Purple in B&W films

Smallclone

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Hello,

I have an LG OLED BX 65 inch which is about 3 years old. I believe it is out of warranty. Sometimes when I watch black and white films, I see a patch of purple. This usually happens when there are items close together like on clothing or grass. The TV did an auto pixel refresh about 3 or 4 months ago, which was the first time it happened to my knowledge. However this defect started way before that.

I have tried turning the colour completely off on the television settings, but if anything it makes it worse. See attached image for example.

Is there anything I can do to stop it?

Thanks
 

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It may be pixel wear. The pixels have just ran out of life.
When one of the colour sets wears out, the pixel cannot display pure white.
Unfortunately, nothing can be done if it is.
The best way to find out, is look at full screen of solid primary colours (RGB)
Youtube has plenty, so type "OLED test patterns" or something like that.
As the full screen colours cycle through, you will soon see what colour pixels have died. They will show much darker and be patchy.

Hopefully it isn't the above, and others may have alternative suggestions.
 
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There are slides in this video that you can use to check for uneven pixel wear.

 
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Watched my 4K UHD disc of 'To Kill a Mockingbird' last night.....the purple defect was more noticeable than ever. Especially on pinstripe suits! So I did a pixel refresh that took an hour. It's more or less the same after it.

So....I tested my screen uniformity with various slideshows, files and videos, and to my surprise....there are hardly any blotches, patches, pixels or anything on any colour.

I'm scratching my head, I don't know what to do. I really can't afford another television. Any other ideas?

Thanks
 
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Watched my 4K UHD disc of 'To Kill a Mockingbird' last night.....the purple defect was more noticeable than ever. Especially on pinstripe suits! So I did a pixel refresh that took an hour. It's more or less the same after it.

So....I tested my screen uniformity with various slideshows, files and videos, and to my surprise....there are hardly any blotches, patches, pixels or anything on any colour.

I'm scratching my head, I don't know what to do. I really can't afford another television. Any other ideas?

Thanks
Do you have another 4K BR player to try? Try a different cable. Try a different HDMI port.

What 4K BR player are you using?
 
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Do you have another 4K BR player to try? Try a different cable. Try a different HDMI port.

What 4K BR player are you using?
It's a Sony UBP X700

I have a 4k media player too and it happens on that also. I've tried turning sharpness down and up....same result.

I'm flummoxed.
 
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Hmm, could be an error with the greyscale. 🤔

But on 1080p sources you'll need minor image processing enabled on the TV, on 4K though you'll need none whatsoever or you'll be introducing artifacts to the source media @Smallclone.
 
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Hmm, could be an error with the greyscale. 🤔

But on 1080p sources you'll need minor image processing enabled on the TV, on 4K though you'll need none whatsoever or you'll be introducing artifacts to the source media @Smallclone.
Which image processing is best for this? I've tried most but none seem to work.
 
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For 4K turn everything off, so no sharpness or anything that remasters the image whatsoever.

Oh, another thing to try is to lower the Gamma setting. As that may help some @Smallclone.

Managed to find some settings for you as well that may help too.

 
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For 4K turn everything off, so no sharpness or anything that remasters the image whatsoever.

Oh, another thing to try is to lower the Gamma setting. As that may help some @Smallclone.

Managed to find some settings for you as well that may help too.

Thank you very much for this, appreciate it - will try it.
 
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This app is not what you should be using. You need to find another 4K Blu-Ray player to play the disc to test if it is the disc or the TV.
Hmmm I only have one 4k Blu Ray player unfortunately. The fact that this effect occurs on every black and white 4k film on multiple devices suggests that it would be the TV.
 
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Have you checked to see if the same problem is happening with all your different sources, including broadcast TV from the TV's own tuners, the TV's own apps and sources connected by HDMI ? If you're able to do this and the problem occurs with all of those, then it has to be an issue with the TV/panel and not your sources or cables.

