Fuji X-T3 reborn with HLG

[androidlad]

2 hours ago, BrunoCH said:

Yes you are right. I don't know exactly the WB. But I use the AWB lock. I did not unlock between the two takes. Normally it is exactly the same balance between the Log and the HLG.

 

I use a samyang with an aperture ring de-clicked. I'm sure it's around F4 for the log and around F8 for the HLG.
I exposed the log and the HLG with the waveform of my SWIT 55.

 

On the screen of my imac, the HLG seems pretty well exposed (on QT and FCPX with Lut) EDIT: Add iPhone photo on my XT3

 

See my F-Log/HLG comparison post, HLG already looks visibly darker with matching exposure, it's impossible for your HLG shot to be 2 stops underexposed. I suspect that you got it mixed up, f/4 for HLG and f/8 for F-log.

FCPX and QT only apply a BT.2020 > BT.709 gamut mapping to HLG material, the gamma curve is untouched. I was able to recreate your FCPX look by applying a BT.2020 gamut to Alexa LUT (gamma passthrough):

Since HLG is an HDR curve, exposing it as if it's SDR won't make full use of it's optimised distribution of DR. You are also looking at the images on SDR displays with no real tone-mapping (as mentioned above, FCPX/QT just make it more saturated).

I shoot HLG strict with external monitor/recorder and load the BT.2100 to Alexa LUT to preview and assist in exposing correctly.

See the difference between the gamma curves and the push in shadow/midtone range for better highlight DR and roll-off:

[BrunoCH]

44 minutes ago, androidlad said:

I shoot HLG strict with external monitor/recorder and load the BT.2100 to Alexa LUT to preview and assist in exposing correctly.

So with a LUT you turn the gamma HLG into a gamma LOG (for monitoring and expose and after for grading)
Did I understand right?
In this case it is easier to use the Fuji LOG directly. No ?
Because the advantage of the HLG that would not have a problem with the magenta hue, I don't see it on my test.

[androidlad]

1 minute ago, BrunoCH said:

So with a LUT you turn the gamma HLG into a gamma LOG (for monitoring and expose and after for grading)
Did I understand right?
In this case it is easier to use the Fuji LOG directly. No ?
Because the advantage of the HLG that would not have a problem with the magenta hue, I don't see it on my test.

The LUT is properly gamma and gamut mapped Alexa 709.

This way you get better DR distribution than F-log. F-log throws away 0-90 in the 10bit range and has banding/blocking issue as well as magenta cast.

You used auto WB, with manual kelvin and tint adjustment the magenta hue is completely absent. See my original post.

[BrunoCH]

6 minutes ago, androidlad said:

The LUT is properly gamma and gamut mapped Alexa 709.

This way you get better DR distribution than F-log. F-log throws away 0-90 in the 10bit range and has banding/blocking issue as well as magenta cast.

Ok I understand. 

9 minutes ago, androidlad said:

You used auto WB, with manual kelvin and tint adjustment the magenta hue is completely absent. See my original post.

When I have time I will start again with a manual WB on the gray card. But I think that does not change anything. You hide the problem by removing magenta and putting more blue on your WB. But the problem will always be there.

[androidlad]

1 minute ago, BrunoCH said:

Ok I understand. 

When I have time I will start again with a manual WB on the gray card. But I think that does not change anything. You hide the problem by removing magenta and putting more blue on your WB. But the problem will always be there.

It changes everything.

In auto WB, the camera adds more magenta to HLG.

In manual WB, with WB shift at 0, F-log still has some magenta while HLG truely has 0.

By the way, the opposite of magenta is green, not blue.

[BrunoCH]

29 minutes ago, androidlad said:

It changes everything.

In auto WB, the camera adds more magenta to HLG.

In manual WB, with WB shift at 0, F-log still has some magenta while HLG truely has 0.

By the way, the opposite of magenta is green, not blue.

I lock the AWB. it's the same WB between the two takes. You're right the opposite of magenta is green.

I will do it again later. I have a lot of trouble explaining myself in English. It's too long. There is a small problem with magenta and Fuji. The XT3 pictures are absolutely beautiful. For me the problem is still there with the HLG.

[androidlad]

1 minute ago, BrunoCH said:

I lock the AWB. it's the same WB between the two takes. You're right the opposite of magenta is green.

I will do it again later. I have a lot of trouble explaining myself in English. It's too long. There is a small problem with magenta and Fuji. The XT3 pictures are absolutely beautiful. For me the problem is still there with the HLG.

Because you locked the WB, magenta was added to HLG. The camera applies the same WB setting to all picture profiles.

If you don't use auto WB and make sure WB shift is 0, there's no magenta at all.

Please do another more controlled test with everything manual, then make your conclusions.

[BrunoCH]

1 hour ago, androidlad said:

Because you locked the WB, magenta was added to HLG. The camera applies the same WB setting to all picture profiles.

