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The State of Digital Cinema - April 2010 Part Two

by siegestate Mon Apr 26th, 2010 at 12:36:53 AM EST

Part I of this series ended with generalities about where DCinema has been and how it got here. Since the series is written for a general audience, these next sections will get only slightly more technical. In addition, a Part 0 was added that goes even more basic.

There are other sources for industry `inside baseball', technical, financial and political. It is best exposed at the sites of Sperling Reich, Celluloid Junkie, and Michael Karagosian, Digital Cinema Business FAQs, and at Nick Dager's Digital Cinema Report. DCinemaToday and DCinemaTools give data from other viewpoints. Mark Schubin's broadcast-centric site Schubin Cafe is so elemental that the data crosses over, and the writing is so good that it needs to be read.

The real inside data is from the standards body, SMPTE (Society of Motion Picture and Television Engineers, pronounced simp-tee). In 1916 they began corralling the many speed, sizes and varieties of film standards that existed then, and they continue to corral.

SMPTE refined the work that the studios sponsored and summed up in a series of compliance documents (See: "DCI Movies) done in the spirit of, "This is the minimum that we require if you want to play our movies." As the saying goes, "Standards are great! That's way there are so many of them." And as an executive stated, "We can compete at the box office, but if we cooperate on standards, it benefits everyone."


In fact, the cinema standard that is known as 2K is beyond good enough, especially now that the artists in the post-production chain have become more familiar with how to handle the technology at different stages. Most people in the world don't get to see a first run print anyway, and a digital print (which doesn't degrade) compares more than favorably with any film print after a few days. Plastic which is constantly brought to its melting point becomes an electrostatic dust trap, stretch and gets scratched, and the dyes desaturate.

To this date, most digital projectors are based upon a Texas Instrument (TI) chip set. Sony's projector is based upon a different technology, and has always been 4K (4 times the resolution of 2K), but not many movies have been shipped to that standard yet. The TI OEMs will be shipping 4K equipment by the end of the year (or early next year.) Except in the largest of cinemas, most people won't be able to tell the difference between 2K and 4K, but the standard was built wide enough to accommodate both.

Confusing the consumer, 2K in pixels (2048 picture elements in each line) seems near enough to the 1920x1080 standard of TV know as 1080p. But there are other differences in the specification besides pixel count, such as the color sample rate, that are more important. In addition, many steps of the broadcast chain degrade the potential signal quality so that hi-def broadcast is subject to the whims of how many channels are being simultaneously broadcast, and what is happening on those channels. (For example, if a movie is playing at the same time as 15 cooking channels, it will have no problem dynamically grabbing the extra bandwidth needed to show an explosion happening with a lot of motion. But if several movies all dynamically require more bandwidth simultaneously, the transmission equipment is going to have to bend some of them in preference to others, or diminish them all.) Blu-ray will solve some of that, depending on how much other material is put on the disc with the movie. Consumers like the "other stuff" plus multiple audio versions. Studios figure that only a relative handful of aficionados optimize their delivery chain enough to be able to tell the difference. So they end up balancing away from finest possible quality for the home, while finest quality is maintained for the cinema by virtue of the standards.

With all the 3D movie releases announced, people question whether they should expect 3D in the home. It is quite possible. The restrictions or compromises are many though. First, special glasses are required, and there seems to be a reaction against the glasses. Many companies are attempting to develop technologies that allow screens to do all the work (no glasses), but when the largest company, which spent the most money over the last few years, pulls out of the market, it isn't a good sign. (Philips pulls out of 3D research | Broadband TV News) The reality is that one person can see the 3D image if they keep their head locked in one position, and perhaps another person in another exact position, but it isn't a marketable item.

Fortunately, there were three companies at ShoWest which offered much cooler glasses for watching 3D, including clip-ons. Since there are 3 different types of 3D technology in the theaters, it a complicated task for the consumer. At best, the cinema will hype that they have 3D, but they rarely give the detail of which type or equipment they are using.

There are several clues that humans use to establish depth data and locations of items from a natural scene. Technically, these items in the 3rd dimension are placed on what is called the `z axis' (height and width being the x and y axes.); Matt Cowan details a few of these clues in this presentation, and there are others. Filmmakers have understood how to use these in 2D presentations for ages.

But the challenge for decades has been synchronizing the projection and display of two slightly different images, taken by cameras 6.4cm apart (the same as the `average' eye distance), in a manner that shuts out the picture of the right eye from the left eye, and a moment later shuts out the picture of the left eye from the right eye fast enough that the eye gets info to the brain in such a way that the mind says, "Ah! Depth." Digital projectors makes this attempt easier. It has evolved even in the last 2 years, and that evolution will continue.

