Vertical chroma artifacts on U-matic Captures

[henryperu77]

Hello, i did some captures with an u-matic player captured directly to the pc using a blackmagic, the problem is that im getting this strange vertical lines on the borders..





My Umatic has internal TBC and DNR , using it or disabling it still have the problem.. What filter can i use on avisynth to remove that artifacts without bluring the image?

[juhok]

Looks like chromashift? Move chroma a bit to the left.

    moveleft=0
    moveright=0
    moveup=0
    movedown=0
    vi = Crop(moveleft, moveup, -moveright, -movedown).AddBorders(moveright, movedown, moveleft, moveup)
MergeChroma(vi)

[henryperu77]

No is not chromashift -_- , i already try that.. for some reason appears that vertical lines in all the edges/borders.. is more noticeable on red colors

[TheSkiller]

I could be wrong, but to me it looks like not the whole color plane is shifted in comparison to the luma, but rather only one of the two chroma planes is shifted (i.e. U is not in alignment with V).

Play around with this a bit:

Shift=2

YtoUV( UtoY(crop(Shift,0,0,0).AddBorders(0,0,Shift,0)), VtoY(), last ) 
#YtoUV( UtoY(), VtoY(crop(Shift,0,0,0).AddBorders(0,0,Shift,0)), last ) 
#use either line

This only aligns U and V, you might still need to align chroma to luma afterwards.

Edit: Btw, isn't that in the horizontal direction?

Edit 2: Corrected and tested the code.

[henryperu77]

The lines are vertical, the problem is not the color shifted, ....
The YtoUV only shift the color... dont correct the vertical lines

[cretindesalpes]

Is the video in a 4:2:2 or 4:2:0 colorspace? It looks like the chroma has been badly upsampled for display, with nearest-neighbour interpolation.

[TheSkiller]

I don't see any vertical (i.e. upwards/downwards) "lines", only a horizontal chroma problem that looks like either the U or V plane is out of horizontal alignment (giving that pinkish outline to the right).
Have you even tried the script I posted?

Due to the screenshots not showing raw video, like cretindesalpes said, part of the problem may be just a bad chroma upsampling. The zoomed screenshot also looks heavily compressed, it's of no use.

We need a short video sample to give proper help.

[2Bdecided]

Originally Posted by TheSkiller

The zoomed screenshot also looks heavily compressed

I think that's what he's talking about.

It does look like point-resized chroma. It might be something else though. A raw video sample would help. Ideally it should be fixed at the point where it occurs - it's unlikely to be on the Umatic tape.

Thinking about it, it might be what's left when something has tried to remove dot crawl.

Cheers,
David.

[henryperu77]

Ok i uploaded a sample of video (no audio)

http://www.mediafire.com/download.php?sb5o8y3djsiy2mb

Its captured with AMV2 encoder you can download the codec here if you dont have it http://www.free-codecs.com/AMV2_video_codec_download.htm

[cretindesalpes]

So it's already in RGB? Here is a quick attempt to fix the vertical line problem and the chroma shift:

ConvertToYV16 (interlaced=true)
mt_convolution (horizontal="-4 7 10", vertical="1", y=2, u=3, v=3)
AssumeFrameBased ()
SeparateFields ()
y = TurnLeft ().Daa ().TurnRight ()
u = UToY ().aWarpSharp2 (chroma=1)
v = VToY ().aWarpSharp2 (chroma=1)
YToUV (u, v, y)
AssumeFieldBased ()
Weave ()