I've been working on restoring some old music videos transferred to DVD-R from a U-Matic tape (from April 1983). The audio/video quality's great for the time (the music and the videos range from OK to hilariously awkward, on the other hand :P ). However, I've noticed that there's a strange smearing, almost like color-bleed. None of my chroma-shift filters have any real effect on it, so I'm guessing it's a luma issue. Strangely, it only appears on certain portions, which leads me to believe it's either a production error (proper greenscreens mustn't have been invented 'til 1990 ), or a recording issue with the original tape.
So...can this be fixed? I mean, it's not a super-huge issue, but if it can be fixed easily, then so much the better
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Thread: U-Matic Luma Smearing?
Well the 1st one screenshot does have some color bleed. You can use avisynth filters to address improve the bleed a little
But the black & white one obviously doesn't have color bleed That just looks like low resolution to me and exposure issues. Can't do anything about low luma resolution. You can local contrast enhancements, or try to sharpen a bit, but you will get halos
In the video sample, you have highlight areas that look to be previously clipped. That can lead to this "luma bleeding" effect , also details will be obscured in those bright areas . You can try to selectively bring down the highlights to recover some details, but most of the damage is permanent. It's tough to get rid of the actual "glow" or luma bleeding around objects in those overexposed sections, short of some rotoscoping / masking work
Last edited by poisondeathray; 17th Jun 2014 at 19:21.
Lots of machines from that era, particularly U-matic & VHS/Beta, exhibited "overshoot" smear, where a bright or dark object left a small & slight trail to the right. The brighter/darker, the worse it got.
This is likely caused by the electronics not being fast enough to accommodate the rise/fall time in the voltage changes of the signal. It goes to the right because that is how it is scanned (both in analog & digital) - that is "later".
I see exhibits of that in all of those clips, though least in the last clip (2 clips, since it's from the same source).
AVISynth is your best bet. Which filter to use...I'm not your best guide there.
Scott"When will the rhetorical questions end?!" - George Carlin
And some of the original footage from that era had smear because of CCD smearing or Tube camera smearing . There are filters and techniques to recreate the 80's look, but few that work well to get rid of it
I just tried something called Exorcist (which is meant for ghosting) and a simple color shift filter, and it seems to have ameliorated the situation:
I actually just looked up the VEVO upload of the first video, and you can just make out a bit of smearing on that copy, too (in addition to some chroma noise on the blue shots). So, I guess it's safe to say it was there to begin with and it's only compounded since I have an nth generation dub instead of the master.
Anyways, here's a fully filtered copy of the video.
Last edited by John97; 17th Jun 2014 at 20:16.
AVIsynth and I could never really get it to work at all. I'm probably doing it wrong Keep in mind I'm on a Mac, so I'm running PC programs via Wine. Virtualdub works just fine (albeit a tad slow, especially with MPEG-2 files and NeatVideo), but command-line programs like AVIsynth are, alas, out of the question
Hmm, maybe I've just had bad luck :\
That's not really what I was talking about. That ringing is easily filtered using a standard DotCrawl filter. This is what I'm talking about. As you can see, the chroma shift doesn't do anything to it.
You need to sharpen the chroma as well as shift it.
Last edited by jagabo; 18th Jun 2014 at 19:20.
How do I go about doing that? Is there a special filter for it?
I did it with AviSynth:
Here are the U (top) and V (bottom) channels before sharpening:
You may be able to do this with an NLE by creating two version of the video, one normal, the other highly sharpened (a big unsharp mask). Then overlay the chroma from the sharpened video onto to the luma of the normal video.
Note that I treated the video as if it was progressive here. That's OK since this is basically a still shot and this is just a demonstration. But for general use you should use proper interlaced handling.
Last edited by jagabo; 19th Jun 2014 at 11:53.