Definitive Gamma Shift Solution for Mac

Happy New Year

As we all know, Rec.709 on a Mac is a quandary because of Apple's choice of gamma and poor tagging standards informing how the gamma of their files should be displayed across various GUI's.

The workarounds are a convoluted nightmare, and don't seem to provide a universally consistent solution to gamma shift in every use case.

In my testing, an sRGB workflow eliminates all gamma shifts. The obvious proviso is that you don't need to deliver in Rec.709 for professional broadcasts (Netflix etc.)

System and Capture Device
-M1 MacBook Pro XDR Display.
-Sigma FP in 12 bit CDNG Raw.

Display Settings
-Set XDR Display to internet and web (sRGB) preset mode.
-Do not tick use Mac display color profile for viewers. It is not needed when using the preset mode because both the Resolve GUI viewer and Mac GUI viewers (QuickTime etc.) are operating within the sRGB preset environment and are consistent with each other in terms of color space and gamma.[/list]
-As such, you will not get gamma shifts between the Resolve GUI viewer and Mac GUI viewers after export.

Project Settings and Color Management
-Color Science is DaVinci YRGB.
-Timeline Color Space and Gamma is Davinci Wide Gamut and DaVinci Intermediate.
-Output Color Space and Gamma is sRGB.

Camera Raw Settings
-Decode Quality is Use Project Settings.
-Decode Using is Clip.
-Color Space is Blackmagic Design.
-Gamma is Blackmagic Design Film.

Nodes
-First Node is Color Space Transform.
-Input Color Space is Blackmagic Design Film Gen 1.
-Input Gamma is Blackmagic Design Film.
-Output Color Space is Davinci Wide Gamut.
-Output Gamma is DaVinci Intermediate.

-Middle Nodes for Grading

-Last Node is Color Space Transform (with or without a Film Look LUT).
-Input Color Space is Davinci Wide Gamut.
-Input Gamma is DaVinci Intermediate.
-Output Color Space is sRGB.
-Output Gamma is Cineon Film Log (with a Film Look LUT) or sRGB (without a Film Look LUT).

Deliver Settings
-Default apart from those listed below.
-Color Space Tag is sRGB.
-Gamma Tag is sRGB.

I have tested this workflow on my Mac, iPhone, iPad and desktop PC, across YouTube, Vimeo, Instagram, different browsers (Safari etc.) and local viewers (QuickTime etc.) and there are no gamma shifts anywhere.

There is variance across color hue, saturation and luminance, probably due to inherent variables in display tech and calibration etc. However, some variance is inevitable and from what I can see it is not significant. The fundamental look of the file remains intact and I am very satisfied with the general consistency.

Thanks for confirming this.
Professional broadcast shouldn’t be a problem, since you can normally choose to deliver MXF.

Great thanks for this interesting workflow. Could you detail more precisely the Deliver format and codec or do they all work ?

Great thanks for this interesting workflow. Could you detail more precisely the Deliver format and codec or do they all work ?

They all seem to work in various configurations without gamma shifts. The most important bit is getting the sRGB tags right.

However, I cannot rule out that some of the variance I am seeing in color hue, saturation and luminance is not being caused by different quality settings in the delivery tab. I will probably test at some point.

-Output Gamma is Cineon Film Log (with a Film Look LUT) or sRGB (without a Film Look LUT).

WTF? No, that can't be right.

Bear in mind that most of us are dealing with Mac people (with many different browsers and players), Windows people (ditto), people looking at iPhones and iPads and other kinds of tablets... there is no simple solution. Rendering out to Cineon Log is insanity.

-Output Gamma is Cineon Film Log (with a Film Look LUT) or sRGB (without a Film Look LUT).

WTF? No, that can't be right.

Bear in mind that most of us are dealing with Mac people (with many different browsers and players), Windows people (ditto), people looking at iPhones and iPads and other kinds of tablets... there is no simple solution. Rendering out to Cineon Log is insanity.

Define 'right' please Marc? As far as I am concerned, if it looks consistent across every device and system I have tested, and viewers are getting a rendition of the grade I saw in Resolve i.e. they are seeing the creative intent, then it is most definitely 'right'. It cannot be wrong in this context.

If it's not right for broadcast (or other use cases where sRGB might not work) then fair enough (it's not something I have tested), but that's not my concern or use case.

I'm not entirely sure whether you have understood the workflow or not.

To clarify, the Film Look LUT is applied to the last node. The LUT is expecting Cineon Film Log (it will not work with anything else) and so this must be set in the Output Gamma. Once the Film Look LUT has been applied, the gamma is normalised, and looks right for rendering using sRGB as the Output Color Space (along with the appropriate tags in Deliver).

If someone doesn't want to use a Film Look LUT, they can just CST to sRGB color space and gamma in the last node and grade under that.

My CST workflow is based on Darren Mostyn's approach

Good luck for reading: viewtopic.php?f=21&t=101253

Good luck for reading: viewtopic.php?f=21&t=101253

Wow, finally a final explanation I'm sure it answers all questions once and for all

No. But we should have a party at 20 pages for all that 'finality'.

No. But we should have a party at 20 pages for all that 'finality'.

And instead of cake everyone can bring their own definition of rec709 to the table.