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Discussion Starter · #1 ·
Last night I was doing a bit more tinkering in trying to reduce the rainbow effect in conjunction with my HTPC. For me, I have found that using anything other than 60 hz refresh rate results in an increase in rainbow frequency. I tried using power strip to find if there was a sweeter spot around 60 hz but I did not find one, what I did notice was that using this test pattern to fine tune phase and tracking helps out a bit. This pattern, created by Mark Rejhon and first introduced in this thread was meant for DILA users but I have found that it helps to reduce rainbow as opposed to just using the auto config button (or whatever it's called, top right button) on the remote.


Essentially all you have to do is open the file in Internet Explorer, right click on it and set it to wallpaper (make sure to tile it!). The finer details are outlined in Mark's original thread.


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System info: LT150, Dalite 57X77 Matte & HP, P3 700, ATI Radeon 64mb VIVO, ATI 7.1 player, WinDVD 2.6.4, WinME



[This message has been edited by DRS (edited 08-07-2001).]
 

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DRS,


Interesting. Thanks for posting your results. Frode pointed out that 60hz also minimized tearing, which I also found to be true. Panning judder is less at that frequency too. To be precise, I actually use 59.97.


I guess 60 hz is the sweet spot of the projector.


I don't see rainbows (actually I saw one once using s-video in on an Avia pattern) but I want my guests to have the best experience.


By the way, I tried 48 hz over the weekend. It synched fine. There was tearing just like at 72hz though...
 

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DRS,


Thanks for the tip. My LT-150 just arrived yesterday, and while I am blown away by the color, shapness and pixel fill, I SEE RAINBOWS.


I really want to keep this projector, but I don't see this "artifact" on my xga lcd, and it is quite distracting. I hope your find helps out.


Thanks again,


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Adam
 

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Discussion Starter · #4 ·
Like you Adam I had a XGA LCD projector prior to the LT150. While the rainbows can be distracting the 100:1 CR was much worse in comparison ;-)


BTW In regards to the test pattern, don't expect it to be a day and night difference, just a noticeable one, of course YMMV since this whole rainbow business is so subjective.
 

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Quote:
Originally posted by lawdawg:
DRS,

Thanks for the tip. My LT-150 just arrived yesterday, and while I am blown away by the color, shapness and pixel fill, I SEE RAINBOWS.
Lawdawg, the first thing you should do is turn off the white segment (if you haven't already). This will significantly reduce rainbow effects right off the bat.
 

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pham,


Thanks to this forum, and the wealth of information it provides, that was one of the first things I did. I've also read in postings that turning the contrast down will help. My hope is that by sitting a little further back, using DRS's idea, and turning the contrast down a little, I can reduce the rainbows to an occasional thing.

I've also read where some say that the screen gain has nothing to do with the rainbows, but I wonder if these people are among those really susceptible to rainbows in the first place.


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Adam


[This message has been edited by lawdawg (edited 08-07-2001).]
 

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DRS totally hit on it in another thread.

it's kind of amusing, but the problem with rainbow 'tweaks' is that you sit there, activley looking for them to prove if the test works or doesn't.

like the wise man said " if you look for something hard enough, you will find it."

i've found over the last 5 days (30+ hrs!) that you have to get in the proper mindset if you want to reduce their annoyance factor.

it sounds trite, but to an extent they will always be lurking and can pounce at any time. the trick is to train your eyes not to follow every instance when the crop up and just to accept and ignore them.

the first night, every single little rgb flash was like a knife twisting in me. my eyes darted to catch it and understand it, see it clearly. All that attention, subverted to catching flaws, just made it impossible for me to concentrate on what an otherwise great device it was.

1/2 empty or 1/2 full?

thankfully the novelty of seeing this 'hard to describe' ephemeral irritation has died down.

"there goes another rainbow"

" yeah big deal..there'll be a few more before this is over"

once you learn to accept them, their power to really irritate and fatigue you will lessen.



jmho, ymmv
 

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Discussion Starter · #8 ·
This sort of tweaking has been painful (judder was similar) because it draws your attention to what exactly you do not want to see and the longer you are exposed to it the longer it takes for you not to notice it (i.e. decay). I'm giving serious thought to doing an experiment to find if the whole rainbow effect is just psychosomatic. I can see it now, "subjects from the AVS forum tended to report seeing the rainbow effect substantially more so than those that did not frequent the forum." hehe...



