Bad Projection Is Ruining the Movie Theater Experience

[Mark Gulbrandsen]

So projector manufacturers are going to ram laser on to every theater owner out there... pretty low if you ask me.

[Marcel Birgelen]

I'm not so sure Mark... Right now, the only new Xenon options available on the market seem to be coming from Christie. You can't buy any new xenon machine from Barco. We've got an aging xenon machine in our screening room and laser isn't an option, so we're going with Christie now. It wasn't my first choice, but little options left...

Any traditional jumbotron LED tile has a nearly solid, black, hard plastic front with rows of plastic louvers between the pixels. There is some metal frame work behind the tile face that holds components and various connectors for power and data. Usually one or more fans are incorporated into the tile back too. Some LED signs can ventilate hot air out of the front. But I don't think the holes in those product designs are big enough to allow audio to pass through effectively. They basically need to come up with some sort of "cheese grater" kind of tile face that allows a lot more air to pass through it. But the design has to be such that it doesn't ruin contrast levels. It's a big challenge. I'd really like to see more closely what MSG Entertainment has done with the sound system for the Sphere. The one in Las Vegas hasn't finished construction. Yet they're already working on a second Sphere venue for London..

There also is quite a difference in "build quality" between the stuff that's made for outdoor use v.s. the indoor stuff. There are fairly lightweight LED wall constructions nowadays for indoor use, that allow for quite some transparency, not just for sound, but also for light effects. A good example is a live show like this one (bad audio and mediocre video quality ahead), many of the "holo" effects rely on a transparent front screen with another LED screen in the back. You can clearly see the structure of the front screen when the back-screen is lit, but this kind of screen would also be audio transparent. Obviously, the pitch between the individual pixels is too large for close viewing. Still, with technology shrinking, an audio-transparent LED wall that works in smaller rooms seems achievable.

[Mark Gulbrandsen]

The second year Laser was out, I made it around to all the manufacturers at Cinema Con and asked them how much to re-laser X projector. After talking to enough people, it seemed like a cover up, as not one could tell me. All they could say was how many hours they will last running at 70%. I determined right then and there that laser was a no go for me. Xenon isn't going anywhere for a long time....

[Bobby Henderson]

LED screens can be built to be audio-transparent, but in order to hide the gaps in the dot-grid, but you'll need a viewing distance that's not practical for most smaller cinema setups. Buildings like the MSG sphere in Las Vegas, will have most of their speaker systems BEHIND the spherical LED screen.

I haven't seen a technical breakdown of the MSG Sphere's audio system. The descriptions of the $1.8 billion Las Vegas venue say the audio system will be "multi-layered," feature 160,000 speakers and use "audio beamforming" technology. It will feature its own proprietary immersive format Sphere Immersive Sound. The Beacon Theater in NYC is getting a smaller scale version of it with its new sound system.

Somehow they're incorporating a bunch of those speakers into or behind the enormous 566' X 366' 19,000 x 13,500 pixel dome screen. Doing a bit of quick math that works out to the LED tiles in the MSG Sphere having a 9mm pitch between pixel centers. For a large venue with 17,500 seats and substantial viewing distances the image should look pretty solid.

Any traditional jumbotron LED tile has a nearly solid, black, hard plastic front with rows of plastic louvers between the pixels. There is some metal frame work behind the tile face that holds components and various connectors for power and data. Usually one or more fans are incorporated into the tile back too. Some LED signs can ventilate hot air out of the front. But I don't think the holes in those product designs are big enough to allow audio to pass through effectively. They basically need to come up with some sort of "cheese grater" kind of tile face that allows a lot more air to pass through it. But the design has to be such that it doesn't ruin contrast levels. It's a big challenge. I'd really like to see more closely what MSG Entertainment has done with the sound system for the Sphere. The one in Las Vegas hasn't finished construction. Yet they're already working on a second Sphere venue for London.

Are there really cinema chains that might spend money to repair a bad pixel on an LED screen?

