

Cary Knoop wrote:You could set up an HLG to Rec709 workflow like this:

settings-hlg.jpg


The timeline gamma above is a log format, it is not essential to the result but depends on how you want the controls to work, you could for instance also use Rec709.

After this, you should map the wider dynamic range onto Rec709, Resolve also has tone mapping functionality but it is an auto mode, better to do it by hand to see what looks give based on the type of footage, exposure etc.



Cary, could you recommend settings for basic transcoding of HLG/2020 to REC709? I use FCPX to transcode my Sony HLG clips to an HLG ProRes master, which I then bring into Resolve to convert into a REC709 SDR final file. I don't really do any grading, I set my camera up so the output should be good from the raw clips, as I shoot TV news. I am not really sure how to set any of the additional mapping settings, or if it matters if my timeline is HLG/2020 or REC709/2.4, in oder to get the best simple no grade transcode.

I find that any REC709 conversion that started out as HLG, at least for my Sony cameras, looks really poor, lots of noise in the blacks and everwhere (compared to shooting native 709), just looks "dirty". I like to make HDR10 clips out of the HLG stuff (no one can really view HLG today), which can look pretty sweet, but these fun clips still need to be processed to REC709 for broadcast by my station.

Paul
Offline

Andrew Kolakowski

  • Posts: 9209
  • Joined: Tue Sep 11, 2012 10:20 am
  • Location: Poland

Re: Grading HLG BT2020

PostSun Feb 09, 2020 3:03 pm

I doubt that without proper approach with grading per scene you can get better results with 'pure' HLG to Rec.709 conversion than from shooting Rec.709 in first place. If you don't know Resolve then I would say shoot Rec.709 and do simple correction in Resolve.

If you want "pure" conversion start project set to managed YRGB, with input set to bypass and timeline/output set to Rec.709 2.4 gamma.
Then put in first node Color Space Converter with these settings:

Image

Play with adaptation setting looking at different scenes in your footage trying to get best average setting. For me lower values (<10) work better. You can also go through your video and adjust scenes which don't look correct- just add cuts with 2nd node after color space conversion and play with basic settings- contrast, curve etc.
Online
User avatar

Cary Knoop

  • Posts: 1437
  • Joined: Sun Mar 12, 2017 6:35 pm
  • Location: Newark, CA USA

Re: Grading HLG BT2020

PostSun Feb 09, 2020 5:25 pm

Paul Anderegg wrote:Cary, could you recommend settings for basic transcoding of HLG/2020 to REC709?

For the most basic conversion I would use this:
hlg-rec709.jpg
hlg-rec709.jpg (84.25 KiB) Viewed 16769 times


If you want more manual control remove the gamut and gamma tone mapping.

It is important to grade on the timeline color space using Rec2020 and not hard clip the gamut using the 'Limit Output Gamut To' option. Only the output color space should narrow the gamut.
Offline

Paul Anderegg

  • Posts: 16
  • Joined: Sun Aug 04, 2013 2:24 am

Re: Grading HLG BT2020

PostSun Feb 09, 2020 6:10 pm

Thanks guys...yes, I agree, REC709 raw looks better than HLG transformed, especially with the high base ISO and noise of my Sony camera. I just like to shoot HLG for HDR10 clips for personal pleasure, but still require REC709 so I can get them broadcast at work on the news. I've got a secondary post out there asking for proper HLG to HDR10 transformation settings.

My new 16" Macbook Pro has a DCI 2020 capable screen, so unlike my 2015 Macbook Pro, I can actually work a 2020 timeline and grade without it looking all dull and washed out.

Paul
Offline

Andrew Kolakowski

  • Posts: 9209
  • Joined: Tue Sep 11, 2012 10:20 am
  • Location: Poland

Re: Grading HLG BT2020

PostSun Feb 09, 2020 11:51 pm

Paul Anderegg wrote:
My new 16" Macbook Pro has a DCI 2020 capable screen, so unlike my 2015 Macbook Pro, I can actually work a 2020 timeline and grade without it looking all dull and washed out.

Paul


This is far from being true :)
Mac screen is P3, not Rec.2020.
If you want to judge your image you need a proper monitoring on a calibrated screen, specially when we are talking HDR. Don't even try to judge HDR on Mac screen.
Offline

Andrew Kolakowski

  • Posts: 9209
  • Joined: Tue Sep 11, 2012 10:20 am
  • Location: Poland

Re: Grading HLG BT2020

PostSun Feb 09, 2020 11:52 pm

Cary Knoop wrote:
Paul Anderegg wrote:Cary, could you recommend settings for basic transcoding of HLG/2020 to REC709?

For the most basic conversion I would use this:
hlg-rec709.jpg


If you want more manual control remove the gamut and gamma tone mapping.

It is important to grade on the timeline color space using Rec2020 and not hard clip the gamut using the 'Limit Output Gamut To' option. Only the output color space should narrow the gamut.


You want to produce Rec.709 master yet you limit gamut to Rec.2020. How is this meant to work? Also simple method is based on pure math which can give strange results. Tone mapping is needed in order to produce better end result (not a reference pure math ones).
Last edited by Andrew Kolakowski on Sun Feb 09, 2020 11:59 pm, edited 1 time in total.
Online
User avatar

Cary Knoop

  • Posts: 1437
  • Joined: Sun Mar 12, 2017 6:35 pm
  • Location: Newark, CA USA

Re: Grading HLG BT2020

PostSun Feb 09, 2020 11:58 pm

Andrew Kolakowski wrote:
Cary Knoop wrote:
Paul Anderegg wrote:Cary, could you recommend settings for basic transcoding of HLG/2020 to REC709?

For the most basic conversion I would use this:
hlg-rec709.jpg


If you want more manual control remove the gamut and gamma tone mapping.

It is important to grade on the timeline color space using Rec2020 and not hard clip the gamut using the 'Limit Output Gamut To' option. Only the output color space should narrow the gamut.


How do you then control how gamut is converted?

That goes automatically from the tmeline colorspace to the output colorspace. The gamut tone mapper automatically limits out of gamut conditions or you can, of course, do it manually by checking the scopes. There is also an OFX for that.

The 'Limit Output Gamut To' option is designed in case you, for instance, want to limit P3 into a Rec2020 container. So you would not want to use that for converting HLG to Rec709.
Offline

Andrew Kolakowski

  • Posts: 9209
  • Joined: Tue Sep 11, 2012 10:20 am
  • Location: Poland

Re: Grading HLG BT2020

PostMon Feb 10, 2020 12:03 am

Cary Knoop wrote:The 'Limit Output Gamut To' option is designed in case you, for instance, want to limit P3 into a Rec2020 container. So you would not want to use that for converting HLG to Rec709.



Exactly and limiting into P3 and outputting as Rec.2020 makes sense.
In our case you limit (already Rec.2020) into Rec.2020 and output as Rec.709.
End results is what- Rec.2020 in Rec.709 ? Makes no sense for me. Higher gamut can't be inside smaller end one.
Online
User avatar

Cary Knoop

  • Posts: 1437
  • Joined: Sun Mar 12, 2017 6:35 pm
  • Location: Newark, CA USA

Re: Grading HLG BT2020

PostMon Feb 10, 2020 12:05 am

Andrew Kolakowski wrote:End results is what- Rec.2020 in Rec.709 ? Makes no sense for me. Higher gamut can't be inside smaller end one.

Correct but that is not what is happening. The output colorspace makes the final transform from Rec2020 to Rec709 (but it does not limit out of gamut conditions).

Limiting the out of gamut conditions can be done by the gamut tone mapping option or manually.
Offline

Andrew Kolakowski

  • Posts: 9209
  • Joined: Tue Sep 11, 2012 10:20 am
  • Location: Poland

Re: Grading HLG BT2020

PostMon Feb 10, 2020 12:14 am

So Output Color Space is last and most important limiting factor.
In this case "Limit Output Gamut To" does actually nothing. It basically passes source's Rec.2020 for final reduction to Rec.709.
I still prefer my settings :D

I'm just not sure if Timeline Color Space makes any difference in my settings. I assume it doesn't as filter will have access to all source data when it performs requested conversion.
Offline

Paul Anderegg

  • Posts: 16
  • Joined: Sun Aug 04, 2013 2:24 am

Re: Grading HLG BT2020

PostMon Feb 10, 2020 12:45 am

Andrew Kolakowski wrote:
Paul Anderegg wrote:
My new 16" Macbook Pro has a DCI 2020 capable screen, so unlike my 2015 Macbook Pro, I can actually work a 2020 timeline and grade without it looking all dull and washed out.