There are four companies (Dolby, RealD, MasterImage and XpanD) who produce 3 different technologies for digital 3D systems for the cinema theater. Each coordinates with the projector in a slightly different manner. The projector assists by speeding up the number of frames presented to the eyes, 300% more in fact, with a technique called "triple flashing".

For comparison, 2D film projector technology presents the image two times every 1/24th of a second. This means that the film is pulled in front of the lens every 24th of a second, allowed to settle, then a clever gate opens to project light through the film to the screen, which then closes and opens and closes again. Then the film is unlocked and pulled to the next frame. With digital 2D, motion pictures are handled the same, presenting the same picture to the screen twice per 24th of a second, then the next picture and so on. Triple flashing a 3D movie increases the rate from 48 exposures per second to 72 per second...for each eye! Every 1/24th of a second the left eye gets 3 exposures of its image, and the right eye gets 3 exposures of its slightly different image; L, R, L, R, L, R, then change the image.

Since it would be difficult to get everyone to blink one eye and then the other in the right sequence for an hour or two, the different 3D systems filter out the picture of one eye and then the other,. The Dolby systems does this (simply stated) by making one lens of the glasses an elaborate color filter for one eye, with the complimentary twin for the other eye. The projector has a spinning color wheel with matching color filters which, in effect, presents one image that one eye can't see (but the other can), then presenting the opposite. RealD does this with a circular polarizing filter in front of the projector lens that switches clockwise then counter-clockwise, and glasses which have a pair of clockwise/counter-clockwise lenses. The XpanD system does this with an infra-red system that shutters the opposing lenses at the appropriate time. There is a 4th system named MasterImage which uses the same polarizing glasses as RealD, but with a spinning filter wheel instead of a very clever and elaborate (read, "expensive") LCD technology.

Suffice to say that there are advantages and disadvantages to each system. Dolby's glasses are made from a sphere of glass so that the eye's cornea is always equidistant from the glass filter. They are also more expensive, though they have had two price drops as quantities have gotten up, from an original $50 a pair, to last year's $25, and now $17 each. They need to be washed between uses for sanitary reasons, which provides jobs of course, but also adds to logistics and cost. XpanD glasses also need washing between use and have a battery that needs changing at some point. (Without going into the detail, the XpanD IR glasses are thus far the technology of choice for the home market, though no company should be counted out at this stage.)

RealD were the first to market and originally marketed with the studios, who provided single use glasses for each movie. Dolby sold against this by taking the ecology banner, announcing that they had developed their glasses with a coating that can be washed at least 500 times. RealD found that their glasses could be recycled to some minor extent and have now put green recycling boxes into the lobbies of the theater for patrons to drop them into for return to the factory, washing, QC and repackaging (of course, in more plastic.) There are no statistics as to how many get returned and how many get re-packaged.

A few cinemas are selling the glasses for a dollar or a euro, and seeing a lot of people take care of, and return with, their glasses. Eventually this model will be more wide-spread, with custom and prescription glasses, but the movie industry was concerned with putting up a barrier while 3D was in infancy, and glasses makers weren't interested when the numbers were low.

Since the three systems are different, and there is no way to make a universal pair of glasses, patrons are going to have to know what type of system is used at their cinema of choice, or buy multiple pairs. In any case, the glasses are not going to be ultra-slim and sexy. In addition to being the filter for the projected light, they must also filter extraneous light. If they allow too much light from Exit signs or aisle lighting or your iPhone, the brain-trickery technology will not work. There are enough problems with 3D in general, and today's version of it in particular, to allow any variables.

The most grievous is the amount of light getting filtered by all the lenses, coupled with the fact that half the light is being filtered from both eyes by making you blink 72 times per second. Less than 20% of the original light is seen in the eye by some systems. Up till now there hasn't been a way to crank up the light level to compensate, and if projectionists tried, the cost in electricity goes up and life of the system would go down. This is one major reason that manufacturers of new projectors are hyping lower light levels.

The other technical compromise with the polarizing lens systems is that they require what is called a "silver" screen to help maintain the polarization (and secondarily, to help maintain light levels.) But there is no free lunch with physics. Silver screens can be optimized, but the worst of them will have 'hot spots' in the room that make the side seats or upper seats see a different (darker) image while some seats have brighter or hopefully some with even the 'correct' amount of light. The major screen manufacturers have done a lot of work to mitigate this effect, and will tell you this problem is now virtually solved, but there are a lot of older screens out there, and incorrectly installed screens and a lot of people who have walked around and still see the effect. Sit in the center of the cinema and you will have the best odds, somewhat toward the front (the projector is higher than you are, and presuming that the screen is flat, the theoretical correct angle to your eyes is down. On the other hand, audio mixers mix from about three quarters back. YMMV.