They better be prepared to do so if they're going to go the route of self-emitting LED screens. A stuck pixel is very distracting. Anyone is going to notice that. Still, we can't underestimate how far venues will go with deferred maintenance.

[Geoff Jones]

Are there really cinema chains that might spend money to repair a bad pixel on an LED screen?

Based on the article at the beginning of this thread, along with my own experience, it doesn't feel that way.

This week, I was looking for a new theater because the ones nearby are so terrible. I was looking farther and farther away (forty-plus miles) because I love moviegoing that much and I'm desperate to find a good experience.

I ended up looking at the Metropolitan MetroLux 12 Theatres + IMAX. Multiple reviews mentioned large black marks or tears on the screens, in more than one auditorium. Yet they were continuing to show movies on those screens.

If there are cinemas in the Annapolis area that are so quality-focused that they would address a single bad pixel, please tell me which ones. I would seriously love to visit them next time I'm on the east coast.

[Steve Guttag]

Having recently worked closely with both leading LED display and cinema audio companies on an install, my impression is that the R & D focus is still on working around it (the inability to pass sound through a LED display) rather than making it possible. Big efforts are being made to improve the audio quality and cost effectiveness of the workarounds, and the sound quality possible is still vastly improved from where it was when the first cinema LED systems went up. But I agree that audio remains the Achilles' heel.

Any company wasting time on mitigating the sound compromise of not having it come from the screen (through the screen) is doing just that. They are coming up with a workaround for a "Beta" system. They are NEVER going to beat the physics on that. No matter what one does, they won't provide the same audio experience from seat-to-seat (and I'm not even talking about different parts of the room). And then if the movie pans the sound around you get another set of differences. Anyone putting in an emissive screen now is putting in betaware at cutting edge prices.

Still, I am very skeptical there will be any sort of mass adoption of self-emitting LED-based cinema screens any time soon. The maintenance costs are just going to be too damned high for any "ordinary" mainstream cinemas to shoulder. It's one thing to replace a tile on an outdoor sign whose display is only 200x80 pixels. It's another thing entirely to maintain a screen with 2048x1080 or 4096x2160 pixels and far more driver board tiles.

There are provisions for tile replacement on the LED screens and they, typically, ship with extra tiles/banks of tiles. So, if a bad pixel does develop, one can replace the tile or the bank (and then re-align all of that to have it in precise alignment and also color/brightness match). They ship the spares so that everything is from the same manufacturing batch with, presumably the same colors. The replacement just won't have the hours on it so those tile(s) will need to adjusted down to match its surroundings.

[Marcel Birgelen]

C'Mon! Spintonics? We could weave a carbon fiber mesh, impregnated with LEDs, then arrange it so that only electrons which have their spins polarized in a certain direction will light up a given pixel/subpixel combination. You could roll it up inside a tube, just like a regular screen, and install it in your existing screen frame. You could even use your existing speakers but you'd probably have to get the rest of your sound system EQ'd again. Hey! You can't win 'em all!

How are you going to address every single pixel/subpixel? :P

LED screens can be built to be audio-transparent, but in order to hide the gaps in the dot-grid, but you'll need a viewing distance that's not practical for most smaller cinema setups. Buildings like the MSG sphere in Las Vegas, will have most of their speaker systems BEHIND the spherical LED screen.

If LED screens could become thinner, more like modern OLED screens, then the screen itself could be used as the transducer, at least for higher frequency part of the spectrum. Sony has been selling OLED screens based on this technology for over 5 years now and the results really aren't all that bad.

[Randy Stankey]

C'Mon! Spintonics? We could weave a carbon fiber mesh, impregnated with LEDs, then arrange it so that only electrons which have their spins polarized in a certain direction will light up a given pixel/subpixel combination. You could roll it up inside a tube, just like a regular screen, and install it in your existing screen frame. You could even use your existing speakers but you'd probably have to get the rest of your sound system EQ'd again. Hey! You can't win 'em all!

