Do you see DLP rainbows and CRT monitor flickers?

...and pixel structure.



...and I can hear the squeal of a standard NTSC set, if overdriven, from 30 feet away.



...and the chroma bug



...and absolute polarity in sound



How do we ever enjoy these things?!


John

Hi,


Last night I saw a old Seleco 200 DLP. I saw NO rainbow. I only see a hair amount of subtle rainbow on the LT150 around bright object edge moving on a dark background. I saw NO rainbow in the new Seleco 200DM and the Sharp Z9000.


I see 60hz flicker on PC monitor but not on a CRT projector.


regards,


Li On

I think there's enough samples to post some preliminary results. Of course, this is not a scientific poll, but I still think the results are interesting.


Lets define the following state variables:


CRT = you see flicker in a 60 Hz CRT monitor

DLP = you see rainbows in a DLP projector


At this time,


P(DLP & CRT) = 18/40

P(DLP & !CRT) = 12/40

P(!DLP & CRT) = 4/40

P(!DLP & !CRT) = 6/40


I was interested is seeing how correlated CRT and DLP are. The below are conditional probabilities:


P(DLP | CRT) = P(DLP & CRT) / P(CRT) = 9/11

P(CRT | DLP) = P(CRT & DLP) / P(DLP) = 3/5


What this means is if you see CRT flickering, you have a 9/11 chance of seeing DLP rainbows. And if you see DLP rainbows, you have a 3/5 chance of seeing CRT flickering.


So how can you use this info? Suppose you are looking at purchasing a projector via mail order, but you can't view a DLP one because you live in the middle of nowhere. If you know you are sensitive to CRT flickering, then you have a 9/11 chance of seeing rainbows on a DLP projector. However, if you know that you aren't sensitive to CRT flickering, then you have a P(DLP | !CRT) = 2/3 chance of seeing rainbows on a DLP projector. While still not very good odds, do improve your odds of predicting if you'll see rainbow given your CRT sensitivity.


Note that P(DLP) = 3/4. Maybe someone from TI can tell us if this number jives with their stats.


I have a LP150 DLP projector, and see rainbows and CRT flicker. At first I was a bit bothered by them, but now I rarely see them. I think I must be getting use to them, and I am very happy with my LP150.


Ross.

Whenever I go to the UK or India, I notice 2 things immediately - the better vertical resolution of PAL and the 50 Hz flicker on the TV. That said, I don't seem to notice 60 Hz flicker in North America on TV, but computer monitors refreshing less than 75 Hz can be bothersome.


With the LT150, something very interesting has happened. Just after I got the projector, I used to notice the odd rainbow here and there when watching movies, but it never got in the way of my big screen experience. Now that I have put some 70+ hours on the projector, I find that my 'rainbow perception frequency' has dropped off markedly. Either this is conditioning (I am still seeing them, but my brain is not registering them) or I have trained my eyes into not flitting around too much. In any case, rainbows on the LT150 are pretty much history for me now. Associated hardware is a Panasonic RP-56 and DaLite High Power screen.


p.s. I should add - NO headaches/eyestrain etc at all. Friends haven't complained either.