If your shooting 28K resolution, then your might as well be shooting in IMAX!

[Robert McGee]

In my above numbers, I did not account for Super35 for a couple reasons. First of all, to relate to the RED One 4K format, which is very close in physical size to 35mm Academy. RED One sensor is 4K at 22.12mm wide vs. 35mm Academy frame at 21.95mm wide.

The frame height makes little difference, it does not matter if it's 2 perf, 3 perf, or even 4. Scanning resolutions are represented and figured off of the frame width. Height is incidental and the same lineal resolution is maintained and the actual area scanned is extended to match the height of your frame on the film neg.

Given the same numbers, it all holds the same for Super35, 65mm and other formats. Full aperture S35 is 24.89mm wide. RED One 4.5K is 24.19mm wide. Epic 5K is 5120 pixels and 27.65mm wide.

These sizes your talking about on the red cameras, are these the sizes of the sensors or the sizes of the images captured on RED measured against the same size image on 35mm?

I know the camera sensor doesn't have to actually be 35mm to actually capture images that match up to the resolution of 35mm film. Despite what the size of the sensor for the Epic 617, we already know where those images stand.

 

[stephenv2]

IMAX facts

IMAX facts

I'm not a expert but I'm currently making an animated IMAX film (www.outsideinthemovie.com) and have researched this heavily, worked with the leaders in IMAX post, seen a lot of IMAX filmout tests and output test footage from my film to IMAX 15/70mm. I've screened my test footage on some of the largest IMAX screens in the world. I've also seen Red, Phantom, HDV, 35mm etc. output to IMAX. My points here all apply to real film IMAX, not the digital "Liemax".

RESOLUTION.

The discussion thus far has been somewhat vague, misleading and incomplete at times. First, film scans are typically done at 4K, 5.6k and sometime 8K for IMAX projects. However, this resolution is not a fixed quality - their are CCD, CRT and CMOS film scanners, so a 5.6k scan is not equal to another 5.6k unless scanner tech, quality etc. is factored in not to mention the negative stock being scanned.

Second, many IMAX films never enter the digital world. DI is very expensive and many projects simply go from negative to print. Thus, resolution is hard to quantify precisely and film stock, grain, exposure, print stock all come into play. Just like 35mm, a print on nice print stock directly from a negative is thing of awesome beauty in 15/70mm - there is no digital camera that delivers any kind of image like this. It's an unknown if the 645 or 617 will as they don't exist at all.

Third, film recorders max out at either 4K or 5.6k (depending on which expert you talk to). You cannot film record out higher levels of detail, no matter what you set it at, it the currently physical limit. 8K/12k scanning exists to take advantage of downsampling to help minimize noise/artifacts etc. in digital processing.

Downsampling makes a substantial difference. I've seen 15/70mm film scanned at 4k and 8K and then both output at 4k and the 8K scan looks much better projected despite still being output at 4k. I think output at 5.6k matters (as does Christopher Nolan) but some industry vets discount this and consider 4k the max (though see aspect ratio below).

RED camera resolution, as is discussed is not an apples to apples because of debayering. Debayering loss is big at these frame sizes. 4K RED one footage out to 4K film recorder does not look good on 8 story screen. In fact, it looks so-so at best (close-ups, with shallow DOF), crappy in wide shots.

35mm film looks so-so as well. IMAX's DMR process is primarily a grain removal process so they can make better prints that project better.

ASPECT RATIO:

IMAX is 4:3 - yes, just like the old TV set you got rid of. This a major factor in the aesthetic and technical properties of the medium, often overlooked in discussion. IMAX 4k is not RED 4k dimension wise. It's 4096 x 3072. The very high/tall screen is the primary factor in the immersive quality of the 8 story screen. Very wide e.g. 3:1 screens don't trick the eye the same way a physically wide but also tall screen does.

This is very effective in IMAX dome screens, which generally create more sense of motion/falling/flying then the best 3D tech available today. Dark Knight is great example of how effective the 4:3 format is on screens 8 stories tall.

PROJECTION:

As there are only a few hundred venues worldwide, there has been little development on 4K and larger 4:3 aspect ratio digital projection chips. 4K 16:9 projectors have to be stacked/stitched to fill an IMAX screen.