While uneven pixel wear (aka 'screen burn') on an OLED can often be caused by particular static elements being on the screen in the same place over long periods of time, the kinds of patches you're seeing were sometimes seen in the centre of the screen, but this was mainly on early generation OLEDs and was an issue caused by premature wear of the red sub-pixel, which was smaller than the other colours. If a red sub-pixel is wearing prematurely, it would give obvious dark patches (or shapes) on solid red backgrounds and make anything yellow look green in those places, but if you're not seeing any darker or strangely-coloured patches on full-colour (100%) slides, then it doesn't sound like your issue is down to 'screen burn'. A BX should post-date this particular issue anyway, as changes were made to the size of the red sub-pixel in OLEDs around 2018, which appear to have helped to alleviate this particular premature wear problem.

Do you see the colour patches in one particular area of the screen when watching B&W content or does it occur in random places on the screen ?
 
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Have you checked to see if the same problem is happening with all your different sources, including broadcast TV from the TV's own tuners, the TV's own apps and sources connected by HDMI ? If you're able to do this and the problem occurs with all of those, then it has to be an issue with the TV/panel and not your sources or cables.

While uneven pixel wear (aka 'screen burn') on an OLED can often be caused by particular static elements being on the screen in the same place over long periods of time, the kinds of patches you're seeing were sometimes seen in the centre of the screen, but this was mainly on early generation OLEDs and was an issue caused by premature wear of the red sub-pixel, which was smaller than the other colours. If a red sub-pixel is wearing prematurely, it would give obvious dark patches (or shapes) on solid red backgrounds and make anything yellow look green in those places, but if you're not seeing any darker or strangely-coloured patches on full-colour (100%) slides, then it doesn't sound like your issue is down to 'screen burn'. A BX should post-date this particular issue anyway, as changes were made to the size of the red sub-pixel in OLEDs around 2018, which appear to have helped to alleviate this particular premature wear problem.

Do you see the colour patches in one particular area of the screen when watching B&W content or does it occur in random places on the screen ?
Thanks,

I don't have an antenna so can't check broadcast TV but it happens with 4K black and white films - on a 4k Blu Ray through a 4k Blu Ray player, on a 4k Media streamer and on a 4k Amazon Fire stick. All via different HDMI slots and different HDMI cables.

Turning the colour off completely can sometimes make it worse, and sometimes make the patches that appear purple, appear a yellowish colour.
 
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Thanks,

I don't have an antenna so can't check broadcast TV but it happens with 4K black and white films - on a 4k Blu Ray through a 4k Blu Ray player, on a 4k Media streamer and on a 4k Amazon Fire stick. All via different HDMI slots and different HDMI cables.

Turning the colour off completely can sometimes make it worse, and sometimes make the patches that appear purple, appear a yellowish colour.
It does sound like a TV/panel issue I guess, but you could see if you can find something in black and white on a streaming service you're signed up to (or a Freeview catch-up app) and watch on both your Fire TV Stick and the TV's built-in apps if you wanted to be sure.

Ensuring you're on the latest firmware and doing a factory reset (in case you've inadvertently changed a setting that could be causing this) are other things to try - my gut instinct says they're unlikely to help, but you might as well try if you want to be thorough with your trouble-shooting and it's the first thing LG will suggest if you were to get in touch with them about the issue.

Do you see the colour patches in one particular area of the screen when watching B&W content or does it occur in random places on the screen ? Make sure you try different picture modes and colour temperatures.

I don't know anything about TV calibration or greyscale issues - it would be good to get a professional TV calibrator's opinion on your problem.
 
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It does sound like a TV/panel issue I guess, but you could see if you can find something in black and white on a streaming service you're signed up to (or a Freeview catch-up app) and watch on both your Fire TV Stick and the TV's built-in apps if you wanted to be sure.

Ensuring you're on the latest firmware and doing a factory reset (in case you've inadvertently changed a setting that could be causing this) are other things to try - my gut instinct says they're unlikely to help, but you might as well try if you want to be thorough with your trouble-shooting and it's the first thing LG will suggest if you were to get in touch with them about the issue.

Do you see the colour patches in one particular area of the screen when watching B&W content or does it occur in random places on the screen ? Make sure you try different picture modes and colour temperatures.

I don't know anything about TV calibration or greyscale issues - it would be good to get a professional TV calibrator's opinion on your problem.

Thanks - it doesn't appear to be in the same area of the screen every time, it can happen anywhere, and as I say it is primarily happening on 4k Black and White content where there are lines or dots very close together. Clothing is the most prominent cause.

