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» Film-Tech Forum   » Operations   » Digital Cinema Forum   » The junk called IMAX with Lasers (Page 1)

 
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Author Topic: The junk called IMAX with Lasers
Marcel Birgelen
Phenomenal Film Handler

Posts: 1915
From: Maastricht, Limburg, Netherlands
Registered: Feb 2012


 - posted 05-13-2017 08:18 PM      Profile for Marcel Birgelen   Email Marcel Birgelen   Send New Private Message       Edit/Delete Post 
I finally had the opportunity to visit an IMAX theater upgraded with their dual-laser projection system and I must say, it was a pretty significant letdown.

I went to see the late night show of Alien: Covenant at the recently reopened IMAX theater in Kinepolis Brussels. It was closed from 2005 until 2016 and before 2016 it didn’t show feature films. It also never got an IMAX 3D upgrade. According to marketing back then, it was the second biggest IMAX screen in the world and according to the marketing now, it’s the largest in Europe. Exactly where it ranks isn’t really that important, but it’s indeed pretty damn huge.

The theater is a traditional 70mm IMAX location, built pretty much according to IMAX specifications. During the recent refurbishment, new seats were installed, the walls got some treatments, a new silver screen was installed and the theater also got the 12 channel IMAX sound system. At the heart of the refurbishment obviously were the new laser projectors. I’m not sure if they also retained their original 70mm projector and if they did, in what shape it is.

Unfortunately, the visit already started on the wrong foot, when I went to the bathroom and they demanded 40 cents for the privilege and my 50 euros were no good, because they didn’t have sufficient amount of change. Yeah, sorry, that’s what the ATM gave me. When I told them I really had to use the bathroom, one of the cleaning ladies actually blocked the entry. I passed her by and went anyway. How can you deny a paying customer bathroom services? What are you thinking? I was greeted by security afterwards, I told them to call the police and tell them they deny people entry to their toilet facilities, which they’re legally required to provide. Maybe they have a right to ask a fee for it, which I think is in itself already customer hostile, but then they also need to be prepared to accept all money considered to be legal tender or provide other means of payment. It ended in two figures barking insults at me, I decided to simply walk away and ignore them. The whole situation was actually quite comical, since it was a whole lot of theater about nothing and I would not let them ruin my evening.

What was more of an impact was the actual presentation, because it was a ton of shit. If this is the kind of quality IMAX believes can replace proper 70mm projection, please count me out.
But let’s start with the sound first. I’m totally aware it’s quite difficult to get sound right in such a large and especially high auditorium. Still, compared to what better Atmos and 7.1 rooms can achieve, this was especially dull and flat. The presentation totally lacked any form of bass. There was no dynamic in the sound and it lacked the punch necessary to leave an impression.

While the sound wasn’t great, it was sufficiently good overall to avoid annoyances. What was annoying was the overall picture quality. I’d say I’ve never seen a picture as bad as this in any digital projection in all those years:

- Laser speckle all over the place. So dramatically visible, it’s like someone threw a bunch of pearlescent beads all over the screen.
- IMAX with Laser uses anamorphic lenses to squeeze the image fill the screen. This results in non-square pixels. Even though the image is supposed to be in 4K, you WILL still see pixels at those screen sizes. The image looks a lot like that on an Apple Lisa, probably one of the few computers in history that featured non-square pixels...
- The non-square pixels result in the necessity to rescale practically all content and it shows. You get FAT and UGLY scaling artifacts EVERYWHERE.
The whole experience is a lot like looking full-screen at an 11-year old YouTube video on a large 4K monitor while pressing your head against it.

So, this is the technology which, according to IMAX (the company), is ready to replace 70mm on GIANT screens? You must be f*cking kidding me. This is just another hack job, to be honest, I even prefer the look of the Digital IMAX with Xenon.

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Carsten Kurz
Film God

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From: Cologne, NRW, Germany
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 - posted 05-13-2017 09:22 PM      Profile for Carsten Kurz   Email Carsten Kurz   Send New Private Message       Edit/Delete Post 
I haven't seen the heavy rescaling artifacts you describe, but the speckle visible on those silver screens is indeed horrendous. Why the hell do they actually still need silver screens with the twin laser installations and color separation 3D?

Your loo story is absurd. They should be ashamed.

