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Discussion Starter · #1 ·
Thought this might help those in the market for a new PJ and wondering what all this talk about screendoor is about.


This if from my newly acquired X1. Image shot from a couple of inches in macro mode on my 84" DIY screen (No comments on the waves, thank you). The screendoor is not visible from 1.5x screen width and can be improved by a slight defocus, as previously suggested in this forum.


I think screendoor is not an issue. The X1 delivers a fantastic display, better than my old RPTV, and more impressive than the 42" Plasma I have used.
 

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I have grown to hate the term 'screen door'. It sounds as if something is 'wrong' with the a projector when it is merely the pixels, the same type you would see if you jammed your face against a TV screen.


If you make your image to large or sit too close to your screen you are going to see the Pixels.
 

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Quote:
Originally posted by Hessian
(No comments on the waves, thank you).
Come on surfin' now, everybody's learnin' how, come on a safari with me! :)


- Cryo
 

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Greetings,



Dean, I could not agree more. While SDE is problematic for some, it is inherent in the design. If this is an issue for people then they should consider that before buying.



Regards,
 

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Its is not inherent in the design. It is a fact of life with all tv's. If you get close enough you will sell pixel structure. Maybe not screen door per say but still. I agree with Dean 100%. As soon as you back off the screen door disappears.
 

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Greetings,


By inherent in the design I was referring to any fixed panel displays. This would include most any display device.



Regards,
 

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Quote:
If you make your image to large or sit too close to your screen you are going to see the Pixels.
But screendoor isn't about seeing the pixels, it'sd about seeing space between the pixels. And I don't think CRT PJs suffer from this, no matter how close you sit.


I can understand how sitting within a distance as specified by THX and SMPTE standards and having noticeable screendoor would irritate some people. In those cases they are not sitting with their noses against the screen and they still see screendoor.


RG
 

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Quote:
it'sd about seeing space between the pixels.
LOL! I think without the space you wouldn't know there were seperate pixels, it's the same difference really.


I don't know about CRT projectors but I think on most regular TV's you can get up close and see pixels, dots, or whatever.


I'm not saying that the issue should not be discussed, it's the term 'SCREEN DOOR" that I take issue with. FOr one it makes it sound worse than it is, and for 2, it makes it sound like there is something inherenly wrong with the equipment when it is just the pixels people are seeing (Or the space between them lol).
 

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Agreed. Sit close to any display and bam, you'll see scanlines and other things.


Problem is people who go on about "screendoor" and compare it to their regular tv don't grasp the concept they are sitting at a much farther back ratio with the tv than with the projector.


In my family room upstairs I have a Pioneer Elite 510 Pro (53") and if I got within say 1.5x screen width I could see funky stuff with how the image is displayed because of how CRT RPTVs work. But since I sit at least 2 screen width back (prolly would come out to more like 3x width) the image looks great...just like how it does on my Sanyo z1 2x screen width back.:)


I challenge anyone who bitches about "screendoor" on digital pjs to go sit 1.5 width away form a direct view tv. Have fun with that. Naturally they won't because they will say something like "I am not going to sit 3 feet from a tv because that is too close" well christ, use the same logic with a projector.:)
 

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I agree with Rick, I don't see how screendoor is "inherent in the design".

I don't see how it wouldn't be possible, in theory at least, to design a

digital display with almost zero gaps between the pixels. And even with

zero screendoor, it is entirely possible that you will see the "pixel

structure". Seeing that the image is composed of pixels is really a matter of

resolution. If the image was of a low enough resolution(composed with

few pixels), then you will definitely notice the pixel structure, even if the

display had zero screendoor.


Using the term "screendoor" is still useful in describing the difference

between DLP and most LCD projectors. It is a real flaw of the display

device.


Also, CRT's don't display the image in pixels. If you are seeing pixels in a

CRT image, then it is from the source material. A CRT is an analog device,

except for the scanlines.
 

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I usually don't venture into this forum and now I'm being reminded why. Are you guys serious? The screen door artifacts is just "normal" or "acceptable" and philosophically shouldn't be considered a "flaw" of a projector design???


A while back someone made the same case that compression artifacts shouldn't be considered a "flaw" in a DVD picture because compression artifacts were somehow an inherent "part of the design" of MPEG2. PLEEAAASE. Semantic games can be useful at times to stimulate discussion but we have to see the forest for the trees while we stare at the semantic tree-bark.

