Correcting for low CRI with ColorChecker Classic

I am preparing for a shoot of workers in their workplace at many different locations that will have mixed light from LEDs, Neon and Daylight.
High CRI video lights will be used as fill-in light sources.
Cameras are P6Ks shooting 6K RAW Q0 or Q1.
A new Calibrite ColorChecker Classic will be in frame at the beginning of each new location.
The white patch will be exposed to false color yellow, i.e. about 80% to 90% IRE.

Color management will be set to "DaVinci YRGB Color Managed" and "HDR DaVinci Gamut Intermediate", Output "Rec.709 Gamma 2.4".

On page 2562 the Resolve manual indicates that "Lighting in the scene with an unusual spectral response or a strong color cast can cause an inaccurate match."
But compensating for unpredictable spectral spikes and mixed light is exactly what I need the ColorChecker for.

There will be NO way to turn off any of the existing light sources.

How can I reliably match between the different locations anyways ?

You can't. A color chart will help you to get a starting point. But with different color characteristics in your highlights, fill and probably in the deeper shadows too, you'll need to do some serious grading, including secondaries. You are lucky to use at least the same type of camera.

Thanks Uli.
Do you have experience with similar situations?

The most important issue is to get a reliable starting point, especially for skin tones.

I am definitively able to grade everything manually but there is no budget covering this effort.
Quickly adjusting highlights and shadows with Primaries Log and Color Warper should be no problem.

When I've done either stills or video in such situations, there were often color casts from certain angles different than others. Shadows and mids and highlights oft needing separate fixes.

Different locations taking very different solutions.

It's great at building your skills ...

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Thanks Uli.
Do you have experience with similar situations?

Yes, both with crappy fluorescent lights in workplaces and, even worse, with coloured lights in theatre.

You'll need to do at least some different corrections for highlights and mids, for example using hue vs hue curves. It'll be a nightmare to get proper skin tones, and with a limited budget or time it'll never look perfect. Deeper shadows can just be desaturated.

In some situations you may even be better off not using your high CRI fills, if the available lights are of the same bad CRI. But it's hard to judge without samples and you should definitely do some tests.

You'll need to do at least some different corrections for highlights and mids, for example using hue vs hue curves.

I get much better and faster results with Primaries Log and the Vectorscope than Hue vs Hue Curves when in "DaVinci YRGB Color Managed".
After that, some minor but very precise adjustment in the Color Warper get me to almost perfect results which will be enough for this production.

I hope the Color Match Tool will give a good enough starting point.

Well, in DaVinci Resolve there are many ways to skin a cat.

Do you know 3D LUT Creator? The name is misleading, it's the big brother of the Color Warper.

Do you know 3D LUT Creator?

I purchased a copy and started working with the 3D LUT Creator long before the Color Warper was introduced.
I did not use it enough before because jumping between applications when working on a grade is not very efficient.
Now with the Color Warper I do not use it anymore but keep it installed and updated on my editing machine.

Well, so you know what you're doing. But I don't envy you for that project!

so you know what you're doing

There can never be enough experience and always something new to learn.
Also, using your experience as a shortcut can lead to unexpected surprises.

I have no experience with the Color Match Tool so far, that's why I asked in this post.

Strictly my opinion: I think Color Match is a reasonable tool for dailies or people doing very casual work with Resolve. But I don't think it's the best way to work.

If you want better results, start with good color management or do it all by hand with a CST node as the first node. Then look at the scopes and get the color chips in the ballpark. The XRite ColorCheckers are not that accurate -- in fact, my opinion is the ColorChecker Classic is way off. They got better as time went on, and the ColorChecker Video is closer, and the ColorChecker Digital is closer still. None of them have the right levels for saturation, but they are "ballparkish" for hue vectors.

With spikey lighting conditions, you're going to have to use manual intervention, and every scene is different. Printer lights, LGG, Log controls, secondaries... there's a lot of potential fixes, but it's hard to convince without seeing anything. I find as long as everything matches, you can get away with quite a bit, assuming the whites are clean, the shadows are clean, and the fleshtones are reasonable.

The XRite ColorCheckers are not that accurate

Thanks Marc, I should have asked before buying it a week ago, but the ColoCkecker should be the latest version (After X-Rite changed to Calibrite).
So you mean that the R-G-B and C-M-Y patches on the card are actually not accurately R B G C M Y in the Resolve scopes.
How much of a deviation did you see?
I am still hoping that the Color Match Tool will bring the different locations to a sufficiently matched starting point.

Do you have any experience with Calibrite ColorChecker that is produced now?
Can you recommend other color charts that are not exorbitantly expensive?

I think Marc is mainly referring to wrong saturation, the hues are not terribly off.

I am still hoping that the Color Match Tool will bring the different locations to a sufficiently matched starting point.

It has been my experience that the color match tool does not do what it advertises and is essentially useless

viewtopic.php?f=21&t=148895

I challenge you to find an example anywhere were someone used the 'one click fix' and then pulls up the vector scope to prove it is accurate.

Expect to have to adjust the hue-hue hue-sat curves manually.

Any chance you can gel the lights when shooting? If you can reduce the number of different color temperatures it will make your life easier. Alternatively you might want to lean into the different colors depending on what your final goal is.

Here are the numerical color values of all 24 patches of the Calibrite Colorchecker Classic.I got them from their tech support.
Perhaps someone with a probe colorimeter would be interested to check how exact the actual color patches are.

I just ran a test.

my opinion is the ColorChecker Classic is way off.

Correct, way off, exept for skin tone patches and red.

the color match tool does not do what it advertises and is essentially useless

According to my current test you are right. Only manual adjustments get me to usable results. The Color Match tool could be very fast and useful with very controlled light and a better chart than the ColorChecker Clasic.

There is so much to this than just a "yep it's not accurate" discussion.

The swatches on the ColorChecker Passports are a known quantity, but they are not targeted for Video so you can't just eyeball the vector-scope like you can with the ColorChecker Passport Video.

I find it's best to do a white balance before trying to do a ColorMatch.

But your main issue will be with mixed lighting hitting the swatches. No automated or manual solution can really fix that problem.

There is so much to this than just a "yep it's not accurate" discussion.

True, but the Color Match tool should make matching the colors fast and easy, right?

One of the reasons I started with a ColorChecker Classic is that it is one of seven options on the list of color charts of the Color Match tool.
So I would expect to see the RGB values I received from Calibrite support and posted above as picker's RGB values after I apply the tool. The picker is showing very different values for most patches.

I find it's best to do a white balance before trying to do a ColorMatch.

I white balance and adjust some primaries before the Color Match.

I never found the Match tool very helpful, even after lots of experimentation.
Went for CineMatch instead, which again is not perfect, but much better. I doubt it'll help with mismatched lighting, though. It's aimed at matching cameras.

Apologies but might be a tad late to the discussion. I am attaching a link to video by Oliie Kenchington where he steps through using the Color Checker Video both 'manually' and using Color Match.
It is very helpful.
Vimeo link: