Purple Snakes, Magenta Banding on Panasonic Plasmas - Page 10

You guys really should swap e-mail addresses and take this out of this forum.

And I can see purple tinges in both my CRT's in certain grayish backgrounds. So, perhaps we are talking "normal."? Very subjective of course.

STOP Flaming and keep on topic or the thread will be locked.

Thanks

Exiting thread again.

Barry, please don't lock this thread. I believe it to be of importance. This is a real issue.

What I saw while watching the U of M Gopher hockey game last Friday was not normal. But I just haven't seen it happen often at all. The set of circustances that needs to occur to see the problem appears to be rare. It is NOT bad enough to change my opinion of the TV. It is a keeper.

Yeah, I've seen pictures of what you were talking about, one was from the movie Panic Room that I posted a little earlier in this thread that someone else reported. That is definitely not normal and I think that's what Lgans316 was talking about on his first set too.

I find it odd though, that I am only picking up on this purple thing now, I guess because of the HD, but the other day when I was taking out the trash, close to night behind my mountains in the background as the sun had gone down, I saw a purple tinge there as well. Talk about "Purple Haze" on the brain. lol

Just to clarify, is there anyone out there with a TH-42PX6U, TH-42PX60U, or TH-42PX600U that is completely free of this problem?

This TV seemed like the best fit for a Plasma in my price range and desired size (40-46") and I don't really want to cross it off the list of contenders, but this sounds pretty serious.

I am not sure you'll find a better set, no matter what brand. Again, my 2 CRT's show "purple tinge," in the same scenes as my plasma. I'm just not convinced this is a problem on mine, and even if I do return/exchange, what's to say the next brand set (or another Panny) would be different, or not have another problem of some kind? The same would apply to anyone purchasing an HD set.

I am on set 7 on the exchange/return game. Absolutely best bet for the money is to wait a few more years and see if companies can "perfect" HD sets. Until then, I can almost guarantee you will find something wrong with every single one of them, atleast I'll bet I can anyway. My .02.

p.s. If you do take the HD plunge, I suggest a store with a liberal return/exchange policy.

I have not read this entire thread. Some of these threads can get so long.

I have been watching my 42PX600 carefully since I learned of this problem for a couple days now. Other than some purple blotches I noticed during a hockey game, I haven't seen any of these problems. I watched Boston Legal and my local news in HD this evening and they looked great. No problems.

I am wondering. Has anyone done any comparison's between the inputs to see if one input does it more over another? I use a CableCARD and a DCT-3416 on HDMI and I just am not seeing these problems.......

The pictures were not taken from my Panny. It is taken from 2 sets (good and bad one). Once the fix is applied the After image is the one your Panny will display meaning that the thick purple bands will be thinned down to purple fizzing pixels which you can hardly notice.

Before image - kind of image that will be produced on-screen if your Panny is affected
After image - kind of image that will be produced on-screen if your Panny is not affected.

Please explain the problem you are facing with your Panny and request them for a fix.

Purple Tinge is acceptable but not Purple Snakes (thick Purple lines crawling on the fizzing pixels).

Well, I own a TH-42PX600U and have never seen this on my set. I am very critical of PQ and would certainly have noticed this, had my tv been affected. Built in Nov. 2006.

I own a th42px60u built in sept 2006 that does not display this problem at all. I am very picky and would notice what you guys are seeing. No matterwhat I watch really crappy SD broadcast, HD, DVD, video games. Nothing not even the purple ting.

It' extremely subtle, and I really had to look hard for purple tinge and know exactly what I was looking for, but it's there on my 2 CRT's as well, so I think it's "normal." Just like some people can see DLP rainbows and others can't I suppose. Also, like those pictures where you have to look a certain way to see the 3D image. Anyway, it's not good to look for trouble. I don't think I have the problem either, but others do, and I think Panasonic should come out with a firmware update, just like they fixed the clay face issue back in Sept.

I have the th42px6u for about 5 weeks now and haven't noticed any purple snakes, banding or for that matter any other PQ issues. Still in break-in mode settings at this point.

I agree! Purple snakes or fizzing pixels along contours is simply a bug in processing. It is not a property of the panel.

