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Oh no! So that's what the rainbow effect is?  

post #1 of 32
Thread Starter 
I didn't want to see it. I've never seen it before. I've even tried not to read posts describing how to see it. But I was watching "Gladiator" tonite on the Dwin Transvision, just minding my own business, totally engrossed in the movie, when all of a sudden I saw this flash of red, green and blue on one part of the screen. Then I saw it again. Now I see it constantly, although it is certainly more visible in some scenes than others. In "Gladiator" it is especially noticeable in the dark scenes aroung the flickering candles, but I see it elsewhere too. The only solution for me is to not blink and stare at the middle of the screen. But how natural is that. Your eyes naturally follow the action. My wife wanted to see it to see what I was talking about, and once I showed her, she saw it quite readily.

I am using a Panasonic H1000 DVD player and feeding the Transvision's external scaler with the interlaced ouput. Is it possible that there is something I am doing wrong that is causing or exacerbating the problem? Is there any way to fix this besides using an HTPC? BTW, DILA's don't suffer from this right? Oh man, am I bummed!
post #2 of 32
I've now owned four DLP projectors. My last projector
displayed the rainbow effect pretty bad and convinced me that
I must be among the people who can see it.
But the thing that I continue not to understand is that my
Davis DL450 clone produced absolutely no rainbow effect
or at least I never noticed it. Do others see any rainbow with the
Davis? If not, then what is the explanation for that?

Bob Wood

~~The Sultan of Cheap~~

[This message has been edited by RobertWood (edited 04-29-2001).]
post #3 of 32
The contrast on the DL450 wasn't juiced up via software or hardware tricks to produce whiter whites. That is probably a big part of the equation, since the "rainbow" is most visible during high contrast scenes.
post #4 of 32
As an aside, let me say that when I posted my less than thrilled opinion of the color wheel artifacts of the non Davis DLP's I saw, I was criticized for even bringing it up! As if it was so trivial. Then in the last few months, something strange happened. It seems like almost overnight, the color wheel artifacts assumed bubonic plague-like proportions. We went from few people caring about it and a small minority feeling it was a deal killer, to many people resolutely ruling out single chip DLP becuase of color wheel artifacts. I have my suspicions about who started this, but I think it's amazing how quickly newbies were stampeded into viewing the "rainbow" as some kind of monumental problem. Even more amzing, is how so many people simply refuse to accept that single chip DLP's can and do differ greatly in the degree which they display the "rainbow". What could be an ever-present nuisance on one projector, is only an occasional problem on another. I know this because I've seen it with my own eyes.

You may want to try and lower your contrast settings on your projector. That may help.
post #5 of 32
I still own Davis DLS8 and I can say it has no probelm with rainbow I can see. I ahd NEC 85 projector before this one, and the rainbow was easily visible with the same source and material. I can only say I am very satisfied with the DLS8 performance!
post #6 of 32
I've now had 6 or so DLP projectors at home in past few months. IMHO, the hotter the whites, the worse the rainbow. Fix the whites, and you (mostly) fix the rainbow.

The projector with the least rainbow has been the Sharp M10S.

post #7 of 32
post #8 of 32
Larry Davis,

I guess you can partially blame me, for I have brought up this issue. However, I do so only in the hopes of finding a potential solution, be it through the manufacturer or someone else who has such a capability.

It is a shame about the Dwin. I have to tell you, that in my honest opinion, it would bother me every day that I owned it. I AM sensitive to the rainbow artifact, and in fact saw it on the Seleco HT200 on the same movie that smitty has been speaking.

You see, the problem with the rainbow artifact is that it isn't always there. It randomly appears, which makes it even more distracting. With LCD and the screendoor effect, it is ALWAYS there, sometimes more so in bright uniform coloured scenes, but it is there. From my own logic, because it is there before, you get used to it and becomes less of a issue. The rainbow artifact on the other hand is a problem, because is rears its head randomly.

Furthermore, like smitty , I like to move my head during movies, because it is natural. This is the reason why I got such a big screen! So I would get the massive feel.

The rainbow artifact IS a matter of contrast. When I first started watching the HT200 with lights on, I didn't see it AT ALL! Hit the switch though, and it was flash flash flash R G B.

I personally, have been FORCED to avoid DLP for all this time. While I CRAVE DILA, I have neither the means, or the ability (I can't explain to the folks what a hush box or a scaler is)to own one. Plus in Canadian dollars, the light bulb cost is like $1200 (I think, this is based on conversion, not what it actually costs, cuz I don't know for sure.) LCD has been my friend for several years. VGA at that! I see pixels, yes, and my blacks are grey too, but never have I seen rainbow.

