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How to tell what colour space a clip was recorded in?

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Dave Smith
How to tell what colour space a clip was recorded in?
on Oct 24, 2019 at 2:15:47 pm

Hi, quick question... how would one know if a clip was recorded dlog and, for example, could benefit from having a dlog-to-rec709 LUT applied? (other than using naked eye)

Backstory: I recorded some dlog footage with my Mavic pro 1 drone but after importing sample footage into a test project/library everywhere i look i see rec 709 as the colour space, for the clip and elsewhere. I assume this is because the default colour space of final cut is rec 709 so it presents the clip as such... although I haven't tried using a wide gamut library/project. I didn't do any transcoding or proxy creation in fcpx when importing/copying footage into the library... and thought I would see the clips colour space listed as dlog somewhere.

The goal was to up my overall game with respect to colours and LUTs, starting to record in dlog, but my inexperience in this area has me stumped on this basic step. Any advice appreciated.


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Dave Smith
Re: How to tell what colour space a clip was recorded in?
on Oct 24, 2019 at 8:59:50 pm

Curious... I downloaded Compressor and see in the Inspector > Video Properties the source Color Space is Rec. 709*. If that's the case maybe the Mavic is not recording D-Log like it should be.... either that or I'm misunderstanding how D-Log clip information should appear in FCPX.

I'd still like to figure out how to confirm source footage colour space in Final Cut though... any ideas there?


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Jeremy Garchow
Re: How to tell what colour space a clip was recorded in?
on Oct 24, 2019 at 10:43:52 pm

DLog is different than the Rec709 color space.

You can recording Dlog (the color and exposure values are encoded differently) and use a LUT to expand the color and luma out to 709 (or beyond).

What FCPX is telling you is correct, it's all 709, because the DLog material fits within the 709 "bucket", but in order to get the material to look more "natural" you would either color correct, or apply a LUT and color correct from there.

There's a LUT on this page which you can load in to FCPX though the Camera LUT settings in the FCPX inspector: https://www.dji.com/mavic-2/info?pbc=mF6h4ZTt#downloads

Jeremy


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Dave Smith
Re: How to tell what colour space a clip was recorded in?
on Oct 24, 2019 at 11:58:06 pm

Ok so it seems my confusion is coming from a lot of loose terminology out there mixed with my yet to be formed understanding. If none of the following is incorrect, I think I understand now...

- Rec 709 is the 'standard' colour space.

- Log is not a colour space, it's simply a term that refers to a shooting profile that records data logarithmically (which has the benefit of more containing more data that can be brought out in post for greater effect).

- Log footage can be used with even better results in a wider gamut colour space like Rec 2020 (provided the display device can show that colour space).

- when I see a LUT that "converts" log-to-rec709... it's not really converting anything, it's just nondesctuctively applying a 'look' to the footage.

Ok so with that, and somewhat back to my original question... how do you know when a clip is recorded with the log profile? Or any profile for that matter? Do you "just know" as part of the recording-editing process or talking to the cameraman? In my situation, as the one person doing it all, I certainly would know... but what if I came across footage I didn't shoot? For example, when I use my still camera for jpg photographs I can see in my editor which shooting profile was used, like 'vivid' or 'natural' or 'muted' etc. I assume 'log' in video can be likened to 'raw' in photography.

Thanks for the reply!


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Joe Marler
Re: How to tell what colour space a clip was recorded in?
on Oct 25, 2019 at 11:06:07 am

[Dave Smith] "how do you know when a clip is recorded with the log profile? Or any profile for that matter? Do you "just know" as part of the recording-editing process or talking to the cameraman? In my situation, as the one person doing it all, I certainly would know... but what if I came across footage I didn't shoot?"

Video camera metadata is not standardized like EXIF in a still photo where you can more consistently find these things.

That said, the free command-line utility ExifTool can often extract color profile info from a variety of video formats. The info is not stored in a common place in the video file header, so you have to dump the data in verbose mode then search for words like "log".

https://www.sno.phy.queensu.ca/~phil/exiftool/


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Dave Smith
Re: How to tell what colour space a clip was recorded in?
on Oct 25, 2019 at 1:11:12 pm

Ah, thanks for that. Ok so things are clearer now... really appreciate all the feedback!


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Jeremy Garchow
Re: How to tell what colour space a clip was recorded in?
on Oct 27, 2019 at 2:39:05 pm

Yes, you seem to have a great grasp of what is going on.

[Dave Smith] "- when I see a LUT that "converts" log-to-rec709... it's not really converting anything, it's just nondesctuctively applying a 'look' to the footage.
"


That's correct, although the values, are in fact, being converted. But you are right in that it is nondestructive.



[Dave Smith] "Ok so with that, and somewhat back to my original question... how do you know when a clip is recorded with the log profile? Or any profile for that matter?"

Most of the time, the footage looks very flat, lots of grey. Sometimes, depending on the camera, FCPX will automatically add a camera LUT to the footage. Not all camera footage has this metadata, and FCPX doesn't have factory LUTs for every camera, so mostly, you have to check and see if FCPX has applied a camera LUT. Looking at the footage in the Finder will show the raw values, not the footage with the LUT applied. You can also check the inspector under "Settings" to see if there's a Camera LUT applied.


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Dave Smith
Re: How to tell what colour space a clip was recorded in?
on Oct 27, 2019 at 3:34:17 pm

Yep ok, got it.... i feel better now haha. Thanks a lot for the help, really!

=]


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