Resolve and P3 screens saga

People with new Macs with P3 screen may noticed crazy misalignment between QT X preview and Resolve GUI preview (without Mac Display Colour Profile for Viewers being selected).
This also applies to Premiere preview, which caused so many people to talk to their support.

If you grade in Resolve using unmanaged view your colors will be all good and saturated. Now export this to QT ProRes and watch in QT X- ups....colors are so less saturated, specially those lovely reds etc:) QT X converting file which is flagged as Rec.709 into P3 gamut (which is correct thing), but because you graded on color unmanaged preview what you saw was "wrong" (Resolve sends preview pixels as the screen would be sRGB, but it's P3 gamut now!). Play the same ProRes file in VLC, Scratch Play, Premiere (or any color unmanaged app) and it will look like in Resolve. Welcome to the world of problems, which are related to fact that most tools are not ready for screens with wide gamut. Apple is doing right thing here, but apps are so not ready for it, so it's all rather messy

This is where I prefer Scratch Play approach, which separates from OSX management and allows me to set that screen is P3 (well it will convert preview data to perfect P3 screen where Macs ones are not 100% P3 perfect). I think you can take Mac screen profile and ask Scratch to convert into it, not perfect P3 (or add a LUT to compensate for it).

I've just notice that Scratch Play has P3 D65 preset for monitor, which is about what new Macs screen is.

So now when we preview some file in QT X and then load it to Scratch Play, interpret source as Rec.709 (this what QT X is reading from headers) and set our monitor in Scratch Play as P3 D65 then both preview should match....

and yes they do match at 99%!

So this proves Apple is doing good conversion (as well as Scratch) (and maybe that Mac screen is really close to P3 gamut).

In theory we should be able to do exactly the same with Resolve (even if it uses different approach and plugs in into OSX management), but somehow it's not working. Why?

Andrew,

You write "new Macs". Do You mean "iMac Pro"?

Not only iMac Pro has P3 gamut screen. Mackbook Pros also. It's related to any screen which has much wider gamut than sRGB. The bigger gamut compared to sRGB the bigger difference. In case of P3 gamut difference is really big.

I've tested, and I agree.

On Mac Pro 2013+Apple Thunderbolt display, QT X and QT 7 show P3. With VLC and Blackmagic Media Express is the same like unmanaged DaVinci.

What will happen? If video will play contains inside by QTs, check Managed viewers by Apple profiles and choose P3 profile in macOS System Preferences. If not, let it be unmanaged and use standard Apple monitor profile.

Standard screen profile is still P3, so it doesn't solve your problem.
Apple does not offer you to "limit" your screen to sRGB gamut. It's always P3 and color sync manages content to make sure it looks good (based on its tagging).

Problem with Resolve is that managed viewers don't give you same preview as QT X, which is key problem here.

New facts.

As I mentioned- all files exported by Resolve with Rec.709 setting will have the same flagging, which is: 1-1-1 (all Rec.709). Problem is that some of them may be done with 2.2 gamma, others with 2.4 etc. QT X won't distinguish between them, so its preview won't be always correct.
ColorSync when sees Rec.709 tagging for transfer function seems to be applying gamma at about 1.96.
Most people use of course 2.2 or 2.4.

There seems to be way to fix it. You need an app which allows to change QT color tagging and then you set:
1-2-1 and add gamma tag set to e.g. 2.4
Such a flagging means Rec.709 for primaries and matrix, but 2 for transfer function which means- Unspecified. During color conversion color sync ignores it and instead uses gamma tag, which we can set to 2.2, or 2.4 etc.

If we set it to 1.96 and compare such a file with one which is tagged 1-1-1 (all Rec.709) they will look identical (at least to the eye).
If we now go back to Resolve, export file as Rec.709 with 2.4 gamma, do mentioned change we should see both files matching perfectly....but they don't Resolve one has very end of blacks much darker. It looks like difference is in the end of the curve. No idea why Looks like they way how Resolve applies 2.4 gamma curve and how ColorSync does it is not the same.

Interesting fact is that Resolve matches mpv player (when both use color managed) preview 100%, so it's something in QT X and the way how it treats those Rec.709 custom tagged files and applies gamma tag.

+100000

Resolve and P3 Mac's don't play well together.

Nice sleuthing Andrew!

Sorry to drag this back up, Ive searched everywhere but there is no definitive answer.

My thinking was to use;

iMac 5K -> UltraStudio Mini -> calibrated Rec709 screen

But its still showing the more saturated (incorrect) footage. Why? How!

I don't care If I never have to look at the iMac Screen anymore

If you grade in Resolve using unmanaged view your colors will be all good and saturated. Now export this to QT ProRes and watch in QT X- ups....colors are so less saturated, specially those lovely reds etc:) QT X converting file which is flagged as Rec.709 into P3 gamut (which is correct thing), but because you graded on color unmanaged preview what you saw was "wrong" (Resolve sends preview pixels as the screen would be sRGB, but it's P3 gamut now!). Play the same ProRes file in VLC, Scratch Play, Premiere (or any color unmanaged app) and it will look like in Resolve.

So are you saying that quicktime player is actually showing us the correct image in this case?

Resolve now has color managed preview, so gamut problems should be gone. Gamma difference is another story. Watch this:
viewtopic.php?f=21&t=95658

QT X shows "correct" gamut, but not gamma.

Thanks Andrew,

Only problem is with my current workflow I have to use non color managed settings and have the “use Mac profile for viewers” preference off too. So when I output and open in QT I assume that that’s what I’m meant to be seeing in resolve? Besides the gamma difference you mentioned?

Do you know how I might be able to work around this with a LUT? So that what I’m seeing in Resolve is what I’m grading?




Sent from my iPhone using Tapatalk

No, with your setting Resolve preview will be wrong, eg. if you set project to Rec.709.
Your end result (watched on accurate preview or even TV) will be way to saturated.
You either need BM monitoring, use color managed preview or set project this way (for Rec.709):
source- as you prefer
timeline- P3 D65
output- Rec.709.
With those you should be fine with saturation, but not necessarily with gamma.