Paul


This is far from being true :)
Mac screen is P3, not Rec.2020.
If you want to judge your image you need a proper monitoring on a calibrated screen, specially when we are talking HDR. Don't even try to judge HDR on Mac screen.


Sorry, what I should have said was that the new Macbooks in FCPX will conform/transform (pick your word) the colorspaces to match the display, where as my 2015, if you throw a 2020 clip (like an HLG2020) on the timeline will look dark, colorless, and lifeless.

Paul
Offline

Andrew Kolakowski

  • Posts: 9209
  • Joined: Tue Sep 11, 2012 10:20 am
  • Location: Poland

Re: Grading HLG BT2020

PostMon Feb 10, 2020 12:51 am

Got it now. Still not very good way of judging HDR :)
Offline

Paul Anderegg

  • Posts: 16
  • Joined: Sun Aug 04, 2013 2:24 am

Re: Grading HLG BT2020

PostMon Feb 10, 2020 1:01 am

Andrew Kolakowski wrote:Got it now. Still not very good way of judging HDR :)


My HDR judging involves spitting out huge ProRes files then transcoding them using the fast 10 bit h265 Quicksync option in Handbrake on my i9-9900K PC, then playing back on. my Sony HDR/HLG TV :-)

I was looking at a BM Mini Monitor 4K for that PC, but it seems to be only HDMI 2.0a, not b, so not worky with HLG? Could be useful for HDR PQ still, for $125 used when they crop up on eBay.

Paul
Offline

Andrew Kolakowski

  • Posts: 9209
  • Joined: Tue Sep 11, 2012 10:20 am
  • Location: Poland

Re: Grading HLG BT2020

PostMon Feb 10, 2020 7:59 pm

This takes so much time.
Offline

Paul Anderegg

  • Posts: 16
  • Joined: Sun Aug 04, 2013 2:24 am

Re: Grading HLG BT2020

PostMon Feb 10, 2020 10:34 pm

You say you grade HLG using a MiniMonitor 4K? The spec I see say HDMI2.0a, which does HDR10/PQ, but HDMI2.0b is needed for HLG. Are you sure your seeing proper HLG on your Decklink? I'm also asking because i am buying one and want to know how you got it to do HLG if it in fact is triggering HLG on your monitor.

Paul

Alex Potemkin wrote:
Cary Knoop wrote:You could set up an HLG to Rec709 workflow like this:

settings-hlg.jpg


The timeline gamma above is a log format, it is not essential to the result but depends on how you want the controls to work, you could for instance also use Rec709.

After this, you should map the wider dynamic range onto Rec709, Resolve also has tone mapping functionality but it is an auto mode, better to do it by hand to see what looks give based on the type of footage, exposure etc.


Hello Cary!

I have a strange problem with HLG.
What I need is to grade HLG (and have more dynamic range) to rec 709.

My settings for color management is exactly the same as on your screenshot.
But it doesn't work.

I have the setup with two displays, one with GUI and another connected via DeckLink MiniMonitor 4K.
I calibrated both GUI and DeckLink-connected monitor properly (for Rec 709 color space for sure); when I applying 3D LUT for GUI, I got exactly the same look in the viewer as on the monitor. I use GUI without 3D LUT therefore to have more control of how my grade may look on uncalibrated system (I work for stock videography, so I don't have a real client nor any particular technical requirements). I use QuickTime Viewer for preview; it don't have any color management and can't use the system CMS.

So, what is my problem?

1. When I use the setup explained above, with DaVinci's color management settings as on your screenshot (which is an expected setting for this task as far as I understand) I can easily get the colors I want on the calibrated display. But after export, the final clips look terrible, with a strong color cast, lake of contrast, and oversaturated colors with lost details. It is more similar to clips' look in a color viewer without 3D LUT but worse, it is not even close match.
2. When I turning off all luts in color management, both for viewer and monitor, I can have something "acceptable" on the screen, but after render the clips appear very different anyway (and again, with flat dull colors but harsh gradients and oversaturated colors and missed details).
3. But if I set color management to "DaVinci YRGB" with Timeline color space Rec 708 Gamma 2.4, the things are changing totally. I can grade clips what I want (I use 3D LUT Creator to set a proper color space conversion, then I polishing grade in DaVinci) and after render, I have clips with perfect colors matching closely the screen.

