Film-Tech Forum ARCHIVE: D-IMAX Aspect Ratio?

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Posted by Keegan O'Brien (Member # 6539) on 12-08-2011, 08:59 AM:

I'm aware that current digital IMAX projectors have a tallest ratio of 1.78:1, but for IMAX filmed movies (TDK, TF2, M:I 4, TDKR), do they put a lens of some kind, or have ratio's in the DCP altered in some way that native 1.44:1 footage can be shown in 1.44:1? A lot, if not most, D-IMAX theaters have 1.44:1 screens, so I'm curious if I should expect IMAX content to fill up that screen, or if I should expect a fair amount of blank screen during 15/65 shot content.

Thanks.

Posted by Edward Havens (Member # 4715) on 12-08-2011, 03:17 PM:

At our D-IMAX location, our screen is 1.44:1, which we played Born to Be Wild 3D at.

Posted by John Thomas (Member # 6509) on 12-09-2011, 03:37 AM:

Ours is 1.85:1, with no masking. So anything that isn't in flat gets letterboxed.

Posted by Carsten Kurz (Member # 5396) on 12-09-2011, 03:47 AM:

The native AR of digital iMax is the same as for all other DCI projectors - 1.89:1, that is, basically, a Flat AR.

What they do to fill existing/modernized screens, is probably dependant on the feature and in how far special AR shots are embedded and which effect is intended with changing ARs.

Bear in mind that digital iMAX was developed to be able to play more mainstream content, and that is either 1.85 or 2.35, so all experiments with classic IMAX ARs are limited, and will probably vanisch in the future anyway. When the last IMAX Cameras have been smashed by tumbling BatBikes, it will be over, even for Chris Nolan.

- Carsten

Posted by Antti Nayha (Member # 4980) on 12-09-2011, 06:56 AM:

So the classically shaped IMAX giant screens with 2K digital projectors are showing 1.44:1 content with a resolution of, what, 1555x1080? Doesn’t sound very ”immersive” to me.

I’ve only been to a digital IMAX screening once and that was at Hoyts, Sydney in January 2009. Their screen was a very odd ”smilescreen” shape – check out my rough drawing here. Is that a common configuration at digital IMAX venues nowadays? Is the DMR mastering any better nowadays? (If you read the whole story behind the link, you will understand why I haven’t gone to another digital IMAX screening to see for myself…)

Posted by Carsten Kurz (Member # 5396) on 12-10-2011, 08:36 AM:

I have no idea in how far digital IMAX theaters play special LieMax versions of mainstream features or plain vanilla DCPs as every digital screen does- maybe a mix of both. Somewhere I read that they have a special processing, be it realtime during playback, or offline in mastering to also accomodate in a special way for their 2*2k projector setups.

I don't think the image experience you wrote about nearly 3 years ago is typical for digital IMAX, maybe that movie was mastered badly anyway or the special digital IMAX mastering was so new for them that they blew it.

IMAX DMR was conceived for 15/70 analog. Any rescaling for digital IMAX might involve parts of similiar processes, but in all, it's a completely different thing, even if they should call it the same for marketing reasons.

Anyway, there are certainly digital IMAX theaters with a better experience around, but at the same time there are a lot of non-IMAX theaters with very large screens which offer the same or even better experience. At least some of them now offer REAL 4k projection from some REAL 4k features, which you will not find in any digital IMAX so far.

IMAX is actively developing laserprojection for their largest theaters, and it seems they are after a split strategy, broadening the brand in medium-to-large conventional aspect ratio digital IMAX first with more mainstream, and replacing 15/70 in their largest flagship and dome venues when their laser technology is ready for market. Maybe then they will be back up to their claims they originally pursued in replacing 15/70 with digital installations.

- Carsten

Posted by Jake Spell (Member # 5294) on 12-10-2011, 08:56 AM:

I find it doubtful that they will be back up to their old standards even with laser projection. Sure it solves the light issue but what about the resolution? Is TI making a special DLP chip thats higher resolution and the correct aspect for the older IMAX 15/70 installs?

Posted by Keegan O'Brien (Member # 6539) on 12-10-2011, 04:58 PM:

Hm. I ask because during the M:I 4 trailer, when scenes were supposed to be 1.44:1, they switched to 1.78:1 instead, leaving the entire bottom section of the screen blank. I hope that was solely for that trailer, and not for the actual film. That'd be highly disappointing.

Posted by Carsten Kurz (Member # 5396) on 12-11-2011, 06:08 AM:

quote: Jake Spell
Is TI making a special DLP chip thats higher resolution and the correct aspect for the older IMAX 15/70 installs?

There are different ways to apply laserprojection to digital cinema - some, like the upcoming Barco solution, simply replace XENON with a laser light source, hence these projectors basically have the same resolution as standard XENON DLP units, aside from some optically improved 'sharpening' through higher contrast/smaller apertures and the like.

But that is not the only way.

I have not seen any indication wether IMAX simply bought into the design of Kodaks recent 'ready to market' laser projector with conventional DLP imagers, or wether the Kodak patents offer a broader approach.
Kodak published papers on laser-projection technology years ago that DID implement DLP technology, but not with a conventional area-imager, and to my knowledge, TI is not the only company producing DMDs for special applications (although they are certainly the only one producing 4k area imagers).

Even if they'd use 4k DLP imagers, they could just as well implement multiprojector installations with edgeblending like they are common in dome installations for digital planetariums. http://www.skyskan.com/products/systems/projection/8k
It would be quite expensive, but 15/70 was never cheap either, and in this case at least they could again buy and modify existing standard gear and could still show mainstream content.

- Carsten

Posted by John Thomas (Member # 6509) on 12-14-2011, 01:20 AM:

We ran MI4 on our D-IMAX tonight, which has a 1.85:1 screen and no moveable masking. A good portion of the movie was in letterboxed scope (as any scope movie looks in that house), whereas the "IMAX" parts did completely fill the screen. Makes me curious as to how they adapted it to 35mm.

Posted by Keegan O'Brien (Member # 6539) on 12-18-2011, 03:55 PM:

Yeah, the 15/65mm portions were shown at 1.85:1, unfortunately.

Posted by Jonathan Goeldner (Member # 4854) on 12-18-2011, 11:44 PM:

@ John Thomas: in recomposing for the 35mm prints I'm pretty sure they did what with 'The Dark Knight' (as well as Transformers 2) in that the 1.85:1 (AR) shot footage is cropped to a consistent 2.35 (scope) image. One would assume for the bluray release the IMAX shot scenes will be in 1.78 and alternate with the 2.35 footage. Question: is the shifting aspect ratio scenes also done for the speciality 'large' screens: ETX, XD, Xtreme, ISD, etc., ??

Also, I'm confused? Bird shot the IMAX scenes in 1.85?? why didn't he shot it in 4:3 the more common aspect ratio for 15/70 IMAX films?

EDIT: okay, from what I'm hearing/reading from folks who saw this on a 15/70 IMAX screen the IMAX shot scenes are full screen 4:3, while the image on IMAX-Digital screens are full screen 1.78/1.85 (cropped)

Posted by Mark Lensenmayer (Member # 134) on 12-19-2011, 01:11 PM:

Saw Mission Impossible on a Rave XTreme screen and there was no shift in aspect ratio.

Posted by Jonathan Goeldner (Member # 4854) on 12-20-2011, 11:38 PM:

^ no aspect ratio shift, but at least the D-cinema version is one up on the IMAX version with the 7.1 soundmix.