Strong noise/blocking on dark surfaces

[GaoGao]

Hi.

I'm having problems filtering away moving blocks and grain in mostly dark areas. It seems whatever I throw at them either doesn't help or has to be set so strong it nukes waaay too much detail.

Sample:
http://rapidshare.com/files/159116860/seirei1.demuxed.m2v

The hair is a good example of where this blocking goes on, but it's on any dark(ish) part of the backgrounds as well to some degree.

Ideas? I've been toying with various denoisers+gradfun2db but without particularly pleasing results.

[Didée]

Ah, 8fps animation. One good thing about 8fps animation is that, even without (slow) motion compensation, one can use a radius=2 temporal median without risking motion artifacts.

mpeg2source("D:\seirei1.demuxed_(GaoGao).d2v")

TFM().TDecimate() # adjust settings if you need to - IVTC is not my world

o=last

m1 = Median2( o.selectevery(1,-2), o.selectevery(1,-1), o, o.selectevery(1,1), o.selectevery(1,2) )
m10 = m1.merge(o,0.5)
m11 = Median2( m10.selectevery(1,-2), m10.selectevery(1,-1), m10, m10.selectevery(1,1), m10.selectevery(1,2) )

m11.fft3dfilter(sigma=4,bw=96,bh=96,ow=48,oh=48,bt=1,plane=3)
gradfun2db(1.51)

If you don't have the "Median2()" function, look here (http://forum.doom9.org/showthread.php?p=1169990#post1169990).

[GaoGao]

Hey, that's pretty effective! Better than anything I came up with on my own.

It's not all 8fps animation, though. There are FILM sections all over, resulting in some funky side-effects (http://i37.tinypic.com/23sjbdy.jpg) with that script. Any easy way to adjust it to accept these sections as well?

[Didée]

Alas, no, not possible.

For 8fps sections, a temporal median radius 2 is safe.
For 12 fps sections, radius 2 is not safe. Here, only radius=1 is safe (but less efficient as well).

For 24 fps FILM sections, a "naked" temporal median is just suicidal. That's what you found already.


Since your sample had only 8fps content, I showed something "easy" that works quite well for such content.

If you have to deal with mixed 8/12/(24) fps content, then it's not that easy. You can jump through all the usual loops, but won't find any "definite" solution, only some compromise to arrange with. Possible methods there are plenty, and *each* single one will bite you back at some point ... It's your decision which bite hurts you the least.