[ SOLVED ] Video editing question.

[Gandalf]

I am in the process of trying to transfer some of my videotapes to DVDs, and was wondering what filter(s) I should use to remove the 'halo' effect from videos? In other words, after I remove the 'noise' from my videos, I notice what looks like a sort of 'halo' effect in areas where there is supposed to be a gradual difference in color shading/brightness, or whenever a bright colored object is near, or right next to, a dark colored object. I had asked this before but got no responses.

Any practical suggestions will be greatly appreciated. Thanks in advance.

[zakk]

Hi it's me again. I think the only way would be to cut the borders with the "crop" filter. Please post a picture, but this will be very difficult to achieve I'm afraid.

[AQUAR]

Is this from capturing analog video?

[Gandalf]

Attached is a picture so you can see what I mean, and yes, this is from capturing analog video.

[zakk]

It would be good to have a picture BEFORE noise reduction, too.

[AQUAR]

Just thinking that this looks a bit like chromashift.

Try capturing with virtualdub and use a plugin filter to correct for the chromashift.
Or maybe use avisynth to see if the already captured video can be corrected with a chromashift plugin filter.

Have a look here for some info that might help.
http://www.doom9.org/index.html?/capture/chroma_artefacts.html

[Gandalf]

It would be good to have a picture BEFORE noise reduction, too.

[Gandalf]

Just thinking that this looks a bit like chromashift.

Try capturing with virtualdub and use a plugin filter to correct for the chromashift.
Or maybe use avisynth to see if the already captured video can be corrected with a chromashift plugin filter.

Have a look here for some info that might help.
http://www.doom9.org/index.html?/capture/chroma_artefacts.html

I tried usinng chromashift, and the effect is still the same (I don't think that chromashift explains the "halo" effect anyway).

[zakk]

The only thing I see are the stripes on the left suit collar of the guy. Is that what you are talking about?

[AQUAR]

I don't see any halo's either, just some colour bleeding that looked a bit like chromashift.
Its a bit harder to get at the problem when there is some difficulty presenting/understanding the issue.

Since its analog video its probably interlaced.
So if we are talking about the stripes on the edges:
Presumably the guy is moving and they are some combing artifacts from a simple (weave!) deinterlacer.
Try a better deinterlacer like YADIF or store as interlaced and let the media player do the hard work..

[FeRD_NYC]

Apologies for the completely-tangential derailment, but: Is that Tom Baker?!? Color me inappropriately curious about the source of those sample images.  (Heck, some backstory might generate more attention to your problem, Gandalf!)

More usefully, though, I'm still trying to understand the nature of the "halo" complaint, exactly. I see two things of immediate interest, comparing the "before" and "after" images provided:

• It's clear from the second (before) image that the input video is interlaced ââ,¬â€ see the "serration" at the edges of the shirt collar, ear, nose, and hairline. It's even more clear that it's being deinterlaced either poorly or not at all. Proper deinterlacing should be able to produce an output video without those alternating-scanline artifacts, but trying to postprocess them away by treating them as "noise" will have much less satisfying results (as you've discovered). I'd recommend experimenting with all of the deinterlacing options available to you, to see if you can find a good fit. Interlacing has extremely predictable effects on the video image. It can usually be mitigated quite effectively without degrading overall quality, and without having to resort to heavy-handed general noise-reduction for "cleanup". Combating it that way tends to just smear the distortions around, instead of repairing them.
  
  


• The other possible source I see for your "halo" complaint, is some slight blocking and lack of gradient smoothness in the fine details of the image. For instance, that area of brightness from light reflecting off the back wall (second quarter of the image, in the background between whatever-that-is on the far left and the foreground subject on the right), which appears as a fairly uniform light-to-dark gradient in the "before", but in the "after" it's been smoothed to more of a solid-color gray stripe, with a harder edge where it transitions to the darker background. The noise-reduction being applied could very well be the source of that effect. Or, it could be a sign of overly aggressive compression in the output encoder. Perhaps the output bitrate/quality is set too low, as that can often manifest as blocking and loss of quality in detail areas.

[Gandalf]

Yes, it's Tom Baker. I'm trying to transfer a Doctor Who video to DVD (so I don't wear out the videotape). Anyway, he "halo" effect is more noticeable when the video is n playback mode (after I have done the editing) but how do I go about editing it so that I don't get that "halo" effect?

[AQUAR]

Maybe in playback mode the de-interlacing is by blending.
This is diffusing the edges where there is motion and might look a bit like halo's.

I support FeRD_NYC in that this seems to be a capture of interlaced video (as opposed to film!).
Best to avoid the 'halo's' by properly processing the analog video.
Use something like virtualdub with a fast/lossless codec as per my suggestion in your audio thread.
Apply a good deinterlacer, maybe try YADIF or the bob deinterlacer with debobbing to avoid jitter.
Then compress/remux with your favorite codec/container using avidemux.   

[Gandalf]

I tried hat, it doesn't do a thing to remove the halo effect. But yes, it's a capture of a videotape, as I clearly stated before (a previously unreleased episode of Doctor who called "Shada"), so how do I go about removing what I call a "halo" effect?

[AQUAR]

We just don't see the halo effect you are trying to describe.
Hence we have made some educated guesses that might lead to what you are trying to point out.
Maybe we should have asked first if this halo is present on the analog video. 

Can you be more specific in what you have tried.
- did you compress with a at high bit rate.
- did you capture using a fast/lossless codec.
- is the halo present on the raw captured video.
- is your pc fast enough to keep up with the capture.
- what deinterlacing methods have you used.
- has anything you tried made any impact on this halo.

The spatial quality of the video capture is poor, probably because it is like that on the analog video tape.
You cannot change that with filters, and some deinterlacing methods will in fact further degrade the vertical resolution.

Only thing I can suggest is to post a sample of this video capture and clearly point out where you see this halo.