Another funny thing is: when I grading in HLG, the difference in colors in the not-calibrated GUI color viewer and on the calibrated external monitor is HUGE and way over the real difference between two displays, with perfect colors on the monitor but dull and oversaturated colors in the GUI, and resulting clips don't match GUI nor monitor looks, even they are closer to the GUI as I explained in p.1. But when I grading in REC709, the looks on the calibrated monitor and in the not-calibrated GUI are different for sure, but this is a "real difference" between two displays (some differences in color tone, brightness, and saturation which are totally understandable), and the final clips going pretty close to the GUI but same time you may consider them as "close enough to the monitor to be good".

I can't explain this. Help me to understand, please!
Online
User avatar

Cary Knoop

  • Posts: 1437
  • Joined: Sun Mar 12, 2017 6:35 pm
  • Location: Newark, CA USA

Re: Grading HLG BT2020

PostMon Feb 10, 2020 11:29 pm

Paul Anderegg wrote:1. When I use the setup explained above, with DaVinci's color management settings as on your screenshot (which is an expected setting for this task as far as I understand) I can easily get the colors I want on the calibrated display. But after export, the final clips look terrible, with a strong color cast, lake of contrast, and oversaturated colors with lost details.

If it is outside of Resolve it is not a Resolve problem.
Bring the exported clip back in Resolve if it looks good it is setup, not a Resolve problem.
Offline

Alex Potemkin

  • Posts: 207
  • Joined: Tue Nov 01, 2016 9:27 pm
  • Location: Queens, NY

Re: Grading HLG BT2020

PostTue Feb 11, 2020 1:11 am

I can't answer because I'm grading HLG to REC.709 and have HLG timeli e but REC.709 output, so, I believe, I see REC.709 not HLG :)

Also, as I posted in another thread, I solved the problem with color shift in output. The trick is: you can't use Gamma 2.4 for output - you have to set output gamma tp REC.709

Paul Anderegg wrote:You say you grade HLG using a MiniMonitor 4K? The spec I see say HDMI2.0a, which does HDR10/PQ, but HDMI2.0b is needed for HLG. Are you sure your seeing proper HLG on your Decklink? I'm also asking because i am buying one and want to know how you got it to do HLG if it in fact is triggering HLG on your monitor.

Paul



Sent from my SM-G955U using Tapatalk
Alex Potemkin
http://yourphoto.nyc
http://yourphoto.biz
http://getty.yourphoto.biz
http://istock.yourphoto.biz
http://alexpotemkin.com
Offline

Paul Anderegg

  • Posts: 16
  • Joined: Sun Aug 04, 2013 2:24 am

Re: Grading HLG BT2020

PostMon Feb 17, 2020 2:53 am

Cary Knoop wrote:
Paul Anderegg wrote:Cary, could you recommend settings for basic transcoding of HLG/2020 to REC709?

For the most basic conversion I would use this:
hlg-rec709.jpg


If you want more manual control remove the gamut and gamma tone mapping.

It is important to grade on the timeline color space using Rec2020 and not hard clip the gamut using the 'Limit Output Gamut To' option. Only the output color space should narrow the gamut.


Here is an HLG test clip using your settings then uploaded tom YouTube at a very low bitrate.

Offline

dmknds

  • Posts: 6
  • Joined: Wed Jan 31, 2018 7:57 pm
  • Real Name: Jean-Pierre Demuynck

Re: Grading HLG BT2020 to Rec.709

PostTue Feb 18, 2020 4:12 pm

Excuse my bad English.

When you shoot RAW with your still camera and grade with Adobe Camera Raw or Lightroom, you can recover all your over exposed highlight with all the details to the lower dynamic RGB color space. You can do the exact same work when converting HLG BT2020 or HLG BT709 wich have more dymamic like RAW to REC.709 which is approx. the same as RGB.

Here is the wokflow that work pretty good for me, without the need to first convert 2020 to 709.

