Rainbow Effect on Panny PX50 Plasma - is sub-pixel controller to blame? - Page 4 - AVS Forum
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Old 06-17-2005, 02:51 PM
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Originally Posted by empire_of_one
It wasn't the first or only one I pursued, but it was the only one that worked.

It was also the one that worked for you, you don't need to explain anything to us schlubbs. You're the one who has to live with it for the next 1 - 5 years. :)
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Old 08-04-2005, 08:11 PM
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OK guys, I hate to resurrect this thread, but empire_of_one you were right.

I just got my 42PWD8UK (commercial monitor) two days ago, and I've noticed this same rainbow-like effect. I'll have to admit that I was more than skeptical when you first noted it. Now I'm a believer. :eek:

I noticed it by chance--I wasn't looking for it. In fact, I had almost forgotten you mentioned it so long ago. But it's there. Mainly on bright/white scenes when I quickly look away from the screen.

Now that I've noticed it, I can make myself see it almost anytime. However, it isn't distracting for my viewing. There's no way I'm sending this plasma back! This TV is part of the family now.

My point is: I apologize for doubting your observation all these months. You were right. :)

Even my wife loves HD.
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Old 08-04-2005, 08:33 PM
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Yep I see it to on my 50px50u.. The issue is the phosphor/plasma response time, firing time, whatever you want to call it, specifically for the greens..

I'm very aware of RBE on DLPs, and I can see them with minmal effort. My 50PX50U arrived about 1.5 weeks ago and while the picture is stunning, my eyes see what I can only equate to a RBE. Only it is greenish yellow. Not only can I see it in dark scenes w/white objects that move, but even the white of baseball players running fast. To my eyes at times i can see a green blur behind them...

If you find a bright scene in a movie or tv. Wave your hand (with your fingers spread) quickly infront of the plasma and you'll see a green and purplish look to your fingers as they move.

Of course I've adjusted the heck out of the tv to minimize it. Reducing contrast does help, but does not alleviate the issue. I'm still in my first 100 hours, so the tv is very new. Yes I have good cables. No it is not just one input. HDMI, DVD (component), Xbox (component) and Tivo (composite) all suffer from the same thing.

So today I was playing around with xbox, and they have this pong screen saver. a white blip moving around. And I noticed that the trailing edge is green, while the leading edge is purpble.. Now this tells me that the green phosphors are not firing at the right time. That is, the purple edge comes from the red and blues firing, then the greens come on, produce a white image and at the end the reds and blues have turned off while the greens are still on. Hence the purple leading edge and the green trailing edge.

You can think of it as this, pretend we've outlined a 3 x 4 pixel box, and it is moving up.

RB RB RB
RBG RBG RBG
RBG RBG RBG
G G G

Thats the end effect... I've yet to go back to a store and sit there and wave my hand infront of all the plasmas...i know i've seen this effect on other brands though... This may just be an issue w/all plasmas.. Ideas? then again, i'm the minority that can see the flicker in the new LED tail-lights on cars... eek.. my eyes must be too good for my own good..

I spoke w/a Panny tech, and its just one of the "gotchas" with the technology, at least according to him... and yes for me, turning down the contrast (duh!) does help.. I'm wondering if with age the phosphors will "die" quicker after being excited as others have reported it being less when the tv had a few hours on it.. May attribute to some Plasmas on display at stores not exhibiting this detail. Also I swear it gets better the longer the tv is on...

-t




-t
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Old 08-04-2005, 11:37 PM
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Apart from the fact that phosphors decay at different rates there is another potential cause for plasmas in particular. One of the root causes of many video artifacts in plasma displays has to due with how greyscale is reproduced.

