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This topic comprises 2 pages: 1 2
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Author
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Topic: Projector Imager Areas and DCI Compliance
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Brian Guckian
Jedi Master Film Handler
Posts: 594
From: Dublin, Ireland
Registered: Apr 2003
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posted 02-06-2009 09:45 AM
I have a query relating to some d-cinema installations that are using imager areas that do not appear to be supported or endorsed by the current DCI Digital Cinema Specification (V 1.2, March 7, 2008).
I first became aware around two years ago of a practice whereby in certain installations, all ratios were being referenced to the 858 x 2048 "flat 'scope" imager area.
Narrower ratios were being fitted into this area, so that for example, 1.85 is displayed at 858 x 1587 and Academy at just 858 x 1180.
This problem seems to originate where, for budgetary reasons, non-motorised zoom lenses are installed for common height screen setups. The lens is set to one position, and because of this, everything is referenced to the 858 x 2048 'scope area.
The DCI Specification seems to be quite clear about how much of the imager should be employed for content display, viz.:
It is intended that the projector project the full horizontal pixel count or the full vertical pixel count of the image container (Section 8.2.2.7., Spatial Resolution Conversion, page 80)
My questions are: has anyone else encountered this? And, are such installations consequently non-DCI compliant?
And even if they are compliant, is there now a SMPTE Standard (given that DCI is a specification rather than a Standard), that clearly defines what the utilised imager areas should be for the different ratios?
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Brian Guckian
Jedi Master Film Handler
Posts: 594
From: Dublin, Ireland
Registered: Apr 2003
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posted 02-07-2009 09:22 AM
Thanks for the info David, accessories like the WCL are clearly a good, cost-effective solution to the problem.
A concern though, is what if an exhibitor or third-party provider doesn't want to pay even for a MALM-style mount, never mind a focal-length adapter?
DCI is consistent throughout in specifying the 2.39 ratio as 858 x 2048 and 1.85 as 1080 x 1998, for 2K d-cinema.
Although one could argue that sections of the DCI document, such as Section 3.2, deal only with the specification of, to quote, "uncompressed image structures and files" (rather than display of such structures and files), nevertheless the overall thust seems to be to ensure that:
"The number of active pixels...shall extend to the maximum in either the horizontal or vertical direction of the defined level of operation as defined in Table 1" [4096 horizontal and 2160 vertical for 4K; 2048 horizontal and 1080 vertical for 2K] (DCI V1.2, pages 26 & 27).
The other point is that the phrase "single-lens solution" never precluded the use of motorised zoom lenses so that, in a common height screen setup, ratios could be displayed using as much of the imager area as possible. In other words "single-lens solution" did not mean that say, only a prime lens could be used.
Also, if you read the rest of the text from DCI V1.2 page 80 from which the initial quote was taken ("It is intended that the projector project the full horizontal pixel count or the full vertical pixel count of the image container"), it is clear that it is a reinforcing, explanatory sentence, that doesn't dilute the specification.
A published Standard would seem to be the best way of preventing the use of compromised imager areas in the future.
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David Zylstra
Master Film Handler
Posts: 432
From: Novi, MI, USA
Registered: Mar 2007
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posted 02-07-2009 11:13 AM
Page 26 & 27 deal mainly with the image structure in the DCDM so I don't think it can absolutely be applied to the projected picture.
Page 80 8.2.2.7 deals with 2 issues - scaling of content from 2k to 4k and projecting the image onscreen. Since the second paragraph starts out by saying "Should electronic image resizing or scaling be used to support constant height or constant width..." the door is open to scaling and the "intended" statement implies that projecting full pixel count is preferred but not implicitly required. The "intended" statement was not in the original 1.0 spec that the initial systems were installed under.
I think on some level the scaling solution was a stopgap while the WCL was developed (at least for Christie), but I'm sure some hoped it would be permanently allowed so they would not have to pay to retrofit the extra lenses on the 3000 Cinedigm screens. I only have experience with the Cinedigm installs so I don't know what TDC or Kodak were/are installing for lenses.
Don't get me wrong, I agree that we should project each format in its native pixel count - and as far as I know the studios are requiring it (as evidenced by the addition of the WCL).
Once exhibitors start buying their own equipment (and VPFs are gone) I'm sure there will be arguments about lens configurations - after all, the exhibitors currently have the financial choice now on how to configure 35mm (i.e. studios will still book 2:1 formats, poorly lit pictures, bad lenses, etc). If you read the NATO DC system requirement it talks about the end display being the exhibitors choice (i.e. scaling, anamorphics, WCL, etc) - I think the end result of no scaling may be more fixed width screens in new buildings.
