One of my first experiments was the opening scene of this badly damaged Ford Library film. There were two bad splices as the camera pans, further complicated by radial lens distortion making it difficult for the in and out points of the new animation to match the original film. As a man walks across the yard from the barn, part of his action is missing. A section of his existing walk at the same angle was used to add this action. There is a remarkable leather belt going from the tractor into the barn which oscillates in a long irregular cycle. Flash was used to analyze and animate this belt. Using the clone stamp tool too much will cause the moving image to chatter. The example above from "On the Farm" is a good illustration of why not to use this too broadly.
Over time as the film lay wound on the reel, the emulsion bled through to adjacent layers leaving yellow stains.
Here are two ways to reduce the visibility of yellowing from nitrate decomposition using After Effects: Effect > Channel > Set Channels
For yellow stains set the Red, Green, and Blue channel sources all to Red. This knocks out the yellow and its gamma without adding noise, at least that is the idea. Another method is to use Effect > Color Correction > Selective Color, which allows you to knock down one color at a time and is more precise. To simply desaturate the image to monochrome will replace the yellow stain with grey and make it a permanent part of the composition. Color key can add edge fringe, which you don't want. Why can't we just reverse Effect > Color Correction > Leave Color?
After Effects Warp Stabilizer
The Warp Stabilizer is designed to work in the background on multiple scenes. It does an amazing job of stabilizing. When applied to a scene the warp effect is set by default, so you must change the settings for each scene to turn this off since Adobe hasn't as yet provided presets. If a scene has major FG action the Warp effect can distort the image dimensionally, so for film restoration it works best if this is turned off. After rendering, check each scene to make sure it has finished because there is a blue band across the field to let you know that Warp is working and this alert prints in your output! There are a lot of demos and tutorials on the internet about Warp Stabilizer. This YouTube link is a great comparison with helicopter footage: After Effects Warp Stabiliser Test (aerial footage before & after). The results can be amazing. For problem scenes you can select individual Warp nodes, and it will even repair rolling shutter distortion.
Granite Bay Software "GBDeflicker" was written to help post production of time lapse image sequences and video. Clone stamp works best if a sequence has been pre-rendered holding the density as even as possible. GBDeflicker lets you sample the whole frame or two points. Price was $99.
Here is a link: GBDeflicker
Dust Busting software is not easy to find on a budget. RE:Vision Effects DE:Noise offers an interesting solution for $150
which sort of works. In layman's terms the software identifies an artifact and fills it in by stretching adjacent pixels
over the area. It is not a magic bullet and gets strange if you set the parameters high. You can see some documentation here:
www.revisionfx.com
For very badly damaged films, you can fix white negative dust by making a copy of the layer, and then turn it into a hi-con mask. Copy the original layer and advance it one frame to provide fill to print through the mask. You have to do some masking to control this. You can also make a clean copy of the BG and hold back the action in front of it with a mask. Blend this with the original so it doesn't freeze and it will knock down a great deal of scratches and dirt in places where they are most noticable. This is especially effective at the edges where there is more wear or decomposition.
Clients like to assume that somewhere there is a button somewhere that will fix anything. They say: 'CAN YOU JUST...?' As Inspector Clouseau once said,
"Well, you know, it wasn't easy."