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Discussion Starter · #1 ·
Since I am sensitive to the rainbow effect on DLP's, I am now looking at other technologies. Today, I saw a Sharpvisio LCD that looked quite good, being run by a progressive DVD player and using the projector's internal scaler. The black levels were not that much worse than on the Dwin Transvision, and the color was good. I did notice the screen door effect, though, but it was not intolerable, as the rainbow effect is for me. (I guess you have to pick your poison.) Anyway, I was wondering if there is a way to reduce the screen door effect, such as by use of an external scaler, and, if so, what scaler would people recommend.
 

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Quote:
Originally posted by smitty:
Anyway, I was wondering if there is a way to reduce the screen door effect, such as by use of an external scaler, and, if so, what scaler would people recommend.
The only ways I know of reducing an existing screen door effect are:


Move farther back.

Some say slightly defocussing will help.

There is a lens that is supposed to help, but I forget what it is called.


I don't think any other sort of external processing will help since we are talking about a physical limitation of the LCD panel.
 

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Smitty,

As long as you're using the entire array, you won't see a difference in the screen door effect by changing the input resolution. A scaler or htpc won't help.

However, there are least 4 things that can be done to reduce the screen door effect, in no particular order.

1. Defocus the image slightly, $0.

2. Buy a Cygnus Depixelizer, see http://www.cgns.com/IMX930.htm ,$895

3. Buy an Isco lens to expand a native 4x3 projector image to 16x9,

see http://www.avscience.com/cgi-bin/quikstore.cgi

assessories, IscoII, $1495, or preorder the Cygnus Panamorph that squishes a native 4X3 projector image to 16x9, see http://www.cgns.com/Panamorph.htm

,~$1100 if you act soon...

4. Move back so your field of view is smaller, $0.


The Isco & Panamorph only help with widescreen material.


Jeff
 

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Look for units with MLA (micro-lens array). They come with a $1k premium over non MLA equipped models usually, but it increases brightness 20% and reduces screen door as well.


dg
 

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Jeff,


Wouldn't the Isco lens actually make it worse since it is stretching the image (wider gaps) vice compressing as the Panamorph does?


[This message has been edited by Mark Lopez (edited 05-03-2001).]
 

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Mark,

Either way you go, the effect is the same with a 16x9 screen. To get a given width with the Panamorph, you need to zoom out or move it back.(So the width fits the screen) This stretches the whole image in both directions. The Panamorph compresses the stretched out height to get the right aspect ratio. The width remains zoomed out and stretched.


With the Isco lens, you zoom in or move it closer.(So the height fits the screen) This time both height and width are compressed vs. being zoomed out. The lens expands the zoomed in image in width to get the right ratio.

Make any sense?

Jeff


[This message has been edited by JSC (edited 05-03-2001).]
 

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Quote:
Originally posted by JSC:
With the Isco lens, you zoom in or move it closer. This time both height and width are compressed vs. being zoomed out. The lens expands the zoomed in image in width to get the right ratio.
Then I suppose it would help for the vertical, but not as much for horizontal since it would end up stretching it back out to about the same width as before zooming in. Therefore, I concede that it may actually reduce the effect to a degree. http://www.avsforum.com/ubb/wink.gif
 

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Yes, the effect with either this Isco or Panamorph will only be in increasing the pixel count in the vertical plane. Horizontally, you still have a fixed count, and screen door. There was a thread not too long ago that had pictures of the various doodads with different technologies. http://www.avsforum.com/ubb/Forum10/HTML/003572.html

Unfortunately, alot of the picture links are broken. They were pointing to www.dilard.com , so Mark might have purged them, oh well.

Jeff


[This message has been edited by JSC (edited 05-03-2001).]
 

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Smitty,


I don't know what projector you're talking about, but I have the Sharp XV-DW100U 4:3 panel and have NO screen door effect. I use an older Cygnus depixelator lens. I also use only a portion of the panel since I project onto a 16:9 (8 ft wide) screen. For 2.35:1 it's even less vertically. I sit at 11ft or so from the screen and see a smooth sharply focused image. I used a Toshiba 6200 progressive, but now have an HTPC and won't go back http://www.avsforum.com/ubb/smile.gif


I have a Panamorph on order, which I was told would reduce the pixelation in the vertical to the point that the depixelator may be no longer necessary. We shall see. The less contraptions up there the better.


I don't know about this zooming business. I would always be projecting so that full panel width matches the screen width, whether using the Panamorph or not (except for 4:3 which is centered in the 16:9 screen). With the Panamorph I'll display 16:9 movies at full panel, which the Panamorph will squeeze down vertically back to screen height. For wider material (e.g. 2.35:1) I will still lose some panel resolution, but will still be 30% better than where I am now (which still looks darn good by the way).


BTW: You should also be able to "pillar box" a 4:3 image to gain the resolution increase of the Panamorph.


Carey


[This message has been edited by Carey P (edited 05-03-2001).]
 

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Discussion Starter · #10 ·
Carey, that was the model I was looking at. The guy I was talking to (who really does the cabinetry at the store and is not the A/V guy) said he thought the Sharp was a native 16:9 projector. Is it 4:3 instead? Does the depixelating lens make a difference, or did you not see the screen door effect even without the lens? Did you see the effect with the Toshiba (I want to avoid having to use a HTPC)? Are you happy with the projector otherwise?
 

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Discussion Starter · #11 ·
In reading one of the original threads on the Panamorph, it was determined that the Panamorph decreased the perception of pixel structure. In fact, the Panamorph was tested with the Sharpvision DW100U. I don't have the link, but it can be found by searching for the DW110U in this forum. (I know I'm answering my own question in part, but I thought I would post this in case anyone else is interested in the same issue.)
 

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Smitty, I am the owner of an NEC LT155 and I sit back about 12 to 14 feet and pixelization is not a problem. One of the best things about this projector is the colors. They are spectacular. If you can, check out this compared to the Sharp. It's a great projector and it is quite a bit cheaper. I think Alan sells them here or check with John at [email protected] At least check this out before you buy.


Scott
 

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Thanks for the heads-up, Jeff.


I must have broken the links with the recent site upgrade. The pictures are back . Thanks.
 

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Smitty,

Just got back. Yes it's a 4:3 panel. I think the picture was a lot "harsher" pixel wise when not using the Cygnus processor. I suppose it would have had screen door. I'm reluctant to take it off to look as it takes some time to set it up just right. I believe you do want to use it if you want the perfect picture. Yes, I was very satisfied with just using my Toshiba player alone. It has very good progressive output and great audio. However, there was much overscan and it was a bit soft in the image. Also, I needed better gamma control (even with the GrayHawk screen). With the HTPC I can get every pixel and line on the screen, plus a sharper and more colorful picture with all the gamma control I want. It looks CRT quality now and on par (or better) than any HDTV image I've seen.


I'm aware of the thread (by Tommyboy2) when the Panamorph protoype was tested. I'm looking forward to seeing the results myself. There's some pics in my first draft of a home theatre website below. Good luck. -Carey


------------------

My in-progress Home Theatre
 

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One surprising benefit of the Stewart Grayhawk screen was that it seems to minimize the screendoor effect. Before the Grayhawk I would notice the effect during bright scenes containing large sections of a single color (a bright blue sky as an example). With the Grayhawk, I no longer consider the screendoor effect an issue. I have a 10HT, 100" Grayhawk, and sit about 12 1/2 feet away.
 

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I have a Grayhawk also, so maybe that is part of me not seeong pixels. As above i use a progressive DVD player into the projector. Although DSS through s-video is at least watchable(can't have alot of lights on though)


Keep looking,

Scott
 
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