Film-Tech Forum ARCHIVE: Imax digital DCPs

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Posted by George Murray (Member # 6991) on 10-01-2013, 09:28 AM:

Does anyone know the difference between imax dcps and regular dcps. How much bigger or smaller are the movie files and does the dmr actually do anything? and what about the sound mix is there a difference there as well?

Posted by Edward Havens (Member # 4715) on 10-01-2013, 03:29 PM:

Doing a Google search for "IMAX DCP" brought me to this IMAX blog post from last year explaining the difference.

Posted by Marcel Birgelen (Member # 6801) on 10-01-2013, 06:55 PM:

This has been discussed here before, but that link to the IMAX page you published is, unfortunately, largely just IMAX marketing bs.

IMAX DMR is supposed to be a way of processing 35mm movies and reducing film grain by scanning them at ultra-high resolutions and use the "otherwise invisible stuff between the grains" as means of recovering this "hidden resolution". Also, it seems to employ some noise reduction algorithms that reduce film grain, probably at the cost of sharpness.

While this might still be true for stuff that was actually acquired on 35mm and was never transferred from some rather low resolution digital intermediate, this would be total bullshit for any digital production...

Still, DMR could mean something entirely different for digital content, but IMAX is not telling us what that could be. But, maybe they just run the same bunch of algorithms on digital content, you never know, there might be some hidden information left between those pixels [Razz]

.

So, are IMAX DCPs different from normal DCPs? Yes, they are, they require different keys to begin with. How do they differ? That's something only IMAX knows for sure and they will probably not tell us, because that's part of their secret sauce(tm).

Why do we know for sure at least some of them are different?

1) IMAX DCPs are sometimes in a different aspect ratio. The normal DCP release might be scope, whereas the D-IMAX version might be 1.77:1.
2) Some productions like The Dark Knight Rises, switch between aspect ratios in their D-IMAX version, but don't do that in the scope DCP.
3) Their sound setup is different from your normal 5.1 or 7.1 setup and I suspect their actual sound mix in the DCP is also different.

Posted by Terry Lynn-Stevens (Member # 7349) on 12-04-2013, 09:44 PM:

quote: Marcel Birgelen
IMAX DMR is supposed to be a way of processing 35mm movies and reducing film grain by scanning them at ultra-high resolutions

IMAX does not scan the 35mm images, they are delivered in a digital form.

quote: George Murray
does the dmr actually do anything? and what about the sound mix is there a difference there as well?

Both the images and sound mix are modified. Whether or not there is a benefit to these enhancements is open to viewer interpretation.

Posted by Steve Kraus (Member # 476) on 12-04-2013, 10:47 PM:

What server do they use?

Posted by Gordon McLeod (Member # 33) on 12-04-2013, 10:52 PM:

imax does scan dkp70mmm inc has a very precise film scanner

Posted by Terry Lynn-Stevens (Member # 7349) on 12-05-2013, 07:39 AM:

I guess that would be the case. IMAX just announced that a third party company will be scanning their 70mm library for release in 4K.

Posted by Dave Macaulay (Member # 813) on 12-11-2013, 07:24 AM:

Imax uses Doremi servers with dual SDI output. Projectors were Christie 2220 and are now Barco 32B, all are 2K. The content itself may be the same as on regular drives, who knows? We won't be able to compare it digitally. The data flow after the server is quite different from normal single or dual projector systems though. There is no link encryption, I don't know whether the servers even have encryption cards. The image data goes through the "magic" box that alters each image so that the dual projector images align very closely. The entire outer monster housings are a secure enclosure because the image data is passed around on unencrypted dual SDI.
There are forum members who have a big hate on for Imax. Jealousy?
Imax digital is far from perfect, and a pale shadow of Imax 15/70 - true.
The daily Imax system "self calibration" keeps the image and sound quality reasonably decent: the chain "ultra" screens get typical attention where focus, brightness, sound setup, 3D adapter moves, etc are unpredictable.
Light level in 3D is better than 99% of non-Imax screens. The polarizers are automatically moved so no 2D feature shows through them ever. 3D images are not alternating, both are on screen simultaneously - other dual projector 3D systems do this but that's a fraction of one percent of non-Imax 3D screens.
It is not 4K, admitted. I expect they are working on that... redesigning the image processor is the likely holdup as it will be handling 4X the data. I'm not sure there has been a 4K 3D release anyway.
The huge advantage - here in Canada at least - is that an Imax screen jumps you ahead of any competition without Imax when booking content. An independent Imax digital cinema next door to a Cineplex with a "super ultra extra whizbang-o-vision 4K Atmos with vibrating recliners" premiere screen will be able to book all the blockbusters on opening night. Without Imax they could maybe open Oogieloves, the Cineplex would get every major release. No chain "premiere" system has that advantage.