Plasmas must use pulses of light to produce greyscale. Current plasma will use anywhere from 0 through 8 pulses depending on the desired intensity (new models are up to 13bit). All 3 sub-pixels will fire simultaneously but since it is pulse modulated there is a TIME component.

sub-pixel #1 fires ( 1 , 2 , 4 , 8 , - , - , - , - )
sub-pixel #2 fires ( - , - , - , - , 16 , 32 , 64 , - )
sub-pixel #3 fires ( - , - , - , - , - , - , - , 128 )
----------------------------- time scale ------------------------>

If you wave your hand in front of your face or move your head or eyes you are essentially just preventing your brain from adding up all the pulses properly. You start seeing them independently or add them up along the direction of motion of your eyes (called dynamic false contouring)

Over thinking, over analyzing separates the body from the mind
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Old 08-05-2005, 07:27 AM
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Quote:
Originally Posted by xrox
Plasmas must use pulses of light to produce greyscale. Current plasma will use anywhere from 0 through 8 pulses depending on the desired intensity (new models are up to 13bit). All 3 sub-pixels will fire simultaneously but since it is pulse modulated there is a TIME component.
so could we attribute this to the "flashing", since it is a flicker, our eyes can pick it up if we move them fast enough? Obviously some being more sensitive than others..

My other thought, I put on some test THX stuff that came from a movie. One block is supposed to display 8 different shades of gray. No matter how I adjust my TV i can't even see 2 different shades. Could the gray's be so far off that if the tv was ISF calibrated I'd see less flicker?

-T
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Old 08-08-2005, 04:36 AM
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Quote:
Originally Posted by wdwms
... I noticed that the trailing edge is green, while the leading edge is purpble.. Now this tells me that the green phosphors are not firing at the right time. That is, the purple edge comes from the red and blues firing, then the greens come on, produce a white image and at the end the reds and blues have turned off while the greens are still on. Hence the purple leading edge and the green trailing edge ...
I too suffered with these symptoms on a TH-42PWD7 and actually returned it !

But I now know, most if not all Plasmas suffer from this.

Would your analysis also explain why even a static object can exhibit this phenomenon.

When I had my PWD7 I created a very simple menu on a home produced DVD - see first attachment.

When played back on the PW7, the white stationary rectangles had obvious green and red edges - see second and third attachments.

However on an old model Samsung Plasma PPM42S3, there were no colored edges on static objects - only if they moved (in other respects the Samsung was much worse than the Panasonic!)

The same DVD player was used for both panels using their respective component inputs.

The Samsung definitely produced a cleaner static image. Also, I took my DVD to several retailers and proved that you could see these colored edges on Panasonic Vieras aswell.

So I can't help thinking that maybe Panasonic plasmas suffer more than others from this particular issue of uneven phosphor processing whilst they may be superior in other respects.

BTW I'm going to repeat my test on a PWD8 as soon as I can locate one here in the UK!

Gussie
LL
LL
LL
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Old 08-08-2005, 04:54 AM
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That doesn't look like phosphor decay timing problems to me. It rather looks like scaler/deinterlacer/board electronics/whatever problems, I think.
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Old 08-08-2005, 06:54 AM
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Quote:
Originally Posted by gussie
I too suffered with these symptoms on a TH-42PWD7 and actually returned it !

Would your analysis also explain why even a static object can exhibit this phenomenon.
What you've described there is also seen on plasmas, and seen on CRTs as well. This one has a simple explanation. The pixels of the TV are ligned up as RBG. If you need to create something white, all pixels will fire. So to make a block we'd fire:

RBGRBGRBG
RBGRBGRBG
RBGRBGRBG
RBGRBGRBG

Look at the left edge, its Red/Blue, hence the purple color, and the right edge is green. Hence the colors you see.

From my experience so far, Plasma's differ from LCD Computer Monitors in such a way that there is color bleed between the pixels. No color bleed is what we expecting, but Plasmas bleed the colors much in the way that a CRT does. Don't forget in an LCD tv the entire pixel can change color as the LCD pixel can mix RGB, with plasmas we are at the mercy of our eyes mixing the colors as the RGB pixels are side by side, again much like a CRT..

The scaler/deinterlacer/etc is not to blame, otherwise all plasma's wouldn't exhibit this.

On a good note, with a good adjustment and the contrast turned down, these trails become less and less apparent. And your eyes adjust to watching, I only see the trails now in super dark/light scenes..

