Here is Guava Comb, a software comb filter. It is meant to get rid of rainbows and dot crawl in stationary parts of an image.
This filter is dedicated to my dad, the guava hunter.
http://students.washington.edu/ldubb...Comb_v0_9a.zip
The Guava works through the efforts of a tiny demon, who watches to see which pixels are changing back and forth. When it spots one, it thwaps the pixel so it will learn to stop being so fickle. The demon’s efforts are quite inexpensive, as he has been unemployed ever since the passage of the second law of thermodynamics.
Oddly enough, that’s actually a moderately accurate description of this filter!
This is a version 0.9 release because I am not all that familiar with the right way to handle interlaced material in a script. That’s something of a handicap when designing a filter meant for interlaced clips. Please tell me if the way it’s handling clips (interlaced or otherwise) is messed up.
Dot crawl and rainbows are an artifact of mistakes in conversion of a composite signal into its individual color components. So if your video was never encoded as a composite signal, this filter will probably be useless. On the other hand, it’s possible that this filter might coincidentally help remove some other kinds of periodic artifacts. To test out that possibility, there is an extra Mode setting called “Progressive” which will force the filter to look for every other frame patterns.
If your video has been encoded as a composite signal — as an over the air broadcast, or over a composite cable — then comb filtering is likely to be very useful. Crosstalk can cause subtle picture problems even in video where it is not obvious.
The down side is that the settings are not easy to choose, and that this isn’t an especially sophisticated filter. As a result, it can cause artifacts. Take a look at the docs for ways to set the options to minimize problems.