those color bands in VHS transfers....

Fullasoul · 23rd March 2004, 17:26

Hello,

I'm curious as to whether or not anyone here knows of a way to get rid of those horizontal color stripes that go across the image of VHS-sourced material. I'm not talking about the ones that move all over the place (which I take to be "chroma noise"), but the stationary bands of color.

Any help would be greatly appreciated,

Fullasoul

rfmmars · 23rd March 2004, 18:27

This is tough one to call. We really need to see a screen shot of this flaw, so to be able to suggest some type of correction. It could some type of cabling ground loop.

The big thing is there is NO COMMON VHS problem like you are discribing.

richard
photorecall.net

Arachnotron · 24th March 2004, 00:11

Are you talking about something like this (Notice the horizontal yellow bands across the upper arm)
I have no idea what causes this but I would love to know

source: NTSC video, capped as PAL-60 from a PAL S-VHS VCR
JVC HR-S7950 with TBC enabled, s-video cable
Terratec Cinergy 400 TV (SAA7134 chip)
VirtualVCR, 704x480, huffyuv

scharfis_brain · 24th March 2004, 01:52

jep.
this occurs only with NTSC-Tapes.

you can try to separate the video into some stripes using crop.

then do some color-correction (hue, color-balance) to the false-colored stripes.

finally stack thos stripes back together using stackvertical.

Arachnotron · 24th March 2004, 02:00

@sharfis brain

Sounds elaborate. This particular tape is not worth it. But I have a lot more NTSC stuff still to do. Keeping as many fingers crossed as will allow me still to type.....

I don't have this tape any more, but if I run into one again I'll try if the stripes keep position when capped several times. If not, I might be able to do something with blending several caps.

@Fullasoul

Is this your problem too?

Fullasoul · 24th March 2004, 04:15

No...actually what I'm talking about is this

Those horizontal stripes are faintly present in the original video...they don't stand out quite so much in that context though since there's still the ever-moving chroma noise and various other VHS "ickies" moving around. Unfortunately once I clean and stabilize my picture to my liking, those darn bars become ever more prominent.

As I mentioned, they don't move. Here is a screenshot from a few minutes later in the same clip. As you can see, the bands of color are still there...still in the exact same place, regardless of the fact that the color behind it at this point is quite different from the color before.

Anyways, someone out there is bound to be able to explain this. I'm ready to chalk this up as one of those VHS "ickies" that just can't be overcome...but I'd be a fool to not ask since there's some very knowledgeable people here.

Thanks,

Fullasoul

scharfis_brain · 24th March 2004, 13:47

the first image - link does not work

Fullasoul · 24th March 2004, 15:13

ugh...I REALLY gotta get a place to host temp files

anyways, I went back and looked at Arachnotron's sample (I was a bit too tired last night) and that is indeed what I'm encountering. So does this mean that aside from tearing the image apart and going trial-and-error color-correction happy on the stripes themselves, there's no other way to deal with this?

Mug Funky · 24th March 2004, 15:58

ARGH! NTSC is a crappy colour system.

i got the complete first season of "Soap" (R4, NTSC, great show if you haven't seen it), and these stripes are all over it, probably from the master tapes.

they have a soft fade in and out, so cropping might introduce some odd effects, also the stripes might move around at scene cuts or whatever (not too likely).

need a way to isolate these stripes somehow... hmm. can't think of a good way at the moment. it would most likely need a treatment like what guavacomb gives - after enough frames the plugin has an idea of where the stripes might be, and can cancel them out.

i'd personally just live with them...

now you know what NTSC stands for: Never Twice the Same Colour.

Wilbert · 24th March 2004, 16:26

Quote:

Are you talking about something like this (Notice the horizontal yellow bands across the upper arm). I have no idea what causes this but I would love to know

Quote:

ARGH! NTSC is a crappy colour system.

i got the complete first season of "Soap" (R4, NTSC, great show if you haven't seen it), and these stripes are all over it, probably from the master tapes.

It also happens with pal. I see it often on skins of girls (captured from vhs tapes). This effect gets worse if your vhs tapes lie in your closet for several years.