Posted by Terry Lynn-Stevens (Member # 7349) on 12-11-2013, 09:09 AM:

Dave, thank you for some mature alternative commentary that is not the typical IMAX sucks and they are going out of business because they no longer use 15/70 stuff.

Most of what you wrote was pretty informative to me. The brightness levels are pretty good, much better than UltraAVX. Some of the images from Catching Fire looked outstanding for a 2K presentation, those images were from the anamorphic scenes, but then there were some images that did not look great. The IMAX sequences of the movie where a little underwhelming in digital I must admit.

I am assuming the current Christie projectors could be upgraded to 4K in the future? I also never knew that IMAX would get the preferred booking, but Cineplex owns almost all the IMAX theatres in Ontario so I guess it makes no difference.

Posted by Steve Kraus (Member # 476) on 12-11-2013, 11:54 AM:

I thought the more recent LIEMAX's were 4K but maybe that info was incorrect.

So are you saying the stuff that is done to the image data where the two projectors are getting slightly different data is being done on the fly there at the projector / server level and not back in Toronto? (On 2D. Presumably LIEMAX 3D is just ordinary two projector 3D like anyone can do if they want to spend the money.)

I think I speak for many when I say what we resent about LIEMAX is not LIEMAX itself which is an excellent presentation for 2K. I support the idea of premium theatres. I don't always think they are worth the upcharge but people can decide for themselves. You can only be fooled once. None of the other premiums that I am aware of even use two projectors. No, what I, and presumably others, resent is the unqualified use and dumbing down of the name IMAX. If they'd simply said IMAX DIGITAL there would not have been so much outcry.

Posted by Bobby Henderson (Member # 840) on 12-11-2013, 03:05 PM:

Dual projectors may not be found in every premium priced big screen theater, but I don't know how else one can show 3D at satisfactory brightness levels on a large screen without using dual projectors. It's really the only selling point IMAX possibly has over its big screen rivals when it comes to showing movies in 3D.

A single projector, such as a Barco DP4K-32B or Christie D4K3560, will throw a reasonably bright 2D image onto a giant sized screen. The same isn't true for 3D. I'm sure some premium priced theaters are probably trying it, but I don't think RealD or Dolby 3D will show an acceptably bright image on a giant screen from a single projector.

Some big screen theaters in my region, such as Harkins' Cine Capri screen at the Bricktown 16 theater in Oklahoma City or the two Grand Auditoriums at the Moore Warren Theater in Moore, OK only show movies in 2D. Warren had tried, briefly, showing movies in Dolby 3D in the Grand Auditoriums but quit that. None of those theaters charges a premium for entry, except for the adults-only balconies in Warren's Grand Auditoriums. The Cine Capri is equipped with Dolby Atmos but still charges a standard price.

If Regal has followed what they mentioned in their press releases when launching the RPX concept all of their RPX theaters should have a dual projector setup.

I don't know if any of AMC's ETX screens have dual projectors. Same goes for Cinemark XD, Carmike Big D, Santikos' AVX Max, etc.

Christie sells a "duo" package that works with most of their cinema grade digital projectors. I don't think they would have such a kit, including alignment software, if they didn't have a good supply of customers.

(Edit)

Maybe someone or numerous participants at Film-Tech should develop a list showing how each like-LieMAX big screen concept is equipped (single or dual projection with projector model if possible and any special sound format, like Barco Auro 11. or Dolby Atmos).

Posted by Tom Mundell (Member # 4555) on 12-12-2013, 03:55 PM:

quote: Bobby Henderson
I don't know if any of AMC's ETX screens have dual projectors.

My understanding is AMC does use duel projectors in their ETX screens; I know at least the ETX at Tyson's Corner 16 uses duel projectors. The one (and only) time I was there getting the two images to overlap was a huge problem for some reason; the trailers were so blurry I complained, the projectionist stopped the trailers several times to try to realign the image. He got it much better than it started but it still wasn't very good. I'm not sure if this is a continuing issue (I have never returned to this theater due to this) or if this was ever a problem at other AMC's.

