Whats the video source in digital theaters?

Ken Burkstrum

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I thought they were just DVDs, but uh...I never actually thought about what a 720x480 dvd looks like on a 100ft screen and now I realize im missing something. What do they use and what is the resolution?
 

Allan Jayne

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They have a computer system with commercial grade proprietary "home theater" software onto which movies are downloaded.

"Eliminates shipping of reels of film back and forth by UPS or Fedex between studios and theaters. No degradation with each showing because of scratches or because a frame or two is spoiled when film is spliced together to make a continuous roll for projection and cut apart to put back on the reels to ship to the next theater."

Video hints:
http://members.aol.com/ajaynejr/video.htm
 

Ken Burkstrum

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sorry, your post wasnt there when I was typing. So they send a copy to each digital theater over the internet? Is there a resolution standard, like 4k or something? 1080p doesnt sound like it would like very good at the theater? Any idea how big the file size is?
 

ChrisWiggles

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2K or 4K.

The data size is gigantic. Not just because of higher resolution, but higher bitdepths and less compression (no temporal compression AFAIK).

The bitrate is also obviously extremely large.
 

Ken Burkstrum

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so basically, they have a ridiculously fast connection and a super computer there to handle the data transfer from god knows what kind of assortment of hard drives out to a digital projector that can handle 2k or 4k.

Makes me light headed.


Are there digital IMAX projectors or do all of them stick with 70mm film?

What produces a sharper picture at a theater, 4k or 35mm film?
 

ChrisWiggles

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Digital will be "sharper" but that doesn't relate to resolution. As far as resolution goes, that is very complicated, and it very much depends on the quality of the film print. An average 35mm film print doesn't actually have that high a resolution, 1080p(a tad less than 2k) should best it. Resolution is a generally more complex discussion than most people really understand. They are used to an X by Y number to define resolution, and that really isn't resolution at all.
 

ChrisWiggles

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I am not aware of any digital projectors in use at IMAX, that would surprise me. I don't think digitals are anywhere close to accomplishing what a really well-handled 70mm print looks like which is what you see at IMAX.
 

Ken Burkstrum

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a single pixel can only be one color right? Can you nutshell this "resolution has nothing to do with a sharp picture" for me? Excluding factors related to compression.
 

frogpond

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Do you live next to one? Consider yourself lucky. As of 2005 of the aprox. 155,000 cinemas worldwide only about 225 of them are digital. Each year less than one percent of the films released in the major markets here and overseas ever make it to digital. Being in the film and television business I am a bit of a purist and still think 35mm film looks the best as far as color saturation, contrast, etc. And yes IMAX still uses 70mm film. Projection is carried out by either of two methods either DLP or D-ILA at a resolution of 1080x1024 or 2048x1536. Feature length movie size on a hard drive aprox. 850gigs. Lumens is between 17-22k and cost well...forget about it...
 

ChrisWiggles

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MTF(Modulation Transfer Function) is probably the best way to describe resolution in my opinion. Trying to attach an absolute number to horizontal and vertical resolution is really a gross simplification of what is being resolved. It works in simplified environments (like PC/graphics) but not when you really get into the nitty gritty of how sharp or not sharp the display is resolving fine detail.

You can have a number of displays all with the same "resolution" but with different MTF profiles, and will appear different in terms of what they are resolving, and how.

Film has a gaussian grain profile that a sharply focused DLP will not have for instance, which may lead to strengths in some instances for one, and weaknesses in other instances. This is best captured by MTF measures than trying to slap a number on how high the "resolution" is. You see this a lot in differences between "sharpness" among various displays all with the same native resolution, and this often has to do with the quality of the lenses and some lenses having lower MTF than others. It's kind of a similar thing.

The same occurs especially with CRT displays which have elusive "resolution" capabilities because the display does not have any kind of fixed pixel lattice.
 

Leo Kerr

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I'm not aware of anyone actually running 4k in a commercial theater; they're all 1280 or 1920 or 2048 displays; the vast majority of them being three-chip DLP. Yes, Sony and JVC are trying to get in, but right now, to my knowledge, they can't compete with maintenance costs. Most of the D-cinema projectors are using "projector heads" that bolt on-to a conventional lamp-house.