Point one: Naturally anyone buying any projector needs to be aware of an picture-quality limitations associated with it and not whine and complain needlessly after they make their *informed* purchase.

Point two: But that does *not* mean that any defects in picture quality should be falsely considered "acceptable" as part of a technology or that we should pretend the image is without fault. You can be content with something that you know has limitations.


The screen-door is no more "necessary" an artifact in a projector's picture quality than any other artifact...like poor contrast, rainbow artifacts, dithering artifacts, scaling artifacts, deinterlacing artifacts etc. These are all flaws of a technology and slowly and steadily they are being solved at each price-point as projection technology evolves.

Anything that adds noise to the picture is an "artifact" by definition. The screen door is one such artifact.


You own a projector with visible screen door at 1.5 screen-widths? You have a right to be happy and content. But that doesn't mean we re-write the laws of image fidelity or redefine a source of noise/artifacting in the image.

There are many projection technologies that can render an image that at 1.5 screen widths do *not* suffer from distracting screen-door artifacting.. LCOS is one such digital technology. Higher-resolution DLP chips (like HD2) are another. TI is also developing new chips (HD2+) that reduce inter-pixels spacing even more.


Visible pixels structure due to limited resolution and visible pixel structure due to inter-pixel gaps are *entirely different*. And both, BTW, are indeed "flaws" if they produce artifacts visible under normal viewing conditions. It is indeed true that reducing interpixel spacing (screen door) can render a smooth film-like image given the same actual pixel-resolution from the same distance (why LCOS often looks so smooth next to other digital projectors of the same resolution...and why DLP looks smoother than LCD of the same resolution).


Eventually all digital projection devices will render smooth apparently pixel-free images from 1.5 screen widths in a few years. And that's good.


Making analogies to a TV's shadow mask proves no point. TVs are not designed to be viewed from 1.5 screen-widths. That's why they are TVs. However, projectors are inteneded to render large-scale images that are viewed and comparatively close ranges. If a PJ can't produce an image that doesn't "suffer" from distracting screen-door artifacts between 1.5 and 2 screen widths then it is indeed a design fault. It very well may be one that someone is happy to live with. But a design fault nevertheless.

Quote:
I challenge anyone who bitches about "screendoor" on digital pjs to go sit 1.5 width away form a direct view tv. Have fun with that. Naturally they won't because they will say something like "I am not going to sit 3 feet from a tv because that is too close" well christ, use the same logic with a projector.
You're right but the whole *point* of a projector is to view it with a larger viewing angle. That's what it *designed* for, to use a popular term, and therefore any noise or flaw that the PJ introduces into the image at that viewing angle is appropriately termed a "flaw".


All display technologies are a trade off of flaws, preferences, and price. Everyone has the right to be happy with his/her purchase decisions. But we can't re-write the rules of image fidelity to do it...instead just be happy!
 

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Quote:
Originally posted by DaViD Boulet
I usually don't venture into this forum and now I'm being reminded why. Are you guys serious? The screen door artifacts is just "normal" or "acceptable" and philosophically shouldn't be considered a "flaw" of a projector design???
Heh, well if you elitist >$5K folks visited more often perhaps we wouldn't have threads like this. :)


Personally, I can see SDE on my XGA DLP at 1.5 screen widths on solid light colors...but its nothing like on LCD. With the HS20 I'm hoping it becomes a non-issue and we're down to rainbows vs FPN.


Nigel


PS In case its unclear, I am kidding about the elitist part.
 

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:D


On a more serious note (and the reason why I've ventured into the sub $5K land...which I can't afford either :) ), last night I went to my boss' house to see his new X1 in action. Really amazing for the price (though both he and I saw screen door but figured for the price it was a tolerable compromise).


What I wanted to ask about is what looked like some sort of contrast or black-level compensation...like a "streaking" when white credits would appear on a black background or dark object would appear on a light background...there was a horizontal 'streak' that looked as though the PJ was processing that horizontal area differently to "pump" contrast in some strange way.


Is this a known flaw of the PJ? Can it be corrected for? Any thread to point me to?


Thanks!


dave :)
 

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DLP screendoor 101


Question:

I don't want to see the DLP screendoor grid. What do I do?