If you don't use auto WB and make sure WB shift is 0, there's no magenta at all.

Please do another more controlled test with everything manual, then make your conclusions.

I redid a test more simple. All in manual. WB 5300K shift 0. I did not make your exposure optimized for the HLG but simply expose for that gray chart is at the same level on the log and on the HLG in waveform. There is only 1 stop difference (for the previous test I noted on a paper F4 and F8 but possibly I had to switch them)
The problem I'm talking about is that there are some kinds of magenta stains on the blue bag and the black sunhood. In final cut I put the LUT WBR on the log and  LUT gamut2020 to 709 on HLG. It is not your optimised workflow but it is a correct workflow, I think.
I see these kinds of magenta stains on both, Log and HLG (save a frame of both in FCPX)
Original file here :

https://we.tl/t-APn94Ttz7P

 

EDIT : I add an iphone photo of the scene. There are also magenta spots on the sunshade, but the blue bag is cleaner.

[Attila Bakos]

15 hours ago, androidlad said:

It's really important to expose HLG correctly because it maps 18% grey at a low 22IRE.

How did you find out that 22%? For a moment let's forget about Lutcalc data. I just shot a grey card at 46% in F-Log, using ISO640 and 1/40s. Then I switched the camera to HLG and shot the same card at ISO1000 and 1/60s. Looking by the numbers it's the same exposure (aperture did not change) but if there's no added gain in HLG then it's practically 2/3 stops lower than F-Log. In this case the grey level is about 32-33IRE.

[Stathman]

Following @androidlad's findings i did some tests trying to decide which to choose, Flog or HLG.

Camera Settings:

FLOG: ISO 640 - SHUTTER 2000 - WB 5300K - F8

HLG: ISO 1000 - SHUTTER 3200 - WB 5300K - F8

Both shots exposed with Multi Metering aiming at 0 on the display meter.

Here are the results:

 

FLOG CLEAN

 

 HLG CLEAN

 

FLOG + FUJIFILM FLOG to WDR BT.709 LUT

 

HLG + LUTCalc HLG to ALEXA X2 LUT

 

HLG + LUTCalc HLG Rec709 LUT

 

FLOG + FUJIFILM FLOG to WDR BT.709 LUT + MINOR EXPOSURE ADJUSTMENTS

 

HLG + LUTCalc HLG Rec709 LUT + MINOR EXPOSURE ADJUSTMENTS

 

 

You can download the original files if you want.

https://we.tl/t-1qqI0lonhz

[androidlad]

7 minutes ago, Stathman said:

Following @androidlad's findings i did some tests trying to decide which to choose, Flog or HLG.

Camera Settings:

FLOG: ISO 640 - SHUTTER 3200 - WB 5300K - F8

HLG: ISO 1000 - SHUTTER 2000 - WB 5300K - F8

Both shots exposed with Multi Metering aiming at 0 on the display meter.

Here are the results:

Nice. I think you got the shutter speed mixed up though?

[Stathman]

8 minutes ago, androidlad said:

Nice. I think you got the shutter speed mixed up though?

Yep! Fixed it, thanks.

I prefer HLG, I have to test it on skin tones though.

Also liked the LUTCalc's Rec709 lut better than Alexa X2 but I had to set black level to -6 for better results.

[androidlad]

33 minutes ago, Stathman said:

Yep! Fixed it, thanks.

I prefer HLG, I have to test it on skin tones though.

Also liked the LUTCalc's Rec709 lut better than Alexa X2 but I had to set black level to -6 for better results.

Cool, I use Alexa X2 because there's a nice saturation roll-off. But it's all quite customisable in LUTCalc.

[Stathman]

Yes, i will do some more testing with Alexa and LUTCalc's settings. Resolve also.

LUTCalc is pretty amazing. I didn't know there is something like this, but now I do thanks to you. So, thanks!

[MrSMW]

Looking forward to getting my XT3 back any day so I can have a play.

In the meantime, been doing some surfing and the HLG looks like my preferred option and looks pretty decent with that Alexa X2 LUT.

[ErisC]

Someone can put "HLG to ALEXA X2 LUT" to download

[Stathman]

49 minutes ago, ErisC said:

Someone can put "HLG to ALEXA X2 LUT" to download

https://www.sendspace.com/file/iemw3r

You can create it yourself though, its not that difficult.

LUTCalc is a nice tool.

 

[ErisC]

33 minutes ago, Stathman said:

https://www.sendspace.com/file/iemw3r

You can create it yourself though, its not that difficult.

LUTCalc is a nice tool.

 

Thank you very much!

[thephoenix]

how do you setup resolve color management input for xt3 hlg footage ?

[Stathman]

38 minutes ago, thephoenix said:

how do you setup resolve color management input for xt3 hlg footage ?

Correct me if I'm wrong, i think the correct way to do it is to use the preferred "HLG to xxx Lut" as a 3d output lut so any further corrections happening before the lut is applied to the image.