Color Management & Shifts

Hello,

i did some research on the subject, and maybe that question have been asked a million times, but i did not found a single topic on the exact same problematic. Sorry if i missed it.

I have come to use baselight and resolve, as a cinematography student. My setup is : a eizo cs2420 linked trough hdmi to a mini monitor ultrastudio linked by thunderbolt to a macbook pro with resolve lite on it.
So i don't use my gui for color correction. And i did calibrate my cs2420 trough displaycal, recently.

My question is about color management on resolve : i do understand it, at least i think so, coming from baselight, the idea is pretty much the same.

But : here is my interrogation : let's say i have a file coming from an arri alexa, in pro res HQ, Log C, or even a file from a Blackmagic Cinema Camera 4K in pro res HQ, Film dynamic range.
If i grade the footage (video levels / export video levels) with DaVinci YRGB, export, then reimport into resolve, there is absolutely no difference on scopes.
But, if, for example, i set the input color space to BK Design Film or Film V3 or Arri Log C, the timeline color space to rec 709 2.4 and output to rec 709 2.4, export, and reimport it into resolve, the footage looks completely different. The only way to get the same looking footage is to set the input on bypass or on the same space as timeline and output. And that way, when in export and reimport the footage, they look the same on scope and reference monitor. Could someone help me understand what i'm doing wrong ?

Best,

Matthieu Abily

In the color managed workflow, are you re-importing your graded clips into the same project, or a new project? And how do you have the input color space set when you bring in your graded clips?


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My advice would be not to mix two different color correction systems on a single project. It's always a good idea to keep things simple and straightforward.

Hello Mr Sterne, thanks for the answer.

I am reimporting them into the same project, via the media pool. The input color space remains the same as before and during the export : for example, if it is Input Color in BlackMagic Film V3, and timeline and output in 1886, it remains the same for the export, and then i add the file exported back in my timeline trough the mediapool, to check..

Hello Mr. Wielage. I want to keep thing simple, but the files are recorded in a specific gamma curves, even a specific gamut if i recall. It is also one of my questions, which profiles / curves should be picked when working with files from a 4K BlackMagic Cinema Camera. For example, on a F55 it could be S - Log 2. Which one should it be ? When working on baselight, it was the same idea, input for the space of recording, timeline for workspace and display referred output. Or we could work in ACES, with IDT & DRT..
So, i don't see why i should not mix different spaces.. or maybe that is not what you meant ?

Thanks

OK, so if your original input color space is BlackMagic Film V3, and your timeline and output are for example Rec 709 2.4, then when you export, the files you export are in Rec 709 2.4.

If you then bring them back into the same project without changing the input color space, then Resolve expects that your input color space is BM Film V3 and transforms them again accordingly. But the new files are Rec 709 2.4, they are not BM Film V3.

And as you note, if you set the input color space to bypass or set it to Rec 709 2.4, they look correct.

...or am I completely misunderstanding your issue?

Hello Mr Sterne, that is exactly right. So i think i do understand the problem.

But, here comes another question : coming from baselight, where you have to setup the color space of the files you're are working on, the color space where you want to work (usually larger) and the output color space (P3 or 1886 Rec 709 2.4), how should i setup the color management in resolve 14 ? I'll do my own research on subject.

Best,

Matthieu

I want to keep thing simple, but the files are recorded in a specific gamma curves, even a specific gamut if i recall. It is also one of my questions, which profiles / curves should be picked when working with files from a 4K BlackMagic Cinema Camera. For example, on a F55 it could be S - Log 2. Which one should it be ? When working on Baselight, it was the same idea, input for the space of recording, timeline for workspace and display referred output. Or we could work in ACES, with IDT & DRT.. So, i don't see why i should not mix different spaces.. or maybe that is not what you meant ?

I think there is a point where people wind up overcomplicating things quite a bit. My philosophy is it's very wise to keep things simple. Unless this is going to theaters, keep it all in Rec709 and work on it shot by shot. Especially if it's a student project.

I think there's a lot of merit to just using standard display-referred projects completely in Rec709. You can start from Log material (RedLogFilm, Alexa LogC, etc.) and then just use curves or contrast/pivot to fix the gamma curve. It does help to shoot a good color chart -- the DSC OneShot is very good -- and have all the cameras shoot that. Matching cameras is just a matter of practice and experimentation. Once you have an overall grade that works for that specific camera, you can store that as a PowerGrade and use it throughout the project, assuming the shots were done under the same conditions and exposure.

BTW, I have a couple of years of experience with Baselight, and even there, I tended to keep things pretty simple and normalized the gamma curve and color settings with layers. Once it's what I would call "Pseudo-Rec709," then I would use Video controls to correct it the rest of the way in Rec709 space.

There are so many options nowadays, I think people get very confused at all the different workflows that are possible. In the real world, we have to work under tight schedule and budget conditions and can't necessarily screw around with a lot of complex buttons and knobs and color spaces -- we just have to get the job done at the end of the day. Using shortcuts like PowerGrades makes this much, much faster. So does using a panel.

BTW, there is merit in using a Color Space Transform Node, as illustrated by Juan Melara in this piece:

http://juanmelara.com.au/blog/an-easier ... og-footage

I think this is a very advanced technique and I would not recommend this to neophytes, but it is worthwhile if you have the time to experiment. Again: if it were a student thing, I would say keep it simple and don't go crazy with this stuff. Get a reasonable-looking picture, make everything match, and move on.

Mr. Wielage.

I read your message with attention, and i'll follow your advice. When i first started color correcting, i did not lose myself in these complications. Those things picked my interest, and that is a good thing. But, if i follow you, you advise me to grade directly from the log, which at the end of the day, what i prefer doing.

And yes, i will make them match, and then only after work specifically on all of them.

I'll follow your advice and stay in Davinci YRGB rec 709 all the way.
It is not the first time you are giving me advices, and for that, i thank you.

Just to be sure : what you are saying, is that working in the indicated color space : Log C for rushes in Log C from the Alexa for example, only help correcting them to a more rec 709 visualisation, if rec 709 is selected in the output space ?

I'm not restricting my informations and signal by choosing to work in gamma 2.4 rec 709 space ?

Best,

Matthieu

Ps : i followed the video. I did not find it cumbersome at all, and rather a good idead. I will try to use it in my project to facilite my grade from Log.