That is why I have become so excited about this new sony 11HT, for if it has better blacks and contrast, and a good scaler, it is the way to go for me.

My greatest fear is that while the six-segment colour wheel seems to be the sure way to eliminate the rainbow artifact, who is going to use it? DWIN, Seleco? In projectors that cost more than $15,000 Canadian List?
I only hope that this new colour wheel becomes standard. But as we already know, for the business projectors, they need the clear section, and have no complaints about rainbow. The only hope is the infocus HT model, but I have no info about that one.

Sorry, just my rant.

Smitty ===>> The rainbow will NEVER go away, unless you use an HTPC and try to raise the frequency, which might help out (but you say you don't want it). I doubt that is why you bought the DWIN though. My suggestion, see if you can return it. DILA nor LCD have rainbow artifacts. There is nothing you are doing to make it worse.

This is the equivelant of buying a Ferrarri whose gears pop out once and a while. Would you expect, or accept such a thing? Then, wait, or get a CRT or one of the newer LCD's. Did you ever see the DWIN before you bought it? If not, what can we say? There is only one to blame. I know, denial works for most of us, until the truth is shown to use directly.

I believe DLP, while supperior to LCD in terms of fill factor and contrast (well, new LCDs are catching up), has a MAJOR flaw with this colour wheel problem that is inherint in its design (1-chip). I WANT DLP to be fixed, I really do, because I want one! I will say again as I have said before, I am amazed that they would release a technology with such a problem as this. I am sure TI knew about this from the get go. And there can be now denying it, because we hear companies working to fix it. Therefore, how can they actually sell you a product which they know has a flaw? Like Seleco, for instance, how is that they could release a new version, so quickly after the old one, that fixes the problem. Boy, if I owned a HT200 and they changed the colour wheel in the new model and didn't offer it to me, for minimal to no cost, I WOULD BE PISSED!!! This should be like a recall on a car.

Well, take care all. Smitty, hopefully everything turns out

Oh, and GO LEAFS GO!!!

David Mendicino
Sharp xv-s55u (Don't laugh) :)
post #9 of 32

A couple of questions come to mind.

Some think that any DLP with a clear segment in the wheel will
exhibit rainbow. But doesn't the Davis have a clear section?

Do we know if the Transvision has a clear segment?

Since the Davis ain't got rainbow then isn't that evidence that
these damn things can be built in a way to eliminate it? And if
so why would Dwin design a projector aimed at home
theater buyers and not address the problem? Or is the Transvision
just masquerading as a home theater projector and is in reality
just another presentation projector?


~~The Sultan of Cheap~~
post #10 of 32
Thread Starter 
David, I did see the Dwin at CES, as well as the Seleco and a few other DLP's. I never saw any rainbow. I have also seen a few other DLP's in local showrooms and never seen the rainbow. Furthermore, I watched the Dwin at home for probably four hours on different types of movies and never saw it, until suddenly it appeared out of nowhere. And once you see it, you see it constantly - at least I do. It's like a subliminal effect that you don't see until your brain recognizes that it is seeing it, and then it raises it to the level of cognitive perception (or whatever the proper term is). And that's the frustrating part of this for me.

I am going to have other people view the projector today to see if they see it. I am hoping that maybe it's a problem that is exacerbated on this particular unit for some reason. I mean, in the course of watching "Gladiator" for one hour, I probably saw 200 rainbows. I find it hard to believe a home theater projector of this quality should do that, or that I am the "Einstein" of rainbow effects perception.

[This message has been edited by smitty (edited 04-29-2001).]
post #11 of 32
I have had three different model Plus DLP projectors at home over the past year. I saw the "RGB flash effect" within minutes of my first ever DLP (and home projector, for that matter) experience. It made me think twice about DLP, but after reading countless posts here about being able to minimize the problem and that not all projectors have it, I definitely have not given up on DLP. If the 6-segment colour wheel alleviates the problem, then bring it on and hopefully all of the major manufacturers will adopt it.

Just my $0.02...
post #12 of 32
Don't worry, I'm not mad at you. http://www.avsforum.com/ubb/smile.gif I know who started this. It was done by a small group of cynics in a certain camp. I consider the rainbow to be a "problem", but only on some projectors and even then to varying degrees. My NEC LT-100 showed it during every single scene of high contrast (torches in darkness, especially). I saw a Plus U2-1080 that had it non-stop. At the time I was getting used to it. Then I got my Davis DL450 and I immediately noticed a relative lack of "rainbow" effects. I began to think that color wheel artifacts are a problem, but again, only on some projectors and the effect varied from one model to another.