Part 3 and 4 deals with acquisition, with and without 3D, more considerations of digital and 3Ds evolution, how to make your own master, where in the world are these digital boxes? and whether there will be 50% saturation by the end of 2011.

Cross posted to: DCinemaTools

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It's also worth mentioning the most basic phenomenon of the movies: the reason why 24 still frames (or more) sequentially presented to the eye over a period of 1 second, are interpreted by the mind as motion.

wiki: Persistence of Vision.

The phrase covers several phenomena, and the jury is still out as to which is the actual 'cause'. The Phi  phenomenon, Beta Movement or the 3 phenomena that are part of the Lilac Chaser, are all part of the PoV.

Frame rates as low as 10 - 12 frames per second can also be interpreted as continuous motion - depending on  the  time that the frame is held stable in vision and the 'blank' time it is being exchanged for the next frame.

Frames rates lower than 10 - 12 start to be seen as individual images or rather as 'jerkiness'. Frame rates in the 6 - 8 can trigger epilepsy (strobe lights or the sun flashing hrough tres while speeding on a motorway can do the same). Alpha waves are electromagnetic oscillations in the brain of 8 - 12 Hz. (there's a neuronal pacemaker). Beta rhythms in the brain are from 12 - 30 Hz, Gamma waves average about 40 Hz (but range from 25 - 100 Hz. Theta waves are 6 - 10 Hz.

Strangely, the early 20th C audiences for e.g. Charlie Chaplin movies never saw the speeded up motion that is now iconic for 'silent movies'. The lack of standards at the time for filming and projections speeds (until the mid '20s the cameras and projected were hand-cranked), along with the cost of early nitrate film stock, meant that shooting speeds of 12 frames per second were common - and the projectionists would attempt to match these speeds in showing the film. As motors were added, a frame rate of 16 fps became standard.

By the time the 'silent movies' were revisited, the technology for presenting the movies at their original frame rates were no longer generally available. Thus they were run at faster frame rates of fixed speed projectors.

You can't be me, I'm taken

by Sven Triloqvist on Mon Apr 26th, 2010 at 05:36:24 AM EST
All very interesting.

It is hard to know what is myth, but it is said that films moved up from that 16-18 frames per second average to 24 frames in order to get smooth sound! not for the purpose of some science of sight (as we are generally taught.)

There is a group (mentioned in the next document) named the EDCF (European Digital Cinema Forum, part of whose work has been to keep the Hollywood powers-that-be aware that there are different needs outside the US. A most obvious example is that much of the music recorded around the world is recorded at 25 frames per second, not 30 (or variations of 25 and 30 to get away from phase beating from the electricity pulse, like 19.96....) These recordings have to be changed in some way by US post houses, such that the original pitch is changed or edited in some fashion.

The sub-group that pushed this was headed by Kommer Kleijn, who successfully got attention and results on an international level for this aspect, as well as lower and high speed alternative display frame rates. Here is a presentation that he gave a couple years ago: Flexibility in Frame Rates. (He mentions IMAGO in the first slide, which is the European Association of Cinematographers.)

As part of this work on behalf of archivists the world over, he worked with the chief engineer at the French and American server company Doremi, Francois HELT. They gave a demonstration 18 months ago that showed what could be done with projectors and old material. They came across the idea that 24*3, which is a natural frame rate in the digital projector, could be utilized to show 18*4. We all sat entranced while they played +100 year old, converted-to-digital films, via a digital projector. We saw some of the first camera tricks for movies from before and shortly after 1900.

I can't say enough nice things about the EDCF, who will gladly allow membership rights to interested parties for a relatively low fee.

Never underestimate their intelligence, always underestimate their knowledge.

Frank Delaney ~ Ireland

by siegestate (siegestate or beyondwarispeace.com) on Mon Apr 26th, 2010 at 10:18:36 AM EST
[ Parent ]
The most basic problem is the 24 fps established for movies, and the nominal 25 fps of PAL standard TV which is linked to the 50Hz AC that originated in Europe. The lower resolution NTSC TV standard was adopted in America with 29.97 interlaced fps. (Not to mention the SECAM system developed in France which encodes colour differently)

I'll have to read up on EDCF, thanks ;-)

You can't be me, I'm taken

by Sven Triloqvist on Mon Apr 26th, 2010 at 11:02:23 AM EST
[ Parent ]
You say "a very clever and elaborate (read, "expensive") LCD technology. " but if anything, the Dolby system is by far the most clever (to me).  Using separate portions of the visible light spectrum has many interesting applications (for example, you could use a very narrow band projector and glasses and allow for watching films in daylight!)  Toggling LCDs on the other hand are fairly brute force and old tech.

