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Author Topic: DCI spec brightness for 3D?
Carsten Kurz
Film God

Posts: 4340
From: Cologne, NRW, Germany
Registered: Aug 2009


 - posted 09-04-2009 02:27 AM      Profile for Carsten Kurz   Email Carsten Kurz   Send New Private Message       Edit/Delete Post 
Hi everyone,

has anyone seen a DCI brightness spec for 3D installations? DCI wants 14 +/-3 fL in general - but when it comes to 3D in practical terms, there seems to be an 'as good as it gets' policy.

- Carsten

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Steve Guttag
We forgot the crackers Gromit!!!

Posts: 12814
From: Annapolis, MD
Registered: Dec 1999


 - posted 09-04-2009 03:45 AM      Profile for Steve Guttag   Email Steve Guttag   Send New Private Message       Edit/Delete Post 
To the best of my knowledge, there is no 3D light spec in the DCI document. At the moment, 3.5-5.5 seems to be the target (as measured though the glasses to see what the actual light reaching each eye is. Naturally, the goal would be to have 14fL for all titles...but the practicality of that is not there yet.

Furthrmore...aside from the center measured brightest point...with 3D, the light uniformity also does not meet DCI spec...all of those flat gain screens people have to get the light...they guarantee that you will have less than desirable uniformity.

So there is a lot of hand-waving, winking...etc when it comes to 3D and what it does to the other aspects of the image.

Steve

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Julio Roberto
Jedi Master Film Handler

Posts: 938
From: Madrid, Madrid, Spain
Registered: Oct 2008


 - posted 09-04-2009 05:40 AM      Profile for Julio Roberto     Send New Private Message       Edit/Delete Post 
Just what Steve said.

Theoretically, DCI wants images bright (14fl) and uniform.

They also want equipment (projector and server) to meet FIPS 1.3 level 3 specs.

But since projection equipment that can meet that security level does not yet exists (perhaps Sony will pass, don't know) and 3D projection has a hard time getting anywhere near that brightness level for 3D, Hollywood is looking the other way for the time being and allowing cinemas to use non-(full)DCI equipment and lower light levels for 3D.

For the time being, they are making their 3D movies thinking they'll be projected between 3.5 and 5.5fl.

Like Steve said, because many of these systems either require either a polarizing-preserving screen, usually a silver screen, and these are high-gain, the uniformity levels are also not obtained.

Other systems like XpanD or Dolby, which do not require silver screens, often times also "cheat" and use very high gain screens to obtain the target ~5fl illumination level sacrificing the illumination uniformity.

They are also allowing for 3D films to be displayed at 4:2:2 10 bits color resolution/sample against their "own rules" that dci images be 4:4:4 12bits.

Hollywood seems to allow a free buffet when it comes to 3D, with, like you said, an "anything goes" attitude.

For the time being. Just keep in mind that they do not meet DCI specs (image or security) and they can refuse to serve movies at any time in the future or force an upgrade later on.

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Frank Angel
Film God

Posts: 5305
From: Brooklyn NY USA
Registered: Dec 1999


 - posted 09-05-2009 02:56 PM      Profile for Frank Angel   Author's Homepage   Email Frank Angel   Send New Private Message       Edit/Delete Post 
Funny how the studios never gave a rat's astrological sign about light unifornity or brightness level or "color space" when they were distributing 35mm prints and there were to many theatres to count that didn't meet ANY benchmarks specs at all. With film, it was, here's a print, run it and pay us the percentage. There was no demand to meet any spec. Hell, till very recently there was a theatre here in Brooklyn running mono sound and projecting on a 2:1, one-size-fits-all screen -- he seemed to have no trouble whatsoever playing first run on opening night.

So why all of a sudden this police state mentality about quality....well, maybe not so much about quality as it is security, but still. It's a different approach with digital. I am not saying it's a BAD thing demanding specs be met, at least for the customer, but I am wondering why all of a sudden since they never were remotely concerned about quality or standards before. Studios never "approved" film projectors, and especially given how hard they want exhibtion to convert to digital, you would think they wouldn't be all that gungho about telling an exhibitor who comes money-in-hand, ready to convert to digital, that he can only buy from this list of equipment which the studio approves (for NOW!) and if he buys some other, they will not service him with product. Doesn't seem like the way to go when they would much rather not have to make film prints for him.