A while ago I watched the pelican brief again (vhs-tape, recorded about 6 years ago). Full of red bands. I still have to buy the dvd one day ...

Those bands are always red or yellow (I think). Dunno why though ...

rfmmars · 24th March 2004, 16:39

Well we call PAL "Flicker Vision" and in fact NTSC has twice the vertical the color resolution, and three times the color resolution in the horizontal X channel (1.5 mhz) compared to PAL's (0.5 mhz) plus more brightness dynamic brignest range. PAL beats NTSC in one area lunmince bandwidth which gives more detail.

NTSC viewed on a Euro made or designed tv does look like crap. If PAL was perfect, why did they make (PAL to NTSC to PAL) converter boxes? Answer, so you set the color correctly on a PAL receiver.

PAL is a low cost copy of NTSC, and if every body in the video chain of production does their job right, and the picture tube doesn't age,
PAL is perfect.

Sorry Mug Funky....... I just couldn't allow your post to be unanswered.

Still your friend

richard

Arachnotron · 25th March 2004, 00:17

@rfmmars

To troll right back

Quote:

Well we call PAL "Flicker Vision" and in fact NTSC has twice the vertical the color resolution, and three times the color resolution in the horizontal X channel (1.5 mhz) compared to PAL's (0.5 mhz) plus more brightness dynamic brignest range.

from rec. ITU-R BT.470-6:

PAL chroma bandwidth:
Fsc +570, -1300
NTSC chroma bandwidth:
Fsc +620, -1300

PAL luma range: 0 IRE (black) to 100 IRE (white)
NTSC luma range: 7.5 IRE (black) to 100 IRE(white)

Three times horizontal color resolution you said?

rfmmars · 25th March 2004, 02:57

Let me check my refs. Nowhere haven't I seen anything thing stated about either PAL's R-Y or B-Y channel having anything higher than ~.5 mhz. In NTSC you can have 1.5mhz for the R-Y, and .6 for the B-Y with either I & Q demod or X & Z demod. With R-Y & B-y the color bandwidth is around .6 mhz for each.

Hope you enjoy the back and forth of this, I do. The statment that NTSC is crappy system would mean PAL is too, because NTSC is the bases fot the PAL system.

As you know there are many PAL and NTSC varients around the world. Lets hear from the SEACAM people who can't even fade to black

If I made a misquote I will be glad to own up to it for sure.

60 cycles to you all of my Euro friends.

richard

Fullasoul · 25th March 2004, 04:05

OK....well I guess that's all the confirmation I need that there's nothing more I can do about these stripes. I didn't want to let this on earlier, but I was REALLY hoping that nobody had a good solution. As much as I want my videos to look their best, I spent many hours on a project BEFORE asking this question...on the assumption that it was one of those things that I was just going to have to live with. While I hope someday somebody comes up with a good solution, I'm quite happy to have been right about this for now....saves me from redoing all that I've already done

Mug Funky · 25th March 2004, 05:45

whoops! sorry to mention that...

obviously people will believe their native system to be the better one...

yes the flicker-vision could be a problem, but typically i don't sit right in front of the teev.

and my european made tv does NTSC beautifully - looks just like pal, except for the obvious differences of less lines and more motion. - the colour is not noticably different, at least with DVDs (i've got a box full of NTSC dragonball Z tapes, and BOY do they look bad, but you can't expect much from a consumer level VCR)

i've had this argument with TV people many times before... we say better res, you say flicker, we say colour, you say sped up sound... hey let's call the whole thing off. (you guy's are all lucky i can't sing through text)

FWIW, i've never seen colour bands on PAL VHS... i'll have to watch one of wilbert's tapes. (it wasn't converted from NTSC was it

)

basically the difference is that NTSC came first, PAL second, so they had some time to sort through the issues and make a reasonable compromise. the flicker-vision isn't actually a "PAL" thing - NTSC and PAL refer only to colour systems (splitting hairs here). the flicker comes from the awful fact that until very recently TV had to be coupled to the freq of the mains power (50hz vs 60hz), and there's way too much inertia to change now.