- Carsten

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Marcel Birgelen
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Posts: 1915
From: Maastricht, Limburg, Netherlands
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 - posted 05-14-2017 03:27 AM      Profile for Marcel Birgelen   Email Marcel Birgelen   Send New Private Message       Edit/Delete Post 
The new Alien movie is in 2D, but as far as I know, the 3D system uses 3D glasses based on the Infitec/Dolby 3D color seperation technology.

Polarization filters in combination with laser sources seem to be highly inefficient.

Still, they seem to use high-gain silver screens. Maybe because of backward compatibility or because they still need the gain given the size of the screen.

The speckle might be a Barco problem? I have no hands-on experience with any Barco laser projector so it's hard to tell, but AFAIK IMAX uses a modified Barco laser projector setup. The Dolby Cinema Christie dual laser setup barely shows any speckle at all though.

I'm not sure if there were technical problems, but there was a massive amount of aliasing going on. Not only during the movie itself, but also during the IMAX feature trailers, which should be specifically tailored to this system.

Maybe there also were some alignment errors between the two projectors, which could explain the general blurriness of the image.

Compared to Dolby Cinema, this is really a loser on all fronts in my opinion. While Dolby Cinema usually employs smaller screens, they are more fit for your average movie presentation. The image also has more contrast, more brightness and the lack of the necessity of scaling to strange, non-integer proportions ensures an artifact-free image.

I've experienced the 12-channel IMAX sound system at two locations now. It's probably not sufficient experience for a definitive conclusion, but I think a properly configured 7.1 room already outperforms this system in overall quality. Compared to a properly implemented Dolby Cinema setup, it really is no comparison at all.

So, nothing positive? Well, first off all let's give them kudos for reopening this long closed location, which obviously wasn't cheap. Also, let's give them kudos for actually running movie-based themed music in the IMAX lobby.

Now, do us all a favor and get a working film setup, so you can show those movies that are still released in this format the way they're supposed to be seen.

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Mike Schulz
Expert Film Handler

Posts: 112
From: Los Angeles, CA
Registered: May 2007


 - posted 05-14-2017 05:27 AM      Profile for Mike Schulz   Email Mike Schulz   Send New Private Message       Edit/Delete Post 
They must have done something majorly wrong with their setup or installation at that theatre. The IMAX laser presentations I've seen at the Chinese Theatre and the Universal Theatre here in Los Angeles were rock solid. The speckle was barely present so I'm almost positive that is not a Barco technology issue. Maybe they didn't put shakers on the screen or something that helps to eliminate that issue. As for the sound, I can agree with you on that. Even the new 12.0 system they are using doesn't hold a candle to a good Atmos setup. Then again, IMAX sound has always been inferior to everything else out there.

While I think the new IMAX laser presentation is a huge step up from the Xenon setup they were using before, it's still not as good as Dolby Vision. I've gotten in many arguments defending my position and I might be slightly bias since I work at a DV venue, but I can still see the flaws with IMAX laser and with Dolby Vision it is a damn near perfect picture every time.

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Carsten Kurz
Film God

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From: Cologne, NRW, Germany
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 - posted 05-14-2017 07:05 AM      Profile for Carsten Kurz   Email Carsten Kurz   Send New Private Message       Edit/Delete Post 
Mike - do you know wether these two locations still use silver screens? I understand they may leave an existing screen in place until it is replaced regularly. But I know one location in germany that had a silver screen when they installed laser-Imax, and received a new silver screen AFTER the system had been operating for a while. The speckle on these silver screens is highly annoying. This speckle alone is the reason I won't visit a laser IMAX theatre again. It's hilarious to attempt to improve major aspects of the audiovisual presentation and then ignore such a major flaw.

I have seen 'standard' Barco Laser presentations locally, and they don't suffer from that issue. While the IMAX laser systems have been built by Barco, I don't know wether they employ the same speckle reduction. The light engines are very different between standard Barco lasers and IMAX lasers.

- Carsten

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Mike Schulz
Expert Film Handler

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From: Los Angeles, CA
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 - posted 05-14-2017 12:15 PM      Profile for Mike Schulz   Email Mike Schulz   Send New Private Message       Edit/Delete Post 
Casten - I'm not 100% sure but I believe both sites have the silver screens and they use shakers to help eliminate the speckling problem. I will say that when I first saw "Furious 7" at the Chinese Theatre, I did notice some hot-spotting and minor speckling happening (everyone else I was with claimed I was taking crazy pills, however) but ever since then when I've gone back, I haven't noticed either of those issues so I think they have worked some more kinks out since their first installations.