Posted by Carsten Kurz (Member # 5396) on 12-12-2013, 06:43 PM:

I heard that recent IMAX digital installs are using BARCO 4k engines. However, real 4k is necessarily IMB based - this will not work with the IMAX image enhancer black box.

They may be using the 4k machines because of some improved brightness and because the pixel pattern is reduced even when showing 2k content. I am sure that these 4k IMAX systems will still be fed 2k over HD-SDI from the image enhancer.

IMAX would need their own IMB with the image enhancer functionality being built in to show real 4k.

Christies DUO works that way - it needs Christie IMBs in both projectors.

Also wondering how digital IMAX does HFR, as they are showing the Hobbit in HFR.
Probably feeding dual 48fps over HD-SDI to both projectors. I doubt, though, that a Doremi Dolphin card supports dual 48fps streams. Maybe they disable/bypass the image enhancer for 3D or HFR, as it is not really needed for 3D.

Anyone with more insight?

- Carsten

Posted by Steve Kraus (Member # 476) on 12-12-2013, 06:50 PM:

The ETX screen I am familiar with at a theatre that opened within the last couple of years is single projector.

Posted by Stefan Vogels (Member # 5573) on 12-12-2013, 06:53 PM:

They are doing HFR by installing an second doremi server which is than in sync with the master server. They send you 2 files, a right eye version and an left eye version. Each is displayed by the seperate server and projector combo. Imax used Christie CP2000SB and later on the CP2230. They are now over onto Barco to co-develop the laser engines.

Posted by Carsten Kurz (Member # 5396) on 12-13-2013, 08:17 AM:

Do you know if the image enhancer box is used for HFR, or bypassed?

- Carsten

Posted by Stefan Vogels (Member # 5573) on 12-13-2013, 03:51 PM:

By-passed!

Posted by Jonathan Goeldner (Member # 4854) on 12-14-2013, 02:51 PM:

quote: Tom Mundell
My understanding is AMC does use duel projectors in their ETX screens; I know at least the ETX at Tyson's Corner 16 uses duel projectors. The one (and only) time I was there getting the two images to overlap was a huge problem for some reason; the trailers were so blurry I complained, the projectionist stopped the trailers several times to try to realign the image. He got it much better than it started but it still wasn't very good. I'm not sure if this is a continuing issue (I have never returned to this theater due to this) or if this was ever a problem at other AMC's.

the double imaging flaw on the ETX screen at Tysons has been a continual problem since it's debut. Thankfully though both 'Frozen' and 'Thor: The Dark World' were flawless. Not if they could just recalibrate the sound levels so it wasn't so damn loud.

AMC also uses dual projectors over at the Uptown theater here in DC. Trailers have the flaw, but the features themselves look corrected - go figure why that is.

I cannot wait to see Seattle's Cinerama new Christie laser system come next year - in terms of brightness AND no doubling imaging. AMC seems so cheap in not thinking this would solve the occasional hiccups at both the Tyson's ETX and Uptown's systems.

Posted by Marcel Birgelen (Member # 6801) on 12-14-2013, 08:45 PM:

Isn't the problem here that the trailers are in 2D and the feature is in 3D?

If both projectors are showing the same, not 100% aligned image without the polarizers applied, you will get a double image. In that case, it's probably a bad case of scripting, they should close the dowser of either one projector.

Posted by Lyle Romer (Member # 1266) on 12-14-2013, 09:52 PM:

Regarding AMC's ETX, I can only speak for the Downtown Disney 24 since it's the only one I've been in. That location is dual projector. They actually have the Real-D filters on a sliding rail system. For 2D, only 1 projector is used and the filter is out of the way. For 3D both projectors are used.

Posted by John Thomas (Member # 6509) on 12-15-2013, 04:39 PM:

The D-IMAX image enhancer also compensates for the darkened edges caused by the silver screen. Part of the morning calibration process involves red green and blue test patterns where you can see it brightening the edges (or darkening the center?) so the image reflecting back is more evenly lit. The image enhancer really is an impressive thing once you consider everything they're making it do. I could vent for days about the GUI on the SMS software however.

Posted by Terry Lynn-Stevens (Member # 7349) on 12-15-2013, 04:47 PM:

Hi John, is this morning test done everyday? Is it all automated?

Posted by John Roddy (Member # 7348) on 12-15-2013, 06:07 PM:

Calibration is done daily at startup (entirely automated). It involves several different image tests and audio adjustments. There is a camera hidden in the gap between the port windows, and at least three microphones scattered throughout the auditorium for this. Of course, in the event of a rushed startup or something, calibration can be bypassed and forced to load the previous day's info, but IMAX strongly recommends against this.