-t
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Old 08-08-2005, 07:37 AM
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Guys,

Admittedly I haven't been following this issue very much. It sounds fairly disturbing. Are people reporting this "rainbow" effect only on a certain Panasonic generation of plasmas? I've lived with my Panny ED 4UY for several years and have never once seen this effect.

Thanks,
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Old 08-08-2005, 08:25 AM
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This is interesting. Must be something specific to the electronics (as others have said) or new gen glass. There's been way too many cumulative years of plasma viewing here for it to be a "feature" of plasmas in general. How could it go unnoticed until now?

larry

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Old 08-08-2005, 10:05 AM
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Quote:
Originally Posted by R Harkness
Guys,

Admittedly I haven't been following this issue very much. It sounds fairly disturbing. Are people reporting this "rainbow" effect only on a certain Panasonic generation of plasmas? I've lived with my Panny ED 4UY for several years and have never once seen this effect.
I can't say that I had ever noticed the effect when I saw plasmas in retail stores. (I really started looking closely at plasmas just before the 7UY's were released.) My only experience was with consumer Pannys because I never saw a commercial monitor up close until I bought mine.

However, the effect is noticible mainly when I quickly look away from the screen while there is a bright image displayed. I hope it's only limited to this generation. Not a deal breaker for me--now that I have it in home--but I wish I had noticed it before I made the purchase.

Even my wife loves HD.
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Old 08-08-2005, 07:30 PM - Thread Starter
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Some of the things people are describing in here sound like a different effect than what I was seeing. Anyone familiar with the DLP "rainbow effect" would have a good idea of the effect I saw. It wasn't anything like fringing or ghost trails that some people are describing. It's a very quick flash of light, a kind of optical effect, produce by high contrast images. The nature of the effect is such that you would not be able to photograph it or capture it on video.

I've looked for it on other brands of plasma since I saw it on the Panny, and there have been a couple times when I thought I saw something similar but couldn't be sure, on a Phillips plasma. I have a very difficult time seeing the effect in showrooms though; it was the same with DLPs, I could very barely see rainbows even when looking for them in a showroom but saw them all over the place when I got one home. So I have no idea if the effect was specific to that model or might be present in others.

I want to eat your brains and gain your knowledge.
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Old 08-08-2005, 07:42 PM
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Quote:
Originally Posted by empire_of_one
Some of the things people are describing in here sound like a different effect than what I was seeing. Anyone familiar with the DLP "rainbow effect" would have a good idea of the effect I saw. It wasn't anything like fringing or ghost trails that some people are describing. It's a very quick flash of light, a kind of optical effect, produce by high contrast images.
That sounds exactly like what I'm trying to describe. I didn't mean to resurrect this debate, nor do I want to turn folks off from the Pannys. My monitor is great--save for this occasional distraction--and I'm not gonna give it up easily. ;)

Even my wife loves HD.
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Old 08-08-2005, 07:53 PM
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Quote:
Originally Posted by empire_of_one
Some of the things people are describing in here sound like a different effect than what I was seeing. Anyone familiar with the DLP "rainbow effect" would have a good idea of the effect I saw. It wasn't anything like fringing or ghost trails that some people are describing. It's a very quick flash of light, a kind of optical effect, produce by high contrast images. The nature of the effect is such that you would not be able to photograph it or capture it on video.

I've looked for it on other brands of plasma since I saw it on the Panny, and there have been a couple times when I thought I saw something similar but couldn't be sure, on a Phillips plasma. I have a very difficult time seeing the effect in showrooms though; it was the same with DLPs, I could very barely see rainbows even when looking for them in a showroom but saw them all over the place when I got one home. So I have no idea if the effect was specific to that model or might be present in others.

Actually Empire, there are 2 effects.. The one you mentioned which is just like a DLP RBE, and the ghosting trails. However, they could be related, as my thought is that the delay in the green phosphor and the timing of the electricity going to the plasma cells hence causes the flash. Also this delay on a slower moving object can cause the trails. It all depends on how fast it is moving.

