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Discussion Starter · #1 ·
Ok, so I have this idea on how to solve my dead pixel problem on my G-15. The bad pixel is in the top 1/4 of the screen, when the 16:9 panel is placed in the middle of the projector's 4:3 native image. Apparently, the Quadscan will allow you to put the 16:9 panel in the bottom of the 4:3 panel. If I do this, I think it will put the pixel on the screen border or above, so it will not be viewable.


The problem is that this will mean most of the light overspill from the 4:3 panel will be on my sloped ceiling, and I think this would be distracting. Obviously, I can't put drapes up there or whatever to absorb the light. I was thinking of maybe getting a replacement lens cover and cutting it out so that it blocks the light overspill on the ceiling. Has anybody ever tried something like this? Does it work okay? Any suggestions, or is this idea just completely wacko?
 

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Great idea, Smitty! Well, the part about moving the bad pixel outside the viewable area, anyway. I don't know about the lens cap idea.


Is it possible to flip the projector? If it's right-side-up, can you install it upside-down (or vice-versa)?


It's true that if you have a bad pixel in either the top 256 or the bottom 256 pixels, you can get it out of the 16:9 image by aligning your 16:9 material in the other part.


Due to some urging on the forum here, I also started a project where you "click" on a bad pixel and an app. creates an AlwaysOnTop window carved into a single pixel WindowRgn. It did cover a pixel. Unfortunately, not having any dead pixels, I couldn't test it right.


OF COURSE IT DIDN'T WORK. Even if you correct the pixel in the source (HTPC in this case), it's the PROJECTOR's pixel that was bad.


Doh! Some days I must just leave my brain behind.
 

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Discussion Starter · #3 ·
Mark, thanks for the encouragement. Unfortunately, I found out that, while I can move the pixel up or down by changing where the 16:9 panel goes, I can't get it out of the viewing area, except on 2:35 movies, in which case it will be within the letterboxing.


BTW, I spoke to more than one JVC service person today, none of whom seemed to have any idea of a JVC spec re when there are too many pixels overall, or too many within a certain distance of the center, etc. Maybe I just happened to get to the wrong people, but it seemed like this would be something they all would know.
 

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BTW, I've experimented with trying to block the lens with a piece of tape over the section that is projecting black border (the stray light is spilling onto the ceiling for me also) but I'm finding that you cant do it properly so close to the lens because its so far away from the focal point.


Try it and see, it ends up darkinging the active image before you've totally blacked out the offending area.


Does anyone have any better suggestions on how to do this? My ceiling is white stucco that I'm not about to paint, so anything I can do to darken the reflection up there would be good.


Andy K.
 

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You can't change the laws of physics, but you can bend them a little.


Light is tricky little beast because sometimes it behaves like a particle and sometimes it behaves like a wave.


If you angle the screen toward the floor the natural effect will be to reduce the light the reflects toward the ceiling. In addition, the light that does reflect from the ceiling will tend to not be reflected along your line of sight. Screens with gain higher than unity would benefit most from this type of trick.


A second idea is to place the screen in a shadow box like frame. Paint the shadow box black or line it with a light absorbing material. This trick has been discussed before on the forum, but it does seem to work. The deeper the shadow box the better the result.


As for a deal pixel. If it is really bothersome, you could take a piece of post-it note and color is a dark grey color. Cut a small square of the colored post-it note material with the sticky backing and place it on your screen where the bad pixel is located. This may look like crap during a daylight scene, but it should make the defective pixel less noticeable. The idea here is to turn a pixel that is stuck on into a pixel that is stuck off. Stuck off pixels are generally less bothersome.


Doh, I think I just understood your problem. There is no way to effectively mask the image after the lens. The masking has to be done as close to a focal plane as possible. In the case of a front projector this is somewhere inside the projector and hopefully the screen.


With a second set of optics external to the projector that refocus the image it may be possible to introduce a masking element, but the alignment of this type of optical mask would have to be done very carefully. A good example is the technique used to observe solar disturbances. This is done by using a disk held in one of the focal planes of the optical system of the the solar telescope. The whole telescope has to track the movement of the sun in the sky in order to keep the sun aligned with the masking element. Not impossible, just difficult.


Ok, so where can you buy such a system for use with a front projector? No where as far as I'm aware. It's a very specialized application and it would be highly unlikely that any company would ever see enough of a market to produce such a system.


In fact, it would be cheaper to order a matched set of Panamorph I and II so that you can minimize the visual impact of the defective pixel while using all the available resolution and brightness of the projector. This also eliminates the need for masking the ceiling since all the light will be on the screen.


[This message has been edited by JoeFloyd (edited 06-26-2001).]
 

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Quote:
OF COURSE IT DIDN'T WORK. Even if you correct the pixel in the source (HTPC in this case), it's the PROJECTOR's pixel that was bad.

[/b]
You know, Mark, your idea could still work. It may be useless for stuck on pixels, but it should work for stuck off ones, right? With your thingy in place, people would get a black pixel in place of one that's a funny color, if they have a stuck off pixel in just one of the R,G,B panels.


- Dave
 

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If your projector and screen are fixed, why couldn't you paste a very small black dot on the screen. A removable dot would be ideal. Sorry, I don't have a digital projector - just a thought.


Tony C
 

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Hi Dave,


I believe that stuck ON is really stuck ON. If you have a stuck on green, it is always green...No matter what color the source material sends at that pixel location.


It's OK...it took me a little while to realize that it couldn't be done, too!
 

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Sir Milori:


Are we talking about the same thing? I know the little pixel blocker thingy would be of no help with stuck on pixels. What I'm talking about is when you have one pixel off on just one of the panels. I have this on my projector, I think. So, when I show black at that pixel location, I get black. When I show white, I get a "cyan-ish" color. When I show something else, it's always off.


I've always thought that only one of the pixels wasn't firing, and the other two were (whatever makes cyan out of rgb - I don't know).


If this is what I have, or for anyone else who does have stuck off pixels, your thing would work - you'd only get black at that spot, which would be better than the funny color you get when one color is missing.


- Dave


[This message has been edited by Dave T (edited 06-26-2001).]
 
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