The Davis has a clear section and presumably, so does the Transvision. The rumor is that the Transvision is a tweaked Davis XGA unit. I haven't seen the Davis XGA units and I don't know how they display color wheel artifacts. But I do know that the XGA units from Davis all had problems with tearing and didn't do triple buffering like their SVGA models. The SVGA units are meant to be run at 72 and 75 Hz without tearing. The projector was designed with video quality in mind. Going back to the clear section, The DL450 is only 500 lumens, the NEC LT-100 is 1000 lumens and the LP350 is 1300 lumens (supposedly). Perhaps the clear section is larger on those models. Who knows. I wouldn't be surprised if the color wheel of the Davis SVGA units spin faster than XGA models from their own factory and other manufacturers. I'll say this: the higher the manufacturer's listed contrast ratio for their single chip DLP's, the more exaggerated the color wheel artifacts are. Perhaps Dwin boosted the contrast of the Transvision and in so doing they boosted the rainbow. I'm not saying that contrast is the source of the problem. I'm saying that boosting contrast can make it worse.
post #13 of 32

It is not something abberant with your projector. Unless something is causing your colour wheel to spin to slow, but if that was the case, you would be able to tell from the image (I am talking about a major difference in speed here, not a minor one). When I was watching the beginning battle scene in Gladiator on the seleco HT200, which has no clear section (I believe), I saw rainbow flashes all the time. You say 200? Well, if I see it every second... then for an hour...well...many times more than 200.

The rainbow is DEFINITELY enhanced by contrast ratio!!! Remember I said that it got worse when the lights were turned off? You DL450 with 500 lumens is not bright enough to cause the artifact to a major degree.
I believe, again, that is has to do with the human eye (obviously), and therefore the brighter the image, the higher the contrast, the greater the imprinting or recognition of it.
Geez, if they could make a 5000 lumen DLP single chip...the entire image would be one big rainbow flash http://www.avsforum.com/ubb/smile.gif

Seriously though, there is definitely a coorelation between contrast and rainbow artifact. Smitty, turn on the lights when you watch your DWIN, on the same scenes. Does it get any better? Probably does, I am sure. Better yet, turn them up so you partially wash out the image and reduce the contrast.

Again, Smitty, I want to reiterate, that in the end there is probably no flaw in your projector. That is the way it is. And that is why I said I would not get one at this time. Like you said, it is hard to believe something of this quality has this problem, but it does. How do you think I felt when I saw a demo of the HT200, and within seconds saw the rainbow artifact (which was supposed to be gone) on this 15K projector?!?

http://www.avsforum.com/ubb/smile.gif http://www.avsforum.com/ubb/smile.gif http://www.avsforum.com/ubb/smile.gif Sony VPL-11HT anyone http://www.avsforum.com/ubb/smile.gif http://www.avsforum.com/ubb/smile.gif http://www.avsforum.com/ubb/smile.gif

David Mendicino
Sharp xv-s55u (Don't laugh) http://www.avsforum.com/ubb/smile.gif

[This message has been edited by David Mendicino (edited 04-29-2001).]
post #14 of 32
Thread Starter 
Well, I tried lowering the contrast quite a bit and it did not appear to help much, if at all. Maybe the rainbow was not as bright or as big, and maybe I saw it only once every two seconds, not every three seconds? Not much help though. I did try other movies now that I see the effect quite readily and it was not as noticeable, but still there. It is very obvious on "Gladiator," especially in Chapter 21. My teenage daughter saw it right away, and it is so obvious that it is hard for me to beleive anybody would not see it on this particular movie. Furthermore, you see it just watching the movie. No need trying to exacerbate it by moving your eyes quickly, etc. Do that on Chapter 21, and you experience what it must be like to have a serious LSD flashback episode.

Also, it's funny when people say that it helps not to move your eyes around the screen. What do you do in a scene where two people are talking in a somehwat dark room, with intermittent lighting, such as by candlelight? The camera focuses first on one of the actors, who is seated at the left side of the screen. Then the next shot is of the other actor, who appears at the right side of the screen. What are you going to do, not look at the actor who is now talking? As soon as the scene shifts, your eyes move to the actor on the right who is now talking and, voila, we have the rainbow.

