LG PB690V Plasma TV green noise/static on dark areas - AVS Forum
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post #1 of 23 Unread 09-16-2014, 06:42 AM - Thread Starter
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Unhappy LG PB690V Plasma TV green noise/static on dark areas

Hello, I'm new here so I apologise if this is in the wrong place, but I was wondering if anyone could help me identify what is going on with the blacks on my new TV. Its an LG PB690V which is as far as I am aware is an EU variant of the LG 6600/6900 series plasma TVs.

Anyway, in the best way I can explain it, it has this greenish static or noise that covers darker areas of whatever scene is being displayed.

Deep blacks seem fine but colours slighly lighter than black start to exhibity these weird meshes of sparkling pixels that follow the darker blobs of colour around the screen. They're not stuck pixels, because they shift and move with the scene. Through some initial research I figured it might be the plasma panel process of trying to create shades of grey but mine looks far worse than screenshots I have seen.

Apparently this should also be imperceptible unless you are sitting right up close to the TV, but what I am seeing is visible (though mitigated) at 6 or 7 feet away. Some suggestions I saw in other threads included turning down the brightness and trying some calibrations settings posted here on the forum...neither of which have eliminated or even reduced what I am seeing.

I should mention I have this TV hooked up (via HDMI to the TV PC Input) to a PC running an NVidia GTX 770 GPU. I was basically planning to use it play movies from the PC. I've tried setting different pictire modes and scan modes and altering the various visual settings both on the TV and from the graphics control panel on the PC but I'm still getting it.

I'm not even sure if this is actually a problem, but if it is something plasmas 'just do' then I'm not sure I can live with it. I will be trying another input source (A PS4) and a new HDMI cable tomorrow to check those variables but I figured I'd check here to see if anyone can tell me what this is.

I've attached some pictures of the problem. They are a bit dark (had to disable flash) but you can make out the weird static ghosting in the areas of dark-but-not-quite-black colour.

Anyway, I'd appreciate any input. Thanks.
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post #2 of 23 Unread 09-16-2014, 06:43 AM - Thread Starter
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Erm, apologies for the lengthy post. It could have been shorter and more to the point
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post #3 of 23 Unread 09-16-2014, 09:44 AM
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Sounds like dithering in near black, try lowering your brightness 1 or 2 clicks.

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post #4 of 23 Unread 09-16-2014, 11:08 AM - Thread Starter
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Quote:
Originally Posted by chunon View Post
Sounds like dithering in near black, try lowering your brightness 1 or 2 clicks.
Yeah, I've already tried messing with the brightness.

I can lower it and the noise/sparkling seems to recede but it doesn't go away unless I turn the brightness down so far as to make the screen very dark.
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post #5 of 23 Unread 09-16-2014, 12:21 PM
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In case you don't know brightness sets the black point, contrast the white point. You really need to set brightness with a pluge pattern. Gamma controls how quick the set comes out of black.

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post #6 of 23 Unread 09-16-2014, 12:26 PM
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Agree with chunon, but that looks quite horrible! Not sure if that is standard fare on the LG? I certainly see a green dithering pattern on my Samsung plasma, but even 2 - 4 ft away it blends into pretty much a uniform gray shade. The posted dithering pattern looks unusually heavy and also not very random in distribution.
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post #7 of 23 Unread 09-16-2014, 12:43 PM - Thread Starter
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I was going to try the AVS HD-709 calibration disk next. would that be sufficient to get the brightness/contrast balanced correctly and see if this is still as bad?
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post #8 of 23 Unread 09-16-2014, 12:44 PM
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Try various inputs; is it there in OTA or DVD/BD playback? How's the internal pattern look? How about the Picture Wizard screens?

This looks like the noise I saw in my US panel when viewing <no input> in a dark room. Adjusting the pots on the PWBs helped lower the black level and eliminate the noise, but that's not for the faint of heart, or those with defects on a new panel.

I'd contact LG about it, after verifying it's not source-dependent...

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PS Picture Wizard has the tools for basic contrast/brightness/color/tint set-up; a built-in calibration disk that I like very much!

