How Do To Remove Compression Noise from Flog?

Engaged ,
Mar 09, 2022 Mar 09, 2022

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Here's a still of my video in fLog:

trashcaneron_0-1646872122478.png

Looks fine until I grade it!

trashcaneron_1-1646872182776.png

Tons of noise / artifacting in the background gradient.

trashcaneron_2-1646872418163.png

A lot of banding happening.

 

Any solutions out there? Seems to me an algorithm could fix it 🙂 

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Adobe Community Professional ,
Mar 09, 2022 Mar 09, 2022

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Depending on the bits ... the total chroma/luma data in the file ... you can only go so far before banding/artifacting come to join the party. And you're doing some pretty heavy changes there. That would take a very properly exposed 10-bit file, if not 12-bit, to work well.

 

And if this is 8-bit, well ... you can't get there from "here".

 

So ... what is that media, what shot it? Your original is pretty low in contrast, and you're upping it a LOT ... maybe lighting for higher contrast and adding some gels in shooting will get you a good share of the way "there" and you won't have to grade so hard.

 

Neil

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Engaged ,
Mar 09, 2022 Mar 09, 2022

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Hey Neil - ! Thanks for chiming in. It's 4:2:0. I suspect under-exposed gradients are where 8-bit really screws you. In my particular case, the BG imagery is so simple that I'd think there's some plug-in that could do it. I remember using "smooth screen" as a technique for this in the past. 

 

Forgot to mention - the background color is definitely power windowed which doesn't help me either ! 

 

Here's what I've tried:

- Neat Video Reduce Noise V5 (not great on debanding after removing other noise, which it is great at)

- RG Denoiser III (did nothing for me for this type of thing)

- Flicker Free (this is not what this product is for, but it's fixed other things for me magically before so gave it a shot in the off chance the banding is consistent enough to be analogous to refresh bands)

- Boris FX Deband (I can see how this could be massively useful but wasn't quite right to solve this issue)

 

What actually worked best? Instead of using Lumetri:

  • I used Colorista's Key Mode to cutout the BG as cleanly as possible, knowing not to push the limit too much.
  • Then I threw a Magic Bullet looks set up on top of it (because I've built out my Lumetri setup clone in MB looks to A/B things in the past) and.... the banding is almost completely unoticeable. Crazy. 

 

MB Looks shows all kinds of gnarly banding in its preview window (a gripe I have with RG's previewer not being WSIWYG):

image.png

 

Full Quality:

trashcaneron_1-1646886335682.png

Whaaaaa??? Still there but so smooth now. Mission accomplished it seems (though I'd prefer to use Lumetri). 

 

Then, just for fun, I turn Neat Video On and render the frame and I end up with this:

trashcaneron_2-1646886561423.png

 

Hmmm it's almost as if there's something happening within the Premiere engine that interprets noise and compression differently... The footage is HEVC H265 whcih I know has a whole host of problems with Adobe. This one is really specific! 

 

For those encountering a similar banding issue, the solve might be "as simple as rethinking your FX stack." 🤣

 

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Engaged ,
Mar 09, 2022 Mar 09, 2022

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Continuing to tweak and I'm pretty happy with this, all things considered:

trashcaneron_0-1646887748537.png

 

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