Restoring an old dirty scratched film (manually if possible)

[rrats]

Opening for an old Yugoslavian film "maratonci trce pocasni krug" which had recently been restored features, although cropped, the best transfer I could find featuring the assasination of King Alexander from 1934. Even though it is a best source I could find, it is far from perfect, as there is a lot of film scratches and god knows what else layered on top of it.

What is the easiest way to restore this with avisynth?

[Selur]

The scratches that are popping up and vanishing could be removed with filters like SpotLess, SpotRemover, DeSpot, RemoveDirt(MC),KillerSpot.
For long-lasting scratches, you would need some inpaining. The easiest way to use inpainting I know of in Avisynth is InpaintDelogo. You will need to create a different mask per scene, so this will require quite some manual adjustments.
Here's an example what SpotLess(RadT=3) does:

VoodooFX probably can help with using InpaintDelogo for this.
Should be similar to: https://forum.doom9.org/showthread.php?p=1975214#post1975214

Cu Selur

Ps.: at the end you might also want to add some cas for sharpening.

[rrats]

Thank you Selur, I think that using both SpotLess and inpaint delogo could hep create a very good result.

also do you by any chance know how to remove that vertical line present thought the video?

[Selur]

also do you by any chance know how to remove that vertical line present thought the video?

For those permanent scratches/tears InpaintDelogo comes into play, since from a general standpoint those are basically logos.

[rrats]

Thank you again Selur

[VoodooFX]

All that dirt is non static, so not like the logos.

[Selur]

@VoodooFX: Sure those scratches are not static over the whole clip, but there are a few scratches that span are static for tons of frames, thus normal scratch and dot removal won't catch them. So I think inpainting is the only way to get rid of them. If you are saying that InpaintDelogo can't be used on only on a specific range of frames because of some restriction I'm not aware of, that is fine.

[johnmeyer]

Vertical scratches are VERY difficult to remove because while you may initially think that they are static, they are not; they wander a little from side to side. This defeats in-painting. The various spot removal techniques are good for things which only persists for one frame (e.g., dust spots and dirt), but fail with vertical lines.

What you need is a tool which lets you create a mask "object" attached to the scratch, and then have software track that object. I'm not sure such a thing exists for AVISynth.

The best way to remove scratches is to do the transfer using a "wet gate." Unfortunately, since you don't have access to the film itself, this option is not available to you.

[rrats]

Doing it manually is still better than nothing. Sure it takes a lot of time but the end result is worth it

[Selur]

You can also get rid of some more of the scratches by using DeScratch.
Here's a quick example with one descratch call:

# descratching using DeScratch
DeScratch(asym=255,maxgap=100,minlen=50,maxangle=45,keep=50)
# despotting using SpotLess
SpotLess(RadT=3)
# grain handling
McDegrainSharp()

adding multiple DeScratch calls, with different settings, should allow getting rid of most of the scratches.
As a general tip, I would also suggest being careful with SpotLess&DeScratch and use them on a per-scene basis since they can cause ugly artifacts.
Also note that the above setting are by no means tweaked for the source. (sometimes it also helps to rotate the image by 90 degree before applying such filters and later flip the source back)

Cu Selur

Ps.: Multiple SpotLess calls with different thSad values might also help.