Avoiding gamma shift when exporting from Resolve 17.2

In this post I describe how to fix two types of gamma shifts in Resolve 17:

  • Unrecognized gamma tag gamma shift
  • Use Mac Display color profiles for viewers gamma shift

Rec709-A gamma tag gamma shift fix

When you export a video file from a Rec.709 2.4 gamma project in DaVinci Resolve 17 on Windows and Macs, the film may look darker than the original in QuickTime player on Macs and YouTube.

The video file will look the same as the original in Resolve and VLC, but QuickTime Player recognizes the 2.4 gamma tag as “unspecified” and the video will look darker. This can be a problem with other gamma tags like Rec.709 Scene also. It can also result in a washed-out picture.

The fix is to use the Rec. 709-A gamma tag when exporting from Resolve. If this is the problem you can skip to:
Rec709-a gamma tag fix

Use Mac Display color profiles for viewers gamma shift fix

sRGB as the timeline color space

If you have enabled “Use Mac Display color profiles for viewers” on a Mac, using sRGB as the timeline color space will not have a gamma shift between QuickTime player and Resolve. But the SRGB tag is not recognized by Youtube and Vimeo.

QuickTime player recognizes the Transfer Function/Gamma tag as sRGB

When you compare Resolve and QuickTime Player they match.

But the SRGB tag is not recognized by Youtube and Vimeo.

sRGB in Vimeo compared to sRGB in Quicktime player

sRGB in YouTube compared to sRGB in Quicktime player

When delivering to YouTube and Vimeo, Rec709-A as the timeline color space does not have a gamma shift.

Rec709-a as the timeline color space

The Rec-709-A tag is expected and matches Resolve, QuickTime player, Youtube, and Vimeo.

Rec709-A in Vimeo compared to Rec709-A in Quicktime player

Rec709-A in YouTube compared to Rec709-A in Quicktime player

Rec709-A on export gamma tag fix

Sometimes it is important to have the Timeline Color space as REC.709 Gamma 2.4. One example is when you drop a DCP in the timeline and the DCP is converted to the timeline color space. It looks the same as the original 2.4 gamma video file in Resolve and VLC, but not in QuickTime player on Macs (tested on Big Sur and Monterey).

How to fix the gamma tag when exporting

The default in Advanced Settings when exporting is:
Color Space Tag: Same as Project
Gamma Tag: Same as Project

The original QuickTime from Final Cut X had these tags:
Color Primaries: ITU-R BT.709
Transfer Function: ITU-R BT.709
YCBCr Matrix: ITU-R BT.709
Code Points: (1-1-1)

The Quicktime with the Rec 709, 2.4 gamma tag was recognized in QuickTime player as:
Color Primaries: ITU-R BT.709
Transfer Function: Unspecified
YCBCr Matrix: ITU-R BT.709
Code Points: (1-2-1)

Choose Rec-709-A as the gamma tag when exporting

If you want to avoid gamma shift in QuickTime player you have to choose Rec.709-A as the Gamma tag when exporting.

When exporting choose

In Advanced Settings:

Color Space Tag Rec.709
Gamma Tag Rec.709-A

The exported Quicktime now has the same tags as a Final Cut X QuickTime and does not have a gamma shift in Quicktime player or YouTube

Color Primaries: ITU-R BT.709
Transfer Function: ITU-R BT.709
YCBCr Matrix: ITU-R BT.709
Code Points: (1-1-1)

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