Rainbow Effect on Panny PX50 Plasma - is sub-pixel controller to blame?  

I have had my Panasonic PX50PXU for a little over a week now, and not long after it arrived I started seeing the dreaded Rainbow Effect on the set. Yes, it IS RBE. I know this is supposed to be an issue that only affects DLPs, but apparently I can see it on this plasma as well. I had a DLP for about a week and a half, and I returned it due to RBE, so I know exactly what it looks like. I also had an RP LCD which had NO rainbows. The effect on the plasma is exactly like the DLP rainbow effect, quick flashes that show up during high contrast scenes with sharp edges; it's an obvious optical effect, not an effect on the screen. There is one difference though, on the DLP I saw the usual three color rainbow. On this plasma I only see yellow flashes. Nevertheless, they are just as distracting and annoying.

I've tried to figure out how a plasma could produce RBE, since I'm sure if this was a normal plasma problem someone else would have seen it by now. The one thing that's different about the new Panasonics are the sub-pixel controller, so I am suspecting SPC may be the culprit. I don't know exactly how SPC works, but I found the following blurb on Panasonic's UK site:

Panasonic UK Viera link

Seamless lines for a superior picture

The new TH-37PE50 and the TH-42PE50 offer seamless lines that allow pictures to look more refined than ever before. The VIERA's Sub-Pixel controller eliminates jagged or blurred diagonal lines to produce smoother, more defined contours to shapes, resulting in a picture that is second to none. Conventional systems process the RGB signal together, but the Sub-Pixel controller processes each colour separately, thus generating crisper, more natural looking images that are sure to impress.

Though it doesn't go into detail, the bolded section above mentions processing each color separately, which could certainly introduce time delays that might affect each color differently, thereby causing them to separate the same way the DLP color wheel does. The flashes I see are yellow, which suggests that red and green are synced (combining to produce yellow) but blue is not.

Does this sound plausible? Is there anything else that could cause rainbow-like flashes like I've described? Has anyone else seen this, or am I lucky number one? And most importantly, does anyone know if SPC can be turned off in the service menu? Obviously, if it can't my only other option is to exchange for a model without SPC and hope that's where the rainbows/flashes are coming from.

I knew when I posted this there would be a lot of doubt, so let me be clear about a few things:

1) I know EXACTLY what the rainbow effect looks like. I owned a DLP RPTV for a week and a half before returning it due to RBE. I have never seen RBE on an RP LCD, on my LCD flat panel monitors, or on a CRT. I have never seen RBE in “real lifeâ€, looking at a streetlight, at car headlights, or anything of that sort. I have seen this effect exactly TWICE in my life: watching a DLP RPTV, and watching this Panasonic plasma. The effect is like seeing flashes in your eyes, the closest description I can give is that I imagine it must be similar to the flashes some people with epilepsy report seeing. I only see these flashes watching these particular kinds of TVs, so I don’t think epilepsy is the cause (unless all DLP rainbow sufferers are actually epileptics).

2) The effect on the Panasonic plasma I am seeing is EXACTLY like the RBE effect on DLP, with one exception: the flashes are all yellow, instead of having three separate colors. It is an optical effect; it is not a screen artifact or motion artifact. I can reproduce the effect the same way as on a DLP, by pausing on a screen with high-contrast or white-on-black content and moving my eyes back and forth quickly. No, I don’t watch TV that way, but I don’t need to do anything special to see the effect during normal viewing. Some people are more prone to RBE than others, and I’m one of those (if I weren’t I’d still have a DLP). It is NOT a subtle effect, at least not in my case. When rainbows show up, they can make a TV unwatchable.