In my earlier post: "I'm very aware of RBE on DLPs, and I can see them with minmal effort. My 50PX50U arrived about 1.5 weeks ago and while the picture is stunning, my eyes see what I can only equate to a RBE. Only it is greenish yellow. Not only can I see it in dark scenes w/white objects that move, but even the white of baseball players running fast. To my eyes at times i can see a green blur [flash] behind them... If you find a bright scene in a movie or tv. Wave your hand (with your fingers spread) quickly infront of the plasma and you'll see a green and purplish look to your fingers as they move."

You can replicate the effect by "shaking" your eyes back and forth fast, especially noticable in white on black situations. If you can't see it, dont' look for it! ;)

Since I had talked to the panny tech, he said this was common with all plasmas. I can see them in store displays, possibly just a blip in this technology..

-t
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Old 10-04-2005, 02:34 PM
 
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I've had my Panny TH-50PHD8UK for about a week now and I see the yellow flashes on contrasty (dark and light) material.

That truly sucks (I am extremely sensitive to DLP rainbows, too).

I am not prepared to return the display yet and hope to be able to train myself not to see them like some people reported with DLP rainbows.

empire - you were right!!!
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Old 10-04-2005, 04:35 PM
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I see nothing like this on my TH-50PHD7UY and TH-42PWD7UY. This IS very disturbing and is certainly cause to pause when considering my next Panny PDP.
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Old 10-04-2005, 06:31 PM
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wojtek, I see the yellow/bright flashes on my PWD8UK, but I think the effect has lessened since I got my display a couple of months ago. I don't know if the display characteristics have changed or if I'm getting used to the effect, but it is not nearly so bothersome as it was right out of the box.

Here's hoping you have the same experience.

Even my wife loves HD.
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Old 10-04-2005, 06:36 PM
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As I said earlier if you see this effect by moving your eyes or head back and forth or looking away quickly etc.............. you are seeing the temporal seperation of colors that plasmas invariably have!

R,G,B are all fired for different lengths, and sometimes at different times, to obtain the desired color. It is called "Address Display Seperation" and it is a form of pulse width modulation.

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Old 10-04-2005, 06:41 PM
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Three things:

1. This sucks if people are seeing this and it's really bugging them.

2. I am extremely sensitive to the DLP rainbow effect and can not buy that technology because of it. But I have tried my best to see the flashes on the new Panny plasmas and I can't see them - even on super-high-contrast images like white credits on black background.
FWIW.

3. While it may not be the effect being described, there is a certain persistance of vision on high contrast scenes on any display. If you move your eyes around on, say, an image of credits on black background, the credit images can persist as "flashes" that jump off the screen and trail in your vision. Endemic to all displays, just due to our eyesight. I'm not saying that's what is happening here, but perhaps it could muddy the waters in terms of people reporting "flashes."
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Old 10-04-2005, 07:01 PM
 
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Oh no... the urban myth of the dreaded RBE effect gets raised once again... :rolleyes:
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Old 10-04-2005, 09:01 PM
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Hi,

I guess I'm somewhwat relieved to come across this thread. Was questioning my sanity until now. :D

I recently purchased the 50PHD8UK and feed it 480i from my lower end Sony DVD player, via component.

It's fairly common for me to see an artifact that is extremely similar to the "rainbow effect" I can easily see on DLP's. It can be seen under the same circumstances as the DLP rainbows. Ie, when darting my eyes to different locations on the screen. But unlike the DLP rainbows, the breakup, or banding or whatever you want to call it, is different. Instead of seeing multiple colors of wierd geometrical shapes breaking up, I see only a yelllowish color basically. and the geometrical shapes seem to be more rectangular and more like stable blocks that don't move around so much. Anyway, that's what I can remember seeing anyway. Probably not the best description, but that's how I'd describe it.

BTW, my set is very new, and I run it on cinema mode or standard mode, with brightness and contrast turned down. I'm only have around 30 hours logged into the set.

