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This topic comprises 8 pages: 1 2 3 4 5 6 7 8
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Author
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Topic: Imax Digital
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Julio Roberto
Jedi Master Film Handler
Posts: 938
From: Madrid, Madrid, Spain
Registered: Oct 2008
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posted 12-15-2008 07:29 PM
quote: Tristan Lane
Hell just froze over.
Must have been the ice age coming. I meant, the global warming coming. Oh, well, whatever is coming this week. ![[Smile]](smile.gif)
I haven't seen or read much about IMAX digital, so all this maybe just me rambling or downright wrong. I've certainly seen my share of all traditional IMAX large format presentations (omnimax, different 3D systems, 48fps, magic carpet, etc).
I've always said that 2K is usually "enough" for most people to watch a satisfying image. What happens is that you are starting with the "bare minimun" to have a "great show", so no compromises after that can be made.
Imax probably digitally "panned-and-scanned" (or whatever) the movie to the aspect ratio of their theaters, matched perfectly to the aspect ratio of the imaging devices (micromirrors).
Lawrence being a 70mm film probably had an aspect ratio to begin with of 2.20 ... a better match to the DMD (DLP) chips than either scope at 2.40-ish or flat.
IMAX probably had access to the master material and made sure it fit (cropped a little or whatever it is doing with the lenses) as well as possible and had the absolute highest data rate possible under the server (very maxed DCI specification or maybe even higher).
Couple that to well designed illumination (lamp/lens/screen/2-projectors) and Lawerence breathtaking imaginering, with lots of light and depth of field, in any format (almost looks good even on youtube ![[Wink]](wink.gif) ) and there. Heck, they probably even fine tuned the screen perforation.
A great presentation. Certainly more than good enough for the average Joe and even pretty good to professionals.
The problem is when compromises and shortcuts start happening to the bare-minimun 2K system.
You start by cropping the image to adjust for aspect ratio, throwing away tons of resolution,"forcing" lamps to fill huge screens with minimun illumination levels, using whatever lenses the projector's manufacturer can save a buck with, using adapters or zooms to fill the screen when the aspect ratio changes (eating even more light, producing internal reflections). Put that projector off-the-screen-center with a significant keystoning or lens shifting, use a high gain screen with no regard to the theater architecture (i.e. curved screen, etc), etc, etc, and what do you have?
What you get at the end is an image with less resolution and "pizzaz" than the $300 HD LCD monitor you are typing this in (I hope it's a true 1920x1200 16:10 24" by now ).
Whenever I watch IMAX (tranferred) films in my HD TV (from HD-DVD or Blu-ray) I go .... Wow ... And it's only 1920x1080 4:2:2 with a guaranteed color space and depth (8 bit color) that is not all that great.
Because IMAX had a great, breathtaking image to begin with. With an aspect ratio they fiddled with to fully fill my HD monitor (instead of wasting resolution on huge black bars on top and below like an scope film), filmed with very high depth of field that makes you able to see every single detail in the frame in focus, and transferred with care using efficient codecs and high bit rates (instead of many HD discs using MPEG2 for compression rather than AVC or VC-1), etc.
In another words, IMAX has always been "the best that we can be with what we got". What they got now is a dual 2K system with two projectors with almost the same specs as a DCI one.
So I suspect they are doing "2K right". Current DCI projectors, i.e., can physically have a higher contrast ratio than mandated by DCI (about 2500:1 instead of 2000:1), so in a way they are underused in that area.
Now. If we could all start with a 4K image, then we wouldn't have to worry that much about "doing it right". In other words, using a zoom or whatever plus cropping could still result in enough pixels on the screen to at least surpass your home HD TV when watching Smallville (1.78 ratio) on blu-ray.
And if a theater wants to fill a 60+ foot screen with digital, they better start thinking of using good screen/lens/lamp design and use 2 projectors. Even more so if they are thinking of using 3D.
2K is good enough when done right. But not when done wrong.
4K is better (duh) and allows more practical choices (read shortcuts/compromises) to the theater owner to go unnoticed.
But most people will not be able to notice a difference between 2K done right (with its limitations of size/light/aspect ratios/etc) and 4K done "normal" (i.e. a few minor compromises made).
You can't pretend that using 2K on a (traditional) IMAX-size screen is enough. But it's perfectly fine for your average multiplex.
