The dreaded vertical green stripe

[grannyGeek]

I have a MINOR discoloration problem in this project, and am hoping for advice.

I captured vhs using VirtualDubMod, using Huffyu to YUY2.

In a number of scenes, the sky has a definite green tint on the left hand one-third of the screen.
These occur mostly in sunrise/sunset scenes, and I speculate that it may have something to do with the sky being significantly brighter in that quadrant.

Also, all of the capture has a slightly darker discoloration in a stripe down the left side approx 20 pixels wide, and mostly not very obvious.
(ya, I know I probably need better equipment, wanna donate?)

But on these scenes, if I adjust the color to get the green out (using ColorMill and/or AviSynth Tweak and ColorYUV), that stripe stays pretty green and much more blatant because now it is in a contrasting color.

Is there any way to correct the green stripe short of “roto-scoping” and manually re-coloring the affected frames? I would rather not spend the next six weeks painting pixels, this film just ain’t that important to me.

Any advice will be gratefully accepted.

[themaster1]

this is common in vhs rips even with pro devices

I noticed the same problem already and sometimes the line is BLUE

I think,... but i ain't no expert that this is caused by the TBC which correct the phase not really well actually

u have a tbc right?

i haven't a TBC and look the results on my vhsrips:

The stripe is here too BUT not at the left or right of the pic but in the middle(well more or less) which fucks up the fina! result :/

[grannyGeek]

Hi, thank you for responding.

Nope, I don't have a TBC either (long story involving on-line purchasing, and none available locally off-the-shelf)

My stripe is always just a darker strip of the underlying color.
But in this case, when I used color-correction, the stripe retains its original color.

So, I guess I am stuck with either leaving it, or manual frame-painting, or else
<sigh> try to find and learn how to use some aviSynth filter to mask the stripe for its own color-correction routine.

Ya know, some days I really don't want to get more educated, I think this is one of those days. :P
But, oh well, I'm off to google for threads about masking.

good luck to us both!

[Soopafresh]

Yup. This method works really well, and is about the only way to effectively reduce the green chroma junk.


MergeChroma(last)
FFt3dfilter(Plane=3, Sigma=8, Degrid=1)


The "Plane=3" line tells fft3dfilter to only process the chroma channels, so the image isn't affected, The "Sigma" part means the strength of the cleaning. You could never do a "Sigma=8" on the Luma channel; it would be way too strong and obvious, but you can crank up the number on the chroma only.

Give it a shot.

[themaster1]

do you have any idea of where get this filter for avisynth

& the way the script must look ? i know what is avisynth but i never really used it yet

[Soopafresh]

search on "fizick fft3dfilter"

Avisynth is a scripting language, so there will be a few weeks of learning curve. Once you see the results, you'll be hooked.

[grannyGeek]

soopafresh, thank you for that !!!!

I just started using FFT3d a couple weeks ago, mostly only using parameters for sigma and plane 4, and it gives very impressive cleaning. Also does a pretty nice job of light sharpening.

I will try your method of cleaning an isolated plane, and post back results.

[Soopafresh]

Crank up the Sigma, and use the "Degrid=1" setting for your regular use with fft3dfilter, it'll make things look more natural if you need to use strong settings.

[themaster1]

how the hell this filter work fft3dfilter

i get an error "UNABLE TO LOAD fft3dfilter.dll"

i read here:http://avisynth.org.ru/fft3dfilter/fft3dfilter.html

i don't understand what to do lol

ft3dfilter.dll>>> i put this in the plugins folder of avisynth

and this:>>>FFTW3.DLL <<< where?

[themaster1]

allright nevermind working now,testing this filter.....if it dont work fine ill slap y'all in the face

[themaster1]

well i don't see any difference really:
before restoration:


AFTER:

[themaster1]

I see this ugly GREEN line still i used

MergeChroma(last)
FFt3dfilter(Plane=3, Sigma=8, Degrid=1)

[Soopafresh]

I'll post some before and afters shortly. Glad to see you got it working. Tough one, huh ?

comparison.avi

[Soopafresh]

Try these settings:

mergechroma(last)
fft3dfilter(bt=4,sigma=19,plane=3,degrid=1)
fft3dfilter(bt=4,sigma=19,plane=2,degrid=1)
fft3dfilter(bt=4,sigma=19,plane=1,degrid=1)
mergeluma(last)

[grannyGeek]

Soopafresh, I used your script with slightly stronger settings. It’s Deep Magic, ‘tis.
Too bad I can’t use FFT3d on my laundry.
The contrasting green is GONE.
A hint of a darker shadow-stripe remains, but no longer in a contrasting color. It’s almost un-noticable on (standard) tv playback.

I’ll have to twiddle ColorMill a bit more to compensate for too much red.
I’ve been playing with Trevlac’s TweakColor plugin because it works in YUY2 and YV12 , but doing color-correction without a gui needs the patience of the Sphinx.

mergechroma(last) 
fft3dfilter(bt=4,sigma=25,plane=3,degrid=1) 
fft3dfilter(bt=4,sigma=20,plane=2,degrid=1) 
fft3dfilter(bt=4,sigma=20,plane=1,degrid=1) 
mergeluma(last)
 # #   --- lightly clean luma to smooth some of the graininess
fft3dfilter(sigma=1,  plane=0)

LoadVirtualdubplugin(vdPath+"colormill.vdf", "colormill",1)
ConvertToRGB32()
colormill(25710, 44388, 31069, 25699, 26212, 25708, 26468,
\ 28516, 29028, 25700, 27260, 25701, 25700, 1124, 5)

Thanks again.

PS -- How do MergeChroma and MergeLuma affect this script?
I still have SO much to learn about color spaces and color planes.

[Soopafresh]

Hey ! Looks Nice ! Yeah, there just aren't that many solutions to get rid of the green junk, and unfortunately, few methods are 100%. But it adds enough Chlorox to the video to make it bearable.