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Old 13-01-2013, 15:51
Sammi87
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Hi guys,

This is something that's been bugging me for a while now and i'm seeing it more often recently.

When watching videos on either my TV or computer, during dark scenes or in dark areas on the screen i'm seeing several faint horizontal lines. While watching a movie in HD on the TV last night these lines were much more noticeable. This isn't just something i'm seeing on the TV though because just now I was watching a trailer on Youtube and as the video faded to black I saw the same thing.

I've managed to take a screenshot of these lines in the Youtube video. I'm not able to show you from my TV but it's very similar anyway.

http://i49.tinypic.com/4kd28.jpg

Do any of you smart people know what this is? Is there a name for it or any way to get rid of it?

I hope i've made sense! (first time posting!) Thanks in advance.
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Old 13-01-2013, 16:01
!!11oneone
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I can't actually see any lines on your screenshot, but it could be to do with interlacing. Can only be sorted out when the video is encoded (using a deinterlace filter)
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Old 13-01-2013, 16:05
max99
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Unless I'm also missing the lines, you need to use a different program to capture the screenshot.

And are you actually watching your TV via the computer, or are you saying that you are seeing the same effect on two complete different devices?
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Old 13-01-2013, 17:20
d'@ve
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If you brighten the screenshot in an image program, the (green) lines are clear and of two or three brightness levels (though all are dark), with a brownie coloured background. They are uniformly bright right across the width of the screen and up to 24 pixels in height (and a few more pixels less bright above and below each strip (perhaps due to compression artifacts or anti-alias). There is one narrow grey band near the bottom of the screen. Yes, horizontal strip or band is a better description than line.

I've never seen anything like this, and I've done a lot of video work and have watched a lot of TV and Youtube.

I would have said there's a display problem but as you say they are on two different displays, I don't know. If the video(s) they appear on are from the same source (such as rented/downloaded/ripped by yourself), or use the same cable (or have anything in common) that will probably be where the problem comes from - a compression/codec issue or using too few colours but if not, I am baffled.

You may be able to hide it by increasing contrast and/or reducing brightness and/or colour intensity.
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Old 13-01-2013, 17:48
max99
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First thing I did was brighten the image, but obviously not enough.

The green lines look a little like a dodgy video card/chip or a loose or dodgy/loose video cable. This will only make sense if both the TV and monitor are connected to the same computer - and even more so if the same video socket (VGA, HDMI) and cable are used.

Video drivers (or their settings) can also cause various screen effect issues, but that's just down to guesswork. As always, the more info that is given, the more chance there is of someone being able to help.

Edit: Looking at them again, I think it's less likely to be a hardware issue. They appear too uniform.
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Old 14-01-2013, 00:47
Sammi87
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Thankyou very much for the replies.

My TV and computer are completely separate and are even in different rooms. Also the video's i've noticed this with were from different sources.

Is it possible that these bands are actually fairly common and that I just haven't calibrated my TV/monitor properly so i'm seeing them? The reason I ask is because all 3 of you had to brighten the image to even see my problem. Whereas I can already see these green bands very clearly as soon as I open the image I uploaded.

I've tried lowering the brightness on both my TV and monitor and it does reduce the appearance of the bands, even gets rid of them completely if I lower it enough. However this obviously reduces the brightness of the entire screen too and loses the detail in darker scenes.

Or maybe I just need to get used to this?

I'm sorry I haven't been much help with providing info. I'm not very experienced at all with this kind of thing.
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Old 14-01-2013, 00:54
d'@ve
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Thankyou very much for the replies.

My TV and computer are completely separate and are even in different rooms. Also the video's i've noticed this with were from different sources.

Is it possible that these bands are actually fairly common and that I just haven't calibrated my TV/monitor properly so i'm seeing them? The reason I ask is because all 3 of you had to brighten the image to even see my problem. Whereas I can already see these green bands very clearly as soon as I open the image I uploaded.

I've tried lowering the brightness on both my TV and monitor and it does reduce the appearance of the bands, even gets rid of them completely if I lower it enough. However this obviously reduces the brightness of the entire screen too and loses the detail in darker scenes.

Or maybe I just need to get used to this?

I'm sorry I haven't been much help with providing info. I'm not very experienced at all with this kind of thing.
I can see them (faintly) without adjustment on my newest PC monitor but not on my older one - but the older one is a bit too dull even on maximum brightness.

Can you link to any Youtube videos on which you see them? An HD one preferably but not necessarily.
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Old 14-01-2013, 01:35
Sammi87
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I can see them (faintly) without adjustment on my newest PC monitor but not on my older one - but the older one is a bit too dull even on maximum brightness.

Can you link to any Youtube videos on which you see them? An HD one preferably but not necessarily.
http://www.youtube.com/watch?v=9246msCh7x4

The above link is the trailer I took the image from. At 0:39 after the gun is fired and the screen turns black. Strangely, i've just realised that the green bars do not appear on 720p or 1080p.

However I do still get this problem when viewing HD videos on my TV.
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Old 14-01-2013, 02:37
max99
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http://www.youtube.com/watch?v=9246msCh7x4

The above link is the trailer I took the image from. At 0:39 after the gun is fired and the screen turns black. Strangely, i've just realised that the green bars do not appear on 720p or 1080p.
I can confirm the green lines are pretty visible (no adjustment necessary) on all resolutions below 720p. However, they don't appear on the same trailer here:

http://www.youtube.com/watch?v=p6wk1XySBTk

So, it looks like it is the source material. The obvious common element with the two examples so far is the Apple logo.

It does seem like you also need to adjust your monitor and TV if you see this issue a lot, so play around with the brightness, contrast, gamma, backlight or whatever relevant settings are available.
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Old 14-01-2013, 02:56
Sammi87
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I can confirm the green lines are pretty visible (no adjustment necessary) on all resolutions below 720p. However, they don't appear on the same trailer here:

http://www.youtube.com/watch?v=p6wk1XySBTk

So, it looks like it is the source material. The obvious common element with the two examples so far is the Apple logo.

It does seem like you also need to adjust your monitor and TV if you see this issue a lot, so play around with the brightness, contrast, gamma, backlight or whatever relevant settings are available.
Ok thanks for your help and confirming it's not just me going crazy!

It does seem like maybe this type of thing is not uncommon in videos and adjusting settings might help hide it. Now to spend the next few days reading up on TV/monitor calibration! haha

Thanks again.
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Old 14-01-2013, 03:18
Helmut10
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I can reproduce that by taking a screen shot and indeed not just various coloured green bands, then putting it into an image editor and change settings, however all this is at a very low level indeed.

On a properly adjusted calibrated monitor such things should not be visible.

I'm using a calibrated CRT monitor for this rather than a LCD back lit monitor for good reasons.

A LCD panel has a backlight and various enhancement features that can exaggerate low level stuff.

With my Nvidia graphics card you can limit the dynamic range to 16-235 rather than full of 0-255.

For calibration I use this website amongst others:
http://www.lagom.nl/lcd-test/
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Old 14-01-2013, 04:31
d'@ve
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Just got back on here, I agree with the above. It's the source material - artifacts of the encoding used by Youtube I'd say. Different encoding will be used for the HD versions.

Nothing wrong with your PC monitor anyway.
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