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post #9 of 23 Unread 09-16-2014, 12:50 PM - Thread Starter
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Quote:
Originally Posted by fbov View Post
Try various inputs; is it there in OTA or DVD/BD playback? How's the internal pattern look? How about the Picture Wizard screens?

This looks like the noise I saw in my US panel when viewing <no input> in a dark room. Adjusting the pots on the PWBs helped lower the black level and eliminate the noise, but that's not for the faint of heart, or those with defects on a new panel.

I'd contact LG about it, after verifying it's not source-dependent...

HAve fun,
Frank

PS Picture Wizard has the tools for basic contrast/brightness/color/tint set-up; a built-in calibration disk that I like very much!
Yeah I've read a little into the process of those adjustments. This is brand new and within warranty so I'll likely contact LG first and see if they send out a tech that can do it for me.

Don't want to void warranty a week after purchase

I'll have a PS4/blu-ray player to test with in the next couple of days as well as another HDMI cable so I'll check that out first. It's just a pain trying to find the time with being in work every day.

Then I'll try calibrating properly with the disk from this forum.

After all of that I'll kick up a fuss with LG ha ha.
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post #10 of 23 Unread 09-16-2014, 12:51 PM - Thread Starter
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I did try that built in Picture Wizard, as well as settings a few users posted on here but the result is what you see in the images I posted!
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post #11 of 23 Unread 09-16-2014, 01:09 PM
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Quote:
Originally Posted by kaymanov View Post
I did try that built in Picture Wizard, as well as settings a few users posted on here but the result is what you see in the images I posted!
I see you are in the UK. Can you not return the TV at your store for an exchange?
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post #12 of 23 Unread 09-16-2014, 01:18 PM - Thread Starter
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Quote:
Originally Posted by orion2001 View Post
I see you are in the UK. Can you not return the TV at your store for an exchange?
Yeah it's possible.

I'll try a few things first and if I can't improve the picture I'll likely return it. I can't unsee it now.

* I have just checked and I have another two weeks to return this no questions asked, and they'll even collect it free of charge.

As I said, I'll try a few things first but I might be leaning towards sending this back now

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post #13 of 23 Unread 09-16-2014, 01:38 PM
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Quote:
Originally Posted by kaymanov View Post
Yeah it's possible.

I'll try a few things first and if I can't improve the picture I'll likely return it. I can't unsee it now.

* I have just checked and I have another two weeks to return this no questions asked, and they'll even collect it free of charge.

As I said, I'll try a few things first but I might be leaning towards sending this back now
Might be worth checking the same TV out at a store and trying to play similar content (or carry a USB stick with some test pictures that you have tried on your set) to compare. That way you can figure out if it is specific to your TV. Don't forget to set the floor TV to Movie mode and tweak down some of the picture settings to make it an apples to apples comparison.
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post #14 of 23 Unread 09-16-2014, 01:48 PM
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Quote:
Originally Posted by orion2001 View Post
Agree with chunon, but that looks quite horrible! Not sure if that is standard fare on the LG? I certainly see a green dithering pattern on my Samsung plasma, but even 2 - 4 ft away it blends into pretty much a uniform gray shade. The posted dithering pattern looks unusually heavy and also not very random in distribution.
Agree with Orion-- at first it sounded like normal black dithering but the pictures look quite terrible. It may be something more.

Even on my 720p plasmas the dithering looks nothing like that-- bring a flash drive, or even better, a blu ray or DVD player with an HDMI cable and run it at the store. Dont wait, dont play around with cal discs-- unless you are doing some weird trickery with your photos I dont think a cal will help at all. Is this a 720 or 1080p model?
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post #15 of 23 Unread 09-16-2014, 03:48 PM - Thread Starter
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This is a 50" 1080p model.

The signal being sent from my PC is 1920x1080 @ 60Hz and the picture mode the TV is reporting is the same.
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post #16 of 23 Unread 09-17-2014, 01:35 PM
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Quote:
Originally Posted by kaymanov View Post
This is a 50" 1080p model.

