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Nick.Boyer
Participating Frequently
October 4, 2022
Question

Lumetri Color adding Compression Artifacts/Pixelation with LUT

  • October 4, 2022
  • 4 replies
  • 1487 views

I've seen a couple of other posts regarding similar issues to this but they seem to be a bit different than the issue I'm having.

 

I have a LUT that I use for all my video and I've been applying it with Lumetri Color. I've noticed this pixelation in some of the colors in the background of this project I'm working on. It almost looks like it's being compressed or something. See image below of what I'm talking about. You can mostly see it in the blue of the background.

It's worth noting that not only do I see the pixelation in the video preview of Premiere, but it's still there when I export the video. The footage I'm working with is shot on my Blackmagic Pocket 6k Pro in Apple Prores 422 LT (1080p). I've done tests with 422 HQ and at different resolutions and the problem still persists. 

 

Interestingly enough, I tried to throw the exact same LUT on using Davinci Resolve Studio and these artifacts do not show up on that footage. See below my image export from Davinci where the footage looks FAR cleaner:

 

I feel like I can safely say it's a Lumetri Color issue because it happens in both Premiere and After Effects. Not sure if it's a bug or it's just the way Lumetri processes footage but I can't figure out why this is happening. I've tried changing different settings in Premiere (sequence settings, project settings, preferences, etc) to see if anything will change it, but nothing makes a difference.

 

I'm editing on a new M1 Macbook Pro with 64 GB of RAM. Not sure if that really matters here or not. I have not yet tried to color grade the footage in Premiere on my Windows computer yet, but I'm not super confident that will make a difference. Although I can give it a try when I get a chance and post an update if it's helpful. 

 

Anyone have any advice for me other than "switch to Davinci"? My current workaround will probably be to edit my project in Premiere and then color it in Davinci but that's not the most ideal fix. So any ideas?

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4 replies

R Neil Haugen
R Neil Haugen
Brainiac
October 6, 2022

In private messaging, the OP tells me that on their end, setting MBD didn't completely 'fix' the image.

 

I've heard of this, and seen it repllicated for demonstration, on a few Macs. Mostly involving DNx variants and XAVC, but also occarionally ProRes. While other colorists also on Macs couldn't replicate on their systems.

 

So their seems to be something where some Macs don't properly process all bit depth information. Anyone with this is MOST welcome to post here.

 

Make sure you have Max Bit Depth set on both the sequence and the exports of course. It's a waste of our time, but until changed ...

 

Neil

Everyone's mileage always varies ...
N
Nick.BoyerAuthor
Participating Frequently
October 6, 2022

Thanks for that update, Neil!

 

I was hoping it wouldn't be a Mac issue for me but that very well just may be it (how unlucky of me). I will try to process the footage on my Windows PC at home and turn on Max Bit Depth to see if I can get it to improve. Worst case, I'll process the color for my project on my home computer or just put into Resolve and color it there.

    R Neil Haugen
    R Neil Haugen
    Brainiac
    October 6, 2022

    And I've had a personal response from a staffer asking if, during my testing of the media, the MBD option was set to 'on' ... checked in the Sequence settings dialog.

     

    No, I did not check that box ... and that was intentional on my part.

     

    Yes, doing so does 'fix' the banding. But we users should not have to carefully set that manually for every sequence and export that has 10 or 12 bit media! And not just for the sequence, but for the exports from that sequence also!

     

    As Jarle Leirpoll and many others have noted, once upon a time in the past PrPro simply correctly handled bit depth of all 10/12 bit media. We didn't need to check that box.

     

    A version or two back, that ... stopped. For some reason. And now, yes, the user for some reason needs to go to the Sequence Settings dialog and set the MBD option to 'on' if there is any 10 or 12 bit media on that sequence.

     

    And THEN ... do the same in the export dialog for every single export!

     

    The default in both the Sequence and Export processes is clearly now to treat and process all media as 8-bit unless the user manually tells the app to do otherwise.

     

    And we users have no way to select a default option to recognize and properly handle all 10 and 12 bit media. Again, it's a manual process for every sequence, and every export.

     

    Most unfortunate. A HUGE waste of user time. And yes, part of my response pattern in this thread has been to push for this getting FIXED.

     

    Neil

    Everyone's mileage always varies ...
    R Neil Haugen
    R Neil Haugen
    Brainiac
    October 4, 2022

    Ok, here's the original clip ...

    And here's with that LUT ... and I'm definitely getting banding in the blues and magentas above/behind the subject. I've got red lines added where they appear on my screen.

    And when 'normalizing' manually I can get a very similar image, but with very much subtler banding.

     

    Here's the manually normalized image at 200% ...

    Basically, if I take the contrast out far enough to fully normalize the image, I start getting banding there. What you noticed as 'blockiness'.

     

    And in Resolve, using that LUT, at 200%, here's the image ...

    Without notable banding.

     

    Yea, Resolve is definitely handling this better.

     

    Neil

     

    Everyone's mileage always varies ...
    R Neil Haugen
    R Neil Haugen
    Brainiac
    October 4, 2022

    What is that LUT? And what settings do you have for reading LUTs in the Project settings ... at the bottom, in the CM section?

     

    Two options there, Trilinear and Tetrahedral ... if it's set for Tri, switch to Tet ...

     

    Neil

    Everyone's mileage always varies ...
    N
    Nick.BoyerAuthor
    Participating Frequently
    October 4, 2022

    Thanks for the response, Neil

     

    It's a LUT made by Phantom LUTs. It's a BMPCC Film to Arri Rec 709. I like it a little bit more than the Blackmagic Film to Video LUT (but putting that LUT in Lumetri also gives me the same problem).

     

    My 3D LUT Interpolation settings are on Tetrahedral

    R Neil Haugen
    R Neil Haugen
    Brainiac
    October 4, 2022

    That may be a "shaper LUT" I think they're called, with a 1D and 3D LUT in the same file. Premiere has trouble working with them. I've seen a comment ... I think it was on LGG, but might have been here or the BM forums ... that in a text editor you can change one line on the shaper LUTs and Premiere can use them.

     

    Don't recall it though at the moment.

     

    And I'd be happy to test it on my PC ..,

     

    Neil

    Everyone's mileage always varies ...
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