New IMAX Digital Camera "4K resolution"

[Matt W.]

I believe the apocryphal "line test" (someone printed line pairs on IMAX film until they were indecipherable as gray, which happened around 4k resolution). But then what's the mft of the printer? Where was the audience sitting and how good was their eysight? Who focused the projector? So who knows. Fwiw, in the still image world, FF digital (20-30MP or so) is generally considered to be comparable to 6X7 film, which is essentially IMAX-sized, even though film resolves more fine detail. This is because digital has much higher mtf until extinction and thus higher acutance (film has a gradual slope) and film is really grainy.

As I've stated before, since film is essentially "one bit," the dye clouds have to be different sizes to have any tonality and latitude. So there's fine detail, but also major grain that's bigger than it. Digital is relatively grainless and texturally homogeneous (flat). So if you measure film based on 100% mtf (which digital cameras don't hit until well before nyquist, to be fair) IMAX is 5 megapixels, and if you measure absolute extinction it's about 85 megapixels. That means the original IMAX negative captures NO MORE than about 11K, and perceptually much less (based on what I've seen from still cameras, I'd say IMAX/6x7 looks similar to 20-30 megapixels but a bit grainier at 100ISO, and downhill from there).

The thing is, the major reason for a large negative is to mitigate graininess, and digital is, well, not grainy at any resolution. The increased viewing distance with IMAX is a factor, too. So I think 4k would make a fine replacement for IMAX, especially if the sensor were larger than super35 and thus allowed for more micro-contrast from the lens...but it would hopefully represent a stopgap before even higher resolutions, because it's not equal to IMAX film.

P.S. Merry Christmas!

 

[David Mullen ASC]

The thing is, the major reason for a large negative is to mitigate graininess, and digital is, well, not grainy at any resolution. The increased viewing distance with IMAX is a factor, too. So I think 4k would make a fine replacement for IMAX, especially if the sensor were larger than super35 and thus allowed for more micro-contrast from the lens...but it would hopefully represent a stopgap before even higher resolutions, because it's not equal to IMAX film.

But if every movie ends up shooting in 4K as Red would like... then why would IMAX be a dramatically better movie experience if it's also 4K? The label would become essentially meaningless. The improvement between 35mm and IMAX is huge and it's not merely due to a lack of graininess, there is a substantial increase in resolution. "Digital IMAX" has to be a similar leap beyond what most digitally-shot movies are achieving -- if it's just a subtle improvement, then interest in the format will die off.

And if you go into a real IMAX theater, there is some increase in viewing distance but also a major increase in viewing size unless you sit near the rear of the theater.

I think a temporary switch by IMAX from 15-perf 65mm origination to 4K origination and projection would more or less kill the format within a few years because people are going to start to realize that they don't have to go to an IMAX theater to see 4K footage projected in 4K, not if 4K takes off for general theaters. The "wow" factor that has traditionally been the appeal of IMAX will be lost and might not ever return.

I can't believe I'm in a forum where some members advocate lifting general movies up to 4K... but bringing IMAX down to 4K! Why is compromise unacceptable in the first case but acceptable in the second, especially since IMAX is supposed to be a special venue system and a unique experience? It shouldn't be average or typical in any way, it should be exceptional as a general rule, if that makes sense. Your run-of-the-mill movie maybe can live with technical compromise, but IMAX movies are supposed to be technically stunning as a matter-of-fact.

 

[David Mullen ASC]

Honestly, does it make sense to anyone that if 35mm is 3.2K resolution that the digital replacement for a film format that is nearly 3X wider than 35mm should be 4K??? By that logic, the digital replacement for 35mm only needs to be 1.3K - then it would make sense that something 3X wider would be 4K.

 

[Tom Lowe]

David, I paid close attention to the 15-perf scenes in Dark Knight, projected at a proper 70mm IMAX theater in Irvine, and I can tell you, they are roughly the same resolution as my 5.6K Canon timelapse shots. This is why I believe strongly that a full-frame 6K Monstro sensor (projected at 4K) will hold up against IMAX 70mm projection just fine.

If you listen to the Redcentre podcast #78 with Angus Bickerton, the VFX supervisor on Narnia (http://www.fxguide.com/redcentre), he points out that after testing all of available cameras at the time (F23, F35, Arri D21, Red One M, etc), he was stunned at how low the resolution was with actual film, and how noisy/grainy it was.

6K res might not seem like a lot, but is a lot, due to the lack of grain and noise -- the ultra-clean image. IMAX 15-perf might have a theoretical resolution of 8K or something like that , but in practice, it does not appear that detailed, to my eyes.