To me, 2K is good enough but 4K should have been the starting point for professional theater application for not other reason that 2K is basically what the average Joe has at home (and lets not argue about bit depth, color subsampling, compression, etc, shall we? ... after all, theaters punch small holes in their screens allowing the information and light in those places to go bye-bye, etc).
4K is not necessary, but it's something that will come sooner than later to theaters (oops, I forgot Sony), so 2K seems to me like a stop-gap for early adopters.
Or not so early. It looks like TI has no intentions to provide cheap 4K for a long time. And then even 4K DCI is an illusion as the specs calls for a compression rate for 4K images that is almost 4 times greater than 2K (to allow current servers to keep the same bandwith usage), pbbly cancelling much of the advantage of 4K resolution.
Oh well. We better get over it. Digital will come one day and it'll be whatever Hollywood and manufacturers want it to be. And it won't be horrible, but it will leave as wondering how pretty it could've been if they did it right instead of playing the milk-the-money game.
There is hope, though. We'll see what is announced at NAB in a few months.
http://www.reduser.net/forum/showthread.php?t=7390
But it's clear that for the next year or so we are stuck with 2K TI or 4K Sony SRX, so there.
I'd hate to be a theater owner today ![[Confused]](confused.gif)
http://www.youtube.com/watch?v=G9-6MPv2pw0
[ 12-15-2008, 09:24 PM: Message edited by: Julio Roberto ]
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Frank Angel
Film God
Posts: 5305
From: Brooklyn NY USA
Registered: Dec 1999
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posted 12-15-2008 11:14 PM
Just to clarify, I have no idea if LAWRENCE has been tranfered to D-Cinema in any format -- 2K or 4K or any K. I only used LOR as a reference because it was the benchmark that I've always had in my head, that if a new technology came along which was supposed to replace film, I felt it had to at least be able to reproduct our cinema heritage to the same level as film did when I first experienced the great classics as a kid. I've always said I am not married to any technology -- I don't love film because it's film, I love film because it was able to give me those incredibly memorable experiences that I was lucky enough to have as a kid and which burned into my brain so intensely that it has been my life career; if another technology was to come along to replace film, then surely we shouldn't be satisfied if it was not capable of giving future generations what we had. If we accepted that, it would be like if someone made it so the only way all future generations could see a Monet painting would be as a lithograph reproduction rather than the actual painting.
My first experiences with digital -- first 1.3K = ![[bs]](graemlins/bs.gif) and next the early 2Ks = ![[dlp]](graemlins/dlp.gif) that were used for the STAR WARS releasr -- certainly couldn't match a 70mm presention of LOR. But this 2x2K IMAX I think could. How that can be possible is the mystery someone else here will have to explain because in theory it shouldn't look that good coming from a 2K scan and using 2K projectors (doubling or even quadrupling the projectors shouldn't increase resolution, right? -- if you start with 2K source, you have to end up with 2K display -- it;s impossible to make information out of nothing). All I can tell you is as nauseous as that horrid 1.3K JURASSIC PARK made me, this IMAX stunned me with how razor sharp it looked. If it was trickery, then so be it, but I would be happy to show LOR or any of the other great 70mm classics to an audience and not feel I'd cheated them or had to apologize.
Now mind you, I am saying that for me, this IMAX 2x2K presentation would be more than acceptable as a replacement display system for conventional motion pictures, i.e., as the DCinema systems in regular theatres. I am not saying that this would work as a replacement for a traditional IMAX type screen. that remains to be seen. So if this is what corporate IMAX is saying hence forth will be the IMAX "Experience," then I think IMAX will just be the equivilent of what 70mm houses used to be -- high end, better venues to see movies. IMAX will be to regular multiplexes what 70mm was to 35mm theatres in the 60s and 70s. Could this IMAX system blow up and still look great on their REAL IMAX screen? That remains to be seen, but for conventional size presentation....HOT DAMN it looked good!
Now all they have to do is figure out in this economy, who can afford to put this in theatres.
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Julio Roberto
Jedi Master Film Handler
Posts: 938
From: Madrid, Madrid, Spain
Registered: Oct 2008
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posted 12-20-2008 12:16 PM
Not all reviews are that good.
