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Discussion Starter · #1 ·
Why can't projectors be built with the ability to change aspect ratios as easily to fit any format? Just tell the projector what size you want and voila, it formats it to fit your screen automatically! INo more masking!
 

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I think you got the whole thing wrong. Even though I'm no expert in this, it's not that the projector doesn't do aspect ratios correctly. It's the screen!


For instance. Imagine you have a completely sqaure screen. Aspect ratio 1:1? There's nothing you can do but have black/grey bars. if you want to fill the width of your screen.
 

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Discussion Starter · #4 ·
What I mean is the ability to just tell your projector "OKay, I have a 80 inch wide by 60 inch high screen - Now make whatever I feed you come out in that size exactly. And do the least image distortion that you can do"


Am I dreaming or just showing my total naivete to the way a projector works?
 

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You are just dreaming. Projectors use panels of a fixed shape and then lenses to blow that out. There are anamorphic lenses that can manage some "natural distorting" of the image. But it's not like a cheap projector could have anything more than an ability to distort across one domain and it's certainly not like it could have some programmable digital "screen match" control.


mark
 

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I think the problem is the source material, If they could just decide on what aspect ratio to film in, and if everyone would stick to it. I prefer 1.85:1


~ Jay
 

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Quote:
Originally posted by ChaCha
What I mean is the ability to just tell your projector "OKay, I have a 80 inch wide by 60 inch high screen - Now make whatever I feed you come out in that size exactly. And do the least image distortion that you can do"


Am I dreaming or just showing my total naivete to the way a projector works?
A projector certainly do that with scaling and some do. However, most people would rather see the black bars on the sides or top/bottom, than always see people and scenes that are either short and fat or tall and skinny.
 

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Oh yes, absolutely. I did not seem to notice this thread, although the present one is slightly from a different angle... Just finished complaining about the lack of a gradual zoom here .
 

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Isn't there some HTPC software that allows you to do something close? But first of all, in order to do automatically what ChaCha proposes, I think some "tag" or "hint" has to be embedded in the source material. Is there such metadata recorded at all in today's DVD that tell the display what aspect ratio the material should be displayed?
 

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I guess we throw OAR out the window, huh?


Honestly, most people who care about their movies don't want this, although we may be in a minority on the planet. They want a source with the correct AR, and they don't want their video device to alter it, just show it. Yes, this creates problems like the one stated in the thread Sonn linked, but nothing will perfectly solve this for everybody since some care about the film and others care about the screen space. Hollywood and the rest have used so many sizes it's a pain, but it's just something to live with.
 

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I'm confused here. So what happens when you have, for example, a 16x9 projector, and play a 2.35:1 movie or a 4:3 tv show on it? Is it just that there are black bars on the sides or top/bottom? (assuming you also have a 16:9 screen). If the projector were able to do away with the black bars, wouldn't it have to either A) distort the image, or B) you would just end up with needing some sort of matting on your screen(either sides or top/bottom)?


If you put some black framing around your screen, do the black bars blend in with that, or are they pretty noticeable?


I could be totally misunderstanding the issue here, I am a total newbie, just doing some research on pre-wiring, probably a year away from purchasing any equipment.
 

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jeff125va-


I think you've got it, and you've answered your question as well!


Yes, black bars appear at the top or sides of a 16x9 screen when displaying 4x3 or 2.35:1 image. Some people put additional removable masking to help lessen the effect of the black-grey/black bars. Even some RPTV owners do this!


What I'd ove is a projector that would allow you to select 2.35:1 or 1.85:1 or HDTV or SDTV or whatever, and display ONLY the image without the bars! That'd be nifty.


Ryan
 

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But thats what it does. If you project a 2.35:1 image on a 16:9 projector, the projector will only insert bars above and below the image. The bars are not projected, but are infact the lack of anything to project.


If what you are saying is that you want to pan-and-scan a 2.35:1 wide screen dvd to completely fill your 16:9 screen, that is easy to do with most software dvd players. I know powerdvd will pan-and-scan to 1.85:1 and 4:3. Recently The Sound Of Music was broadcast in HDTV. As I recall, but I may be wrong, the movie should be 2.35:1, but it was broadcast as 16:9. This REALLY bothers me!! If you have a properly sized screen (about 31 degrees of viewing angle) then cutting the edges off the screen ruins the film.
 

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Sounds like what we're talking about is comparable to anamorphic widescreen vs. letterbox (except of course we're talking about different aspect ratios, but the same basic concept).


Your first paragraph puzzles me Salin. If the projector projected only the image and not the bars, wouldn't you see white bars (the color of the screen/wall)? If this is the case, to me the masking would be pretty much a necessity. I could live with the black bars if they sorta blended in with the framing around the screen, especially with the room darkened, I'd think they'd be hardly noticeable. But like I said, don't know much about these things.
 