[Leo Enticknap]

Having recently worked closely with both leading LED display and cinema audio companies on an install, my impression is that the R & D focus is still on working around it (the inability to pass sound through a LED display) rather than making it possible. Big efforts are being made to improve the audio quality and cost effectiveness of the workarounds, and the sound quality possible is still vastly improved from where it was when the first cinema LED systems went up. But I agree that audio remains the Achilles' heel.

[Bobby Henderson]

I'm kinda curious about LED screens after they've run a lot of "Scope" movies if those LEDs are faded enough that when they run a "FLAT" movie if there will be a bit of a reverse letterbox where the areas above/below the Scope image will be brighter due to less LED use.

I haven't seen any kind of burn-in effect with LED jumbotron displays. This is coming from seeing businesses with LED signs playing the same damned two or three ads over and over and over again on their street sign. They spent all that money, but they're not going to figure out how to make the most of their investment?

20 years ago the early RGB full color LED tiles weren't so great. The technology has improved enormously. Brightness, contrast and color depth levels are tremendous. SMD LED technology has allowed pixel pitches to drop down to very tight, high resolution levels -like the .085mm pitch of Samsung's "The Wall" product. I'm really impressed by the extreme refresh rates. In the late 1990's going into the early 2000's such boards were stuck at 60Hz. Today modern boards can refresh into the thousands of hertz. That's one reason why you can point a video camera at a jumbotron now and not see all kinds of ugly missing pixels, strobing and other artifacts. The image is rock solid.

Still, I am very skeptical there will be any sort of mass adoption of self-emitting LED-based cinema screens any time soon. The maintenance costs are just going to be too damned high for any "ordinary" mainstream cinemas to shoulder. It's one thing to replace a tile on an outdoor sign whose display is only 200x80 pixels. It's another thing entirely to maintain a screen with 2048x1080 or 4096x2160 pixels and far more driver board tiles.

LEDs fade over time. Sales literature from companies like Daktronics, Samsung, Watchfire, etc will claim things like 68 trillion colors or whatever. No content is going to display color that wide. But the attenuation is there so you can fine tune the existing boards as they age. When one board gets a stuck pixel or something and you have to replace it with a new board that new board needs to be adjusted so it matches the aged look of the existing tiles. Otherwise you'll have an odd patch-work quilt appearance to the screen.

I don't even know if any of the leading LED display companies are even trying to solve the problem of getting sound to pass through a LED display. I'm not convinced they're even the slightest bit interested in developing a solution.

[Marcel Birgelen]

the keystone and curved distortions as a result of one's personal perspective and optics (eyeballs) are compensated for in the brain...just like time delay when talking with someone. One has to really exaggerate these things to exceed the brain's ability to make it seem normal. Conversely, the projector's perspective is not something that the brain has to compensate for in nature so when the image on the screen has a different perspective than the viewer, the keystone is apparent. There are many visual cues to it like leaning buildings or bent/slanted horizon lines.

What you're saying is that the brain is able to "transparantly" compensate for the perspective skew introduced by the angle towards the 2D projected plane on screen, but going one step further, aligning towards the skew introduced by the alignment between screen and projector is one step too far.

I'd say, it's probably more complicated than that. I guess it's dependent on the amount of deformation being present in the "end product"and how detectable the deformation is in the provided image material. White noise would have a detectability of zero, while any pattern with lots of straight lines would have a detectability of 1.

Consider for example, deeply curved screens. Although I personally like the concept, there are edge cases where the "deformation" crosses some treshold in the brain and starts to become obvious.

Many if not most cinema projection setups have some slight trapezoid skew. The slanted edges that this produced can be hidden with screen masking or digital masking. That solves most of the problems, because the slanted edges of the picture look weird to people. The deformation usually only becomes apparent once big objects with straight lines start to appear on screen.

I still remember the THX Broadway trailer with its big blue glowing box around the frame. This always was a nice reference to see how much deformation there was in the projected image. Nowadays, it's often the cinema's own info sheets they often play in the pre-show how much deformation there is in the image and how much of the edges is getting cut off.

