Douglas Dutton

RCM Workflow - White Balancing in Log space

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Hi everyone!

I've been experimenting with RCM and Davinci Wide Gamut and really enjoy it so far!

However I like to do my White Balance adjustment using printer lights to the log space of the image.

When I work with Prores, RCM cannot detect which camera the footage has been shot on, so I can balance the footage in the log space.

However when I work from the Raw or the  native camera file, Davinci will convert the footage to Rec709  2.4 (set as my output color space).

And that seems to be how my footage is inputed in Resolve.

In RCM workflow, How do you balance your footage in the log space and not in an already converted space?

Many thanks

Douglas

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Hey Douglas, 

I have also been working in Davinci wide gamut a lot myself lately and have been running into the same issue. I dont know if this will help but this has been my solution thus far, not sure if its entirely correct but I have had good results and more control over my images. I just keep my color space in rec709 and use a cst to convert my image into DWG so that i still have control over the log image since i find it comes in with something crushed from time to time. Like i said im not sure if this is right and if someone has a better workflow for DWG please respond LOL i would love some more perspectives

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RCM has a lot of bugs.
I think the best is to stay in DaVinci YRGB and to set timeline colorspace according to your source footage.
So for alexa source files you set timeline colorspace to Alexa LogC.
So HDR pallete works as it should. And Global now behaves like WB in RAW (Gain in linear LMS) or like chromatic adaptation plugin. And for mixed cameras I'd use Color Space Transform effect.


I use ACEScct timeline color space. And DCTL as IDT and ODT (it's works faster than ACES Transform effect). And global wheel behaves the same. The main reason why I use ACES is it's amazing gamut compressor (currently available as DCTL). I hope it will be included in Resolve out of the box with the release of ACES 1.3.

On 4/3/2021 at 10:57 AM, Douglas Dutton said:

Rec709  2.4

Your file should be rec709(-ish) with linear segment near black or any kind of similar tone-mapping. Not a pure gamma 2.4, which is a display gamma only. So you probably should use rec709 scene, not gamma 2.4. I guess gamma 2.4 was default until v17 for creating DCP, where, I believe, transformation goes from timeline color space (to p3 gamma 2.6). So probably this is why timeline default color space is display gamma, not the gamma of the video file.

Edited by Anton Meleshkevich
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@Samuel Holdridge Thank you Sam, that's interesting!

@Anton Meleshkevich Hi Anton and thanks for your detailed comment!

What you say about YRGB is interesting and if it's the only way to work on the footage in linear fashion then it's a no brainer...

I thought that in YRGB changing the timeline color space didn't change anything as when you do, your footage looks the same. Or does it? :)

And basically what I read about it is that if you want to change your export's gamma, you do need to add a CST Timeline node to convert it.

Thanks a lot for your input!

Douglas

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