I have read somewhere that doing regular pixel refreshes can actually improve the screen panel uniformity, so I may try that if a factory reset doesn't work.
 
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Thanks - it doesn't appear to be in the same area of the screen every time, it can happen anywhere, and as I say it is primarily happening on 4k Black and White content where there are lines or dots very close together. Clothing is the most prominent cause.

I have read somewhere that doing regular pixel refreshes can actually improve the screen panel uniformity, so I may try that if a factory reset doesn't work.
I think that pixel refreshes are designed to combat the effects of 'screen burn' (uneven pixel wear) so if this isn't the cause of your problem, then running them may not help. Running a pixel refresh manually actually puts more wear and tear on the panel and, as a result, it isn't actually advisable to run them yourself too often unnecessarily, AFAIK.

If your problem had anything to do with uneven pixel wear or poor panel uniformity, then you would expect the problem to be restricted to certain parts of the screen and it doesn't sound like this is the case.
 
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If you've got a specific scene in a program or film on a streaming service that causes a problem, then let me know as I'd be curious to see what it looks like on my Panasonic OLED. If you wanted to do that, I've current got access to Netflix, Disney+, Prime, YouTube and the Freeview catch-up apps.
 
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If you've got a specific scene in a program or film on a streaming service that causes a problem, then let me know as I'd be curious to see what it looks like on my Panasonic OLED. If you wanted to do that, I've current got access to Netflix, Disney+, Prime, YouTube and the Freeview catch-up apps.
Well I know that it was happening in the film 'Roma'. I think that's on Netflix. From memory one example was the hospital scenes and the riot scene .
 
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FWIW, I just had a quick flick through Roma on Netflix, watched the scenes you mentioned and couldn't see any coloured patches on my 2019 Panasonic OLED.

It'll be worth checking the known-problematic scenes on the BX's own Netflix app and then at least you'll know the problem isn't HDMI/source/cable-related.

If it persists after a factory reset when viewing the TV's own apps using different picture modes, then I'm not sure there's going to be anything you can do about it yourself and I'm not sure whether a proper calibration would address it either - possibly not if it's a fault with the panel.
 
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Is this issue always confined to areas with narrow stripes in them (as is the case with the shirt in the example photo)?

If yes then it may be a moire pattern issue. That's most likely to occur if the TV is (as I suspect many are) doing the nowadays largely unnecessary thing of "overscanning" (an historic tem related to CRTs but still inaccuaretely used). Meaning, it's taking the incoming signal and, rather than displaying it pixel-for-pixel, is attempting to upscale it by about 5% so as to crop off the extreme edges of the image.

Online manual suggests this:
Picture > Aspect ratio settings > Just scan
will give you 1:1 pixel mapping, which is what you want.
 
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Is this issue always confined to areas with narrow stripes in them (as is the case with the shirt in the example photo)?

If yes then it may be a moire pattern issue. That's most likely to occur if the TV is (as I suspect many are) doing the nowadays largely unnecessary thing of "overscanning" (an historic tem related to CRTs but still inaccuaretely used). Meaning, it's taking the incoming signal and, rather than displaying it pixel-for-pixel, is attempting to upscale it by about 5% so as to crop off the extreme edges of the image.

Online manual suggests this:
Picture > Aspect ratio settings > Just scan
will give you 1:1 pixel mapping, which is what you want.
Thank you, that's really helpful, I will try this.
 
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FWIW, I just had a quick flick through Roma on Netflix, watched the scenes you mentioned and couldn't see any coloured patches on my 2019 Panasonic OLED.

It'll be worth checking the known-problematic scenes on the BX's own Netflix app and then at least you'll know the problem isn't HDMI/source/cable-related.

If it persists after a factory reset when viewing the TV's own apps using different picture modes, then I'm not sure there's going to be anything you can do about it yourself and I'm not sure whether a proper calibration would address it either - possibly not if it's a fault with the panel.

I tried again last night and I managed to find a particular setting where it doesn't happen so much, this meant lowering the contrast quite a bit and upping the gamma and brightness I think. Trouble is, the blacks aren't deep when I do this and it also isn;t that bright. The picture looks a little washed out.

But there is a bit of hope there for it, and if I have to just switch modes to this one when I watch black and white content I can probably live with that!
 
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