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Discussion Starter · #1 ·
I can only conclude that some of the (minimal) artifacts I see on DVD aren't screen door. Am I just paranoid about LCD and blaming any stairstep or jaggie I see on screendoor? Since the pixels don't shrink, why would HD eliminate them?


I am now in a "sharpness at 0" phase (however, there is no sharpness adjustment for HD, so that isn't the explanation). This "0" trick applies both to the projector and the RP91 DVD player. This seems to have helped the "artifacts" (whatever their source) tremendously. I have often read that increasing sharpness any at all merely adds noise to the picture on direct views. Is this also true for LCD's? It seems to be (at least at this point)...(for me)...(now).


Anyone have the info? Can you throw me a frick'n bone here?


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Joe


Boxlight 38t

Panasonic RP91

RCA DTC-100

Da-Lite 100" 4:3 1.3gain

Studio Experience SE616's

and some other stuff.
 

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Screen door is a physical light obstruction surrounding the pixel. It will exist with any source media at any resolution, it has nothing to do with DVDs, players, HD, STBs and can not be eliminated with HTPCs and Video Processors. LCD have the largest screen door issue and I think DILA has the least but it is intrinsic with the design of digital projectors. To see the screen door, turn your projector on and walk up to the screen. You should see a grid that looks like someone put a screen over the front of the projector. That is "screen door".


There are 3 things you can do to mitigate it with your LCD:

1. Try defocusing the lens slightly. This is what I to and it works great. If you defocus just at the sub-pixel point of the projectors resolution you are just removing some of the artificial sharpness that is intrinsic with a large screen door effect. This should not affect your perceived over all focus of the entire projected image.


2. buy a special lens. IMO it is a high tech expensive way of defocusing.


3. Only watch film http://www.avsforum.com/ubb/wink.gif


Regards,


Brian
 

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I posted this in another thread, but it was off-topic. It should have been posted here instead.


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Source pixelization, 'Jaggies', 'Stair-Stepping', etc. are artifacts from the source material or processing of same. Antialiasing, smoothing, bicubic averaging, bilinear resampling, etc. are some possible solutions for that problem.

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All of that is happening in the source. It is independent of any 'Screen door' that is in the display device. It sure will affect how good the picture appears, but it's not the same as 'Screen Door'.


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'Screen Door' is the informal name for Fill Factor, which is the amount of usable area in each pixel, expressed as a percentage.


If a pixel on a large screen takes up 1 mm, and .9 mm actually contains material from the source (whether it has 'jaggies' or not is irrelevant) then that device has a 90% fill factor...which is very good!


DLP usually has from 80%-90% fill factor and D-ILA has about 93%, but LCD projectors vary...a lot. Some are as low as 40% fill factor, but those wouldn't get discussed in this forum very much http://www.avsforum.com/ubb/biggrin.gif .


IMO, the Sanyo units have really fantastic colors for LCD projectors, and I like them a lot, but I believe that their fill factor must be rather low.
 

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Discussion Starter · #4 ·
I know what screen door is. When I look at the dividing lines between the pixels they are almost as small as they were on the LP350. But I had been attributing some artifacts to screen door. But that can't be right because "it" (whatever it is) dissapears on HD? What I'm saying is that whatever I've been working to eliminate from DVD's on the RP91(from progressive output through component output) can't be screen door, because it goes completely away on HD. If it was inherent in the LCD chip/projector pixels, I would see it all the time, but I don't. So ... if it's not screen door, then what is it?


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Joe


Boxlight 38t

Panasonic RP91

RCA DTC-100

Da-Lite 100" 4:3 1.3gain

Studio Experience SE616's

and some other stuff.
 

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I respectfully suggest that screendoor is most apparent in fields of adjacent pixels of the same color. The higher resolution the source, the more likely that adjacent pixels are (at least slightly) different colors, and hence the screendoor effect is less noticeable.


Lower resolution sources will end up with many more adjacent identical pixels due to the scaling upwards by the projector or HTPC.


[This message has been edited by Michael St. Clair (edited 08-02-2001).]


[This message has been edited by Michael St. Clair (edited 08-02-2001).]
 

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Joe, how did you decided how to hook the projector up? Doesn't the XP21N have vga and wouldn't this be better than component? (All) What's the optimal way to hook up this projector to the Panny 91?


Also, what you may be seeing is simply the higher resolution of HTPC looking better. To get the smoother look on DVD you may have to invest biggo bucks on something like a Rock to get superior scaling. But is it really that bad that it's worth spending $5 grand on?


Dan
 

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DVD do not provide as good of a source as good HDTV. The artifacts are simply due to the DVD source or perhaps the scaling.
 

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Quote:
Originally posted by Michael St. Clair:

I respectfully suggest that screendoor is most apparent in fields of adjacent pixels of the same color.
I agree (1/2-3/4 of the way down).



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The button is labeled "Play", not "Pay". STOP the MPAA!

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Man,


I had not seen your post. We are in full agreement. People need to understand that this is not a scaler-related artifact; the scaler is doing what it is supposed to do. It is a screendoor artifact, which happens to be more noticeable under certain circumstances even though it is always 100% present!
 

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I agree with Michael St. clair. I can definately perceive less of the screen door affect as the resolution of the source material increases. I've noticed this on the three LCD projectors I've owned.
 

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There is no such thing as a screendoor artifact. The disagreement is just semantics, but it is all due to the lack of resolution. You can blame the screendoor or you can blame the scaler, but the real culprit is the lack of information.
 

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There is no spoon.



