This is a free plugin for VirtualDub (and Video Enhancer) for removing film dirt-like noise.
It uses information from previous and next frames to understand what pixels are noise and
fix them using values from neighbor frames. Some before / after examples:
How it works
It uses motion search and
calculates motion flow in both directions - from previous and next frames. For each block
of current frame it compares corresponding blocks from neighbor frames. If they are similar
enough, they are used to bracket pixel values in the block of current frame.
If they are not similar
enough, the block in current frame remains intact. If too many blocks are kept intact, then there
is probably a cut or just too much rapid changes, so the whole method is not applicable. In this case
the whole frame is processed with degrain procedure instead.
When deciding whether two 8x8 blocks are similar, the plugin compares corresponding pixels
and if more than N pixels differ in brightness by more than some noise threshold T, these
two blocks are considered not similar. So the two parameters in the settings dialog are
noise threshold T and max number of noisy pixels N.
Where it works
This plugin uses advanced features of VirtualDub API and works in YV12 colorspace, so
it requires VirtualDub 1.9.1 or higher, or Video Enhancer 1.9.12 or higher.