I mean, for example, even if his color space is off slightly with digital and he is displaying 4:2:2 10 bits color, when he was projecting film, he could have conceivably been showing a terrible image -- and who cared? He played the run, he made money for the studio; end of story. Seems now they are telling him, if you are not x % compliant, you don't get product. To which he could easily say, "Then I am back to showing film."

The thing I find fascinating is that the studios can let an exhibitor use equipment that is not 100% DCI compliant NOW, but sometime in the near future they can decide they won't book product to him because they changed the rules and now they want 100% compliance. Seems counter productive if the goal is to get as many screens converted to digital and to eliminating film.

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Julio Roberto
Jedi Master Film Handler

Posts: 938
From: Madrid, Madrid, Spain
Registered: Oct 2008


 - posted 09-06-2009 03:30 AM      Profile for Julio Roberto     Send New Private Message       Edit/Delete Post 
Yeah, I've wondered about that too.

What I think, is that DCI is using the quality measure as an EXCUSE to force the security measures, the single format delivery, and a reduced crop of projectors they can easily control.

When they "designed" DCI the EXISTING equipment pretty much already could do 4:4:4 12bits easily by adopting JP2K and manufacturers where touting the capability, along others like watermarking (I remember philips running ads in trade publications, or the microcode developers touting their JP2K-in-a-chip FPGAs), etc.

DCI wanted three things: a SINGLE DELIVERY FORMAT that, if possible, would surpass home viewing so they didn't get too-much a direct competition from blu-ray, and a HIGHLY SECURE system, which would make it "impossible" to (digitally) copy the movies and easier to trace them when videotaped, and MORE CONTROL OVER THE EQUIPMENT (i.e. internet "spy" connections to projectors, KDM, etc), so they could track what theaters where projecting what/when/how/why.

The quality part of it was just an excuse to justify why theaters had to use expensive (secure) equipment rather than $1000 home projectors, capable of virtually exact quality levels as DCI when doing 3D today, and to move away from the existing-at-the-time MPEG compression, as independent distributors could charn those out too easily.

By requiring a system based in absolute color coordinates with no convertion from master to the screen (i.e. 4:4:4 xyz all the way), they avoided the problem of having to deliver but a single file fits all. Less mastering, even less hussle and cost for them on "print" delivery and archiving. Less trouble for video servers to comply with security on simplified code.

But I think quality only comes fourth to them. First, it's security. Second, it's single-delivery-format. Third is "print control" and theater (projector) surpervision. Fourth is quality, partly because why not? and partly because it's an excuse to go into single-format and more expensive "exclusive" equipment that it's easier to control (FIPS security, fewer serial numbers/server types, KDM, network "spy" connections, etc).

Otherwise, they don't really care if you DCI projector is doing 4:4:4 or 4:2:2 or 12bits or even 8bits or out-of-focus or lower lamp or high-gain screen or 14fl or 5fl or wathever. They are more likely to cut you off for not having a network connection that they can check to see what you are projecting on what screen at what time than on the quality of your show.

It's said that early Sony's didn't meet color accuracy targets. Did DCI banned Sony? I think quality is mostly a red herring. They DO care about it, of course, but it's not what drives DCI, but just a last-minute-afterthought when everything else in their agenda is met, presented as an excuse to justify the cost of everything else.

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Steve Guttag
We forgot the crackers Gromit!!!

Posts: 12814
From: Annapolis, MD
Registered: Dec 1999


 - posted 09-06-2009 09:30 AM      Profile for Steve Guttag   Email Steve Guttag   Send New Private Message       Edit/Delete Post 
Frank,

Just for a reality check...the only "police state" in DCinema is the security stuff. There is nobody going around checking to see if the colors were set up or the illumination or anything else. You just need the DCinema equipment in order to get the content (or get the content to play).

