Stabilizing Level Fluctuations

[TruthOverFacts]

This is from a 2K scan of a 16mm dupe with very poor timing. The levels are all over the place, and they change quite drastically at times, even in the middle of the same shot. The waveform is constantly drifting as the image gets brighter and darker.

Here's an example of what I'm seeing:

https://www.mediafire.com/file/ei0ygfgm00u9n74/LumaProblem.mov/file

Any suggestions on how to deal with this?

Thanks,
TOF

[johnmeyer]

Your sample is too big for my slow Internet connection, so I don't know how quickly the levels change. There was a long thread over at Videohelp a month ago that discussed a similar problem:

Removing Slight Brightness Variation From Video (https://forum.videohelp.com/threads/420468-Removing-Slight-Brightness-Variation-From-Video)

My usual advice on removing flicker from film is:

1. Use DeFlicker.

2. Use MVTools2 with DCT=1 in the MAnalyze section.

3. Always make sure you recover the original frames before you do any of this (i.e., use TFM/TDecimate to remove telecine).

Here is a link to a relatively recent version of my film restoration script. You will see various flicker removal lines, some of them commented out, and some referred to in my comments. You should be able to use some of what you see there:

Here is a link to my current script:

John Meyer Film Restoration Script 2024 (https://drive.google.com/file/d/1eLUhz-LL3v_tSLlaH1spnwCNUVWMJn1_/view?usp=sharing)

[TruthOverFacts]

Thanks for the suggestions, John. You might want to wait until you've had a chance to look at the sample, as the issue is a bit more complicated than simple flicker. It's not really the traditional frame-to-frame flicker it's more of a gradual drift in the levels.

Also, this is a progressive film scan, so there isn't any telecine involved and TFM/TDecimate wouldn't apply in this case.

I'd be interested to hear your thoughts once you've had a chance to view the sample.

[johnmeyer]

I viewed it and it is pretty typical flicker related to common chemical development variations in early movie film. It is more common in nitrate film from the silent era, but I have seen it is early one-reel talkies, like Laurel and Hardy.

This is one of my restoration "before/after" compilations, queued up to a segment that had a lot of flicker. This was corrected using Deflicker.

Restoration Before/After (https://www.youtube.com/watch?v=tBAHzO7rJS0&t=115s)

Your clip has flicker that is more profound, so you might need to change some of the Deflicker parameters. I just use the default. Here is a link to the Deflicker settings:

https://avisynth.org.ru/deflicker/deflicker.html

[videoFred]

Very good restoration John! :)

[johnmeyer]

Very good restoration John! :)Thank you for that. It is quite a compliment, coming from the master. :)

I frequently watch YouTube videos of old restored film, and if I decide to continue to transfer and restore film, I am going to need to improve my techniques. The results I have seen recently, all of which have been done by individuals and not post production houses, are truly remarkable. The following is one example. Based on the residual artifacts I suspect that the flicker was worse than the OP's sample. The stabilization, detail enhancement, and grain reduction, are all a cut above what I've been able to do. Also, while I am generally not a fan of colorization, the result here is reasonably muted and not offensive at all. The added foley (sound) is something I have done on a few films and, if they'd spent a little more time making it less generic, it might have been a good addition as well.

San Francisco 1920s in color (https://youtu.be/60vJCP_Keuo?si=MOW0McIghj7XaO40)

I did a little research and found the much longer movie from which this was taken. I don't know if the person used the version available through this link or if they were able to download a higher-res, lower-artifact version:

Original (https://archive.org/details/6416HMCroftCollectionCan56FlyingInSmallPlane01445306)

On a related note, I have also seen several recent YouTube clips that have been either AI enhanced, or simply AI generated. They are unsettling, and sometimes quite creepy, and are full of details that the AI algorithms simply made up. Despite that, I can see that eventually we are going to have a new level of restoration available. Here is one example. Even if it is totally made up, imagine being able to "train" an AI model with one of your old film reels and have it create a result like this:

Oh California, Take Me Back to the 1950s Golden Era! doo-wop Music ! (https://youtu.be/GNEmhVAOi6s?si=HR6ELZlCZDTGCYmC)

[TruthOverFacts]

Thanks for the suggestions John but the level changes were just so drastic and inconsistent that I don't think any automatic process could have fixed this.

In the end I ended up having to manually adjust the levels in chunks using keyframes, sometimes a frame at a time. After that, I applied the deflicker to even it all out.