It implements 5-tap user adjustable horizontal and vertical filters designed to (slightly) reverse previous efforts at softening or edge enhancment that are common (but ugly) in DVD mastering. Since DVD's were intended originally for interlaced displays this has caused content providers to vertically filter them even a bit more to hide interlacing artifacts. I don't know why they sometimes over do the edge enhancement.
When softening it will attempt to approximate the inverse of a simple 3-tap edge enhancement filter. When sharpening it will attempt to approximate the inverse of a simple 3-tap softening filter. For the math and logic involved see the comments in the UnFilterALL.inc member included in zip file.
The effects are fairly mild but be aware that excessive sharpening makes things harder to compress and may bring about the dreaded "edge enhancement artifacts" the people complain about in DVD's from some studios. And while excessive softness may hide noise it loses detail and generally just looks ugly. So it is probably best to just try to reverse whatever has already been done to your source.
In your Avisynth file use commands similar to:
LoadPlugin("F:\UnFilter\UnFilter.dll")
AviSource("D:\wherever\myfile.avi")
UnFilter(HSharp, VSharp)Of course replace the file and directory names with your own and supply the integer values for the amount of horizontal and vertical sharpness. Valid values for each are from -100 (max softness) through zero (neutral) through +100 (max sharpness).
$Date: 2004/08/17 20:31:19 $