At the Universal Theatre, I saw "Batman vs. Superman" which was probably the best showcase of the laser technology as it had a lot of 15/70 scenes that filled the whole screen and I was actually quite shocked by how good it looked. In my opinion, Universal is the better venue to see the laser presentations as it is a proper dimensioned real IMAX theatre and the sound is way better there, too.

If I were to take a guess as to why Marcel's theatre looked so bad, I would guess that they hadn't installed the screen shakers yet since the symptoms were hot-spotting and noticeable speckling which is what the shakers eliminate.

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Dave Macaulay
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 - posted 05-14-2017 12:49 PM      Profile for Dave Macaulay   Email Dave Macaulay   Send New Private Message       Edit/Delete Post 
The shakers can't eliminate hotspot but do get rid of speckling. The speckling is quite bad if the shakers are not working. Sometimes that system does fail.
Yes the pixels are slightly rectangular but so what? There's no magic in square pixels.
They are not Barco laser projectors but many components are produced by Barco. The light engine is very different from the Barco laser projector models.
Dolby Vision® is definitely impressive in a properly designed cinema. The extended contrast is usually wasted because of exit aisle lighting to meet local rules... or because someone stumbled and the manager turned the aisle lights up.
The Imax laser system has considerably better contrast than a normal xenon DLP digital cinema projector. Imax tries to keep interior lighting minimal but local codes have to be followed.
Sound quality is subjective, Imax sound is at least consistent as the system runs daily self-checks on all channels to confirm levels and that there are no blown drivers or failed amps. That usually takes a patron's complaint in standard cinemas.
Overall I find Imax laser to be very impressive. Much better than the standard 2K DLP stadium cinemas. Worth the upcharge? For some movies yes.

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Marcel Birgelen
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From: Maastricht, Limburg, Netherlands
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 - posted 05-14-2017 05:48 PM      Profile for Marcel Birgelen   Email Marcel Birgelen   Send New Private Message       Edit/Delete Post 
Hotspotting wasn't really the issue here, we were watching a scope feature on a 1.43 screen, so hotspotting would only be visible in the left and right edges if it would be a problem. Which actually negates the whole idea of such a giant screen, because the effective screen size isn't much bigger than that of a larger, normal auditorium.

For those interrested, they made a small making-of video about the refurbishment.

I'm still wondering, where the screen shakers are placed, if they're present at all and if they work similarly as described in the Dolby patents. If you look at the video, you see there are a bunch of speaker-alike looking cylindrical devices mounted in the frame, are those the screen shakers being used by IMAX? If so, it seems to be an ultrasonic system.

Apparently, Dolby uses screen shakers in their Dolby Cinema venues, although everybody I asked has been a bit sketchy about them, it's like they're some kind of big trade secret. Maybe someone here can shed a light on them, if they're actually being used.

quote: Dave Macaulay
Yes the pixels are slightly rectangular but so what? There's no magic in square pixels.
No, there's indeed no real magic in square pixels, but I guess we've gotten used to them and therefore our brain will more easily "discard" them, if they're visible.

And yes, they are pretty much visible all the time. Also, the ever-present subtitles in both French and Dutch didn't help to make them less visible.

For some reason, my mind was constant telling me: The picture looks vertically stretched. It almost told me to try to find the button to resize it to the proper proportions to make it look "right". Maybe it's a "me" problem, but I really think our mind has been trained, over the years, to accept square pixels as a normal fact of life. So, non-square pixels just look odd, just like a Apple Lisa looks odd, if you happen to find a working model somewhere.

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Dave Macaulay
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 - posted 05-14-2017 07:05 PM      Profile for Dave Macaulay   Email Dave Macaulay   Send New Private Message       Edit/Delete Post 
Yes those cylinders are the screen shaker. I don't know if the system is a "trade secret" - and I'm not going to find out by describing it.

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Carsten Kurz
Film God

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From: Cologne, NRW, Germany
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 - posted 05-14-2017 07:59 PM      Profile for Carsten Kurz   Email Carsten Kurz   Send New Private Message       Edit/Delete Post 
Screen shakers are not a trade secret, but projector manufacturers prefer to hide their necessity - because it shows their inability to get rid of speckle on their side.