The signal being sent from my PC is 1920x1080 @ 60Hz and the picture mode the TV is reporting is the same.
Theres no way the dithering should be that obvious on a 720p panel, much less a 1080p one. Again, its hard to sit here and diagnose the problem from a few dark blurry pictures, but that REALLY looks fishy to me. This is not something plasma owners "just deal with". We are used to great pictures in bright and dark scenes. There looks to be something wrong with your set. Bring it back.

I dont own a LG, but 3 Samsungs-- that said , we have a 60" wall mounted LG 1080p plasma in a conference room at work, and it makes a great picture from all I have seen.
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post #17 of 23 Unread 09-17-2014, 01:59 PM
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Might not make any difference, but I wonder if maybe applying ferrite cores to the power cable can help? My 51" Samsung came with three.

But yeah, I too notice green dithering on dark gray on my display, but nothing like what I see in these pictures. It is only from up close, and goes away pretty quickly as I move away.

I agree that if you can not find a solution to this, it is not something you should live with. Getting it back to the store to compare other sets might be best.
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post #18 of 23 Unread 09-17-2014, 03:56 PM - Thread Starter
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Okay.

I've tried with three separate input sources (PC, PS4 and iPlayer from TV apps) and three separate (and new) HDMI cables in different input ports.

Problem persists.

Even with calibration and severely lowering the brightness, all it does is shift this green sparkly mess to other areas of the screen that are still dark grey-ish.

I'm going to call the retailer tomorrow and get them to take the TV back.
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post #19 of 23 Unread 09-18-2014, 04:50 AM - Thread Starter
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Quote:
Originally Posted by alextr75 View Post
Might not make any difference, but I wonder if maybe applying ferrite cores to the power cable can help? My 51" Samsung came with three.

But yeah, I too notice green dithering on dark gray on my display, but nothing like what I see in these pictures. It is only from up close, and goes away pretty quickly as I move away.

I agree that if you can not find a solution to this, it is not something you should live with. Getting it back to the store to compare other sets might be best.
Using the ferrite cores was one of the first things I tried to no avail.
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post #20 of 23 Unread 09-19-2014, 11:45 AM
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If you are in the return period, return the tv. What you are seeing is not normal. If you are outside the return period, call LG and get a tech out. You may have an issue with one of your boards.
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post #21 of 23 Unread 09-20-2014, 10:30 PM
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This issue is present on my 50PB6600 (US model) as well, but I'm not sure whether or not if it is as pronounced as kaymanov is seeing ...

I've only noticed it so far via Blu-ray/DVD (I've tested 2 different players - both via HDMI, haven't tried component yet - including using different settings - such as 4:4:4 sampling and RGB, and even using PC levels with both the Low(wrong) and High black level adjustment on the set - same result) test patterns and some "darker" content(but not video black) - I've never noticed it from my normal viewing distance (8 FT+), and previously thought that it was only visable very close to screen ... but I do see it is noticable(but probably not if you are not looking for it) at a viewing distance of about 6FT or so, and, raising brightness slider a bit(beyond where I'd have it - at about 60) - I notice I can just make it out in darker shades in some test patterns, and some content as far as 8~9ft away (For instance, some green "stars" which shouldn't be there during opening of = "Star Wars" Phantom Menace ..... another specific spot I've noticed is beginning of chapter 2 of "Cars 2" Blu-ray ... Note: Tried 24p and 60p as well as sending 720p and 1080i from the player - no difference regarding this issue....

Oh, I've also noticed in some cases raising the "color" (saturation) to 100 removes the visable green(it's not green if you lower color slider to 0, but it's still there - So It's not specifically a chroma thing)noise ...

I've also noticed some odd (apparent) dithering otherwise in darker shades of grey ... take the THX Black level pattern on the Star Wars DVD's ... raise brightness to the level you can see the "drop shadow" - and all is normal(well except for the green noise in places)... but put brightness(black point) slider where it actually needs to be/where I prefer it to be, and the top portion of the darker bars gets cut off(top portion of the small barsturns video black more or less) ..

