Need help understanding HLG display and workflow

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Level 1

102 points

Need help understanding HLG display and workflow

OS X 10.15.4 on iMac Pro

FCPx 10.4.8

Video recorded on a Sony a6400 with the HLG profile.

I'd really like to better understand proper workflow and why on-screen display in FCP has been inconsistent. I realize I do not have an HDR monitor and am working only with rec709 timelines.

Up until recently, any HLG footage imported (to a Standard def library) would appear highly overexposed. in browser and timeline. My understanding is that this is due to HLR being an HDR color space. The "fix" I found was to do a Color Space Override and change the space to Rec 2020... although I do find it odd that the same clip would look fine when viewed in other apps (including Finder and QT Player).

Suddenly, some things have changed. I don't recall updating FCPx, but there was a recent minor OS update that may be the cause.

These same HLG clips now appear properly exposed when brought into FCPx - both in the browser and a rec709 timeline. RGB Parade shows the exposure as in camera. (While previously, the camera would show proper exposure and FCPx would show blown out highlights). Color Space Override is no longer necessary.

Has something changed?

This also leave me curious as to the proper workflow when shooting in HLG.

Some recent information I have seen suggests using a Wide Gamut library, but working in rec709 timelines. This would supposedly allow for easier changeover once HDR displays become more affordable/commonplace for editing.

Any suggestions?

iMac Pro, macOS 10.15

Posted on May 29, 2020 9:47 AM

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Answer 1

May 29, 2020 12:36 PM in response to Joe M21

HLG is designed for compatibility in terms of gamma and grades like rec709 with scopes in IRE

No computer is compatible with HLG in mac, windows or linux and tone mapping is not supported in FCPX it is unlikely to change in the future as HLG is for broadcast and does not work well with a computer set up

There is no reason why HLG should look overexposed on a rec709 timeline until you get to the highlights where it will clip

Using the HDR tools HDR to Rec709 should do the trick

Personally I have spent one year trying to make it work and ditched it now I work in HDR-10 that is supported by catalina except I have some issues with my display

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Answer 2

Joe M21 Author

Level 1

102 points

May 29, 2020 1:09 PM in response to Interceptor121

A few points in your response definitely have me confused.

What do you mean by not compatible with HLG? FCPx reads the files and indicated the color space correctly. The viewer has an option to "Show HDR as tone mapped."

As to the overexposure, I don't know why but it does. There are several YouTube videos discussing this issue.

HDR Tools... I just tried is and things are more confusing than ever.

Working with a rec709 timeline and HLG footage.

Here is a screenshot of the RGB Parade. It was the SAME for browser and timeline:

in other words, image appeared exposed as expected.

Next I applied HDR Tools with HDR to rec 709:

So far, things make sense but here's where things get weird.

If I remove HDR Tools, the image goes to this:

While browser still shows the original RGB Parade and looks fine, the timeline looks blown out. If I delete HDR tools from the clip, nothing changes. Any further insertion of this clip into any timeline results in the same "overexposed" look.

Even more strange, the "overexposed" look (and RGB Parade) transfers to ALL my other imported clips. Prior to using HDR Tools on ONE clip in the timeline, everything looked fine. Now, everything is back to overexposed.

Unless you are saying that something is broken. The inconsistency in how the clips are displayed seems to support that.

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Need help understanding HLG display and workflow

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