I'm sorry to hear that it is probably not this particular unit. It is so noticeable in "Gladiator" that, again, I find it hard to believe that anyone could miss it. I'm am going to return the projector to the dealer to see if he can see it, and to determine what Dwin has to say about the problem. I am hopeful that there is some problem with the unit or some fix that Dwin can suggest because, other than this, this is truly a great projector. The picture is incredible.
post #15 of 32
I am using the Transvision and have played Gladiator but I do not see the rainbow effect. I guess I do not have sensitive eyes but I have seen this effect before on a NEC LT-150 and agreed it would be annoying.
I will play this again on chapter 21 but I am sure I would have seen it.

Its hard to think you have never seen this in all your testing and shopping . If I remember rightly Alan and Tom did not see it either but Tom2 did.
I hope its a fault not your fast eyes.
My unit is now running on the Grayhawk and the picture is stunning
I can not wait for the Panamorph.
Boy its good to not have this drama.(thank god for old age)


[This message has been edited by David Wallis (edited 04-29-2001).]
post #16 of 32
Thread Starter 
David, let me know what you see. Maybe you could try a few scenes in "Gladiator." Any of the many candlelit scenes are good for rainbow, as are the ones with fast-moving action. If you don't see it at all, that would be a good sign, as it suggests that maybe it does vary from unit to unit. Again, I can't believe anyone wouldn't see it on mine. Maybe I'll use a neighbor or two to experiment.
post #17 of 32
Guys, The Davis 450 DOES indeed have the rainbow effect! I have seen two of these projectors and noticed it both times but it didn't really bug me until I actually bought one myself. The first time I actually had to watch a two hour long movie with these constant rainbow artifacts it just about drove me nuts.

Now, if I am watching tv on the SVHS input then I see absolutely NO rainbow artifacts, it's like the just don't exist. But, if I am watching a dvd movie from my HTPC then, depending on the scene, they are very obvious. This seems backwards to me as the 60hz refresh on the SVHS input should be displaying more "rainbowing" than the 72, 75, or 85hz refresh on my HTPC, but it doesn't.

Here is what I don't understand, watching an X-Files broadcast on the SVHS input produces no rainbow artifacts but watching the Dark City or ST First Contact DVD's produces tons of them. I would think that X-Files would produce just as many rainbow artifacts as those movies (being that it is just as dark and filled with hi-contrast shots) but it doesn't. I figured the rainbow was exacerbated by hi-contrast shots but it doesn't seem to hold true on the SVHS input like it does on the RGB input. Has anyone else noticed this?

post #18 of 32
I will check it out.

post #19 of 32
Hi All!

I have been reading this forum for several months and thought it was about time I joined in the discussions.

I've done tons of reading on HT and this forum has helped me greatly in narrowing my choices for purchasing a front projector! My thanks to everyone for sharing there wisdom and experiences.

Recently I had a chance to demo the DWIN Transvision at a local custom A/V shop. Here is the setup:

- 80in. diag. Draper M2500 (2.5 gain) screen
- DVD player was a Marantz 930
- The Transvision processor - and of course the DWIN DLP projector
- DVD movies: Star Trek:Insurrection, Gladiator, Austin Powers
- HDTV via DTC100 (DirecTV hi-def demo loop)

I should note that I am sensitive to the rainbow effect, and the DWIN was no exception in this regard. I noticed it more often during Gladiator, but all sources produced the effect, especially the darker scenes and scenes where the camera pans quickly or abruptly changes to a new scene entirely. Colors and black level are awesome - I compared this to a Zenith Pro 900X CRT in the next room running the same setup and movies and it was comparable, though CRT is still better. The DWIN produces a crisp and bright image to be sure, however, I noticed during scenes with lots of white that the image (like the white uniforms Picard and company were wearing) buzzed and jittered almost like you could see the mirrors oscillating.

There was little in the way of motion artifacts and only occassionally did I see the picture lag as if the processor couldn't quite keep up.

Anyway, if it weren't for the rainbow effect, I'd buy this projector in a heartbeat. It seems 1-chip DLP's, at this stage in their development will, to some extent, have this problem.

Smitty - how long have you had the DWIN? Any chance you can exchange it for a different projector without additional expense - if the effect bothers you as much as it does me, I'd have to find something else!