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The button is labeled "Play", not "Pay". STOP the MPAA!

Our Silent Angels

Please visit The Manny Page!
 

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It is purely a phenomena. The eye tends to focus on sharpness. A fuzzy image behind a pixle structure will reveal a sharper pixel structure hence greater screen door. As you go to HDTV the image itself becomes so sharp and clean that the eye fails to focus on the pixel structure although the structure has not changed....the shaprer image typically has a more 3d lok to it drawing the eye int ot eh image


Regards,

JOhn
 

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Discussion Starter · #14 ·
I don't know my @$$ from my hat.


But, I would think that uniform colors would show the screen door more, like in white patches, but a varied blotchiness would mask it. But it still makes no sense to me why a higher resolution (HD)image, which the projector scaler (not deinterlacer) can obviously handle quite perfectly, would mask screen door. I can't buy the argument that we are seeing the detaial in the picture behind the screen door, because it isn't behind it. It is made up of the stuffe between it. Isn't each pixel just one homogonous color and brightness level? I mean, there isn't more than one color or brightness level in a single pixel at one time is there?


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

Joe


Boxlight 38t

Panasonic RP91

RCA DTC-100

Da-Lite 100" 4:3 1.3gain

Studio Experience SE616's

and some other stuff.
 

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Discussion Starter · #15 ·
Oh, and did I mention that the artifacts I see tend to be on the edges of objects? That is why I was assuming it was the result of screen door. And why I am puzzled that HD makes it dissappear. I'm flummoxed.


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

Joe


Boxlight 38t

Panasonic RP91

RCA DTC-100

Da-Lite 100" 4:3 1.3gain

Studio Experience SE616's

and some other stuff.
 

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Discussion Starter · #16 ·
Thanks Man E for tipping me to the other thread.


But it makes me consider another explanation. I have seen detail with the 38t that I never saw on the 350. The difference is startling. Textures, grain, etc. Am I seeing artifacts that I just couldn't see before because of the increased brightness, color and especially contrast? Have I gone so far that I now need to fix things that I didn't know were broken before? Did the 350 homogonize things so that I didn't notice?


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Joe


Boxlight 38t

Panasonic RP91

RCA DTC-100

Da-Lite 100" 4:3 1.3gain

Studio Experience SE616's

and some other stuff.
 

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A couple things occur to me:


1. Too much screen gain for this very bright picture. Why don't you have Hank send you a swath of Da-Lite HC and stick that up on the screen and do a comparison.


2. Maybe you need to defocus this thing some.


3. When they start shipping seriously, see if someone down there in Houston has a Panamorph and try that out. It will do two thing: Increase your pixel density on a 16:9 image; and (2), apparently it acts somewhat of a depixellator according to reports.


Dan
 

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Discussion Starter · #18 ·
Thanks Dan, I may try your suggestions, if my medication won't work. But I've tried defocussing, and I just can't stand the thought of it. I want the clarity even if it lets me see some ugly.


So I put on my glasses again and started over. I started experimenting with the extensive still frame capabilities on the RP91, examined the pixels individually and noted the following things about DVD's:


1. 80% of all individual frames aren't in focus because of movement. The film was too slow to stop the action. So the frame is a blur.


2. When you see an individual human hair in perfect focus on a close up it is actually 3 to 4 pixels wide and fuzzy as heck.


3. Each pixel IS only one color and one level of brightness.


4. The more focused a scene or frame is, the fewer the edge artifacts. That's why well focused close-ups of faces always look perfect. It seems as if the software kind of guesses or alternates on blurry material, especially at edges, which causes a checkerboard effect rather than a sharp demarcation.


5. Most of the filters and fix-it-up settings on the RP91 make things worse. You can get rid of one set of artifacts but you will always get another set you like even less. It offers so much control it gives you the power to screw things up really badly, like an Uzi in the hands of a 3 year old.


So this is where I am now. The RP91 gets all defaults except gamma at +4, edge at -3, and whatever-it-was at Auto 1. The 38t gets all defaults except sharpness at 0 (the lowest). I've concluded sharpness really does just add noise, just like on a CRT.


I checked these setting out on the usual 5 DVD's, and the only thing I spot now is very occasional and very minor edge jaggies in really high contrast differential areas. No one notices them but me (I guess we've heard that a lot around here) and everyone else says the picture is awesome. As I keep saying (trying to retrain myself to be normal) if you just watch the content, it looks fantastic. I will also say that when I have looked at RPTV's lately (which I used to think were great), they absolutely suck cat litter. I guess you really can't go home again.



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Joe

My current idea of the best:

Boxlight 38t

Panasonic RP91

RCA DTC-100

Da-Lite 100" 4:3 1.3gain

Studio Experience SE616's

and some other stuff.


[This message has been edited by JHouse (edited 08-03-2001).]
 

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Joe:


Thanks for the setting recommendations. When I get my setup here, I'll contact you for a summary.


As for trying to be normal, if you do that you'll have to leave the AVS forum! http://www.avsforum.com/ubb/biggrin.gif


What's it like watching a movie at night when the room is really dark? Is the image too bright?


Dan
 

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Joe,


I'm glad that the medication, er, um, settings are working out for you http://www.avsforum.com/ubb/biggrin.gif


The P752 that I viewed at the Panamorph Party reduced screendoor presence by 200%-300% on an older LCD. I was amazed. Not to mention to increase in vertical resolution and brightness. It's like waiting for Christmas when you're 10.




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The button is labeled "Play", not "Pay". STOP the MPAA!

Our Silent Angels

Please visit The Manny Page!
 
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