Gamma Shift!

I have a master file DNX UHD 12bit which I am exporting from Davinci Resolve 17.4.2, When I export I get a gamma shift (the image becomes brighter and less saturated) in QT and Vimeo but in VLC it looks good.

I am using an iMac. The file is from a color correction done on resolve (on a Windows machine).

I created a new project and the Color Management settings are DaVinci YRGB, Timeline Color Space is Rec. 709 Gamma 2.4.

The master shows 709, Gamma 2.4 in the Input Color Space.

When I export to H264 or ProRes I set the Color space tag to same as Project and the Gamma tag to same as project and the files have a major gamma shift in QT and on Vimeo. I then tried changing the Gamma tag to Rec. 709-A to create a 1-1-1 file but there is no change (data levels are set to Video, but I"ve tried Auto and Full to no avail). I Have tried changing my Color Management Timeline Color Space to 709-A. But that also didn't work.

Actually I have tried many variations but I have not found a way to make the exported files look good in QT or on Vimeo.

I have read several threads and websites about the Gamma shift problem but perhaps I missed one. Has anyone had a similar experience? And has anyone found a solution?

I am losing my mind here. I know the Mac Gamma shift problem is well known but I personally have never encountered it in this way (mostly my files looked too dark and I always found a solution).

Thank you for any help!

DNx if it’s 444 has to be set to Full and custom tag your color space and gamma accordingly. HQX can be left at auto.


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[quote="dariobigi"]DNx if it’s 444 has to be set to Full and custom tag your color space and gamma accordingly. HQX can be left at auto.

Thank you. What do you mean by " custom tag your color space and gamma accordingly."

Read these:

"Grading for Mixed Delivery: Cinema, Home, and Every Screen in Between" by Cullen Kelly
https://blog.frame.io/2019/10/14/gradin ... -delivery/

and

"How to Deal with Levels: Full vs. Video"
by Dan Swierenga

https://www.thepostprocess.com/2019/09/ ... l-vs-video

and I think both cover the issues and the solutions very well.

Understanding color management is also helpful:

"Color Management for Video Editors"
https://jonnyelwyn.co.uk/film-and-video ... o-editors/

I generally try to export a second or two of SMPTE Bars at the head of the project, and I import the file back into Resolve to check it on scopes to verify all the levels are correct. The above articles will explain why things change on different displays, different playback engines, and the importance of calibration.

Thanks! These were very helpful.

Read these:

"Grading for Mixed Delivery: Cinema, Home, and Every Screen in Between" by Cullen Kelly
https://blog.frame.io/2019/10/14/gradin ... -delivery/

and

"How to Deal with Levels: Full vs. Video"
by Dan Swierenga

https://www.thepostprocess.com/2019/09/ ... l-vs-video

and I think both cover the issues and the solutions very well.

Understanding color management is also helpful:

"Color Management for Video Editors"
https://jonnyelwyn.co.uk/film-and-video ... o-editors/

I generally try to export a second or two of SMPTE Bars at the head of the project, and I import the file back into Resolve to check it on scopes to verify all the levels are correct. The above articles will explain why things change on different displays, different playback engines, and the importance of calibration.

I think I solved the problem.

I calibrated my iMac Screen to 100 nits and generated a profile. The profile seems to be the culprit. When I switch to the iMac Profile and view the 1-1-1 tagged exports in QT or from Vimeo in Firefox they look pretty good.

Learn something new every day.

During monitor calibration, which gamma Tone Curve should I choose for Rec709-A workflows?

On DisplayCAL3 options are: "As measured", Gamma 2.2, rec709, sRGB, L*

On xRite i1Profiler gamma options are a Gamma slider which is set to 2.2, and sRGB

To be honest I gave up on using the SpyderX profiles for grading.

I now use the Apple HD 709-A color profile and set the Brightness for 100 nits.

But I can say that this is only good for non-critical color corrections. For my films I have been working with a professional colorist on a calibrated system (not an iMac monitor).

During monitor calibration, which gamma Tone Curve should I choose for Rec709-A workflows?

On DisplayCAL3 options are: "As measured", Gamma 2.2, rec709, sRGB, L*

On xRite i1Profiler gamma options are a Gamma slider which is set to 2.2, and sRGB