"IMAX Experience" questions

[Tom Lowe]

So IMAX has converted hundreds of large-screen theater rooms in large multiplexes and dubbed them "IMAX Experience" theaters. From what I (might mistakenly) understand, they have two 2K projectors side by side, projecting two 2K images simultaneously, resulting in "greater than 2K resolution".

How does this system work? If I submitted an "IMAX Experience" film to IMAX for display in these theaters (not 70mm IMAX proper screens) at 3K RGB master file, would this be enough resolution for "IMAX Experience"?

Thanks!

 

[Andrew Walker]

If they do have two 2K projectors up there working at the same time I bet its just to get the right light out on the screen and has nothing to do with resolution.

 

[Tom Lowe]

I have heard some discussion about these IMAX EXPERIENCE theaters having "greater-than-2K resolution".

 

[Iannis Holwech]

The aspect ratio of IMAX is 1:43:1.
It is possible they stack a split of the image from two projectors above each other with horizontal edge blending.
That will bring the image into "the ballpark" of 2048 x 1432 @ 2.9 megapixel.

Framing RED one to 3640 x 2540 @ 9.2 megapixel and downsample should be about right.

Edit; Adding that Imax probably will get 4K projectors faster than anyone. So save your 4K files. :thumbup1:

 

[Stuart English]

IMAX

IMAX

Framing RED one to 3640 x 2540 @ 9.2 megapixel and downsample should be about right.

That's taller than a single RED ONE camera can record, but it certainly could be done on a single EPIC.

So if you wanted to do this on RED ONE, sync two cameras using RS170A Genlock.

 

[Iannis Holwech]

That's taller than a single RED ONE camera can record, but it certainly could be done on a single EPIC.

So if you wanted to do this on RED ONE, sync two cameras using RS170A Genlock.

Ok! What is the tallest frame RED One can do? Then frame for 1:43:1 based on the vertical.

Slightly OT; http://www.avsforum.com/avs-vb/showthread.php?t=1310227 (Somewhat messy report, but they showed some RED 4K (AFAIK) and shootout 4K vs 70mm)

 

[Keegan O'Brien]

They use dual projectors so they can cast as much light as possible on the screen, which will make 3D showings significantly better. The images resolution is still 2K, although one with think with two 2K projectors you'd get a 4K image. Having seen a film via D-IMAX, I think it was a BIG mistake to go with DLP's 2K projectors as opposed to dual Sony 4K projectors. If you're paying attention you can make out pixels on the screen, which is unpleasant.

 

[Tom Lowe]

I am talking about IMAX Experience theaters, NOT proper 70mm IMAX theaters. The aspect of IMAX Experience is closer to 16:9, nowhere near the taller aspect ratio of proper 70mm IMAX, which might range from 4:3 to 3:2, depending on the theater.

IMAX Experience is all digital -- 2 x 2K projectors. IMAX 70mm is mainly 70mm film.

What I want to know is: at what resolution would I deliver an IMAX Experience film to the IMAX corporation? 2K RGB? 3K RGB?

 

[Andy Jarosz]

This should clear up a lot of confusion, via downinfront.net.

http://downinfrontshow.blogspot.com/2009/11/test.html

 

[Keegan O'Brien]

They use something called DCP files Tom. That's all I know.

 

[Tom Lowe]

This should clear up a lot of confusion, via downinfront.net.

http://downinfrontshow.blogspot.com/2009/11/test.html

So it sounds like they are working from a 4K file, and breaking it down into two, separate 2K files. I would if this could be accomplished directly from a 3K file?

 

[Tim Hole]

Tom, I don't know if there is a single answer to the question. IMAX do the conversion in-house. As it depends on the the case by case film asset. I cannot forsee any difficulty in IMAX doing this conversion from a 3K file. Animation is obviously a different kettle of fish however if it originated on film then their scans may well be 4K, but they have their own pipeline for blowing up films that were shot on lower resolution. A 3K file would be ample resolution for them to convert to their own exhibition format which is still 2K per projector but it is the nature of how the two images are used.

I think the one thing though that would need consultation is the aspect ratio.

As a side note they did test IMAX with two 4K projectors however they considered the difference to be negligable and not many people noticed a difference. So they decided to go 2K.

Clarification also. IMAX EXPERIENCE image format is 4096x2160 which is 1:90:1

 

[Andrew Walker]

So does this two projector 4K info show up on their site. In my experience in projection, when you have two projectors its for light. I could see this being the case with IMAX because most of the screens I have seen are huge but have a very short throw (Distance from lens to screen). So the light gets spread out too much and looks very dim. So the second projector helps get past this problem by adding to the light. You can only blast these DLP chips with so much light before they start to cook.

But for what you could deliver to IMAX Tom I would think a 3K master should be good...DPX files of course. Best to talk with IMAX. But if you need a 2K DCP made I've made them on my own and played them back at Warner Bros. on their 2K projector and it looks amazing. You can do this all for free with open source tools. Might be able to do a test for you over there. I know its not IMAX but gives you an idea as to what a 2K version of your material will look like on the screen.

 

[Tim Hole]

So does this two projector 4K info show up on their site. In my experience in projection, when you have two projectors its for light. I could see this being the case with IMAX because most of the screens I have seen are huge but have a very short throw (Distance from lens to screen). So the light gets spread out too much and looks very dim. So the second projector helps get past this problem by adding to the light. You can only blast these DLP chips with so much light before they start to cook.

Not sure if the info is on their site or not. I only know that from having conversations with them about it. Having two projectors is absolutely all about brightness and contrast.

I imagine that the resolution is the result of the subset from the two images. I am not sure however as my knowledge of the mechanics is limited, but I'm not sure how much is the physical position of the projectors, the lens construction, and how much is dual projection - when it comes to the curved screen which is obviously one of the main features of IMAX.

The argument is that Digital IMAX screens do not need to be as large as traditional IMAX screens because the seating distance is shortened. Thus you peripheral vision can be filled with a smaller screen.