(frequency multiplexing also allows for plain white screens)

by njh on Tue Apr 27th, 2010 at 12:32:41 AM EST
Sometimes the pioneers get the arrows, but sometimes being first to market gives one an edge that is hard to overcome. In this case, RealD has done OK by being first.

I suppose, before any details, that it should be noted that the cinema business is not the main target market for the 3D companies products. 3D simulation for product design, medical, military applications and the eventual home market (among others) are all huge or have huge potential.

RealD has also recently released upgrades that remove some of the problems with their system; one change is a device that is able to amplify the light in systems and another eliminates the need for special 'pre-ghost-busted' release print. (Ghosting is a cross-talk problem that showed up as light shadows in some images, particularly on the RealD system.)

Whether the Liquid Crystal method is inherently better or whether another technology has some future advantages, I can't say. Right now, it is making the most waves. But it is early yet. Less than 15% of market saturation for digital in general, and half capable of 3D...with a lot of market factors still to be seen...???

Daylight movies is actually something I haven't thought about. This makes me think about cell phone conversations on airplanes...more stimulus, all the time.

Never underestimate their intelligence, always underestimate their knowledge.

Frank Delaney ~ Ireland

by siegestate (siegestate or beyondwarispeace.com) on Tue Apr 27th, 2010 at 04:27:15 AM EST
[ Parent ]
In research and design applications it's often one or two people at a work station. Simple double image red/green 3D or even vertical lenticular is possible. Sun had a system I saw demoed in the 90s for looking at and rotating molecule simulations in 3D.

I did some large (1.5m high) lenticulars a few years ago for a cruise ship that contained 8 separate static images. As the passengers walked past the image changed. No glasses needed. Lenticulars have a quite wide viewing angle, and I would guess that putting up two images (the stereo pair) on a lenticular screen is possible. Digital images are stable horizontally - but the vertical lenticular lens sheet would have to be almost directly on the surface of the screen image.

You can't be me, I'm taken

by Sven Triloqvist on Tue Apr 27th, 2010 at 11:53:42 AM EST
[ Parent ]
I meant putting two moving images up behind a lenticular screen. The images are vertically sliced to fit behind the lenses. That could be done by image processing.

You can't be me, I'm taken
by Sven Triloqvist on Tue Apr 27th, 2010 at 12:28:27 PM EST
[ Parent ]
Indeed; the advertising display technology folks are wild about this. It catches the eye of people walking by, it doesn't have to be perfect to get the message across, and it grabs people from the walkways.

Here's last week's latest and greatest from Display Daily on an Autostereoscopic Cinema Display Proposal.

So, what you think? A few dozen straight lines, this Dremel Tool and my friend's iPad screen might lead to the next coolest thing?

Never underestimate their intelligence, always underestimate their knowledge.

Frank Delaney ~ Ireland

by siegestate (siegestate or beyondwarispeace.com) on Tue Apr 27th, 2010 at 02:54:43 PM EST
[ Parent ]
Very interesting...

The guy I worked with on the lenticulars was David Burder in the UK - something of a 3D genius living in a leafy suburban street and doing 3D in his (large) garden shed. A true British eccentric - but he knows his stuff.

He was also involved in the Nimslo still camera concept.

You can't be me, I'm taken

by Sven Triloqvist on Tue Apr 27th, 2010 at 03:37:39 PM EST
[ Parent ]
Oh my. I have seen the David Burder site before. Now I have some back story.

So, you think I should be asking him about my iPad etching?  ;-)

Personally, I don't have a problem wearing glasses to watch 3D, as long as they have a comfortable nose piece and block out extraneous light. And these are now available...even clip-ons are available.

So the concept of going through all this trouble for TV 3D without glasses is madness to me. Skip all that, handle some other real problems with 3D TV (such as children not having 6.4cm eye spacing and the different sitting distances for TV making the big screen and TV experience different) and put all the future efforts into hologram technology.

There is a piece that I am working into the next series piece. Normally I blow by all the doom and gloom, eyeballs will be bleeding stuff. But I have attended presentations by Dr. Marty Banks in which he commented on this issue of TV 3D "problems". (Of course, just because I attended his presentation doesn't mean he is validated...but,) I don't think that he is someone who should be blown off.

EETimes.com - 3-D TV disparities said to cause physical, mental strain

Never underestimate their intelligence, always underestimate their knowledge.

Frank Delaney ~ Ireland

by siegestate (siegestate or beyondwarispeace.com) on Tue Apr 27th, 2010 at 04:29:29 PM EST
[ Parent ]


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