 

[David Mullen ASC]

6K digital origination would probably be fine for IMAX screens today, for lots of reasons... but if more and more movies are shot in 4K, then 6K may not seem like a dramatic-enough leap in quality. But when compared against typical 35mm photography, I'm sure 6K digital-to-IMAX is going to look similar to general IMAX photography due to the lack of grain and higher MTF.

But again, we're talking about the future of IMAX, which not only has to be about not lowering the current quality of 15-perf 65mm photography, but also about staying ahead of the competition, and if the future is 4K for movies, then the future for IMAX in an ideal world would be at least double that to provide a significant jump in quality.

But we weren't talking about a 6K standard for IMAX, we were talking about a 4K standard for IMAX, which just strikes me as short-sighted and, well, uninspiring.

If you believe Red when they say they can measure 3.2K out of a 24mm-wide strip of movie film, simple logic and math says that the same film stock but 70mm-wide instead has to be measuring well more than 6K unless the lens MTF starts to become the limiting factor. Like I said, in theory, it should measure 9K, but let's just say that the lower MTF of large format lenses starts to kick in and you end up with 6K. I can see that as a possibility, though testing it would be nice. But I have a hard time believing that if you can achieve 3.2K on a piece of 35mm film, you can only achieve 4K on a 15-perf 65mm piece of film.

I just don't get the attitude around here that says we need to improve the moviegoing experience, make 4K the standard... and then people turn right around and start saying that 4K is good enough for IMAX and start bringing in all sorts of excuses for lowering the standard, etc. You can't have it both ways, you can't be high-minded about general moviemaking but then say that IMAX should start making compromises. It starts to smell like excuse-making, "Red is now making 4K and 5K cameras so movies should aim for that higher standard because 1080P/2K is not 'good enough'.... but since Red doesn't make 6K and 8K cameras, IMAX should consider lowering their standards down to 4K and 5K because that's 'good enough' for IMAX."

 

[Deanan]

Sure, but that line of thinking leads to shooting features in 1080P, doesn't it? We all heard plenty of talk when "Attack of the Clones" went into production about how a projected 35mm release print from a dupe neg is barely 1K, so there is no point in shooting any higher than 1080P.

It sure does lead to that kind of thinking

I tend to think of Imax more of a theatrical presentation system rather than a capture format though.

 

[David Mullen ASC]

I tend to think of Imax more of a theatrical presentation system rather than a capture format though.

That's the result of all these IMAX DMR blow-ups, now IMAX is mainly seen as the successor to the old 70mm blow-ups of the past: just really, really good presentations of the same movies showing in the regular theaters.

But I still think of "classic" IMAX, like when I was a kid and saw "To Fly" in the Smithsonian Air and Space Museum and was totally knocked-out by the immersive large-screen experience. I don't want to see that disappear.

 

[Tom Lowe]

David, I don't think any of us disagree with you. We would all like to see IMAX adopt an 8K display standard, for example. But that might be a few years away. No one is really making the 10K or 12K Bayer camera that would be required for an 8K finish.

We're just saying, in the meantime, that 6K acquisition and 4K projection can probably fill the gap for a few years. You said yourself just now that "I'm sure 6K digital-to-IMAX is going to look similar to general IMAX photography due to the lack of grain and higher MTF." So it should work as a stop-gap measure.

I am super excited to shoot an IMAX film, and to see it presented on proper IMAX screens. But I would rather shoot it on Jim's 6K FF35 Monstro camera than on 15-perf IMAX cameras the size of refrigerators.

 

[Craig Ryan]

I'm with David 100%. I think until there is an acceptable replacement for IMAX for both digital acquisition and digital exhibition, they should stick to film. Nothing beats current IMAX film projected on film, period. So why the rush for a digital replacement? I'm sure Epic oriented material will look great printed to IMAX. But it won't look as good as real IMAX still.

 

[Craig W. Bickerstaff]

I'm with David 100%. I think until there is an acceptable replacement for IMAX for both digital acquisition and digital exhibition, they should stick to film. Nothing beats current IMAX film projected on film, period. So why the rush for a digital replacement? I'm sure Epic oriented material will look great printed to IMAX. But it won't look as good as real IMAX still.

Exactly, I think it would be far more interesting to explore doing a digital cinerama camera with digital projection.
with new digital tech you could create a much more manageable camera then the one that had to run 3 strips of film at once not to mention a custom built projection system would make showing a cinerama flick a little easier they keeping 3 strips of film in sync.

 

[Matt W.]