To understand how it might happen, you have to realize that the data coming into the panel is YBR data, which must be converted to RGB before driving the panel. The scaling, contrast/brightness, and EE can be done in the YBR, RGB or some proprietary intermediate colorspace.

It is very possible to input a YBR pixel value which is an intense, almost white color, yet mathematically has green hue. In fact, what has happened is that although the hue is green, the intensity brings it close to the white point.

The problem is that if you do the conversion from YBR to RGB, the green value can actually go beyond maximum. On a buggy system, a green 256 on an 8-bit output can roll around to zero, instead of saturating at 255!!

Hence, on a greenish-but-almost-white contour, the color turns purple (actually a magenta).

This is a rookie image-processing mistake. It is a firmware bug -- pure and simple. It should not be accepted by anyone who sees it. Panasonic has acknowledged the problem, and have a fix which involves firmware and a new board (from reading this thread). It has nothing to do with the plasma panel.

Now, purplish tinges in dark areas is a different story, and has more to do with calibration of the various colors at low intensity (perhaps this is difficult to calibrate on plasma?).

Just my $0.02 from an image-processing professional.

To the people with "purple" tinge, NOT snakes. If you can, view the same material on a CRT monitor, CRT TV, other brands, LCD, etc, whatever you have. You might notice the same purple tinge as I did on 2 of my CRT's (A Sony Trinitron and ViewSonic monitor).

This only says "to me" that SOME of these purple tinges are somewhat normal for all displays. It would be great if others could confirm this. Try any other TV's or displays you might have (Plasma, LCD, DLP, CRT, whatever) and see if I'm right a little bit. Check it out. Just view the same scenes where you are seeing the "purple" on your Panasonics.

Don't get me wrong, I'm not saying ALL are "normal" here. SOME of these sets are obviously messed up. But, if you can see "purple" on other sets, different brands and different technology, maybe you don't have a problem after all.

Wasn't sure I completely understood all stated,

1. "Purple snakes or fizzing pixels along contours is simply a bug in processing. It is not a property of the panel."

Are you separating the actual Plasma panel, from the rest of the Panasonic TV in your statement? You're still saying it's a TV specific problem with Panasonic, right?

2. "This is a rookie image-processing mistake. It is a firmware bug -- pure and simple."

So, Panasonic is a "rookie?" Firmware bug means bad software/hardware? Are you speaking of the purple tinge I see in all my displays? (2 CRT's and a Plasma)

3. "purplish tinges in dark areas is a different story, and has more to do with calibration of the various colors at low intensity (perhaps this is difficult to calibrate on plasma?)."

But I see purple tinge in certain gray areas on all my displays. So, are all my displays calibrated incorrectly at the factory?

Thank you.

I'm saying it is likely a problem with the digital image processing in the Panasonic TV. I was only trying to say that it is not a property of the panel itself -- i.e. another company using the same panel, but with their own digital processing, wouldn't necessarily have the problem.


I work in software image processing. Bugs happen! I can spot obvious bugs like this instantly -- if I see them! However, sometimes bugs get out in the field, and get reported by users, because quality-assurance people don't have the expertise to realize that something isn't normal.


You always see purple fringing? I never see purple fringing, but I've always used CRTs (direct and projection) so far in my HT.

I have seen purple and green fringing on computers, when running nVidia graphics cards. The nVidia hardware (it may be fixed in the latest generations) conversion of YBR to RGB has round-off errors which reduce the number of real color levels visible in the blacks, and a gray-ramp gives alternating purple and greenish tinges. This is subtle, but there. It is like the result you get when you use a 16-bit screen color depth instead of TrueColor. So, on 8-bit/plane output, weird processing can introduce subtle color banding.

Another source of purple blacks could be incorrect calibration of the blacks on the display, between the different colors.

I can only think of the above 2 reasons (round-off in digital calculations, or incorrect black-level calibration between colors).

Of course, if it is always on the same source material, maybe it has to do with the source!

No I don't see purple tinge everywhere, but on some of the shows that others reported seeing purple on, so do I, and on all my displays. ie. Superman Returns in the clouds. Even then, I have to look close up.