Arachnotron · 25th March 2004, 10:45

I just got an off-forum from i4004. He said lines like that can originate from physical damage to the tape from things like pausing in a freeze frame etc. and can happen to both old PAL and NTSC tapes.

Since my tape probably has been paused many times (it's a Yoga training tape) that is very likely.

As to the PAL vs NTSC thing: what would we spend our time with if we didn't have these nice crappy NTSC-PAL-NTSC-PAL conversions to solve?

Mug Funky · 25th March 2004, 11:13

how would pausing cause a line to persist over much of the recording? the line affects tape that is completely static and spooled up in a pause situation. pausing causes tape wear and probably mis-tracking, but any changes to actual information would (i would think) be confined to the tape that is in contact with the head, ie about 12cm of tape at the most.

i shall have to do some reading on this topic... i thought it was an NTSC thing, and haven't seen it on any PAL tapes (though i've not been looking).

Arachnotron · 25th March 2004, 12:00

Quote:

how would pausing cause a line to persist over much of the recording?

That was just an example (pausing in freeze frame). I would imagine anything that causes excessive tapewear like fast forward with picture or slow motion (my tape), playing with dirty tape guides or dirty heads etc. etc.

I became curious about this, so I have been trying to find a site which shows what various damage to tapes looks like, but so far without success. There is plenty about tape storage and longlevity, but not with examples of what old or damaged tapes actually look like on playback.

(As an aside: here is a hilarious example of a tape restoration technique

)

Malcolm · 25th March 2004, 14:09

Hello,
if these lines/bands are static (they don't move) then the following idea could lead to a solution: (this should work for all sort of static errors)
Let's assume that everything except these lines is noise. If you look over the whole length of the video, everything is moving except these lines. So if you combine all frames together (or every tenth or hundredth frame) then you should get a difference-map (one single frame) that only contains these lines. (The question is what blend-mode to use.)
This difference-map could be used to change saturation / color / lightness of the video only where thes lines reside.

greetings,
Malcolm

scharfis_brain · 25th March 2004, 15:14

I've tried this too.
The lines faded away too, when trying to layer hundreds of frames.
It seems to be some hue-problem. (phase-error within the NTSC-Signal, hehe)

23rd March 2004, 17:26	#1 \| Link
Fullasoul Registered User Join Date: Oct 2003 Posts: 39	those color bands in VHS transfers.... Hello, I'm curious as to whether or not anyone here knows of a way to get rid of those horizontal color stripes that go across the image of VHS-sourced material. I'm not talking about the ones that move all over the place (which I take to be "chroma noise"), but the stationary bands of color. Any help would be greatly appreciated, Fullasoul

24th March 2004, 01:52	#4 \| Link
scharfis_brain brainless Join Date: Mar 2003 Location: Germany Posts: 3,484	jep. this occurs only with NTSC-Tapes. you can try to separate the video into some stripes using crop. then do some color-correction (hue, color-balance) to the false-colored stripes. finally stack thos stripes back together using stackvertical. __________________ Don't forget the 'c'! Don't PM me for technical support, please.

24th March 2004, 13:47	#7 \| Link
scharfis_brain brainless Join Date: Mar 2003 Location: Germany Posts: 3,484	the first image - link does not work __________________ Don't forget the 'c'! Don't PM me for technical support, please.

24th March 2004, 15:58	#9 \| Link
Mug Funky interlace this! Join Date: Jun 2003 Location: i'm in ur transfers, addin noise Posts: 4,267	ARGH! NTSC is a crappy colour system. i got the complete first season of "Soap" (R4, NTSC, great show if you haven't seen it), and these stripes are all over it, probably from the master tapes. they have a soft fade in and out, so cropping might introduce some odd effects, also the stripes might move around at scene cuts or whatever (not too likely). need a way to isolate these stripes somehow... hmm. can't think of a good way at the moment. it would most likely need a treatment like what guavacomb gives - after enough frames the plugin has an idea of where the stripes might be, and can cancel them out. i'd personally just live with them... now you know what NTSC stands for: Never Twice the Same Colour. __________________ interlace... right or wrong, just deal with it.