- Set your camcorder in HLG and the HLG Color Space to Rec.709
- Shoot normal contrast scenes in standard Rec.709 and shoot only in HLG when the contrast is to high, such as bright white clouds or a backlit scene in front of a bright window.
- Shoot never in HLG1 nor in HLG2 because the camcorder will only respectively use the 16-207 and 16-226 range of the 16-255 8 bit signal. Losing bit depth in 8 bit is dramatic (banding artifacts)
- Shoot in HLG3 (the Zebra must be set at 97%, there is clipping at 100%) or better in HLG with the Zebra at 100% (there is clippng at 104%). On my PXW-Z90, I must add a little Color Saturation for HLG, not for HLG3.
- Shoot the highlights just with a very little ZEBRA. In the most cases, you have to seriously increase the aperture compared to the automatic exposure. This will ensure that you shoot with the minimum noise and that the full 16-235/240 values of the bit depth will be used. The high mid tones will be shifted to the beginning of the log part of the HLG gamma curve and are thus with poor contrast but this will be fixed in the next steps.
- Import your clip in Resolve in standard Rec.709 mode and set the Clip Attributes to Full level. Your project and the external monitor must also be in Full level. With this settings, the clip is imported as is without the 16-235 to 0-255 conversion, so the byte values are as is, and nothing is above 1023 in the RGB parade. The Black Level on the computer monitor will be at 16 instead of 0 but will be correct on the external monitor wich receives also 16, which is black for him.
- Add a curve or gain node so that the peeks are just at 1023.
- Add a curve node. Many points are needed to build the curve to recover the correct contrast in the shadows and the mid tones because the clip likes on Slog2, but more colored. Look at your external monitor. The last right point may not be to far to the right (~ 75%) and not higher than 80% to preserve informations in the highlights wich will at the moment appear with a lack of contrast, but this is fixed in the next steps.
- Export your clip in 16 BIT still TIF's (essential to avoid banding artifacts), and never in an YUV codec because the Adobe programs do always the 16-235 to 0-255 conversion at YUV import time, wich destrois all your highligts.
- Import this sequence in a 16 BIT After Effects project (or make an automated Action in Photoshop to execute the following steps).
- Put a Levels filter in the clip with Input Back at 16 so that black is now at 0 and then a manualy tuned Shadow/Highlight filter. I find it's the most important filter that exist and wich can not be found elsewhere and that can never be replaced with a LUT because it's an auto adaptative filter in function of the image contents. With this filter, you can recover all the contrast in the shadows and independently manly here in the highlights. It's difficult to adjust but the result is often as good as recovering shadows or highlights in a Raw file with Camera Raw if your black or highlights are not burnt out.
- You can now export a still photo. To export a clip for a standard Rec.709 Resolve project, you must first add a Levels filter with Output Black at 16 and you must export in an PSD or TIFF 16 BIT sequence. Never export in an YUV codec because the programm will do a conversion from 0-255 to 16-235, what is catastrophal in this case.
- If your Curve Node and Shadow/Higlight filter was correctly setup, you have almost the same result as when shooting the same scene in RAW + Camera Raw grading. The Shadow part of this filter is even better than the Camera Raw tools.
- The most difficult part of the above workflow is the correct tuning of the curve node in Resolve, but once done, save it in a Still Grade wich can be later adjusted for other clips.
- Enjoy.
- With this worflow, you have lesser average banding artifacts and lesser noise with a 8 bit HLG camcorder than shooting in HLG with a 10 bit camcorder in Auto Exposure.
- The same workflow is OK for Slog2 and Slog3 but you must then add Color Space and Gain conversion Nodes in Resolve before the readjusted curve Node.
Online
User avatar

Cary Knoop

  • Posts: 1437
  • Joined: Sun Mar 12, 2017 6:35 pm
  • Location: Newark, CA USA

Re: Grading HLG BT2020

PostTue Feb 18, 2020 6:04 pm

I am sorry, but I can't call the posting above by member dmknds anything else than improper hacking.
It's not the way to properly handle an HLG source.
Offline

dmknds

  • Posts: 6
  • Joined: Wed Jan 31, 2018 7:57 pm
  • Real Name: Jean-Pierre Demuynck

