P3 DCI luminance shift/tint

[mathes]

Hej everyone!

We have a slight problem here: Exporting a DCP and reimporting it or opening it in the player changes the brightness/color a bit.
Our film is in P3 DCI Gamma 2.6 and I read Carl's message in the forum:

viewtopic.php?p=10864&sid=8d3dad849c786 ... cdf#p10864

settings.png

As you see, we used the adjusted settings for P3 DCI, but there still seems to be a tiny tint and it is quite darker...

OV.png

OV (brighter)

These two screenshots show the film in the OV project preview (above) and the imported DCP in the VF project (below).
You might not see that much of a difference looking at them here, but downloading them and switching from one to the other, it's quite a lot.

VF (darker, tint)

VF.png

As changing the color management in the OV project does not change the preview, my guess is it shows the original ProRes 4444 input colors and not an actual preview and my instinct is to trust the reimported DCP preview (or the player, which previews the same).
But all in all, I'm very unsure which output to trust, especially looking at a DCP on a screen.

I also saw this thread, which seems to work on a pretty similar problem, but my VLC snapshots of the 4444 & the DCP mxf do not look similar either...:

viewtopic.php?t=1750

We have only limited access to a cinema projection, so it'd be very interesting to know if this is just a screen <–> projector display issue or will look different in cinema than in grading and needs to be fixed...

Thanks a lot for this very fine piece of open source software and thanks for any help in advance!
All the best,
Mathes

[mathes]

Here's the MediaInfo-output of the ProRes 4444 export from DaVinci:

mediainfo.png

I'm using DCP-o-matic 2.16.79 on a M2 Macbook Pro.

[Carsten]

The player can not simulate a perfect DCI system's color reproduction. Also, you may know that there is no perfect neutral grey. That's fiction.
You always notice slight color shifts when doing a side-by-side comparison.

In a cinema, there is no technical option for a color shift comparison. You assume the projector to be calibrated, and viewing the content, your eyes' adoption will shift it to perceptive neutral.

[StephW999]

Hi,
P3-DCI = 0.314 0.351 (white point)

[mathes]

Thanks you two!

@Steph: That's the P3 preset in DCP-o-matic, too, but that way it turned out far greener, see this thread:
viewtopic.php?p=10864&sid=8d3dad849c786 ... cdf#p10864
Which is why I used Carl's P3 DCI white point settings as posted there...

@Carsten:
Okay, so you're saying I should trust the program and not the preview/player and the DCP should be fine? Or as fine as it can be.
Of course I don't expect it to be a 100% perfect match and every projection looks different anyway, but in the preview it turns out way darker than I'd expect to be a normal luminance shift.

Best wishes
Mathis

[StephW999]

Hi Mathis,
Are you sure that your project Resolve to a destination color space set to p3-dci?
Because if it is set to p3-d65 and you encode with a p3-d63(dci) matrix then the output will be tinted green.
Maybe give us more details on the Resolve settings, in color management.

Steph.

[mathes]

Hej Steph,

hmmm, it was definitely set to P3 DCI Gamma 2.6 in both project settings and delivery. Which is also confirmed by my MediaInfo-output (see my 2nd post here).
Are there any other settings I could share?

Reading through the following thread again, I see that I misunderstood it and Carl's altered white point settings from my initial post here probably aren't for me... although it drastically improved the player's preview colors:
viewtopic.php?p=10864&sid=8d3dad849c786 ... cdf#p10864

This is what the reimported DCP is previewed like with standard P3 settings in my DCP-o-matic VF project...

OV P3 DCI.png

For what it's worth, here's another screenshot from the Davinci grade – how it's supposed to look in a perfect wysiwyg world
So: even brighter than the OV preview from my first post.

davinci.png

All the best
Mathes

[StephW999]

I see in your first post that the DOM settings are on "Full JPEG 0-255" while you are using a video. Settings should be: 16-235