Sorry for the long note - it's my first post! http://www.avsforum.com/ubb/smile.gif

post #20 of 32
Smitty and David Wallis:

The GreyHawk may be the cause of the difference here. Smitty, you aren't using a grey hawk are you? If not, the greyhawk, while increasing contrast, must undoubtedly reduce the brightness. This would definitely lead a reduction in the rainbow effect. And, yes, David does say that the Tommy, one of his fellow evaluators of the DWIN, did see the rainbow effect.
As well, on the Seleco, in any scene where it was dark except for fire, drug trip r' us, my friend, I saw rainbows.

As I said earlier, I would really suggest you might consider returning this particular projector and trying a demo at your dealers of an other Transvision. Bring along your gladiator disk, and your daughter (cuz if she saw it quickly, it means she is sensitive to the artifact, and will be a good benchmark!)

If you see it there too, then hope is lost..

David Mendicino
Sharp xv-s55u (Don't laugh) http://www.avsforum.com/ubb/smile.gif

[This message has been edited by David Mendicino (edited 04-29-2001).]
post #21 of 32
Thread Starter 
I am using a 96"x54" GrayHawk. I had three other people in the neighborhood come over, two from one family and one from another, and all of them could see it right away. One said they don't see how anyone could watch a movie that way. Then I had a friend come over and he couldn't see it even when we told him what to look for and how to see it. It was almost funny, as he said if he didn't know us so well, he would think we were just playing a joke on him. He just could not see it, and he was awed by the Dwin's picture.

Does anyone know where there is another Dwin set up on So. California that I could get a look at to see if it's just my unit?
post #22 of 32
Given the fact that other posts mention seeing this in the DWIN and the fact that I also saw it on the DWIN I demoed (in fact, on every DLP I've ever looked at) it is unlikely that there is anything wrong with your projector. It is simply the nature of 1-chip DLP's at this stage of development. Perhaps, as has been suggested, enhancements to the color segment layout or different spin rates will resolve the issue for most people, but ultimately this is a limitation of the 1-chip DLP technology. The fact that certain DLP's exhibit the effect more than others, suggest that improvements can and will be made to reduce this problem.

How long have you had the projector?

post #23 of 32
Thread Starter 
I have had it since this past Friday.
post #24 of 32
So it has only been a few days.

What is the return/exchange policy of the place you purchased it from? Would you be able to return it for a full refund or exchange it for something else?

I remember reading on another forum where someone had sent in his DLP for some calibration work and was told that his color wheel was misaligned. Maybe you have the same issue? Just a thought!
post #25 of 32
Thread Starter 
Yes, I'm pretty sure the dealer will refund my money or let me exchange it for something else. I have a good relationship with this dealer as I have bought other stuff from him, plus he is a real good guy, and he was, in fact, going to put this unit in his showroom before he sold it to me. I'm going to talk to him tomorrow to see what we can work out, and also to see if he can get more info from Jeff at Dwin. I would love to keep this projector if I could resolve the rainbow problem, but maybe that is not possible. We'll have to see what options are available.
post #26 of 32
Hope everything works out for you! Let us know how it turns out.
post #27 of 32
I think I will mention this effect to some neuro-psycologists I know.. they could use this to build some interesting 'sensory-perceptive/mental conditionals' data. It May be that those who cannot see it are prone to 'blinding themselves', and are not very 'aware'.


Ken Hotte
post #28 of 32
As for lack of artifacts on NTSC, I believe that it will turn out to be due to the interlacing of the image, causing it to be 'interlaced' to a certain extent (the rainbow effect, I mean.. I know the image is interlaced, I just said so!)


Ken Hotte
post #29 of 32
Would somebody who has a problem with "rainbow and lives in the Toronto, Ottawa, or Kingston area please e-mail me so we can get together and try some experiments with respect to DLP "rainbow". I have two DLP projectors and we can try an interlaced feed, a progressive feed from a progressive scan DVD player and a progressive feed from a HTPC and switch between two DLPs. I don't see this artifact, but some of my friends do and have noticed huge differences when the processing quality is elevated!

Quick example - major complaints when I feed the Infocus LP350 an s-video signal. When feed a signal through my HTPC (does power of processor in HTPC make a difference?) at 60hz, yes 60hz, the arifact disappeared for one guest completely and the other guest said it was corrected by 90% for him! In fact he bought a DLP with a HTPC! I personally think that the makeup of the HTPC has something to do with it. Could be a lot of variables here.

My personal opinion is that if you have a DLP and aren't using a "good" HTPC then you're simply missing the great potential your projector has!


Grant Smyth

If seeing is seeing rainbows then I don't want to believe!
post #30 of 32

I emailed you yesterday...tell me if you got it.

David Mendicino
Sharp xv-s55u (Don't laugh) :)
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