Re: Grading HLG BT2020

PostWed Feb 19, 2020 10:59 am

I am not a hacker, but an electronic engineer and I have participated in the past in the development of the ITU-R standards. I never said that you should shoot in HLG as described if the goal is to create legal HLG. My workflow has the only purpose of using the HLG gamma curve in a non standard way to obtain a result in Rec.709 that it is impossible to do with the current tools! It will help the very many producers who believe that it is too early to abandon Rec.709 but who find themselves in front of scenes that it is impossible to shoot in this standard. The first clip was shooted in Rec.709 and the second was shooted in HLG3 converted to Rec.709 with the method described. You will never have the same result with a LUT and grading! This was shoot in 10 bit and it is possible that I had little banding artifacts in the sky if I had shoot in 8 bit. Excuse for the vignetting caused by a filter with a to small diameter. There is no any noise in the shadows, which was not the case if I had shoot in Slog2 or Slog3 and graded in the standard way.
Attachments
Rec709.jpg
Rec709.jpg (593.89 KiB) Viewed 16350 times
HLG to Rec.709.jpg
HLG to Rec.709.jpg (580.64 KiB) Viewed 16350 times
Online
User avatar

Cary Knoop

  • Posts: 1437
  • Joined: Sun Mar 12, 2017 6:35 pm
  • Location: Newark, CA USA

Re: Grading HLG BT2020

PostWed Feb 19, 2020 4:40 pm

dmknds wrote:My workflow has the only purpose of using the HLG gamma curve in a non standard way to obtain a result in Rec.709 that it is impossible to do with the current tools!

Sorry, but that is nonsense.

DaVinci Resolve has a colorspace transform from HLG to Rec709 (optionally with an automatic tone map) that works just fine.
Offline

ProDigital

  • Posts: 1
  • Joined: Wed Feb 19, 2020 1:32 pm
  • Real Name: Jean Drand

Re: Grading HLG BT2020

PostWed Feb 19, 2020 6:27 pm

The result obtained by dmknds (take a good look to this 2 photos) is very, very impressive, I tried it and it works beyond my expectation! I spent months trying to grade with all the Resolve tools (color transform + grading) without ever being able to get a result close to that of dmknds.

Many camcorders do not shoot 4K HLG in 10 bit but in 8. Furthermore, if you shoot in auto exposure, only a small part of the bit depth is used (often the 16-185 range). How can you put a so big dynamic in a so little space without banding artifacts? if you read the advice of Pros shooting in Slog, you will see that they advise to overexpose Slog2 by 1 stop and Slog3 up to 2 stops to reduce the noise and to better use the bit depth. This is exactly what dmknds does but using the HLG log curve with the advantage of shooting directly in the BT709 color space.

It seems there is a lot of confusion in most of the posts. BT 2020 not only has a bigger gammut but the color matrix is totally different (the byte values used to encode colors). If you watch BT2020 on a BT709 monitor, the colors are very strange. This phenomenon is not due to the biggest gammut but is due to the unmatched color matrices. It is the same issue as between BT601 and BT609, which was less serious because the color matrices do not diverge as much in this case. The first thing to do is therefore to convert BT2020 to BT709 (or better, shooting directly in HLG BT709) which can be delivered as is, but it is dark, the highlights lack contrast and there is quickly noise in the shadows. In the workflow of dmknds, it is not really essential to put Resolve in Full Data Levels, but it is important to have the highlights peeks just at 1023 with a Gain Node, otherwise recovering the contrast in the highlights in Adobe is less effective. If Resolve is set in Video Levels, then you have to export for example in 10 bit uncompressed YUV (v201 codec). Because Adobe automatically converts 16-235 YUV to 0-255 RGB and again to 16-235 YUV for export, the 2 Levels filters in Adobe are no longer needed. This will deliver a movie wich is directly broadcast safe. But, with the mentioned method, there are never twoo 16 to 10 bit conversions: the exchange between Adobe and Resolve is in 16 bit (in fact in 15 bit because Adobe works in 15 bit, not 16!), which is obviously better. This is recommanded for mastering.
Offline

4EvrYng

  • Posts: 610
  • Joined: Sat Feb 19, 2022 12:45 am
  • Warnings: 1
  • Real Name: Alexander Dali

Re: Grading HLG BT2020 to Rec.709

PostSun Apr 09, 2023 3:37 am

dmknds wrote:Your project and the external monitor must also be in Full level.

When you say project must be in full level what do you mean by that, please? Which setting is that?

Return to DaVinci Resolve

Who is online

Users browsing this forum: Google [Bot], Jim Simon, jtfgrading, panos_mts, shikawkee and 207 guests