Automatic Dirt Removal, Deflicker, Noise - which order?

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Zack_W

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Automatic Dirt Removal, Deflicker, Noise - which order?

PostSun Jul 25, 2021 4:23 pm

I'm trying to clean up some scanned 16mm film, and am working with the Automatic Dirt Removal, Deflicker, and Noise FX filters in DR 17 Studio. Two questions:

1. These filters seem to interact to some degree. Is there a recommended order in which to place them?
2, Does it make any difference whether I work with the filters on the Edit page using the Inspector, or work with them on the Color page using nodes? I've already done some work using the Edit page, but just read somewhere that the processing is slightly different on the color page, allowing the filters to run more efficiently (and possibly leading to slightly different results?)

Thanks for any help! I'm using a M1 Mac Mini running OS X 11.4 (soon to update to 11.5).
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Marc Wielage

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Re: Automatic Dirt Removal, Deflicker, Noise - which order?

PostSun Jul 25, 2021 10:55 pm

Chapter 141, "Image Processing Order of Operations" (starting at p. 2808 in the Resolve 17.2 manual) goes into this in a little detail, but it doesn't reveal how multiple OFX plug-ins would affect each other in a row.

Image

To me, you'd have to experiment a little, do some tests, and use some judgement as to how each effect is affecting the image. My guess is you'd want to use Deflicker first, then Automatic Dirt Removal, then a Noise FX filter (I assume you mean Noise Reduction) at the end. But according to the Order of Operations graphic, Noise Reduction actually affects clips before color, so that's a surprise to me. I'm not sure if it makes any difference if you use the normal Noise Reduction mode vs. the OFX Noise Reduction, or even a third-party OFX noise reducer like Neat Video. I'm guessing the latter would be long after Resolve's processing and would happen depending on where you put it in the node tree, but it's definitely something on which you'd have to experiment.

Having done this with film, in some cases we do multiple passes and might do one just with Deflicker (and no NR), then do the NR in a later render with a new file. And we might do some Automatic Dirt Removal, then bypass it and only use manual Dust Removal instead, to avoid any risk of harming the picture with excessive processing.
marc wielage, csi • VP/color & workflow • chroma | hollywood
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Mike Warren

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Re: Automatic Dirt Removal, Deflicker, Noise - which order?

PostSun Jul 25, 2021 11:25 pm

Marc Wielage wrote:Image

Having done this with film, in some cases we do multiple passes and might do one just with Deflicker (and no NR), then do the NR in a later render with a new file. And we might do some Automatic Dirt Removal, then bypass it and only use manual Dust Removal instead, to avoid any risk of harming the picture with excessive processing.


I'm struggling with understanding the benefit of not having the NR filter first in the chain. Especially after motion blur, which is going to blur the noise.

I always do NR first, in audio files, in photos and in more recent years (since I've had video NR) in video files. If performance is an issue, I'll either turn off the NR (and other heavy effects) while editing, or render out a high quality intermediate.
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Dermot Shane

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Re: Automatic Dirt Removal, Deflicker, Noise - which order?

PostMon Jul 26, 2021 1:29 am

i put NR last as it's destructive, and turns otherwise decent footage into visual mush
when it's last in the tree you can judge how little you can get away with, select the shadows, leave skintones, eyes, anything you care about un-trashed...

i have done some mild restoration for a feature doco recently, i ended up with node
1 = BCC's optical stab
2 = deflicker
3 = auto dirt with lots of properties animation
4 = manual dirt
5 = BCC scratch remover
6 = NR
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Marc Wielage

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Re: Automatic Dirt Removal, Deflicker, Noise - which order?

PostMon Jul 26, 2021 7:31 am

Dermot Shane wrote:i put NR last as it's destructive, and turns otherwise decent footage into visual mush
when it's last in the tree you can judge how little you can get away with, select the shadows, leave skintones, eyes, anything you care about un-trashed...

I think that makes a lot of sense.

In cases where we do a lot of NR and have it really high, we do it as a second pass on a flattened file and use Neat Video. Neat has got 4-5 frames of analysis in it, so it quickly reacts to cuts and there's no fear of lag or other issues. I also do essentially a "scene-to-scene" (but not shot-to-shot) NR pass and have a light level, a medium level, a heavy level, a day setting, and a night setting, or whatever the project needs. That works for me. A tiny bit of enhancement after NR (very subtle) helps a bit.
marc wielage, csi • VP/color & workflow • chroma | hollywood
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Jim Simon

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Re: Automatic Dirt Removal, Deflicker, Noise - which order?

PostMon Jul 26, 2021 3:14 pm

Mike Warren wrote:I always do NR first...If performance is an issue, I'll...turn off the NR...while editing
I prefer to do it this way as well. Follows the processing order.
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Dermot Shane

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Re: Automatic Dirt Removal, Deflicker, Noise - which order?

PostMon Jul 26, 2021 5:43 pm

Like Marc, if it's toooo much for Resolve i'll turn to third party options on flatened file before i'll trash the footage with Resolve's native and pretty good NR, but pretty good is not the same as awesome

also judgeing NR is highly dependant on screen size.. something that looks fine on my 25" OLED can look ott on my 55" OLED, and complete crap on a 32 foot cinema screen

if you are delivering to various web services and feel safe judgeing the NR trashfest with the screen you have, all good
if you are delivering for QC's deliverables and large screens then a lot more caution is called for, same for all the temporal effects, includeing the one's in the restore folder (deflicker/ auto dirt)
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Zack_W

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Re: Automatic Dirt Removal, Deflicker, Noise - which order?

PostWed Jul 28, 2021 3:07 am

Thanks for the replies and suggestions! I have on further question:

I will need to add a bit of sharpening, which should go last after all the other filters. So far I've been applying Resolve FX filters using the Edit page and the Inspector, but it may be easier for me to add sharpening using a node on the color page. Can I assume that color page nodes will be processed after the filters on the Edit page? Or is there a setting by which I can control this? As recommended, I read chapter 141 in the manual but didn't find the answer to this question there (or perhaps it's there, but I failed to understand it).

Incidentally, I did some tests and to my surprise found that on balance I was getting slightly superior results by putting the Automatic Dust Removal filter first, followed by Deflicker. The difference was very slight, but this order gave me fewer artifacts on tightly spaced parallel lines (which my footage has a lot of), and also was slightly more effective at removing dirt specks. This order also gave me very slightly worse motion artifacts, but given the footage I'm working with the trade-off is worth it. I was also pleased to discover that the Resolve FX Deflicker filter at a minimal setting really took the curse off of the film grain while giving it a nice organic feel. This means I can skip using a noise filter, which is a big relief.

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