The "source" is generally a RAID; generally RAID-5 configuration (striped for redundancy and transfer rate.) It's not a super-computer by any stretch of the imagination; it's just a computer set up to do one thing reliably - play sustained high speed data streams without glitches for long periods of time.

Leo
 

Arthur S

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What ever happened to the Sony SRX-R110, 4K SXRD projector from a year ago? 4096 X 2160.
 

ChrisWiggles

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It's around. I know one person in Germany who had one for a time. He also had stacked Qualia 004s I believe. Not sure what he's using now.
 

ChrisWiggles

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It's around. I know one person in Germany who had one for a time. He also had stacked Qualia 004s I believe. Not sure what he's using now.
 

Ken Burkstrum

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I didnt know they used such low resolutions. I would of thought it would look terrible on a theater screen.

Chris, I appreciate the effort your putting in for me. I don't understand what your talking about however.


I don't really understand what your saying as far as what goes into making a sharp picture for digital images. Your making it seem like it's possible to have a sharp picture with a low amount of pixels on screen and that's making it difficult for me to picture what your saying.

I always imagined it like this. To get a clear digital image, you need a good number of pixels to make up that image. After that, it's all up to color and saturation and all that good stuff to make it a good lookin picture. I never realized that until I saw that homemade HD videos still look terrible. Then I figure from there it's up to the monitor to accurately display that picture how it's meant to be shown and by viewing different screens right next to each other I realized it's kinda hard for it to be perfect.

I'm still not seeing what else goes into making the image look sharp.

Something I've been wondering. Chris or anybody, would you happen to know why movies have nice smooth lines but video games always have to use anti-aliasing techniques to smooth out straight lines and curves so that they don't look jaggy?

I didn't know film used pixels? Wouldnt 1080x1024 on a screen as big as an IMAX look terrible?
 

Seth=L

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Rave Motion Pictures is a digital theater. Awesome stuff man, they have 2 rooms with DLP for newer releases at least the heavy hitters. Got one about 15 minutes away in Fort Wayne.

Does anyone else have experiance with Rave Motion Pictures?
 

ChrisWiggles

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The confusion is what is meant by "sharp." Sharpness to a layperson usually has more to do with how well resolved and sharp edges are, which is probably revealed strongest in full on/off transitions like black and white lettering (text) etc. Sharpness is a confusing subject because it involves both spatial resolution, and contrast resolution. This is why we have MTF to describe resolution, because it captures spatial resolution (frequency) and contrast resolution (amplitude). A lot of people simplify their understanding of resolution, especially because of the unfortunate heritage of PC jargon of naming resolution with an X by Y number, by only discussing the spatial component of resolution.

So, if you have a grid of say 4 pixels, well that's not really high enough resolution to display much of anything, but what's missing in that is any description of the contrast capable between the adjacent pixels. Some displays can display high-frequency spatial content (many many of these "pixels" for instance) but at lackluster contrast. That is to say, at very extreme transitions between black and white, the transition is blurry because the contrast is low. This can be due to many reasons, like bad lenses, bad focus, dirty lenses, the nature of the display itself (like Film or CRTs which have a gaussian profile and smear things out etc).

So having "enough" pixels in a digital display that uses a fixed grid to create an image does not tell you everything. If you have some display with X native panel "resolution", another display with the identical native panel "resolution" may look sharper or it may look blurrier. If you really look at what's hitting the screen od seen by the viewer or measurable through the system as the ACTUAL resolution, you would say that the sharper display has a higher resolution than the one that is less sharp, despite the fact that they may have exactly the same number of raw elements that go into creating that image. And this is something that MTF would capture, that a simplified grid-number label to "resolution" does not.

So if you have a display that is say 1080p, well that's great, but that may look different than a different display that is 1080p. Can you still say that they have the same resolution, i.e. the same capability to resolve fine detail? No, you can't, despite the fact that they are both 1920x1080 displays. And there are some legitimate reasons why some might prefer the softer of the two machines, despite the fact that it cannot resolve some details as well.
 

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