There is nothing to stop one from using the cheapest DCinema projector they can find for most anything and NOT set it up worth a flip, with the smallest lamp it can run. Who is going to know? How many people verify that a proper "EQ" was done on most sound systems? That is all defined too by SMPTE.

However, just like with film, if you have a studio screening done in your theatre where the studio is paying for tech(s) to tweak your system, that is when you'll get "caught." Most likely before the actual play date as an advance survey is normally done on a "new" site. How many of you all have studio screenings in your theatres? Those that raised their mouses probably also ensure that they are reasonably well set up...just like those that run such screenings with film prints.

However a difference between film and digital on things like color and brightness are the tools available (to just about everyone) to get these things right...especially color on a DLP. With a calibrated chromaticity meter, it doesn't take long at all to properly set up the projector so it will be darn near perfect. As for light, either the theatre equips with right light level or they don't...I don't suspect that being digital will improve on that area...cheap before, cheap now.

Steve

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Frank Angel
Film God

Posts: 5305
From: Brooklyn NY USA
Registered: Dec 1999


 - posted 09-07-2009 01:07 PM      Profile for Frank Angel   Author's Homepage   Email Frank Angel   Send New Private Message       Edit/Delete Post 
What you guys said....my gut should have told me that it was much more about security control than presentation quality cause like I said, they never were any too concerned about presentation in the past (unless it was for their exec and press screenings when with film, those screening invariably would get EK prints).

And hey, like you say Steve, putting a digital projector in a booth that was sloppily run when there were film projectors in it won't change much -- give it time and they will find a way to degrade digital presentation as well, although it might take a little longer give they won't need anyone to "handle" the digital equipment as much as film. But you're right -- a cheap exhibitor can run the bulb in the digtal projector long after it darkens and can barely strike, just like he did in his 35mm projector lamphouse.

Thing is, the DCI compliant thing is where they do seem to have an powerful hold on the exhibitor's gonads. This business about what percentage of DCI compliance they will or won't allow and when and where is the kicker. I mean Disney, which has never been shy about kicking exhibitors' gonads, came right out told exhibitors that the current digital equipment, even the stuff on their "approved" list, was ok FOR THE TIME BEING, but it's not 100% DCI compliant, so in the future when equipment DOES become 100% DCI compliant, the exhibitor will have to upgrade or not get Disney product. They also added in that memo that if for some reason the venue was not being serviced Disney film product, shelling out a hundred grand to convert to digital, even the digital stuff on the approved list, the guy STILL won't get Disney product. Not exactly the kind of thing you would expect a company that would just as soon sell its toon grandmother down the toon river to get more digital penetration, would say to exhibitors.

Besides, if I were seriously contemplating converting to DCinema and heard that statement, I would say, "Hey, you know what? My film projector runs just fine....keep supplying me with those dastardly 35mm prints which you distributors now seems to collectively loath and I'll wait until everything is totally 100% DCI compliant when The Rodent nor any other studio will be able to tell me I have to spend even MORE money on NEWER equipment or they will pull the plug. Then again, for just such an eventuality, maybe I will already have put Quik-Connect plugs all the connections on my film projector and put it on a dolly so I can roll it right back to the port, plug it in, and before I can finish cussing distribution from here to next Sunday, I can be showing 35mm prints again.

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Steve Guttag
We forgot the crackers Gromit!!!

Posts: 12814
From: Annapolis, MD
Registered: Dec 1999


 - posted 09-07-2009 04:21 PM      Profile for Steve Guttag   Email Steve Guttag   Send New Private Message       Edit/Delete Post 
I think you are confusing two things Frank...VPFs and getting product. Booking is booking...digital or film, that isn't changing. Disney will only pay VPFs if a theatre stays current on the DCI thing up to the current spec.

Now, while they may allow you a digital print...that print WILL have the latest DCI encryption...etc in it so if you theatre doesn't have say cine-link II decryption, it isn't going to play. Disney's position is that if you want them to foot a huge part of the digital bill, YOU have to keep it current to the established (and possibly moving) spec. You'll find anyone else on the VPF thing is on that too.

Personally, I think they should honor any equipment that was as current as it could be at the time.

Steve

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