DLP Answerman:

Use an 800 pixel projector tightly focused and don't look at a picture bigger than 2.25x


Use a 1024 pixel projector tightly focused and don't look at a picture bigger than 1.8x


Use a 1280 pixel projector tightly focused and don't look at a picture bigger than 1.5x


OR slightly defocus any of them and you can make a slightly bigger picture and still not see screendoor.


Of course you also have the option of making a picture as big as the side of a barn and looking at the screendoor.


The choice is yours.
 

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Quote:
Originally posted by DaViD Boulet
Is this a known flaw of the PJ? Can it be corrected for? Any thread to point me to?
Gee, for someone who seems to know so much about projector technology and how DLP is better at this and LCOS is better at that, I find it quite amusing that you don't know a RAINBOW when you see one. And guess what? It's BY DESIGN! Infocus designed in that "artifact" that you saw while watching those credits. They just didn't have the luxury that LCOS and HD2 DLP chip-based projector makers have in erradicating these artifacts and still keep the projector priced competitively.


I don't mean to be harsh, but I was slightly offed by your first thread and it's matter of fact tone, which was clearly pulled somewhat out of your behind after reading your next post.
 

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First post on the forums after months of lurking, so I guess I'll say "HI" first! Just got my X1 and I'm enjoying it -- thanks guys for your posts that helped me out during my lurk phase!


Regarding the screendoor issue -- would particular DVD sources have an effect on how bad it is? After a few nights of auditioning, I've noticed the worst screendoor effect on the Star Wars EP 1 and 2 discs. Bright scenes, with characters at a long shot (full body height visible) are the worst. Scenes that have a lot of motion (ie Pod Race) seem to obscure the effect. Closeups also show great detail, and minimal (or no) screendoor.


On the other hand, Futurama is great at full size. My room is 20 x 16, and I can run Futurama at a 9' screensize with a very acceptable picture. There are other live action films (Mad Max) which seem fine as well. Star Wars, however, needs to be a good bit smaller before the pixels get to the point where they don't bug me.


What's the deal?


-Raj
 

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The only effects seem to be a darkening of the image with slight loss of contrast (darkening does that). Obviously it IS a visual artifact and could be distracting to some, mainly because it separates pixels and increases the apparent aliasing of the image. The higher the spacial resolution of the display though, the less apparent this will become. Spacial resolution can be increased by increasing pixel count, decreasing image size or increasing viewing distance.


So, an X1 (800x600?) on a really big screen will be bad news compared to a 1280x720 image or the same X1 on a smaller screen or from a greater distance.
 

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Quote:
Gee, for someone who seems to know so much about projector technology and how DLP is better at this and LCOS is better at that, I find it quite amusing that you don't know a RAINBOW when you see one.
Ahh...I know what a rainbow is. That's not what I'm talking about (yes...saw plenty of *them* too with the X1). I'm talking about a strange dark-light contrast "pumping" that looks like a CRT television that's modulating the beam dark/bright with some sort of dynamtic black-level or brightness expasion boost or something. Absoltely nothing like a rainbow artifact at all (which is more like an RGB strobe-light effect).


Also, when scene switches from dark to bright...the PJ takes a moment and "pumps" the image dark/light while it "settles" on the new brighter image. Very strange. There *must* be some setting in the menu that I'm not aware of to turn something off that's activated...

Quote:
They just didn't have the luxury that LCOS and HD2 DLP chip-based projector makers have in erradicating these artifacts and still keep the projector priced competitively.
Which means that those are *compromises* there by design...and are indeed flaws in regards to high-quality image reproduction. Flaws that the manufacturer was not able to mitigate given, as you say, the price-point of the product.


Appologies for my forward tone. Reading posts proposing that we classify artifacts like screen-door as non-artifacts because they are there by "design" makes it difficult for me to not come accross adamantly.
 

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Quote:
Originally posted by RobertWood
DLP screendoor 101


Question:

I don't want to see the DLP screendoor grid. What do I do?


DLP Answerman:

Use an 800 pixel projector tightly focused and don't look at a picture bigger than 2.25x


Use a 1024 pixel projector tightly focused and don't look at a picture bigger than 1.8x


Use a 1280 pixel projector tightly focused and don't look at a picture bigger than 1.5x


OR slightly defocus any of them and you can make a slightly bigger picture and still not see screendoor.


Of course you also have the option of making a picture as big as the side of a barn and looking at the screendoor.


The choice is yours.




I'd feel like less of a man if I shrunk down my screen any. I take the barndoor and screendoor for my self esteem's sake. :)
 
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