Paulski92, after further study I think here is what you've done. Note some of these are guesses, so correct me where needed:
- You shot a Rec.709 SDR clip with your camera
- You imported that clip to an FCP Wide Gamut HDR library
- You created an HDR Rec.2020 PQ project
- You put the Rec.709 SDR clip on the timeline
- You did File>Share>Save Current Frame
- You exported the Rec. SDR clip from the FCP HDR Rec.2020 PQ project, producing a file with NCLC tags 9-1-9, meaning:
Color Primaries: ITU-R BT.2020
Transfer Function: ITU-R BT.709
YCbCr Matrix: TU-R BT.2020
- When playing that clip in Quicktime Player and comparing it to how Quick Look shows the exported frame, the exported frame is darker.
Cause: The BT.709 SDR clip in an HDR Rec.2020 PQ timeline would normally have been too dark in the FCP viewer. However the FCP automatic Color Conform feature (see Inspector) applies SDR to HDR (PQ) conversion. That converted state is retained when you export that clip, tagged as 9-1-9. However the Save Current Frame export does not retain that. I am investigating why.
Your best current workaround is export that as a one-frame video. That is easy to do using the JKL keys. Put the playhead on the desired timeline frame, tap I to select the In point, hold K and tap L to advance one frame, tape O to select Out point, then export that. FCP will automatically export the selected range (one frame in this case).
This is actually not an esoteric workaround because there has long been an industry standardization problem concerning video tag attributes applied to still images. Regardless of your current situation, it is not really reliable to take a screen capture or even save the current frame from a video file.
I'll post more info when available. Let me know if you have additional questions.
