Edge chroma shifts on videotapes?

[BmacSWA]

I’ve run into a phenomenon on someone the older tapes I’m capturing. The ones in particular I’ll post images of are nearly 40 years old. The tapes have been preserved well and running them through my LS workflow the have in the first picture. A green band on the left and a magenta band on the right. I wish I knew the camera it was recorded on, but I promise it’s old and gone. Anyway, the center looks stellar crisp and without any chroma shift I can recognize, just the right and left sides. The second picture shows the green band moved to the same area but on the left and the entire rest of the picture has a magenta tint. It was the same camera at the same even on the same tape. It is the original tape as well. My questions are this 1) is there a way to shift the chroma only on the edges to regain as much of the viewable picture as possible or is this just normal VHS covered by the old TV bezel and just has to be cropped 2) how do I address it shifting it completely on the second frame? It’s been a while and hello again to LS, Sellur and arminkot.

Bmac

[aramkolt]

That is an interesting sort of chroma problem for sure, but I don't know that we can call it a shift. You are right that typically a chroma shift would affect the entire image equally, but that doesn't seem to be the case here, it's almost like there's just missing chroma information on the extreme edges or that for some reason it either was recorded that way or degraded into that pattern over time.

Does the tape play that way on any other VHS players you might have tried? I kind of doubt that the issue is other components of the capture chain, but you might want to hook the VCR up to a modern TV and see if you get the same output directly from the VHS player. The trick will be making sure that the TV will show all the way to the edge and not do the typical "overscan" that CRTs do where you may not even get to see the area of interest.

[vwestlife]

It was probably there all along. Even on TV shows that were shot on professional studio cameras, on older ones you often see color convergence flaws and/or vignetting in the overscan area that were unnoticeable on CRT TVs of the era, but which modern digital transfers make visible. (Sometimes other things, too, like boom mics, camera rigging, or even the hand of a puppeteer, that they thought wasn't visible in the shot.)

[lordsmurf]

Quote:

Originally Posted by BmacSWA

It was the same camera at the same even on the same tape.

I have to question that. Most people misremember something this old. Our brains can paly tricks on us, when it comes to memory. It's not uncommon to use different tapes at different times. Either in the lifecycle of the same camera, or another camera entirely.

Quote:

Originally Posted by aramkolt

That is an interesting sort of chroma problem for sure,

Nah, very typical. Expected, in fact. I've seen that the entire time I've been capturing tapes, 25+ years now. Nothing unusual, and nothing can be done about it.

Quote:

but I don't know that we can call it a shift.

Correct, not a shift. It's just missing data causing the cast. It's a byproduct of the camera CCDs.

Quote:

but you might want to hook the VCR up to a modern TV

That won't help, it's all in the overscan.

Quote:

making sure that the TV will show all the way to the edge and not do the typical "overscan"

Most modern TVs still overscan, even those with "disable overscan" type features. My Sony set has "disable overscan", but it's still not 100% image coverage. HDTVs all heavily process video.

Quote:

Originally Posted by vwestlife

It was probably there all along. Even on TV shows that were shot on professional studio cameras, on older ones you often see color convergence flaws and/or vignetting in the overscan

You're an "old tech" guy. It's in the CCDs, and it is vignetting. You should research that sometime. I should have many samples of this.

[BmacSWA]

Ok little blue man in red pants, you’ve picked apart everyone’s responses without a single suggestion. Whattya got? Any ideas on how to correct these tapes? It was your flow that captured it, we should be able to rule out capture hardware.

B

[Aya_Rei]

Most likely Avisynth scripting, maybe this will help?

Or perhaps this

Other than that I don't think there is anything else you can do, it's a flaw in the camera that filmed it.

An example, did two 8mm tapes that were shot on a Sharp branded Video8/8mm camcorder, the kind that looks like a regular photo camera.

Had a huge chunk of black on the right edge and rather nasty red chroma bleed.

[BmacSWA]

Those tips offer some interesting ideas. I’m not going to obsess over it, but I’ll sure as hell give it a try.

[lordsmurf]

Quote:

Originally Posted by BmacSWA

Ok little blue man in red pants, you’ve picked apart everyone’s responses without a single suggestion. Whattya got? Any ideas on how to correct these tapes? It was your flow that captured it, we should be able to rule out capture hardware. B

But that's not what I did?

To restate what I wrote above: You ran into an apparent chroma vignette, likely as caused by the "home movie" camcorder CCD of the era. It's very common. There's nothing to do about it. It is what it is.

At best, you can try another VCR. However, I've done that many times, and it has no real effect on most tapes with this "issue". (I wrote "issue" because it's arguably not an issue, since it's located in the overscan.)

You can attempt some Avisynth magic, but I've never seen anything that is consistently good scene-to-scene. My suggestion here is to archive as-is, save the lossless captures, and hope that "AI" (LLMs) get better at processing video in the next decade or two. I think AI will be a game-changer for video restoration, eventually, but probably much further out than hype suggests.

Quote:

Originally Posted by Aya_Rei

An example, did two 8mm tapes that were shot on a Sharp branded Video8/8mm camcorder, the kind that looks like a regular photo camera.
Had a huge chunk of black on the right edge and rather nasty red chroma bleed.

Yes, in-camera masking was often employed.

[Haunted_TBC]

I had a 3rd gen NTSC-J tape (several S-VHS-C to (presumably) VHS edit master to VHS distribution copy, but I am not sure if the copying method was good enough to prevent this from becoming “nth gen” before generation four or five) also rendered digital by Lordsmurf, and it featured very noticeable green and color vignetting on the left and right sides of the frame. The tapes the footage originated from were shot on a domestic Market Panasonic NV-S1, so an S-VHS CCD camera that could easily cause the aforementioned vignetting. I’m not sure if it was that bad on the original tapes or if it was worsened by generational loss via copying. That being said, one really just has to live with the CCD vignetting for now, with the exception of the 8 pixels on each side which I believe are cropped out, and then further junk is just masked using the Hybrid letterbox feature.

[vwestlife]

Quote:

Originally Posted by lordsmurf

You're an "old tech" guy. It's in the CCDs, and it is vignetting. You should research that sometime. I should have many samples of this.

It happens with tube cameras, too. See the discoloration at the edges of the image from a 1984 Saticon tube camera:
The confusing Minisette - What is it?