Removing stroke around edges of VHS capture

[cedricm]

Hello everyone,

I've become more and more interested in the restoration of VHS tapes. I bought some prosumer Panasonic SHVS decks lately and I've been googling around alot for the last 1,5 year. The videohelp.com forums have helped me alot, so today I've finally decided to create an account over here.
I started playing around with VirtualDub and some filters. Since a few days ago I started experimenting with Avisynth since it seems to have much more powerful plugins and scripts.
I've discovered the great GTGMC deinterlacing script for example. None of the virtualdub filters even come close to this one.

Now I'm facing a weird effect when restoring some VHS tapes. Here's an example:

I'd like to get rid of that white stroke around the edges. I've been playing around with chroma shifting plugins but haven't had much luck...

This is my current avisynth script:

AVISource("D:\test.avi", true) #PAL VHS Capture
QTGMC( Preset="Medium" )
SelectEven()
ConvertToRGB32()
LoadVirtualDubPlugin("C:\Documents and Settings\User\Desktop\virtualdub\plugins\NeatVideo.vdf", "NeatVideo", 3) 
NeatVideo("C:\AVS\test.dnp", "C:\AVS\test.nfp", "1.0", "3", "1", "0")
ConvertToYV12()

[jagabo]

That's an oversharpening halo. Turn off the sharpening filter in the VHS deck and capture device if you can. If not, use a DeHalo filter in AviSynth. Like Dehalo_alpha().

[cedricm]

That's an oversharpening halo. Turn off the sharpening filter in the VHS deck and capture device if you can. If not, use a DeHalo filter in AviSynth. Like Dehalo_alpha().

It looks like the sharpening on the vhs deck was all the way open... I've put it halfway and that indeed helps
However, it feels like I'm losing detail now. If it's not supposed to be all the way open, what would be the best setting?

[sanlyn]

Hard to say for certain without seeing an unprocessed frame, but the result looks over filtered and oversharpened. There are hard sharpening effects on edges as jagabo noted, but inner detail of objects look a bit smoothed. The image has zero grain. Removing tape noise is a good idea -- and not that easy to do, really, without removing other elements that you'd want to keep. NeatVideo should be tweaked using the Advanced Interface. It helps to have a good noise sample, too. Sometime you just have to play with the plugins and with NeatVideo to find what's called the "sweet spot" for denoising and sharpening -- not too little, not too much. But once you get there you can use pretty much the same settings for the entire video.

[cedricm]

Hard to say for certain without seeing an unprocessed frame, but the result looks over filtered and oversharpened. There are hard sharpening effects on edges as jagabo noted, but inner detail of objects look a bit smoothed. The image has zero grain. Removing tape noise is a good idea -- and not that easy to do, really, without removing other elements that you'd want to keep. NeatVideo should be tweaked using the Advanced Interface. It helps to have a good noise sample, too. Sometime you just have to play with the plugins and with NeatVideo to find what's called the "sweet spot" for denoising and sharpening -- not too little, not too much. But once you get there you can use pretty much the same settings for the entire video.

Thanks for your reply. I will experiment a bit more with the sharpening and neat video filter. I'll keep this topic up-to-date

[manono]

I've put it halfway and that indeed helps

Turn it all the way off. If you want to do some sharpening, do it with a better AviSynth sharpener after you're done doing whatever else you're doing.

[jagabo]

I've put it halfway and that indeed helps

Turn it all the way off.

On some devices halfway is off. Lower settings might blur. He'll have to experiment.

And note: When sharpening VHS you need to sharpen more along the horizontal axis than the vertical axis.

[sanlyn]

Nothing particularly bad about NeatVideo's sharpener, but it's definitely set too high in the sample image. It has a range from 0 to 200, with 100 the default -- which is too high. I seldom use it at greater than 50, and often turn down sharpening on the Y channel and lower it on the Cr and Cb channels ("mid" and "high" channels) as well. The lower-level values give stronger halos, and the Y channel if set high will just make halos brighter. Tune NeatVideo in its advanced GUI and don't use NV's built-in defaults -- even for messy video, those defaults are far too strong.

[manono]

On some devices halfway is off. Lower settings might blur. He'll have to experiment.

cedricm says he has "some prosumer Panasonic SHVS decks" I have the PAL Panasonic NV-HS860 with separate TBC and 3D DNR. The sharpness settings on his may be different (if different models, and there are several good PAL ones), but mine are Sharp, Auto, and Soft. As near as I can tell the Soft setting doesn't actually soften the picture, but just doesn't add any crappy sharpening/edge enhancement. And that's why I suggested he just turn it off. LordSmurf is all the time harping on the default sharpening of the Panasonic VCRs, but maybe he's only seen the NTSC ones.

[2Bdecided]

The old Panasonic machines always used to say that the "EDIT" position was the "do nothing" setting for dubbing (it also disabled the variable sharpness slider) - but it doesn't always seem ideal for dubbing to PC, and the "newer" decks I have don't have that setting.

I'm sure some of my camcorder tapes have oversharpening halos on the tape. Even at the softest setting on any deck, the halos are still there, but re-blurred!

The OP has the sharpness way too high.

You want to avoid removing halos in AVIsynth is possible - it's a really lossy and difficult process. Much better not to have them in the first place.

Cheers,
David.

[cedricm]

Hi everyone,

to clear up some things, these are the SVHS decks I own:
- Panasonic AG-7330 (studio deck without TBC)
- Panasonic NV-FS200 (prosumer deck with TBC)

for both devices, pictures can be found on google if you are interested

The screenshot comes from a capture with the first one.