- Carsten

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Bobby Henderson
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 - posted 05-15-2017 12:10 AM      Profile for Bobby Henderson   Email Bobby Henderson   Send New Private Message       Edit/Delete Post 
Kind of a stupid question, but "screen shakers?" There's something literally shaking the screen to suppress the appearance of speckles? How does this work? This "shaking" taking place, is it rapid vibration or something? Wouldn't this shaking or vibration yield a dramatic, negative hit to image sharpness and resolution?

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Marcel Birgelen
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From: Maastricht, Limburg, Netherlands
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 - posted 05-15-2017 02:01 AM      Profile for Marcel Birgelen   Email Marcel Birgelen   Send New Private Message       Edit/Delete Post 
Well, yes... they shake, vibrate, or how some call it, "massage" the screen.

There seems to be more than one way to do it, one is via mechanical contact to the screen assembly itself and another is via ultrasonic actuation. To me, it looks like that's what IMAX is using.

There might be other implementations, like electromagnetic or even electrostatic actuation. I've seen electromagnetic actuation mentioned in patents, but it wasn't further explained in the ones I read.

The vibrations should not be visible to the naked eye and therefore should not create a noticeable impact on image focus as such.

The general idea is that by shaking the screen, you diffuse the high intensity spots created by laser interference and therefore reduce the visible speckle. In some of the patents, they also describe a special diffusing screen coating in combination with “screen shaking”. Essentially, you rough up the surface in a random fashion, combined with vibrating the screen, this should further eliminate visible speckle.

Since most IMAX locations seem to be using silver screens, the screen shaking itself seems a bit counter-intuitive to me. Since the silver coating on the screen is designed to be less diffusing than normal, white screens.

quote: Dave Macaulay
Yes those cylinders are the screen shaker. I don't know if the system is a "trade secret" - and I'm not going to find out by describing it.
Thanks for pointing out they are the screen shakers.

I'm not sure if you're willing to tell, but I guess they don't actually contact the screen?

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Carsten Kurz
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From: Cologne, NRW, Germany
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 - posted 05-15-2017 04:26 AM      Profile for Carsten Kurz   Email Carsten Kurz   Send New Private Message       Edit/Delete Post 
http://www.google.com/patents/US20130010356

As far as I know, every RGB (3p/6p) laser installation uses screen shakers. The cheaper phosphor conversion lasers do not suffer that much from speckle, so they don't need it.

I'm wondering why they don't use them in our few german laser IMAX installations. Maybe they are installed, but not in operation for some reason?

At the level IMAX is usually driving their audio system, you would think there is no need for dedicated screen shakers...

- Carsten

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Marcel Birgelen
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Posts: 1915
From: Maastricht, Limburg, Netherlands
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 - posted 05-15-2017 07:27 AM      Profile for Marcel Birgelen   Email Marcel Birgelen   Send New Private Message       Edit/Delete Post 
As you can see in the Brussels installation and confirmed by Dave, they were actually installed.

Yet, there was still a massive amount of speckle visible. So either the result is still pretty meagre or they were simply not operational.

AFAIK there are three IMAX Laser locations in Germany. Berlin, Sinsheim and Karlsruhe. Maybe I'm missing one, but IMAX's presence in Europe always has been a bit of a hit and miss. Many locations closed before feature films became IMAX's new business model.

All of those locations were former 70 mm locations and at least two of them (Berlin and Sinsheim) were former 70 mm IMAX locations, pretty similar in layout to the one in Brussels and comparable screen sizes. I guess, it would be odd if none of them got the "shakers".

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Geoff Jones
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 - posted 05-15-2017 07:48 AM      Profile for Geoff Jones   Author's Homepage     Send New Private Message       Edit/Delete Post 
I will readily admit that I barely understand what you guys are talking about, but it sounds asinine to me.

Your new technology looks like shit unless you physically shake or vibrate the screen? Does it get shaken evenly across the entire surface? What effect does shaking the screen have in the long run?

quote: Marcel Birgelen
The Dolby Cinema Christie dual laser setup barely shows any speckle at all though.
quote: Mike Schulz
The IMAX laser presentations I've seen at the Chinese Theatre and the Universal Theatre here in Los Angeles were rock solid. The speckle was barely present.
Is it really okay if there's just a little speckle? That sounds sorta like saying, "Oh, the film was barely scratched."

I haven't seen anything in 2k LieMax except for the Raiders of the Lost Ark re-issue several years ago, and the pixelation and low-res blurriness was terrible from the front third of the auditorium. It sounds like I don't need to bother with SpeckleMax.

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