When I get a chance(which may not be soon as I'm in the middle of home renovations), I'll look at some better test patterns (ramps, greyscale bars, etc), including via USB(as well as Actual content, including HD and 2.35:1 movies via USB or the SmartTV interface for that matter), as well as looking more carefully at some of the internal patterns(although, I don't recall seeing any oddities when I looked at them previously) ...

The letterbox bars for 2:35:1/etc. movies exhibit odd behavior as well, and I do believe I have seen this mentioned in the LG 6600/6900 thread -- mainly during fast vertical camera pans, you'll see portions of it "encroch" into the content area like waves on a "video black" sea, as the pans occur LOL .... again, so far, I haven't seen/noticed this occur in other circumstances(other than via DVD/Blu-ray) - including, for example, 16x9 letterboxed material (via OTA or a SD dish network receiver) viewed using the set's 4x3 aspect ratio setting, or come to think of it, 2.35:1 movies via one of the epix or HBO channels via dish SD viewed with the set's "zoom" aspect ratio setting(with the annoying +3 increase vertical picture size you have to do everytime you change to the zoom setting if you want (more or less) accurate screen geometry(i.e. circles to be circles) ...

Whatever is going on here, At this point, I could be wrong, but I wouldn't be at all surprised to find out this is "normal" for this set ...

Jeff

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post #22 of 23 Unread Yesterday, 05:02 PM
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Quote:
Originally Posted by Nitewatchman View Post
This issue is present on my 50PB6600 (US model) as well, but I'm not sure whether or not if it is as pronounced as kaymanov is seeing ...

Whatever is going on here, At this point, I could be wrong, but I wouldn't be at all surprised to find out this is "normal" for this set ...
what you are describing sounds more like normal dithering. plasmas can't actually reproduce the thousands of shades natively(in every pixel), so they have to fire a percentage of the pixels to get those really dark, just above black levels.


although the 'waves of black'(haha) is totally new to me. no idea there.


think of it like this, when the pixel is 'off', it has a black level of 1. but when it's on the dimmest the pixel can go, it jumps to 10. in order to get an overall black level of 5, half the pixels will be on, and half off. to get a level of 2, 20% of them will be on, etc. and they will constantly change which 20% are on, so from a distance far enough that you can't make out individual pixels clearly, it should look like a uniform brightness.


what it looks like from viewing distance: sorry I didn't have any pics of JUST the plasma displaying this pattern

up close:

super close: notice that the lower the black level, the fewer pixels are turned on, but the pixels are equally bright.


Displays: Samsung PN64F8500/JVC X35
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post #23 of 23 Unread Yesterday, 09:39 PM
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fierce_gt - first - thanks for the excellent explanation+description/pics of the plasma dithering issue ...

Quote:
Originally Posted by fierce_gt View Post
what you are describing sounds more like normal dithering.
Yes - that is what I originally suspected was the case as well, but having never actually seen it in person before - I wasn't sure .. and still, it does seem awfully pronounced ...

Quote:
although the 'waves of black'(haha) is totally new to me. no idea there.
I would think it's related to the dithering as well, but looks quite odd, and it's also odd, as explained earlier I've only seen it via Blu-ray or DVD ---

Other than "waves of black" -- Best way I could explain it perhaps --- is It looks like in areas near the top letterbox bar (I haven't seen it happen near the bottom bar) in a non-uniform fashion when "near black" areas of the content occur near that line between the content and the letterbox bar -- areas where one would "expect" to see the dithering noise are instead "replaced" with "video black" with no visable dithering noise - or at least a very dark shade of grey for which the noticable "diterhing noise" isn't present ... Whereas any brighter areas near the line are displayed "as normal" .... The line otherwise(between the 2.35:1 content and the letterbox bar) is perfectly straight if there isn't something "near black" near top of screen ..

This is most noticable during vertical pans, but (I haven't fully explored this yet), but is not necessarily exclusive to vertical pans as per pics below ....