3) I believe that plasmas, in general, are not susceptible to RBE. That is why I suspect there is something unique about the Panasonic that is producing this effect, and that is why I think sub-pixel control may be the cause. DLP color wheels produce rainbows because the each color is displayed separately as the wheel spins, rather than simultaneously. According to the brief SPC quote in my OP, SPC processes each color separately. If any delay is introduced during that processing, then like a color wheel the colors would not be displayed simultaneously. The difference in time between displays of separate colors would be similar to a DLP, and that is why I suspect sub-pixel control is a possible cause of the effect I’m seeing.

I can tell you that I have no doubt whatsoever that I AM seeing RBE on this Panasonic plasma. I’m not imagining it, I don’t have epilepsy or visual impairments, and I’m not misinterpreting some other kind of artifact or issue. I know exactly what I’m seeing. What I’m trying to figure out is WHY I’m seeing it. It’s possible that my set is defective and there is a problem with the color processing that is causing the effect. It’s possible that sub-pixel control is producing the effect. If SPC is to blame, I’d like to find out if that’s something that can be turned off, perhaps in the service menu, because that’s the only way to find out if it is the cause. I’d happily turn off SPC if it got rid of the flashes, because otherwise this TV looks fantastic. I guess I’ll have to contact Panasonic and see what they have to say.

Thank you. It is nice to have some confirmation, on the odd 0.0001% chance that I was losing my sanity. Unlike you, unfortunately, I am very sensitive to RBE and when it shows up it pretty much ruins my ability to watch the set. I gave up on DLP altogether after the DLP rainbows hit me, and I figured I was safe with plasma. It was definitely a big surprise to me also when I started seeing it on the PX50 too. Just my luck I'd end up with probably the first plasma to suffer from this effect.

I'm holding out hope that SPC can be disabled in the service menu, since I'm about 70% certain that is the source of the effect. I'll post whatever I find out about it here.

It happens on all sources. I don't have HD yet, but on DVD and on SD via DirecTivo it's there. How much it shows up depends on how much high-contrast material there is on screen. I can only guess that SPC may have something to do with it, but no way of knowing yet.

This is not the same thing that I'm seeing. They are quick flashes generated by bright whites/yellows against a dark background. It happens on a live moving scene, or a paused scene. If you have seen RBE on a DLP before, it's exactly the same except it's only yellow instead of three colors.

Well, I've watched a lot of plasmas in store environments, and I've never seen it there. But I've also never seen RBE on a DLP or on this model of plasma in the store either, only when I get it home and watch in a normal environment. RBE in general seems a lot harder to see with all the bright ambient light of a showroom.


The link describes how each RGB dot per pixel is processed separately, which concurs with the previous blurb I read. I still believe that this processing could cause one of those dots to "fire" slightly behind the other two, mimicing the way DLP color wheels produce time differences between the time that each color is rendered. I can see rainbows on an HD3 DLP chip with a 7-segment color wheel spinning at 9600 rpm, which works out to each color of the wheel being "flashed" 1120 times per second. So the time difference between consecutive color wheel segments "firing" is approximately 0.0009 seconds. That's all the time difference any processing would have to introduce to reproduce the effect. Since I've never heard of RBE-type effects on other plasmas, I am only guessing that the SPC that is unique to the Panny could be introducing that delay. It could easily be something else too though.

If anyone's ever seen RBE-like effects like what I've described on other plasmas, I'd definitely like to hear about that. I'm hoping it's a Panny-specific issue so that if it can't be resolved somehow, I can at least consider other plasmas.

I have talked to Panasonic tech support as well as my local service provider today about the issue. As expected, I had a tough time convincing them I was seeing RBE on a plasma, but I'll have a service call soon and will see if there is anything they can do to resolve this. I'm hoping SPC is the cause because if it is, and if it can be disabled in the service menu, that's probably my only hope for keeping the TV.

I'm a very rainbow-sensitive person, for whatever reason. I saw them like crazy on the DLP, and I see them like crazy on this TV. Even though I can see them at will with the rapid-eye-movement technique, I easily see them frequently just watching the TV normally. It's possible I could get used to them, but I'm not willing to pay $4-5K for something I have to get used to.