This is a bit of a let down for me, but I haven't really even considered returning the set. It doesn't bug me near as much as DLP rainbows and this TV is a massive upgrade for me even with this "drawback". I don't see them very often on this panny, and the effect isn't as hard to stomach for me as the DLP rainbows. I hope this is something that can be "tuned out", either by TV settings or by me getting used to it.

I hope this review is helpful. Now, I'll just have to keep a close watch for how to adjust in order to reduce this effect. Not a huge deal, IMO, but worth trying to reduce. :)

HM
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Old 10-04-2005, 09:50 PM
 
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Quote:
Originally Posted by optivity
Oh no... the urban myth of the dreaded RBE effect gets raised once again... :rolleyes:

umm, be happy that you don't see them and don't question people who do.

You are absolutely wrong to call a myth what is quite obviously a real phenomenon for some people, myself included.

What are you really saying when you say this effect is an urban myth??? :mad:
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Old 10-08-2005, 08:51 PM
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I received a TH-50PX50U last week and noticed an occasional yellow flash during high-contrast scenes but it was hard to tell if it was just my mind.

I loaded Sin City today and I can definitely see yellow flashes during scenes of fast motion and high contrast (bright white against black).

I've turned down the contrast from +4 to 0 but it still happens a bit. It's hardly a major issue for me but for those who need an absolutely perfect display I suppose that's a reason to not purchase a plasma television.

To be honest there are many reasons to be dissatisfied with a plasma television from any manufacturer and I honestly consider the yellow "rainbow effect" one of the more minor issues.
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Old 10-09-2005, 08:05 AM
 
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Quote:
Originally Posted by MathewM
When I was checking out the PD50 model at CC I noticed some strange artifacting when I looked downward and at an angle. It almost looked like a moire effect when you see thin horizontal lines on a NTSC display. Not sure if this is similar to what you were seeing.
Quote:
Originally Posted by jacx
I noticed the same thing the other evening on my 42PX50U, empire. I have a DLP front projector in my video room, so I'm familiar with the rainbow effect, which I notice occasionally, but which doesn't bother me at all. Like you, I was surprised to see a very similar effect on the Panasonic plasma which produces a yellow or green flash. Now that I've seen it, I can produce the effect at will by darting my eyes rapidly from one side of the screen to the other during a scene of high contrast. Mostly I don't notice it, and as with my DLP, it doesn't bother me at all
Quote:
Originally Posted by wojtek
umm, be happy that you don't see them and don't question people who do.

You are absolutely wrong to call a myth what is quite obviously a real phenomenon for some people, myself included.

What are you really saying when you say this effect is an urban myth??? :mad:
What I'm saying is most likely there is some other problem with your set-up or picture settings that cause these anomalies. I seem to recall one poster said if he watched his PDP through his fingers while off center he could also reproduce the dreaded RBE effect! Since I don't watch TV that way, this may explain why I've never seen it myself. Here is a far more plausible explanation:

Quote:
Originally Posted by Brucer
Rainbows are probably the wrong descriptive phrase for what you are seeing. It reminds me of the discussions from the past about green phosphor latency (more so on the Pioneers). One interesting comment in these archived discussions, was from an ISF guy that if the artifact was red, blue or purple related, that meant the contrast was set to high. There are other issues discussed, as well, and attached jpg examples of symptoms, etc. (high contrast black box with dimmed white background, etc).

May or may not be an issue, but so far you have only partially described the symptoms, conditions or the factors of occurance.
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Old 10-09-2005, 08:20 AM
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I have a feeling this sub-pixel controller uses a similar algorithm to ClearType font smoothing on Windows machines that have LCDs. The idea of ClearType is that each pixel of an LCD consists of a Red, Green, and Blue section. When scaling a font, rather than treating the pixel as one unit, you break it up into the three units and can achieve higher resolution scaling, which makes for smoother fonts.

The downside, however, is that you can see the colors on the edges of the scaled fonts. Take a look here:

http://www.microsoft.com/typography/ClearTypeInfo.mspx

Note the image titled ClearType magnified. Another good resource is here:

http://grc.com/cleartype.htm

Note that they even call it Sub-Pixel Font Rendering.