You can also go into the IE settings and force it to run part or all of the entire calibration at any point during the day.

Posted by Terry Lynn-Stevens (Member # 7349) on 12-15-2013, 08:36 PM:

Thanks John, I never knew IMAX projector self calibrated. If you don't mind me asking. How long does it take?

Posted by John Roddy (Member # 7348) on 12-15-2013, 08:48 PM:

Daily IMAX calibration takes about 40–45 minutes. About 30 minutes of that is spent just idling while it waits for the lamps to warm up. The actual calibration itself runs for maybe 10–15 minutes after that. The auditorium also needs to be clear during this time. All lights need to be shut off and doors closed as well, for the most accurate results (as recommended by IMAX).

Posted by Marcel Birgelen (Member # 6801) on 12-16-2013, 04:27 AM:

I've never seen it in action, but if you take a look at the manual of Christie Duo (which also has been previously mentioned), it can potentially do anything that IMAX does in regards of dual projectors aligning on screen and it indeed does support both HFR and 4K.

It also uses a camera to check and calibrate the alignment. You can even program it to do an automatic calibration and log messages if stuff is not working out.

Besides the brand recognition, to me, this looks like yet another competitive advantage in regards to IMAX.

Posted by Steve Guttag (Member # 268) on 12-16-2013, 06:09 AM:

Christie Duo has the advantage that it gets the lenses VERY close to begin with...the potential downside is that it uses a mirror on one projector.

Posted by Terry Lynn-Stevens (Member # 7349) on 12-16-2013, 09:03 AM:

quote: Marcel Birgelen
I've never seen it in action, but if you take a look at the manual of Christie Duo (which also has been previously mentioned), it can potentially do anything that IMAX does in regards of dual projectors aligning on screen and it indeed does support both HFR and 4K.

Looks like a real PITA, Christie does not recommend side by side set up and RealD XL only works on the stacked set up which is recommended. Anyways, no theatre within 10 hours driving distance of me runs dual projectors aside from the IMAX locations.

Posted by Steve Guttag (Member # 268) on 12-16-2013, 10:30 AM:

When running the Christie Duo...you would not use an XL...you'd run just a polarization filter in front of each. Both projectors are active at all times.

As far as set up, I think Christie has it reasonably well thought out. There would be time aligning the mirror on the initial set up (the mirror is conformable to deal with curved screens even)...then the auto alignment system will take care of any lens variations. The demo I saw was quite good.

Posted by Marcel Birgelen (Member # 6801) on 12-16-2013, 12:33 PM:

Page 52 of the manual accurately summarizes what works and what not.

Steve already said it, a normal RealD XL unit would be impractical in a normal dual 3D projector setup, since you would run Left and Right eye from a separate projector. There's a RealD XL-DP, which uses static polarizers instead of a ZScreen, but still offers the added brightness of the XL setup by inverting reflected light that get's reflected back from the polarizer. The problem with this setup is that it obviously doesn't fit in front of the mirror construction. The plate polarizer Christie offers also comes with a split-plate configuration that should fit in front of the single/dual mirror.

Christies plate polarizers are manually movable, but I didn't find any information what kind of polarization they use (linear like IMAX or circular like most of the rest).

It would be interesting to see the difference in convergence that can be achieved between the different setups (stacked, side-by-side, single/dual-mirror) that this Duo setup offers.

Posted by Steve Guttag (Member # 268) on 12-16-2013, 08:29 PM:

I'll say that I've seen the convergence on the Duo system and it was rather impressive...even in the corners. This was a test set up so YMMV in the field but it was enough to convince me that the concept was sound. With the Duo, one need not just think about 3D but also extra-bright 2D for large/outdoor screens too...the convergence was THAT good.

Posted by Carsten Kurz (Member # 5396) on 12-17-2013, 06:42 PM:

@Stefan Vogels:

Previous IMAX installations, Christie or BARCO based, used 2*2k DLP Projectors. There have been rumors that (some?) recent installs used BARCO 4k engines - I would guess, basically to get rid of the 2k pixel raster. Can you comment on these 2*4k rumors?

- Carsten

Posted by Stefan Vogels (Member # 5573) on 12-19-2013, 03:00 PM:

It's true IMAX has used some DP4K-32B's for new installs but that would besides the extra pixels be more about light output. The 1,38" chip is more light efficient which they need badly on the bigger screens. They are not switching entirely to 4K on all sites but await the Laser solution.