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System info: LT150, Dalite 57X77 Matte & HP, P3 700, ATI Radeon 64mb VIVO, ATI 7.1 player, WinDVD 2.6.4, WinME


[This message has been edited by DRS (edited 08-07-2001).]
 

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Sorry, I don't think that ignoring the problem makes it go away. My brother doesn't see it, I asked him to point out flaws in the picture, and this wasn't one of the things he said. But I see them, all to clearly. I've done the above tweaks, and such. But I just don't know who you can NOT "dart" your eyes around the screen to follow the action. I don't even have to shake my head, or move it (I'm not an owl.) I've sat well over 25 feet away from my 120" screen, and I still see them.


Having said all that, I'm going to give it until the weekend is over, to try and think like a slow eyed person. Someone suggested a little vino, while watching. Perhaps I need a little wine to go with my whine. http://www.avsforum.com/ubb/smile.gif I want to keep this projector, everything else is superior to my current one. I'm not done, yet.


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Adam
 

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guess this is still just theory, but since they bothered me quite a bit the first night, i racked my brain, trying to understand this problem so that i could finally seal the deal on the only pj that really fits my budget.

so as i thought about this i came to a few conclusions

...whether anyone else sees validity in these is up to them.


Since Rainbows DO bother me and since that first night i saw them pretty easily, i found i was on the defensive whenever i put anything in to watch.

i was just a bit tensed up, almost imperceptibly bracing for the next rainbow.

being 'on-guard' is also fatiguing, and generally isn't condusive to a pleasant, relaxing experience.

by putting myself in a mind-set to 'accept' them beforehand, i find my body ... my eyes...my general attitude more relaxed, that makes being able to ignore( i.e. not going looking for them on purpose) them just a bit easier.

if i purposley seek them out, i will find plenty.

thats what i was getting at.


i don't see rainbows all the time, thankfully. it's very much dependant on certain characteristics of a scene and these don't always show up across the board. i still find plenty of scenes where i can let my eye roam across the screen freely. that, to me, is the exactly quality of a large screen display that i always wanted.

i'll admit this is still just conjecture. i had a couple discs ( The Thin Red Line, Die Hard) that were seemed like non-stop rainbows. i'm kind of afraid to put those in again, but when i do i want to be sure to be relaxed first.

hate to advocate one recreational drug over another, but a bit of the grape might help at that.
 

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Just a quick note on rainbow "suppression." This morning, I pulled my Dalite High Power screen up, and just projected onto the off white wall behind it. The rainbows, while still there, where significantly reduced.


I think this backs up what our esteemed host, Alan Gouger, wrote about high gain screens not helping the rainbow effect. High gain screens can increase the frequency of rainbows, if you are susceptible to them. Based on this and what others have reported, it seems that if you are lucky enough not to see them, then the high gain won't increase the frequency. But if you do see them, then the high gain has the potential to increase them.


I'm going to try a quick ceiling mount, which should lower the light reflected to my seating position, and see if that helps.


Also, I have to give the don't look for them theory a little more credence. My brother who did complain of them on Gladiator before, now sees them. He kept asking me what I was looking for, and I finally gave in. Now he wishes I never told him. http://www.avsforum.com/ubb/frown.gif




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Adam
 

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Discussion Starter · #13 ·
That was my observation as well, see this thread for more info if interested.


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System info: LT150 XGA DLP, Dalite 60X80 Matte White, ATI Radeon 64mb VIVO, ATI 7.1 player w/DC's O IRE patch , WinME.
 

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i may just end up painting the DIY. seems at least one person is trying to market some screen paints. i probably be living with the blockout material for a while...i'll just have to make the best of it.


[This message has been edited by ckolchak (edited 08-08-2001).]
 

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i've been using blockout fabric (low to no gain) for my screen, so now i'm very leary of jumping to Hi-power.

however, in my own limited tests, white surfaces with even just a bit more sheen than this fabric (which is basically matte) DID influence colors and blacks, imo.

i hope there is a compromise out there, 'cause at this point there looks to be some big pluses and minuses with any choice of screen surface.


i'll be interested to hear how ceiling mounting works with the hi power.
 
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