To be fair, I'm also in the camp of crazy people who sees no significant advantage to 4k over 2k. I'm also on the coast with bad, bad movie theaters. I'm thrilled with anything that's not SD.

The 5DII (in stills mode only, obviously) having approximate image parity with IMAX film sounds exactly right to me. IMAX is basically 6x7, which is grainier but a bit sharper than the 5DII. The Phantom 65 on IMAX is then kind of on the low end of acceptable, I guess, with 27% less linear resolution than the 5D, but a much larger sensor and thus the potential for better micro-contrast levels. (Although an IMAX projectionist recently told a friend that they do shows off DVD now and people don't notice. When I saw one....I did.)

 

[Frank Glencairn]

I hope you aren't arguing that IMAX should limit themselves to 4K origination because there aren't any digital projectors in existence higher than 4K, after arguing that regular 35mm Hollywood movies and TV shouldn't limit themselves to less than 4K for future-proofing.

IMAX has to promise something radically bigger and better than the average Hollywood production format uses or else there is no point to the format.

I might get some flak for this, but David, isn´t the limiting factor the human eye?

I mean, how close to a - let´s say 8k future digital IMAX projection - you have to sit to actually benefit from that resolution?

You got resolution, screen size and viewing distance in that equation, and as far as I know there is a sweet spot beyond that you just can´t see more resolution anymore.

That means we have than an architectural problem.

Frank

 

[Jeff Coatney]

Hey IMAX, screw the projector!

The next IMAX version should be made of an array of LED displays seamlessly knitted together to form the large screen. The pixels should be either hexagonal (or paired-square on a diagonal) format and each paired pixel structure should be polarized to allow for 3D content display. Pixels in the range of 2.5mm square should be able to resolve the 6120 x 4500 discernible pixels in a screen 15 meters (49ft.) wide by 11 meters (36ft.) high.

Are you capable of seeing a 2.5mm pixel with your naked eye from a distance of over 40 feet? Its challenging at arm's length for most people. So, if they develop with these targets in mind, they will replicate the best IMAX image available using 70mm film on a screen that is larger than their average venue. However, if they develop with a 1.25mm square pixel, they can approach the theoretical resolution limit for IMAX of 12000 x 8700.

In a projected image model, that resolution gets eaten up by the optics, the variance in resolving focus over a compound curvature, the air itself and the native reflectivity of the dusty screen. However, in an LED display, you can avoid all those shortcomings and deliver more lumens to the audience's retinas. This is very important while wearing 3D glasses.

The signal is distributed across synced controllers for each screen array of about 2 x 6 meters (2400 x 800 pixels per array), keeping the localized pixel bandwidth manageable per image segment. The surplus localized bandwidth could be used to deliver higher frame rates or higher resolution stereo pairs for amazing 3D imagery.

So really they only need to start with a 6K or 8K camera and push to a 12K camera. Which should let a 6K image resolve to approximately 4K projected and almost full 6K on the LED display. So Epic 5K has enough resolution to perform amazingly in LED IMAX native and it would rival and possibly exceed 70mm film in a projected IMAX venue scenario when you take into account a DI finish. The Epic 645 would achieve off the shelf parity with IMAX at the highest resolutions-- why should IMAX spend a dime in development on cameras when the work has already been done?

Red should make these LED display panels and the resulting "Red Ray" based engines for them. They will be limited in their volumes, but simple in the design and fabrication. If Red makes them, we get the holodeck from Star Trek, if others make them we get the Times Square Jumbotron.

 

[Imran Farouk]

Curious...what happens to imax when RED starts churning out beyond Epic-M etc.

Obviously I realize, they will still be around but RED seems to have the aim of putting the best options in the most hands possible without sacrifice of quality or anything that a film maker or cinemaphotographer would possible claim to be a total loss if it wasn't in the cam...

With that thought, then surely starting at 4K now wouldn't be the best idea. Rather, for them to jump ahead even further beyond 6K would be a smarter move

If RED had any plans to push more features and keep the price or drop it or increase it to add even more features then it already has...then I'm not sure how other companies would compete so easily...

On the quality front i can understand, possible, on the price front, also possible, feature front, maybe. Though I'm sure RED knows it and they're covering all the fields (obviously they are since HDRx is pretty damn amazing if not just mind blowing and it's not going to cost an arm and a leg to have it).

Just saying, from a business stand point, where does IMAX stand in the digital camera battle with everyone coming out all over with guns blazing at RED and RED already half way to the peak if not (considering first shipment of EPIC) at the peak...

They should just work on getting the display tech right and nicer...if everyone else is blazing out cams, don't go head on, go around and make the viewing experience better...