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Quote:
Originally posted by jeff125va
... If the projector projected only the image and not the bars, wouldn't you see white bars (the color of the screen/wall)? ...
Ummm, no. If you think about it, how do you think black (say a black dinner jacket) is constructed? It is the absence of light. So what Sailn said is quite correct:
Quote:
The bars are not projected, but are in fact the lack of anything to project
The fact that a white screen looks black is a cool illusion.
 

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Quote:
Originally posted by joebwan
Ummm, no. If you think about it, how do you think black (say a black dinner jacket) is constructed? It is the absence of light. So what Sailn said is quite correct:


The fact that a white screen looks black is a cool illusion.
Actually, in your example, a black dinner jacket is black because of black pigmentation in the material, normally a dye in clothing. My white clothes don't have any more light than my red or blue or black clothes. They just have less pigmentation. True white, by definition, would have no pigmentation.


Something has to cause the black bars to be black. If you turn the projector off, those portions of the screen appear white again. How are the black bars any different from say, the black background that appears when the credits are rolling in a movie? (assuming it's the same shade of black, of course, I'm just making a point)


I really think that what ChaCha is talking about is something like the 16:9 anamorphic mode that some 4:3 TVs (like my Sony WEGA XBR) have. With the 16:9 mode turned off on the TV, and my DVD player set for a 4:3 TV, if I play a letterbox (16:9) DVD movie, it will send an image that includes the black bars. They'll appear as a slightly different shade of black than when my TV is just turned off. If I turn on the 16:9 mode on my TV and set my DVD player to send a 16:9 image, it will send only the movie part of the image, not the black bars, and it will display in the same 16:9 portion of my screen, but the area with the black bars look just like the TV is turned off. If there were truly a "lack of anything to project," the screen would appear as it does when it is off (or the projector is off).


Maybe we're just on a different page here or there's just a semantic difference in what we're talking about.
 

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Jeff, In a perfect world (and boy this isn't:D ) the projector would project nothing for the black bars. Then the bars would be the color of the screen as seen under lighting conditions the viewer is viewing the screen. In fact, many projectors, read LCDs in particular, are unable to really block all the light and project nothing. CRT projectors do a much better job wrt to this. Additonally, light reflects off of surfaces in the room and back to the screen.


If you are using a HTPC try this:


In a totally light controlled room (ie: pitch black, and you can not see the screen)


put a solid black image on the projector and look at it. You will in all likelyhood be able to see the screen. The reason is that the projector is projecting light even though the image it is projecting is 0,0,0 pure black.


Inorder to compensate for this, many people make masks for the screen. In my case, I use triple black velvet covered styrofoam. My screen is 8 ft wide (2.35:1). When I project a 1.85:1 film I add velvet covered panels to the left and right edge of the screen and zoom out the image. 2:55:1 movies require that I move to bottom mask up and vert. shift the image so that the horizontal black bars disappear.


What is really interesting is how much better the image looks with really black masks instead on dark grey "black" bars on the screen. The contrast appears much better even though it really isn't.
 

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Quote:
Originally posted by jeff125va
... in your example, a black dinner jacket is black because of black pigmentation in the material, normally a dye in clothing. My white clothes don't have any more light than my red or blue or black clothes. They just have less pigmentation. True white, by definition, would have no pigmentation.


Something has to cause the black bars to be black. If you turn the projector off, those portions of the screen appear white again. ... Maybe we're just on a different page here ...
I was talking about a projected image. That is, if you project an image of a black dinner jacket onto your screen. As this was a discussion on how a projector creates the illusion of black on a white screen, I didn't think there was a need to spell this out.


What you are saying about the colour of clothes and what I am saying about projected images are two totally and absolutely different things. While what you say about pigmentation is correct, a white piece of material looks white because it reflects (or absorbs less) all of the three primary colours (red, yellow and blue) evenly. A Red piece of material looks red because it reflects more red and less yellow and blue (or absorbs more yellow and blue and less red). A black piece of material looks black because it absorbs (or reflects less) all of the three primary colours evenly. This is additive colour mixing.


Projectors are totally different. They use subtractive colour mixing and create colours by mixing 3 primary beams of light. These primary colours are red, blue and green. To maintain a colour balanced image, the surface reflected off needs to be pure white (for simplicity's sake. I'm not going anywhere near grey screen theory!). The colours you perceive are very simply all beams on in equal intensity = white; and all beams off = black. This is why a projector looks soooo much better in a totally light controlled environment (read pitch black room) when using a 1.0 gain white screen. As soon as ambient light is introduced into a theatre, your black is no longer black as you have a some light that now is reflecting from your screen, so your black is now grey.


This is a fairly basic explanation, of a very complex subject. But I hope that it gets us both somewhere near the same page. Because yes, we were on very different pages.


:D


(BTW, this discussion is very OT, so it might be an idea to start a thread in the screens forum, if you want to continue it.)
 
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