I've attached some pics to illustrate. Note I used Long exposure times (~1 second) and froze the frames which exaggerates the dithering noise/etc a bit and for instance makes MLL appear brighter than it is in some of the pis - also, some of the weird angles(sloping letterbox bars/etc) are due to the camera being at odd angles/off a 90 degree axis to the screen when I took the pics - also some of the bright specks you see are either dust on the lens or bad pixels in the CCD as I used an ancient Canon Powershot G1 for the pics - there is also some of looks like Moire in some pics that is artifact of the photography as well ...

Description of attached pics(sorry these aren't in the order of the thumbnails, the forum software has changed since the last time I posted images/etc) :

WavesofBlack1.jpg - Full frame - the top right slopes down at angle due to camera angle - but notice the "jaggedness" at the top, and notice the bottom is straight ... (used ASA 50 film speed setting for this pic, so along with exposure times being roughly the same as the other attached pics, the MLL/apperent black level should be closer to actual than most of the other pics)

WavesofBlack-closeup.jpg - small area of frame(same or similar frame as "wavesofblack1.jpg") at top "letterbox line" .. The "slope down to the left" between the blue and black isn't due to camera angle ....

WavesofBlack2.jpg - another example - full frame ...

WavesofBlack3.jpg, and WavesofBlack3A.jpg - another example and closeup (same exact frame this time)

thxpattern1.jpg - This is a portion of THX test pattern I mentioned in earlier post with brightness slider (as set with a pluge pattern) at my normal setting .... Note these boxes are near top of screen in the pattern ... compare to thxpattern2.jpg and notice the top of the right(darker) box is replaced with video black(more or less) .... If you lower brightness slider further to the left, each box exhibits the same behavior -- top of box vanishes first, you see the dithering noise on the "end box"(you can see it as small lines in the boxes from a distance of ~8-9+FT) as you go down further, then the box disappears(as it should) .....

thxpattern2.jpg - this is same as thxpattern1.jpg, except I've raised the brightness slider to a point just above where it should be -- but notice the right box is the same "height" as the slightly brighter box next to it (as should be the case) ....

StarWarsNormal.jpg - This frame taken with my normal brightness slider setting ... (long exposure, ASA 200 faux "film speed" setting on digital camera makes for much higher mll, and much more noticable dithering noise than is actually the case) .. The dithering noise(most of the green) you see here is not visable from normal viewing distance ... but note the lack of it near top of frame(but where there still are some stars, not where the letterbox bar is) ....

StarWarsBright.jpg - Same as "Star Wars Normal", except I've raised the brightness slider a few notches above where it should be ... Compare to Star Wars Normal --- The dithering noise is not necessarily noticable as noise from normal viewing distance -- However -- it IS noticable as a slightly brighter shade of Grey(with perhaps a green "dot" seen here or there), that doesn't quite fill the entire frame --- In other words, compared to "starwarsNormal.jpg -- Now you can Really see the line where the dithering noise appaerently "stops" near the top, but seems "replaced" with video black where there are still "stars", not yet to the "letterbox line" .... again, some of the smaller (generally "colored") dots that are in the letterbox area, probably dust on camera lens/bad CCD pixel/etc ....

-----------------------------------------------------------------


The effect with motion(during the vertical camera pans) looks like (small) waves of black encroaching on the top of the frame with the actual content ...

Just some wild speculation ---- I've done some work with various AVIsynth and other video filtering - and I have to wonder if maybe they are using some sort of temporal filter and a relatively large block size to attempt to "disguise" the dithering noise in shades of "near black" near the letterbox borders(but why, what would be the point, as the noise would still be there elswhere in frame) -- and, why am I only noticing it at the top, and why(so far) only via DVD/Blu-ray ? Some sort of oddity concerning whatever the LG set is doing and the video processing/output of whatever chipset is doing it in My Sony Blu-ray player or Philips(funai) DVD/HDD recorder/player? Perhaps I should test other players and see what happens ....
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Jeff

Last edited by Nitewatchman; Yesterday at 09:55 PM. Reason: grammar
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Reply Plasma Flat Panel Displays

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blacks , noise , picture quality , plasma

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