If Panasonic is using similar technology in their scaling algorithm, which I'd be willing to bet on, then you could see "rainbow edges" in high contrast areas. While the source of the issue has nothing in common with the DLP RBE, it has similar symptoms.
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Old 10-09-2005, 08:30 AM
 
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This is a reasonable explanation, which means if someone is seeing the problem they should consider turning the brightness down.
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Old 10-10-2005, 12:24 PM
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Just wanted to chime in and say that I see the rainbow effect on my Vizio 50' plasma.The colors are not red-green-blue,it is yellowish.Very easy to see with a PC connected.Durning bootup if I glance around I see yellow trails,even if the text is still.If I open a window and drag it arouond the screen I see the yellowish effect trailing.Not sure if I can handle it.Being my first plasma and all,I wasn't sure how normal it was.After all I don't see rainbows on DLP's so it came as a shock to me.
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Old 10-10-2005, 04:28 PM - Thread Starter
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Originally Posted by aranganath
I have a feeling this sub-pixel controller uses a similar algorithm to ClearType font smoothing on Windows machines that have LCDs. The idea of ClearType is that each pixel of an LCD consists of a Red, Green, and Blue section. When scaling a font, rather than treating the pixel as one unit, you break it up into the three units and can achieve higher resolution scaling, which makes for smoother fonts.

The downside, however, is that you can see the colors on the edges of the scaled fonts. Take a look here:

http://www.microsoft.com/typography/ClearTypeInfo.mspx

Note the image titled ClearType magnified. Another good resource is here:

http://grc.com/cleartype.htm

Note that they even call it Sub-Pixel Font Rendering.

If Panasonic is using similar technology in their scaling algorithm, which I'd be willing to bet on, then you could see "rainbow edges" in high contrast areas. While the source of the issue has nothing in common with the DLP RBE, it has similar symptoms.
The only problem is, the effect that I and others have seen is yellow and blue, instead of red, blue and green. I think the phosphor delay explanation someone offered before sounds like the most plausible one.

You could try reducing brightness or contrast to mitigate the effect, if you're willing to accept a muddy looking picture. When I had a DLP, I reduced contrast and brightness, and while I saw slightly fewer rainbows, it wasn't worth it considering the cruddy PQ that caused. I used DVE to calibrate the brightness and contrast on my PX50, and at the correct settings I saw the effect pretty constantly. Sure I could have reduced brightness and contrast, but why should I have to put up with sub-standard picture quality to get rid of some kind of annoying artifact? I've been able to force myself to see the effect on other brands of plasma, though it was never as obvious as on the PX50 (of course, I never had those sets in my home environment either). On the PX50, I couldn't stop myself from seeing it if I tried (and believe me, I tried!). So unfortunately I had to conclude that plasma just wasn't for me.

I want to eat your brains and gain your knowledge.
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Old 11-10-2005, 07:29 PM
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Originally Posted by E-Coli
Just wanted to chime in and say that I see the rainbow effect on my Vizio 50' plasma.The colors are not red-green-blue,it is yellowish.Very easy to see with a PC connected.Durning bootup if I glance around I see yellow trails,even if the text is still.If I open a window and drag it arouond the screen I see the yellowish effect trailing.Not sure if I can handle it.Being my first plasma and all,I wasn't sure how normal it was.After all I don't see rainbows on DLP's so it came as a shock to me.
e-coli, i have the same set...do you see this on any other input? are you using RGB input?
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Old 11-12-2005, 01:12 AM
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Originally Posted by empire_of_one
I used DVE to calibrate the brightness and contrast on my PX50, and at the correct settings I saw the effect pretty constantly. Sure I could have reduced brightness and contrast, but why should I have to put up with sub-standard picture quality to get rid of some kind of annoying artifact?
At this price point, I couldn't agree more. And if some people weren't such Panny PDP zealots, this issue would be out in the clear so more folks could make a more informed buying decision. :cool:
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