25th March 2004, 05:45	#15 \| Link
Mug Funky interlace this! Join Date: Jun 2003 Location: i'm in ur transfers, addin noise Posts: 4,267	whoops! sorry to mention that... obviously people will believe their native system to be the better one... yes the flicker-vision could be a problem, but typically i don't sit right in front of the teev. and my european made tv does NTSC beautifully - looks just like pal, except for the obvious differences of less lines and more motion. - the colour is not noticably different, at least with DVDs (i've got a box full of NTSC dragonball Z tapes, and BOY do they look bad, but you can't expect much from a consumer level VCR) i've had this argument with TV people many times before... we say better res, you say flicker, we say colour, you say sped up sound... hey let's call the whole thing off. (you guy's are all lucky i can't sing through text) FWIW, i've never seen colour bands on PAL VHS... i'll have to watch one of wilbert's tapes. (it wasn't converted from NTSC was it ) basically the difference is that NTSC came first, PAL second, so they had some time to sort through the issues and make a reasonable compromise. the flicker-vision isn't actually a "PAL" thing - NTSC and PAL refer only to colour systems (splitting hairs here). the flicker comes from the awful fact that until very recently TV had to be coupled to the freq of the mains power (50hz vs 60hz), and there's way too much inertia to change now. __________________ interlace... right or wrong, just deal with it. Last edited by Mug Funky; 25th March 2004 at 05:50.

23rd March 2004, 18:27	#2 \| Link
rfmmars Registered User Join Date: Feb 2004 Posts: 729	This is tough one to call. We really need to see a screen shot of this flaw, so to be able to suggest some type of correction. It could some type of cabling ground loop. The big thing is there is NO COMMON VHS problem like you are discribing. richard photorecall.net

24th March 2004, 00:11	#3 \| Link
Arachnotron Alias fragger Join Date: Jul 2003 Location: the Netherlands Posts: 863	Are you talking about something like this (Notice the horizontal yellow bands across the upper arm) I have no idea what causes this but I would love to know source: NTSC video, capped as PAL-60 from a PAL S-VHS VCR JVC HR-S7950 with TBC enabled, s-video cable Terratec Cinergy 400 TV (SAA7134 chip) VirtualVCR, 704x480, huffyuv

24th March 2004, 02:00	#5 \| Link
Arachnotron Alias fragger Join Date: Jul 2003 Location: the Netherlands Posts: 863	@sharfis brain Sounds elaborate. This particular tape is not worth it. But I have a lot more NTSC stuff still to do. Keeping as many fingers crossed as will allow me still to type..... I don't have this tape any more, but if I run into one again I'll try if the stripes keep position when capped several times. If not, I might be able to do something with blending several caps. @Fullasoul Is this your problem too?

24th March 2004, 04:15	#6 \| Link
Fullasoul Registered User Join Date: Oct 2003 Posts: 39	No...actually what I'm talking about is this Those horizontal stripes are faintly present in the original video...they don't stand out quite so much in that context though since there's still the ever-moving chroma noise and various other VHS "ickies" moving around. Unfortunately once I clean and stabilize my picture to my liking, those darn bars become ever more prominent. As I mentioned, they don't move. Here is a screenshot from a few minutes later in the same clip. As you can see, the bands of color are still there...still in the exact same place, regardless of the fact that the color behind it at this point is quite different from the color before. Anyways, someone out there is bound to be able to explain this. I'm ready to chalk this up as one of those VHS "ickies" that just can't be overcome...but I'd be a fool to not ask since there's some very knowledgeable people here. Thanks, Fullasoul

24th March 2004, 15:13	#8 \| Link
Fullasoul Registered User Join Date: Oct 2003 Posts: 39	ugh...I REALLY gotta get a place to host temp files anyways, I went back and looked at Arachnotron's sample (I was a bit too tired last night) and that is indeed what I'm encountering. So does this mean that aside from tearing the image apart and going trial-and-error color-correction happy on the stripes themselves, there's no other way to deal with this?