It will be interesting to see where this goes once VPFs are gone (some people I've talked with think the studios are going to eventaully allow use of cheap off the shelf HD video projectors - I certainly hope this does not happen).
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Brian Guckian
Jedi Master Film Handler
Posts: 594
From: Dublin, Ireland
Registered: Apr 2003
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posted 02-07-2009 12:17 PM
Well, no matter how you cut and dry it, there are images out there being displayed at 858 x 1587, and it looks like there's nothing to stop it.
Admittedly, it's easy to fall into the trap of associating image quality purely with pixel count, when perceived resolution is also a function of contrast and image stability.
So - on a small screen, with rock-steady stability and a very high contrast ratio, a 1.85 film displayed at 858 x 1587 may well "look" acceptable, in a subjective way.
But is it? If you are a top-line Cinematographer, would you accept your work projected this way, on a 2K digital system?
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Peter Castle
Expert Film Handler
Posts: 220
From: Wollongong University, NSW ,Australia
Registered: Oct 2003
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posted 02-07-2009 08:48 PM
All this discussion seems to me to herald major problems with DCI.
Here in Australia, there's a VERY slow introduction to dCinema, mostly with 3d systems. Unfortunately our exchange rate to the US dollar has dropped dramatically, so that from near parity last year, everything from the States now costs double. So we're looking at A$150,000 for a dCinema system. But there's still discussion about VPFs here, and things may improve - although the current global economic crisis doesn't bode well for an early recovery.
The use of non-DCI compliant projectors, at least in the independent cinema area, has developed a strong local eCinema market. Distributors not aligned to the US majors are using digital distribution to boost their boxoffice very effectively. "Slumdog Millionnaire" is one case in point. And the resolution of these digital copies are now often at full HD (1920 x 1080), although most of the cinemas are using 1.3K projectors to display.
If there's such discussion about projector imager areas, why don't DCI-supporting distributors consider allowing non-compliant projectors to be used?
I'm involved in a University cinema that shows once per week. I guess we're about as sub-run as you can get. Yet eCinema helps us get many quality films closer to release. And we'd love to be DCI but no distributor is going to support us with VPFs. But we do have fullHD projection just waiting to show major studio films.
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Julio Roberto
Jedi Master Film Handler
Posts: 938
From: Madrid, Madrid, Spain
Registered: Oct 2008
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posted 02-08-2009 10:07 AM
DCI is messed up, which is what happens when you let an interested one-sided partner (Hollywood studios) decide what hardware and software manufacturer should do or not do. And they will even tell the owners of this equipment what they should or should not do. They are so jacked-up on security (for a change), they don't get the real matters (technical specs) right.
They, i.e., don't allow for technical improvements (i.e. TI DLPs being capable of better contrast currently), settling for fixed short-sighted standard.
All they care about is security and control of who is projecting what, at what time on what auditorium. If the could put a webcam inside each theater to count the attendance, I'm sure they would make it part of the requirement.
A POST phone line or, far worse yet, a broadband connection for EACH projector (server) requirement is bull-caca. In many countries, a phone line or ADSL is a $80 thing a month that it's TOTALLY uneeded as a single line can more than service an entire location.
And in many countries, a goverment regulated software ticketing system clearly reports every day to interested parties how much attendance each show had and how many times per day it was shown etc already, w/o the need for more keys or locks that can break one day and leave you with a missed show.
They keep delivering half-cooked requirements that are but compromises on their own quality goals. Now they don't seem to care about quality anymore but about making current equipment, whatever it is nowadays (i.e. triple-flash full res 3D, lens magnifiers, zooms, 4fl 3D screens, ... anything goes) even more "secure" and "good enough".
They made a mess, while neglecting important things.
How long until DCI 2.0?
They seriously need to let the technological market do their thing and just concentrate on the content delivery format standard. Let the hardware manufacturers make the most of it and hand out decryption keys to all the stuff that meets a minimun standard, period. It's none of their business to decide if an anamorphic should be used in my projector or not. If the result is right, the resolution is enough and the input format doesn't change, why should they care if I zoom-in, magnify, anamorph or use a 2-lens barrel?
I agree. SMPTE should take over the whole thing and require content to be opened (decryption keys given) to any manufacturer that can read and reproduce it to specs.
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Julio Roberto
Jedi Master Film Handler
Posts: 938
From: Madrid, Madrid, Spain
Registered: Oct 2008
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posted 02-08-2009 01:09 PM
That would be too easy and too good.
I guess the line of thought here is that soon (virtually) no "true scope" is ever going to be used again.
And if (for practical purposes) 2K Super35-scope only has (about) 872 pixels of atteinable "resolution" in the DI, well, no point in upsizing.