Also, I have an ATI Radeon 9800 Pro card with the latest drivers in my computer and am in 32 bit, so it's not Nvidia. And, my Sony Trinitron is similarly affected in the few scenes others use as an example. My sources are both cable (component) and DVD (HDMI).

Anyway, thanks for your replies. I think I am way too fixated on this purple thing, when I think it may just be me being so into the detail of the thing, that I see it when looking too close. My point was that I believe it's possible to be part of the scene in the show. Again, not all, some people really have a problem with this being much more pronounced than what I am talking about for sure.

A couple of questions for you since you are a professional:

Do you think getting an ISF certified tech out to calibrate would solve any possible problems you describe? And,

Do you think a firmware update only (no hardware change) from Panasonic would correct any problems you described?

Thank you.

For Superman Returns, it very well may be the movie itself that is at fault. I know that on The Fifth Element, I have seen some major contouring in the blacks in one scene, and sometimes these contours are slightly coloured (so I guess I have to take back that I've never seen something like this). If we all had uncompressed, 48-bit color we wouldn't see things like this

For problems like this in the source data, no calibration can help. For a persistent color cast to your blacks, yes calibration should help.

I would expect a firmware update might fix the Panasonic problem, but only they know how they designed things.

Now if only I can save up for a plasma ...

Well another major snake for me.While I'm not looking for the problem, this snake just jumped to me. When the Ocean Liner Poseidon completely flips over, I saw about two huge purple bands in the water. Worst case I've seen so far on my set and not happy about it. Quite dissapointing if you ask me, the previous Panasonic ED plasma didn't have this.

Maybe your previous ED plasma had the same problem, but you couldn't see it as clearly as with your current plasma? I have found the purple ting/hue condition on both my CRT displays to a lesser degree with the exact same shows.

Not saying your set isn't defective, it could be. I would recommend having a Panasonic service person come take a look. I have found every HDTV set I've seen to have some problem or another, and I've had 7 (kept 2). What do other people around you think? My wife rolls her eyes at me sometimes, and doesn't see the big deal. Now, if you have snakes all over, and all the time, that's a different story. My .02.

Anyway, I've considered an ISF calibrator, but man oh man, they're expensive. A well respected and known calibrator I found, charges $500 ($400+$100 mileage) to properly calibrate my plasma (25% of purchase price). I'm no expert, but after all my research for the past couple of weeks on this, I think mine just needs that work done and wasn't done to perfection at the factory. Maybe you're not as picky as me though, and your set is defective?

Here's a couple of links to some sets with varying degrees of the problems to help put things in perspective:

http://picasaweb.google.co.uk/lgans3...66127515137906

http://www.cc.jyu.fi/~jakeisal/pictures/

Sadly you can now add my 37 to the list.

July build, had it since September. Haven't upgraded the firmware to 1.25 since I
haven't had an issue with "clay faces"

I have been looking for the snakes since I found this thread in December and never saw the issue until this last week. I've now seen it 2 separate times but only only my local NBC channel ( they do multi cast). Both times being during Law and Order. I'm using the QAM tuner as the input source.

I also follow the Burn in/IR thread, saw some station logo's remaining for days, so I been playing around with lower picture and brightness settings. I was able to fade them away with in a few hours.

Have I done something to make them more visible ? Guess I'll have to do some more investigation on my part.

sonydude,

Thanks for posting these pictures. It really helps for those of us who may or may not know what to look for. (I would like think I at least have an idea what to look for).

I have had my 42PX600 for a little over two weeks now, and I became aware of these issues just after receiving my set. My 42PX600 was made in November and I am happy to say that while my set may have some of these issues, but it is much less severe than I am seeing in these pictures. The ONLY time I see excess purple is during a sporting event such as hockey or basketball when there is "glare" from lighting on the ice or on the court. I did not notice it during the HD broadcast of the Minnesota Wild game last night although I did see a small amount of purple on the court during the SD broadcast of the Timberwolves last Friday evening.

I have no doubt new firmware will fix this. As I said earlier, I think this set is a keeper and I will wait patiently for an update.................

I've got to say sonydude some of those pictures look like they came from very badly calibrated displays. like this one



not saying there isn't a problem, but couldn't the calibration be enhancing the problem?

That's what I've been saying.