Is this filter possible or impossible to code?

[Zep]

The problem I'm having appears to be luminance banding. Old VHS tapes and also my
analog cable on certain channels I get this interference band across the whole screen
horizontally and it slowly rolls. It is brighter in the middle and then fades above and below
to a normal picture. The color is fine just brighter in this band. I can get rid of it in
Photoshop perfectly by doing a inverse gradient fill over the band in the luminance channel
so i know it is possible but how to do it in an algorithm for use in a filter is beyond me.

here is an example clip of what i mean . It is 6 megs DivX 5.0.3 and no filters.

Banding.avi

My thoughts are the banding should be detectable because it is a straight horizontal
band across the whole screen and rolls very slowly and at a steady pace. This is
something you see in footage itself almost never so I thought its movement should
be detectable temporally.

Can any of you gurus here take a look at the clip and tell me if you think a filter
like that is possible and worth doing? Are there any band removers filters out
there that i missed? So far the best filter to at least soften the bands without
destroying the the rest of the picture via blurring and ghosting is Pixiedust filter.

Thanks


Zep