Worse is brightness/contrast. A big factor in IMAX projection is those lamps that throw 5 to 10 times as much light as the brightest digital projectors. The human eye does adjust for this but IMAX domes especially suffer with digital. I recently saw Sony's newest prototype 4K in a IMAX dome A/B tested with 15/70mm of the same footage. It was like watching something through thick ND material. Grey, washed out, flat.

BOTTOM LINE:

It's unclear if any announce RED camera is suitable for full display 4:3 8 story screens. The slightest artifact is a big deal at those sizes and substantial cropping of the image would be required to fill the screen.

The 645 might work although it's physically smaller sensor size (42mm vs 48mm). The 617 is quite odd for IMAX work. Resolution would be okay but the 4:3 crop would mean huge pixel waste on the sensor sides. It's certainly not the ideal sensor for IMAX and seems like a Cinerama camera, not an IMAX camera. You would really want a 10 to 15k 3:2 or 4:3 camera with windowing to other aspect ratios for IMAX.

It's also unclear what giant screen digital projection will be that can match 15/70mm IMAX projection. Laser projectors are the latest thing I've heard inside the industry as a possible solution. But right now, there is zero, so if you are going IMAX in the next few years, you are going to film.

FYI:

I'm mastering my film in 4:3 5.6k in 32-bit color. That's 5600 x 4200 pixels in floating point, about 900 MB a frame as a uncompressed TIFF. If you have not worked with data like this, it's a bear on the fastest hardware today. If a 617 were shipping today, only the insane would want to post full-rez.
And there would be no way to see it anyway.

I will crop 16:9 out of my 4:3 master - which is actually not a big deal since composing shots from IMAX is very different especially for dome safe. What works on a 16:9 screen in home or local multiplex is very different that what works on a giant dome.

 

[JohnF]

Interesting write up Stephen, Cheers!

Just a quick note on:

ASPECT RATIO:

IMAX is 4:3 - yes, just like the old TV set you got rid of. This a major factor in the aesthetic and technical properties of the medium, often overlooked in discussion. IMAX 4k is not RED 4k dimension wise. It's 4096 x 3072. The very high/tall screen is the primary factor in the immersive quality of the 8 story screen. Very wide e.g. 3:1 screens don't trick the eye the same way a physically wide but also tall screen does.

This is very effective in IMAX dome screens, which generally create more sense of motion/falling/flying then the best 3D tech available today. Dark Knight is great example of how effective the 4:3 format is on screens 8 stories tall.

The immersive quality experienced by audiences has more to do with the angular size of a screen relative to the viewer. It has been found that once a screen crosses the 80º size from the perspective of the viewer their eye-brain no longer sees a screen but interprets it as the world. I've done tests with home 1080 projectors and found this really does work (including the sense of motion etc). The vast size of the IMAX screen is simply a way to bring this experience to larger audience numbers.

It is interesting to note that this psycho-optic effect and its immersive qualities are not dependent on resolution. It was found to work(to the point of creating motion sickness) when the first generation of virtual reality head mounted displays were built using screens that had pixel resolution half that of SD! Though I suspect that higher resolution would improve the effect.

So it is probable that the 645 Epic (and possibly the FF35 Epic) might be able to provide such immersive qualities but only, as you have noted, if digital projectors come up to scratch.

All the best

JohnF

 

[stephenv2]

Interesting write up Stephen, Cheers!

Just a quick note on:


The immersive quality experienced by audiences has more to do with the angular size of a screen relative to the viewer. It has been found that once a screen crosses the 80º size from the perspective of the viewer their eye-brain no longer sees a screen but interprets it as the world.

I should have clarified my note a bit. I agree the angular size is key foundation of IMAX. What I was pointing out is the screen height makes IMAX much more immersive than just wide. The combination of height and width, especially in IMAX domes beats the Cinerama wide only (which is immersive but you can easily see screen top and bottom.

 

[Robert McGee]

Grain reduction is a major factor, and it's something that just wasn't possible when you look at some 35mm to 70mm blowups that predate the IMAX DMR process.

Yeah Stephen, it does seem to where in most cases that the only times when IMAX takes one of their films throw a digital scan is when there going to have like a DVD or Blu-Ray release.