[Steve Guttag]

the keystone and curved distortions as a result of one's personal perspective and optics (eyeballs) are compensated for in the brain...just like time delay when talking with someone. One has to really exaggerate these things to exceed the brain's ability to make it seem normal. Conversely, the projector's perspective is not something that the brain has to compensate for in nature so when the image on the screen has a different perspective than the viewer, the keystone is apparent. There are many visual cues to it like leaning buildings or bent/slanted horizon lines.

[Marcel Birgelen]

You're looking at a rectangular 2D plane on which another 2D plane is projected. Unless you're sitting dead center in front of the screen, both vertically and horizontally, there will at least be a trapezoid deformation from the perspective you're looking at the screen. The same happens when you look at your TV at home from an angle, but I seldomly hear complaints about that either.

Unless you create a perfectly spherical display and you're sitting exactly in the center, the edges of the screen will be farther away and at an increasing angle than the center of the screen. But as already indicated, that would only work for the person sitting perfectly center and such a screen introduces all kinds of new deformations.

We're reaching the limits of our technology here, only a light field display or some other magically non-existent holographic technology would be able to create deformation-free images for everybody in the room. The only semi-workable solution for now is providing VR goggles for everyone.

[Leo Enticknap]

Old news... bad projection has ALWAYS ruined the moviegoing experience. The switch from film to digital has done a little to help that, but as often said on this forum, any cinema who couldn't do film right won't do digital right either.

Added to which, audience expectations are growing. Keystones are a classic case in point. We've all seen photos of 1920s and '30s picture palace booths, with the projectors pointing down at a 10° angle, or worse. The resulting keystone was accepted as being an unavoidable thing that we just had to live with. Now, far milder keystones are complained about. I suspect part of the reason to be graphics and titles leave much less "overscan" headroom to the edge of the picture. In the most recent Jurassic Park movie, there is a mockup TV news report, with a CNN/Fox style ticker graphic at the bottom. It makes even a tiny keystone in projection immediately visible and obvious, and caused a few customer complaints at one site I serviced.

[Steve Guttag]

Jeez until reading this thread I used to think laser projection was the way of the future, now I'm not so sure.

I will say that the one time I saw a laser presentation (GDC suite at Cinemacon 2021, I think) I wasn't all that impressed with the contrast. Will the presentations at CC 2023 be from laser projectors?

Mike, like all technologies, lasers have their ups and downs. And like most things sold, salespeople over-sell their technology because they are there to sell things. Laser is the current technology for cinemas with just Christie still offering a couple of xenon choices.

Lasers should be, inherently higher in contrast. Only NEC seems to have been able to go with low-contrast laser(ish) projectors. You should also distinguish between RGB laser separate lasers for each of the primary colors) and some form of LP (Laser Phosphor) projector where green and possibly yellow are being generated via a blue laser into a phosphor wheel. NEC's lower-end projectors use two blue lasers...one for blue and one into a yellow phosphor wheel to get the other two colors by making yellow. Their upper-end projectors use a Red, and two blue lasers with one generating blue and the other shooting into a green phosphor wheel to make green. It is the lower-end NEC projectors that have a notable low-contrast that is, seemingly, no better than their HMI lamp counterparts (down in the 1600:1 range). Plus they are S2K projectors (.69" DMDs) so you are starting with bad contrast and, generally, the lower-end of the lens lineups. Combine that with really poor motorized lens accuracy, and you are at the entry level projector that does claim laser (all of the light is laser generated). When you get up to their .98" DMDs, then you get back into the 2000:1 ratio.

Compare that to Barco's RGB lasers in the S4 products that are 2300:1 (and with lensing it can get up to 3000:1. Christie, which lensing on their Cinelife + (RGB Laser) projectors can get up to 6000:1

So, you can't just ding laser, as a category for contrast. It should be better than lamp based. Only NEC seems to have found ways to keep laser's contrast down (because their lasers are using a more conventional lamp based optical path and they are depending heavily on laser-phosphor). Then again, with the laser-phosphor approach, they are less likely to have speckle problems.