I feel the industry moving to all digital 4K adquisition very soon, or 3perf Super35 those remaining on film. True scope is probably heading a slow but sure death.
But don't get me wrong. I'm all for a 2K 1.26x anamorph for TODAY. After all, they did use it in the previous generation of 1.3k digital projectors ...
I just wish they would just all move to 4K, where reduced vertical pixel count is not such a big issue and not using anamorphs allows sharp cheaper optics. The anamorph can give more light, but the lens elements themselves also take away some, so a bit of the advantage is loss there.
I would be happy with a square pixel 4096x1744 4K "scope" array even with the loss of 20% potential raw light and raw pixel count in widescreen films in exchange for the cheaper, sharper optics ...
Now we just need a 4K projector. Wait, we already have Sony. Now, seriously, we need ANOTHER 4K projector manufacturer.
Look at the current top box office offers: Taken (Digital Genesis 4K and 3perf super35), Coraline (digital cameras), Pink Panther (flat), Mall cop (Digital Genesis 4K), Push (super35), Slumdog (digital SI 2K and 3perf Super35), Torino (here is your true scope), Uninvited (flat), Hotel for Dogs (flat).
You get the point. Pbbly only 10%/20% of films are true scope anymore. Soon, digital will take over adquisition format too, as quality cameras with far (far) more true resolution than Imax (yes, you heard that right ... but let's leave that discussion for when we are past this 2K thing and the time arrives) come to market in just a year or two at prices unheard of.
Those that are sceptical remember you can have a 22 Megapixel "35mm" digital photo canon camera today in your house for $2500 or a 24 Megapixel Sony one for about the same price.
Or if you rather shoot 24fps CINEMA, you can BUY a 4.5K (12 megapixel, touted as 4.5K but truly equivalent to about 3.5K "DCI" specification, about 3400x1900 "true" full-color pixels, from the raw array of 4900x2580, 12bits, 4:4:4) for $17.500. Say another $3-$6k for a matching zoom lens. This is the PURCHASE price to shoot effectively, no compromises, 3.5K images into inexpensive flash memory media.
You would then need to downsize it to 2K to display them in a theater .... Welcome to brand new world of cutting-edge digital.
Movies like Bloody valentine or Jumper used them.
Panavision's Viper is a true 4K camera too, obtaining the image from a 6K subpixel array.
Those believing that Imax's huge frame equals an enormous quality ... are right, of course, but also haven't heard of the little hush experiment that Imax did. Better explained here by John Galt, Panavision Senior Vice President of Advanced Digital Imaging:
quote:
A number of years ago some IMAX engineers – and I don’t think IMAX ever let these guys out of their lab again -- did this wonderfully elegant experiment at the Large Film Format Seminar at Universal Studios Imax theatre. They showed this film they made that began with 2 rows of 2 squares: black white, white black, as if you had 4 pixels on the screen.
Then they started to double and double and double the squares. Before they got to 4K the screen was gray. Do you know what the means? There was no longer any difference between black and white, which is what allows you to see sharpness. It's the contrast that we see, not the actual information. Technically, the MTF (Modulation Transfer Function) was zero at 4K!
Let's just pretend for a moment that IMAX truly is 4K. You watch IMAX at between one and one and a half picture heights from the screen. But in order to get to appreciate 4K on a regular movie screen, you would have to sit much closer than normal. In other words, when you go to a movie theater, and most of the modern theaters with stadium seating are designed so that the middle of the theater is 2 ½ to 3 picture heights from the screen, for most of us who watch movies, that’s pretty where we want to be sitting. Maybe just a little bit closer from some of us who do this for a living, because we're maybe looking for artifacts or issues. If you sit much closer than 2 ½ picture heights, that's what you're seeing, artifacts, not movies!
I've run my own calculations and conclude that, generically speaking and in theory, for most auditoriums, 2K is indistinguishable or better than flat 1.85 projected film at 4 times the screen height (back rows of most auditoriums). Scope film is better than digital scope up to about 3 screens heights.
And 4K is indistinguishable or better than Imax at 2 times the screen height. Closer than 2 times the screen height, and Imax wins. So for all those not sitting in the first 3-6 rows or so, 4K *is* Imax (real 15perf 70mm Imax, I mean).
Imax huge frame size has reasons to be other than resolution, like support the light flux for such huge screens w/o melting or fading quickly.
4K at 2 times screen height is already at the about 36lp/degree of limit of the human eye of person with perfect vision ... so we just can't see more detail even if it was there. We would have to move closer to see it.
[ 02-08-2009, 02:29 PM: Message edited by: Julio Roberto ]
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