Some people notice the pixel pattern right on.
http://www.lfexaminer.com/editorial200810.htm
Quote from the article:
"Using two high-powered digital projectors, the IMAX digital system projects an image that is bright, with good contrast and slightly better resolution than other digital projectors. But every IMAX digital theater I’ve been in has also had a noticeable “screen door effect,” that is, a visible dark grid pattern separating the pixels. It is particularly noticeable in lighter image areas, and is less visible the farther you are from the screen. But even with my 53-year-old eyes, I was able to see it from the front half of most of the five theaters I’ve been in. If you move back to eliminate the pattern, your field of view becomes narrower, and hence no different than an ordinary movie theater.
At the New York demonstration, I was seated in the fourth row next to a long-time IMAX theater manager. I had not said anything to him about my perceptions of the IMAX digital theaters I had already seen. But the moment the first image came up on the screen — it was the MPAA rating card for the first trailer — I heard a gasp as he noticed the screen door pattern that made the card’s white-on-green text look “jaggy.” He later confirmed being stunned at how obvious and distracting the pattern was.
Although many people I spoke with after the demo shared this reaction, to my surprise not everyone found the pattern as noticeable or distracting as I had. Some didn’t see it, others did, but didn’t mind it as much.
But for me it is clearly the biggest reason to say, “This is not IMAX.” I grant that the image is bright and contrasty, and has good color. And it only took hearing a shuttle launch in Space Station 3D to know that the new sound system is fully up to IMAX standards. I might even be willing to compromise on the aspect ratio.
But IMAX — real IMAX — presents reality. Not reality as seen through a screen door."
----- End of quote
This is obvious. As we all know, "physics" can't be cheated. And 2K is not enough resolution to seamlessly fill really large screens with enough resolution to compete with large format films.
I'll say it again. 2K is fine for a small multiplex and for most people it's just great. But this industry is shooting itself in the foot because it could have easily done 4K (DCI+servers+Sony supports it ... only TI is still doing 2K) and 2K is basically what people have in their homes (or will have in the next 5 years).
Sony did the math.
http://pro.sony.com/bbsccms/static/files/mkt/digitalcinema/Why_4K_WP_Final.pdf
Hollywood is quickly moving fully to 4K, as new digital cameras and workflows reduce the cost to almost nothing. Heck, there is even talk of domestic A/V going 4K in a couple of years ...
Not to mention a 28k camera for $53.000 with a monster sensor that would probably surpass (or rival) IMAX. Doing the math, a single sensor has more pixels than BOTH human eyes have BOTH rods and cone detectors (261,352,000 vs 126,000,000 x 2 eyes = 252,000,00).
http://red.cachefly.net/14/mysterium.jpg
http://red.cachefly.net/14/list2.jpg
What we need is a $50k total cost system close to 4K in quality and that can work reliably for a long time at high brightness levels with modest 2-4Kw lamps. But there is not such thing yet.
Oh, wait. There is. It's called a 35mm film projector
http://www.cnet.com.au/projectors/0,239035440,339290009,00.htm
[ 12-20-2008, 02:53 PM: Message edited by: Julio Roberto ]
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Julio Roberto
Jedi Master Film Handler
Posts: 938
From: Madrid, Madrid, Spain
Registered: Oct 2008
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posted 12-20-2008 10:48 PM
Just an interesting quote from some random people . They are talking about perforated screens:
"... I should tell you about the world of electronic cinema, where the issue of holes in the screen is once again being addressed. The Digital Cinema Initiatives, LLC (DCI) did a presentation where a 4K-image source from an animated feature was projected by a 4K projector on a screen that was about 50 feet wide. That same image was downconverted to 2K and projected by a 2K projector. On the perforated screen, you couldn’t tell the difference between the two images. Put up a solid screen, and the differences were significant. Put up a solid screen on the 2K projector, and it looked seriously better than on the perforated screen. The quick lesson in all of this is that image detail passes through the holes in the screen and never comes back to the audience. Who would have ever thought such a thing possible? ..."
And then:
"Several years ago, (Joe) Kane ran tests using the JVC D-VHS D-Theater HD tape format at a peak video bit rate of 24 Mbits/sec and saw that a perforated home theater screen masked the difference between MPEG-2 and WMV encoding and hid image details, while on a non-perforated screen. The difference was obvious to all observers. The Digital Cinema Initiative ran similar tests at the University of Southern California processing laboratory in Hollywood and found that a perforated movie screen mostly masked the difference between 2K and 4K projected images, yet the difference was obvious with a non-perforated screen." From the SMPTE Journal, Issue: 2008 01/02 January/February, Section Meetings Report, Washington, D.C.- October 2007.
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