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Discussion Starter · #1 ·
I spoke with a guy in the TI booth at CES and he told me that the color wheel spins so fast now that no human can see rainbows. What I don't quite recall was if that was only true when LED is the light source.


What are your thoughts?


~Jay
 

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nope still rainbows.


I think they need 32x color wheels to completely eliminate it. We are at 7x now.


I cant imagine what that rate of spin would sound like as some of the current crop sounds like a turbine engine now
 

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Quote:
Originally Posted by Jay M /forum/post/12941561


I spoke with a guy in the TI booth at CES and he told me that the color wheel spins so fast now that no human can see rainbows. What I don't quite recall was if that was only true when LED is the light source.


What are your thoughts?


~Jay

I see RBE on some mono DLP PJ's even models with 10800 rpm wheels. So I would suggest the comment from the TI isn't currently accurate.


D
 

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No, rainbows are still there and probably will never go away (unless you're talking 3-chip DLP). Faster spinning color wheels introduce other problems.


Some manufacturers are now using color wheels with primary and secondary colors to make the image brighter at D65. While this is good for more light output, it increases rainbows as well. So a CW with primary and secondary colors is a step forward and backward at the same time.
 

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i see rainbows on all the new dlp televisions. I have not seen any new dlp pjs lately.
 

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I have a friend who can't watch my HD70. He sees rainbos all over. I told him to take a nother hit of acid and calm down.
 

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Quote:
Originally Posted by Jay M /forum/post/12941561


I spoke with a guy in the TI booth at CES and he told me that the color wheel spins so fast now that no human can see rainbows. What I don't quite recall was if that was only true when LED is the light source.


What are your thoughts?


~Jay

Not a single guest I have had over has ever mentioned "rainbows". Then again, almost all of them know nothing about AVS. AVS members I have had over must simply be too polite. I keep looking and dang if I see them.

BTW, my neighbor has an RS1 for comparison.
 

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Quote:
Originally Posted by Jay M /forum/post/12941561


I spoke with a guy in the TI booth at CES and he told me that the color wheel spins so fast now that no human can see rainbows. What I don't quite recall was if that was only true when LED is the light source.


What are your thoughts?


~Jay

He is absolutely incorrect. Every single chip DLP I've seen, including the latest models I've been able to see, have shown obvious rainbows. (Obvious to folks like me, that is, who sees them). In fact, in some instances manufacturers, in tring to cut some costs and prices, have actually lowered the speed of their color wheels (I believe Marantz is one example...someone can correct me if that's wrong).


I only wish Mr. T1 Booth was correct. If he was, I would possibly choose one of the new DLP models.
 

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Coming from a tech company, that is typical of sales talk. That person receives sales literature that states that the projector vendors are developing higher segmented faster spinning color wheels that virtually eliminate rainbows. So he takes it as the bible and as any good sales person does, repeats it with a dash of exaggeration. Events like CES with booths full of LCD manufacturers and the DLP vs LCD wars going strong, those types of comments will always occur. What would surprise me is if he actually said "we are working with projection manufacturers to reduce the rainbow effect and are getting better at it, but some will still be susceptible to it until we get rid of the color wheel altogether."
 

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Quote:
Originally Posted by reio-ta /forum/post/12943067


...and even 3-DLP.

I see occasional rainbows on my front projector, but am not overly succeptible to them. I have seen 3 chip DLP and have never seen rainbows.


Rainbows are an artifact of how single chip DLP uses the persistance in your eye/brain to construct colors. A single chip DLP doesn't display the 3 primary colors at the same time. 3 chip DLPs don't have this problem. In a 3 chip system, there is one DLP chip for each primary color. This is how LCDs and LCOS display color, and you've never heard anyone complain about rainbows, have you?
 

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Quote:
Originally Posted by ScottS /forum/post/12943155


I see occasional rainbows on my front projector, but am not overly succeptible to them. I have seen 3 chip DLP and have never seen rainbows.


