BMPCC4k Gen 5 - Color Card correction in resolve

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smunaut

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BMPCC4k Gen 5 - Color Card correction in resolve

PostMon May 10, 2021 11:03 am

So I have a bmpcc4k and I have a couple of questions on how to properly use the color card correction feature of Resolve with it. I did lookup the manual but it's really not that clear :/

First, assuming I'm not in a Color Managed project. I get my footage from the BMPCC4k (on 7.3 fw, shot on "Film" dynamic range) and it's decoded as Gen 5. What should I pick as "source gamma" ?

There is :
Blackmagic Design Film
Blackmagic Design 4k Film
Blackmagic Design 4.6k Film

and I'm not even sure what the difference is. And to make matter worse, if I look at the LUTs under "Blackmagic", there are :

Blackmagic 4.6K Film to Extended Video v4.cube
Blackmagic 4K Film to Extended Video v4.cube
Blackmagic Broadcast Film to Extended Video v4.cube
Blackmagic Film to Extended Video v4.cube
Blackmagic Gen 5 Film to Extended Video.cube
Blackmagic Pocket 4K Film to Extended Video v4.cube
Blackmagic Pocket 6K Film to Extended Video v4.cube

which seem to imply none of those 3 are even equivalent to "Pocket 4k", or "Gen 5" ...


Second is if I choose to use a Color Managed in the project settings. If I use the color match tool, I have to pick a "Source gamma". Should that be REC709 since RCM should have already converted to that, or does the tool look at the "raw" input and I should pick the same as in the first case of non color managed ?
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smunaut

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Re: BMPCC4k Gen 5 - Color Card correction in resolve

PostWed May 12, 2021 8:08 am

So now the question is : Does resolve 7.2 have anything relevant to this question in the update given its notes about gen 5 color support improvements ?
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Howard Roll

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Re: BMPCC4k Gen 5 - Color Card correction in resolve

PostWed May 12, 2021 12:56 pm

The Chart Match feature, lacking the proper input gamma, is not goint to be accurate. The nearest neighbor is BM Film 4.6K.

The best tool for correction in a non-managed workflow is the OFX color space transform. It has most of the correct handles for patching G4 input to output gamma/gamut.

"Video" and "Rec709" aren't synonymous, neither the P4K to video or extended video LUTs are accurate. There can be only one and it's neither of these.

The Camera Raw tab works much the same as the CST but now you're in 709 space on node 1 when folks prefer grading under a normalization node. For G5 native (12k, P4KP) I believe the only (non-managed) correct way to transform into 709 is in the Camera Raw tab.

G5 video isn't accurate at all but it's kind of dummyproof which is what people have been asking for.

Good Luck
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Re: BMPCC4k Gen 5 - Color Card correction in resolve

PostWed May 12, 2021 10:54 pm

Howard Roll wrote:For G5 native (12k, P4KP) I believe the only (non-managed) correct way to transform into 709 is in the Camera Raw tab.

There is Gen 5 support in the CST plugin and RCM in Resolve 17.2 that was released last night.
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Re: BMPCC4k Gen 5 - Color Card correction in resolve

PostThu May 13, 2021 12:50 am

And support for ACES 1.2.
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Re: BMPCC4k Gen 5 - Color Card correction in resolve

PostThu May 13, 2021 3:47 pm

@CaptainHook : So for the Color Space Transform node, assuming bmpcc4k shot with Gen5 Film, the input colorspace should be "Blackmagic Design Wide Gamut Gen 4/5" and Input gamma "Blackmagic Design Film Gen5" ?
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smunaut

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Re: BMPCC4k Gen 5 - Color Card correction in resolve

PostThu May 13, 2021 4:37 pm

Somehow I would have expected the same output from using RCM and CST with those settings but ... nope, they look different :/
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Re: BMPCC4k Gen 5 - Color Card correction in resolve

PostThu May 13, 2021 5:30 pm

Resolve Colour Managed is applying your camera inputs automatically; it you’re adding a CST you may be doubling the effect if you specify the inputs. If you’re using Resolve (non-managed), you can supply the input definition. But for RCM, see how it compares when you leave the inputs blank.
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Re: BMPCC4k Gen 5 - Color Card correction in resolve

PostThu May 13, 2021 5:39 pm

I was using "Non-managed + CST" vs "Managed alone"

But talking to someone on discord I found the discrepency, the Non-managed one defaulted to "Rec 709 Scene", while the managed one defaulted to "Rec 709 Gamma 2.4".
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Re: BMPCC4k Gen 5 - Color Card correction in resolve

PostThu May 13, 2021 5:42 pm

And which do you prefer?
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Re: BMPCC4k Gen 5 - Color Card correction in resolve

PostThu May 13, 2021 10:17 pm

smunaut wrote:@CaptainHook : So for the Color Space Transform node, assuming bmpcc4k shot with Gen5 Film, the input colorspace should be "Blackmagic Design Wide Gamut Gen 4/5" and Input gamma "Blackmagic Design Film Gen5" ?

Yep, that's correct
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Re: BMPCC4k Gen 5 - Color Card correction in resolve

PostFri May 14, 2021 2:41 am

smunaut wrote:I was using "Non-managed + CST" vs "Managed alone"

I’d recommend trying out ACEScct instead.

With Resolve 17.2, ACES 1.2, and Gen 5 colour science, CST from Pocket 4K to Rec.709 appears to be working remarkably better than before.

In fact, Film Gen 5 output gamma seems to be giving ARRI LogC a good run for its money.
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Re: BMPCC4k Gen 5 - Color Card correction in resolve

PostFri May 14, 2021 3:46 am

Thanks for the advice. I just started Resolve 17.2 ACEScct 1.2 today but didn’t do any real work yet. Good to know there are benefits to be using these latest updates.
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Ellory Yu

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Re: BMPCC4k Gen 5 - Color Card correction in resolve

PostFri May 14, 2021 5:56 am

Forget RCM and all this crap about manage and un-manage. I have started using ACES cut 1.2 and CST in the nodes. I think they have a more accurate result.

I hope that BMD produce a guidance document on color management, not just a reference but a how to depending on the various combinations of settings. But until then when there is good directions, I'm going with ACES.
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