In hollywood where the format of choice is 35mm, it's slowly but gradually moving away from film to digital video. There is one thing you might not know here, when a hollywood studio is about to release one of it's films in IMAX or IMAX 3D, a negative backup for video backup is handed over to IMAX and they work with it to make the DMR master that they'll use for their 70mm film prints and digital prints.

The DMR being more like a grain reduction process rather then something that would start with a high 8K scan, that makes alot of sense but what about enlarging the images after the scan, would they do that as well?

 

[stephenv2]

The DMR being more like a grain reduction process rather then something that would start with a high 8K scan, that makes alot of sense but what about enlarging the images after the scan, would they do that as well?

Good question - IMAX does not exactly say but Gizmodo did a tour of DMR that's interesting. As best as I can tell, they are scanning hi-res (probably 5.6 or 8k, grain reducing like crazy, some sharpening after but unlikely any real uprez. Also, they are letterboxing, so they don't need to fill the full screen height.

 

[Robert McGee]

I would guess for film, Anamorphic film would have alot less grain to remove as apposed to Super 35. When dealing with HD video for other films like the Star Wars prequels, Avatar, and Tron Legacy that just means alot more work.

Letterboxing isn't bad, it works for me.

Here is another question, what type of film formats (both 2D and 3D) go throw the DMR process faster then others?

 

[stephenv2]

DMR for 3D is obviously much more work than 2D - but other than that I would guess it's a case by case (how much grain removal etc.).

 

[Robert McGee]

I think when it comes to a digital camera that can shoot for the IMAX format, I would say 10K minimum and 12K maximum at the IMAX standard 1.44:1 aspect ratio but some of you may want to shoot at 1.66:1 where it will crop better to 16:9 or just shoot at the 1.78:1 aspect ratio to begin with.

So far, there are only two Hollywood films that where shot partially in IMAX and even though there pushing for the next Batman film to be 100% IMAX, it won't be the first time a Hollywood studio has shot a commercial in IMAX. Disney released Fantasia 2000 in IMAX on 1/1/00 back in the day and it's set for it's first Blu-Ray release this year. It's hard to say what the reviews will be because it's never been released in high-def.

IMAX has their own 35mm film scanners that's said to capable of 8K, and only very few of those film scanners have been made unlike the 4K and 5K scanners where used too. Just scanning alone will take 2 & 1/2 to 3 months for a 2 & 1/2 hour film.

The most recent IMAX DMR release, Inception was shot anamorphic 4/35, vista-vision 8/35 and 70mm 5/70. Chris Nolan said he felt he wasn't able to shoot on IMAX because of how the sets where built.

 

[stephenv2]

8k scanning is brutal - but film recorders max out at 5.6k in 15/70. However, the 8K really helps with oversampling. Saw a filmout test at GSCA a couple of years ago of 4k vs 8k scans output at 4k. 8K really makes a difference on 8 story high screen.

 

[Tom Lowe]

I think when it comes to a digital camera that can shoot for the IMAX format, I would say 10K minimum and 12K maximum at the IMAX standard 1.44:1 aspect ratio but some of you may want to shoot at 1.66:1 where it will crop better to 16:9 or just shoot at the 1.78:1 aspect ratio to begin with.

A pristine 4K RGB finish shot on 5k+ RAW, large-sensor cameras and projected at 3:2 aspect ratio should be more than sufficient for IMAX screens.

 

[Palmer Woodrow]

One thing is beyond debate

One thing is beyond debate

You + are = you're

 

[C. Jagan Mohan]

All these speculations of resolution is meaningless. You can see so many films shot in Academy are being upscaled and shown in IMAX. So why break your head of speculating very hi-res shooting?

 

[stephenv2]

A pristine 4K RGB finish shot on 5k+ RAW, large-sensor cameras and projected at 3:2 aspect ratio should be more than sufficient for IMAX screens.

Not if "sufficient" means equal to shooting 15/70mm. I've seen 4K RGB (Dalsa, Red etc.) on IMAX screens and it looks very mediocre on soft close-ups and balls ugly on detailed wides.

I've also seen VHS, miniDV, HDV etc. on IMAX and there are some that think this is "okay" as in "watchable". I don't think so and despite being a digital nut, 15/70mm projection on film is unparelleled still for resolution, color, brightness. Digital sensors have basically caught up on dynamic range but only if you go out to film as digital projection is poor on 8 story screens. Dim, very low contrast.