Rainbows are an artifact of how single chip DLP uses the persistance in your eye/brain to construct colors. A single chip DLP doesn't display the 3 primary colors at the same time. 3 chip DLPs don't have this problem. In a 3 chip system, there is one DLP chip for each primary color. This is how LCDs and LCOS display color, and you've never heard anyone complain about rainbows, have you?

Actually, I along with a few others have noted a rainbow effect - a similar type of image break up (without the color fringes) on some 3 chip DLPs. I thought it couldn't be, for just the reasons you state. But when I brought it up others mentioned seeing the issue as well and when some of the more technically knowledgeable joined in they said it was indeed a possibility. Not exactly the rainbow effect, but similar. I can't remember the exact technical details though, unfortunately.
 

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"Rainbows are an artifact of how single chip DLP uses the persistance in your eye/brain to construct colors. "


It uses persistence for both color *and* brightness.


"A single chip DLP doesn't display the 3 primary colors at the same time. 3 chip DLPs don't have this problem. In a 3 chip system, there is one DLP chip for each primary color. This is how LCDs and LCOS display color, and you've never heard anyone complain about rainbows, have you?"


That is not an accurate comparison. DLP pixels are binary. They are either on or off. To control brightness levels of the pixel they dither... flash on/off very very rapidly and uses the persistance in your eye/brain to construct relative brightness levels. So even with 3 chip DLP the possibility of rainbows exists as you can have times when one color is on and another is off due to the dithering of the pixels for the various color/brightness components on the different DLP chips. Should be much less obvious then on single chip but still a possibility.


Traditional 3 chip LCD and LCOS are not binary pixels. The pixels are not simply on or off. They can directly modulated the brightness of the pixel as such they do not have to dither and rely on persistence of vision for brightness levels which means you won't have the situation of one color being on while another is off and getting RBE.


Shawn
 

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Quote:
Originally Posted by sfogg /forum/post/12943662


"Rainbows are an artifact of how single chip DLP uses the persistance in your eye/brain to construct colors. "


It uses persistence for both color *and* brightness.


"A single chip DLP doesn't display the 3 primary colors at the same time. 3 chip DLPs don't have this problem. In a 3 chip system, there is one DLP chip for each primary color. This is how LCDs and LCOS display color, and you've never heard anyone complain about rainbows, have you?"


That is not an accurate comparison. DLP pixels are binary. They are either on or off. To control brightness levels of the pixel they dither... flash on/off very very rapidly and uses the persistance in your eye/brain to construct relative brightness levels. So even with 3 chip DLP the possibility of rainbows exists as you can have times when one color is on and another is off due to the dithering of the pixels for the various color/brightness components on the different DLP chips. Should be much less obvious then on single chip but still a possibility.


Traditional 3 chip LCD and LCOS are not binary pixels. The pixels are not simply on or off. They can directly modulated the brightness of the pixel as such they do not have to dither and rely on persistence of vision for brightness levels which means you won't have the situation of one color being on while another is off and getting RBE.


Shawn

I have noticed a similar type of "color break up" on 3 chip systems. I work in a post production facility, and our film colorists (3 of them) each have a Christie 3-chip dlp projector in their suite, and I can see it on the screens. I also noticed it at a dlp cineplex. Not anything nearly as bad as your run-of-the-mill 1 chip home theater projector, but something quite similar is definately there....
 

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It seems to me that some of the latest DLP projectors have more RBE than recent past products. Maybe it is the whole secondary color wheel thingy that was mentioned above.
 

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One other thing....


I wonder if people that have had Lasik see more RBE?
 

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Discussion Starter · #20 ·

Quote:
Originally Posted by Timbelmont /forum/post/12944384


97% of all people who see DLP rainbows are on this forum.


TA

I think that's because 97% of people who see them had to look for them



That's the case with me, and now I am learning to ignore them.


Right now I have in my house a h710 DLP, and a VW60. Except for rainbows I think DLP is better in every way.


I was hoping that new DLP projectors had solved the problem.


the guy at CES was not a sales guy, he was an engineer working with LED. I think he was saying that the LED can turn on and off so fast that it can be in sync with the color wheel to eliminate rainbows. Maybe he was wrong.


~Jay
 
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