24th March 2004, 16:39	#11 \| Link
rfmmars Registered User Join Date: Feb 2004 Posts: 729	Well we call PAL "Flicker Vision" and in fact NTSC has twice the vertical the color resolution, and three times the color resolution in the horizontal X channel (1.5 mhz) compared to PAL's (0.5 mhz) plus more brightness dynamic brignest range. PAL beats NTSC in one area lunmince bandwidth which gives more detail. NTSC viewed on a Euro made or designed tv does look like crap. If PAL was perfect, why did they make (PAL to NTSC to PAL) converter boxes? Answer, so you set the color correctly on a PAL receiver. PAL is a low cost copy of NTSC, and if every body in the video chain of production does their job right, and the picture tube doesn't age, PAL is perfect. Sorry Mug Funky....... I just couldn't allow your post to be unanswered. Still your friend richard

25th March 2004, 02:57	#13 \| Link
rfmmars Registered User Join Date: Feb 2004 Posts: 729	Let me check my refs. Nowhere haven't I seen anything thing stated about either PAL's R-Y or B-Y channel having anything higher than ~.5 mhz. In NTSC you can have 1.5mhz for the R-Y, and .6 for the B-Y with either I & Q demod or X & Z demod. With R-Y & B-y the color bandwidth is around .6 mhz for each. Hope you enjoy the back and forth of this, I do. The statment that NTSC is crappy system would mean PAL is too, because NTSC is the bases fot the PAL system. As you know there are many PAL and NTSC varients around the world. Lets hear from the SEACAM people who can't even fade to black If I made a misquote I will be glad to own up to it for sure. 60 cycles to you all of my Euro friends. richard

25th March 2004, 04:05	#14 \| Link
Fullasoul Registered User Join Date: Oct 2003 Posts: 39	OK....well I guess that's all the confirmation I need that there's nothing more I can do about these stripes. I didn't want to let this on earlier, but I was REALLY hoping that nobody had a good solution. As much as I want my videos to look their best, I spent many hours on a project BEFORE asking this question...on the assumption that it was one of those things that I was just going to have to live with. While I hope someday somebody comes up with a good solution, I'm quite happy to have been right about this for now....saves me from redoing all that I've already done

25th March 2004, 10:45	#16 \| Link
Arachnotron Alias fragger Join Date: Jul 2003 Location: the Netherlands Posts: 863	I just got an off-forum from i4004. He said lines like that can originate from physical damage to the tape from things like pausing in a freeze frame etc. and can happen to both old PAL and NTSC tapes. Since my tape probably has been paused many times (it's a Yoga training tape) that is very likely. As to the PAL vs NTSC thing: what would we spend our time with if we didn't have these nice crappy NTSC-PAL-NTSC-PAL conversions to solve?

25th March 2004, 11:13	#17 \| Link
Mug Funky interlace this! Join Date: Jun 2003 Location: i'm in ur transfers, addin noise Posts: 4,267	how would pausing cause a line to persist over much of the recording? the line affects tape that is completely static and spooled up in a pause situation. pausing causes tape wear and probably mis-tracking, but any changes to actual information would (i would think) be confined to the tape that is in contact with the head, ie about 12cm of tape at the most. i shall have to do some reading on this topic... i thought it was an NTSC thing, and haven't seen it on any PAL tapes (though i've not been looking). __________________ interlace... right or wrong, just deal with it.

25th March 2004, 14:09	#19 \| Link
Malcolm Registered User Join Date: Sep 2002 Location: Germany Posts: 315	Hello, if these lines/bands are static (they don't move) then the following idea could lead to a solution: (this should work for all sort of static errors) Let's assume that everything except these lines is noise. If you look over the whole length of the video, everything is moving except these lines. So if you combine all frames together (or every tenth or hundredth frame) then you should get a difference-map (one single frame) that only contains these lines. (The question is what blend-mode to use.) This difference-map could be used to change saturation / color / lightness of the video only where thes lines reside. greetings, Malcolm

25th March 2004, 15:14	#20 \| Link
scharfis_brain brainless Join Date: Mar 2003 Location: Germany Posts: 3,484	I've tried this too. The lines faded away too, when trying to layer hundreds of frames. It seems to be some hue-problem. (phase-error within the NTSC-Signal, hehe) __________________ Don't forget the 'c'! Don't PM me for technical support, please.

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