Eventually, this will change. But 4k Bayer RAW is not IMAX, not even close. 4K 4:3 or 3:2 true RGB is much, much better, but requires a 7-9k Bayer RAW sensor.

 

[Robert McGee]

All these speculations of resolution is meaningless. You can see so many films shot in Academy are being upscaled and shown in IMAX. So why break your head of speculating very hi-res shooting?

On a hunch, I wanted to see how the 2 70mm formats measured up against eachother. On Inception, I mentioned that some scenes where the older 70mm format that pre-dates IMAX 15/70, I saw that even that format would not bypass the DMR because of what I was able to figure out. 5/70 is horizontal and 15/70 is vertical.

And yes, you can do a DMR on an older film. On Gond with the Wind's IMDB page some time back, this one guy suggested the film be converted to 3D and then I suggested the film be in IMAX. I wonder how many movie buffs would say that Clark Gable looks good in IMAX? The old 35mm Academy format is 1.33:1(1.37 for silent films) IMAX is 1.44:1, so a little pillarboxing is a must if it's demanded by the filmmaker. And we do know that if that is ever done for that film, it won't be the first time it's been blown up to a 70mm format.

 

[Tom Lowe]

Not if "sufficient" means equal to shooting 15/70mm. I've seen 4K RGB (Dalsa, Red etc.) on IMAX screens and it looks very mediocre on soft close-ups and balls ugly on detailed wides.

Eventually, this will change. But 4k Bayer RAW is not IMAX, not even close. 4K 4:3 or 3:2 true RGB is much, much better, but requires a 7-9k Bayer RAW sensor.

I wasn't talking about 4K Bayer cameras like Red One or Dalsa. I was very specific in what I said. I was talking about 5K and 6K+ Bayer cameras shooting RAW or RedRAW and finishing at 4K RGB 3:2 for digital projection on IMAX screens. I shoot 5.6K RAW every day on my Canon cameras. Believe me, the quality will be plenty for IMAX.

The only thing is, does anyone make a 4K projector at 3:2 aspect ratio?

 

[stephenv2]

I shoot 5.6K RAW every day on my Canon cameras. Believe me, the quality will be plenty for IMAX.

Have you actually output your material to 15/70mm and screened in a GT theater? 5.6k RAW Bayer is barely adequate - I have a 7D and know exactly what it looks like. 5.6k RGB works pretty good especially for CGI (Dark Knight VFX were done at 5.6k and 8k RGB - generally filmed out at 5.6k. But 5.6K Bayer is barely 4k RGB and that's simply not enough for live action. A/B compared against 15/70mm and it looks pretty bad - like HDV single 1/4" vs. 4K Red MX.

 

[Robert McGee]

5.6K is only slightly a bit higher resolution then 35mm but not really good enough for a 15/70 film out. You saw my windowboxed 70mm 5/70 frame inside an IMAX frame. So if 5/70 is no good, then what makes you think that a 5.6K source or film scan is good enough for a 15/70 IMAX film out?

IMAX is not going to release a film onto their format unless they can get it to where the images don't look grainy on their film, that was the challenge when they did the first DMR with Apollo 13 back in 2002.

 

[Tom Lowe]

Hehe. 5.6K RAW shot on a Vista Vision sensor DESTROYS standard 35mm cine film in image quality. It's not even close. 6K FF35mm RAW shot on high-end glass is comparable to 65mm 5-perf acquisition.

You saw my windowboxed 70mm 5/70 frame inside an IMAX frame. So if 5/70 is no good, then what makes you think that a 5.6K source or film scan is good enough for a 15/70 IMAX film out?

Digital RAW acquisition is totally different from film acquisition, due in part to lack of grain. It's much, much cleaner. I can show you some 5.6K RAW frames that will drop your jaw. DMR will not be needed.

Do not underestimate what is happening with digital RAW cinema. People are going to be completely shocked when full-frame 35mm RAW cameras, like Jim's forthcoming FF35 Epic, start shooting IMAX.

 

[Pawel Achtel]

but then, a few IMAX films were shot on...HDCAM (1080p)...

I believe 4.5k is more than enough for IMAX projection. It's not only the K's that matter. It's the glass, it's the focus, lighting, contrast,...and just about everything before and behind the lens.