THE PHANTOM MENACE, DIGITAL PROJECTION AND YOUR HOME THEATER by Dan Ramer

It isn't very often that I get a chance to experience the stirrings of fundamental technological change. It may be even harder to recognize it. When I bought my first personal computer in 1983, an IBM running at little slower than 5 MHz and hobbled with no hard drive, I had no idea at the time that within a decade PCs would revolutionize the way we communicate and do business. But on Sunday the twentieth of June, I think I had just such a fundamental experience.

George Lucas is rightfully credited for being responsible for a dramatic revolution in special effects. His Industrial Light and Magic has certainly pushed the limits of computer generated images (CGI). We've read that Lucasfilm is working in concert with Sony to produce the first practical system for principle photography without film. And every filmed frame of The Phantom Menace was digitized and brought into the computer for manipulation - a reality that would facilitate a fascinating experiment, motion picture theaters without film.

Weeks ago, Lucasfilm announced that it would offer special showings of The Phantom Menace from a digital source and with electronic projection. I was delighted to discover that the Metropolitan New York area would be served by two Sony/Loews theaters, one in Secaucus and the other in Paramus, the latter only twenty-five miles from my home. So having seen The Phantom Menace twice before on film, I was eager to compare the presentations.

I arrived early enough to score a first row center seat in theater one. My field of view was about 54 degrees, so the image was large enough to reveal any flaws. (This image size was very similar to my two film viewings.) And what I saw was quite startling. The images seemed more three-dimensional. Objects seemed to have more a visual depth. There was vanishingly little film grain and CGI was no longer camouflaged by it. In shots of actors or sets caught directly on film, a subtle film grain characteristic in their projected images remained, but not the CGI. (I thought I had read that ILM had developed a digital simulation of grain to make the CGI less noticeable.) There was no image noise. Colors were vivid and richly painted on the screen. Reds were particularly striking. The level of detail seemed higher. During the sweeping, long shots of the Pod Race Arena, leg movements on the tiny figures walking across the sand were never clearer. I was very pleased, very impressed.

Not that there weren't flaws. Very bright objects like light panels in the bulkhead of a ship exhibited very thin red fringing to the right and occasionally above, something I initially interpreted as misconvergence. But it only occurred on very bright objects, implying a potential blooming problem. Some very bright scenes seemed slightly overdriven and a touch washed out (the first glimpse of the Naboo palace courtyard grounds - another long shot - and some of the scenes in the Tatooine desert). I spotted what appeared to be two tiny stationary brownish-red dots; I assumed they were dead pixels (I would be wrong). I felt that the reds were a little too hot based on skin tones, but neither grays nor whites exhibited any hint of pink.

I searched for any regular pattern that would give away some kind of pixel structure and was completely unsuccessful, but I did notice an extremely subtle stationary, random granularity that's hard to describe. And, finally, during any scene that was fairly uniformly lit, as I smoothly ran my eye down the screen such that it took about four seconds to move from top to bottom, I saw some nearly invisible, horizontal, intensity-banding characteristic of video. Some nitpicking to be sure, but interesting nonetheless.

During the closing credits, I sought out the theater manager to see if there were any press kits available that described the technology. There weren't, but he did introduce me to Ken Bylsma, Advanced Applications Engineer from Hughes-JVC Technology Corporation, who happened to be on site. The projector was theirs. (I had expected the Texas Instruments DLP projector. But this was a Cinecomm presentation, and they chose to use the Hughes-JVC ILA-12K projector.) Mr. Bylsma invited me into the projection booth for a tour of the hardware and was very generous with his time. The film was stored on a RAID array of hard drives (as those of you who are computer savvy already know, this provides a redundancy that allows the show to go on even if a drive fails). MPEG-2 encrypted digital video (compressed by Lucasfilm) is decoded and drives the projector with RGB.

Interestingly, the video was anamorphically squeezed to maximize the vertical resolution and was restored to correct proportions by reducing the height of the images on the CRTs (just like our 16x9 DVDs and our vertical squeeze adjustment). The projector has a unique structure in the form of ILA's (Image Light Amplifiers), which I'll try to describe as simply as I can. For each color, there's a five-inch high resolution CRT that emits near-IR and some visible red. The IR is focussed on a liquid crystal panel about the size of a deck of cards. This panel is not divided into pixels; it is one single, uniform area whose active material responds locally by turning from reflective to non-reflective based on the pattern of illuminating IR. Each of the three ILA's is provided a pure color (R, G, or B) from a set of dichroic mirrors (filters). So, light from a powerful Xenon Arc Lamp passes through the dichroic filters, then a prism, reflects off the ILA, passes back through the prism, then through projection lens onto the screen. When all three colors are present, the screen image is properly displayed. This system is able to deliver a contrast ratio in excess of 1000:1, typically 1200:1. That's a tad over 61 dB; very impressive. That may explain the effective illusion of object depth. (For many more technical details, see the links below.)

You may find it interesting to know that a film print was run in parallel with the video projection. Had the video system failed during the show, the projectionist could have replaced the video image with a filmed image before the audience could hit the screen with a jumbo Coke. After I complimented the presentation, I asked Mr. Bylsma about some of the problems I had observed. (Let me stress that these flaws were subtle and some were extremely small. Mr. Bylsma acknowledged what I saw and was somewhat surprised that I had noticed them at all, but I'm a trained viewer with an image processing background. He and I agreed that 99% of my fellow audience probably did not see them.) Mr. Bylsma was unsure what might have been causing the blooming/misconvergence-like effect. He explained that he and the other technicians had observed the same image problem on their proof monitor in the booth, so he suspected a source problem. The two tiny brownish-red dots were attributed to manufacturing imperfections in the liquid crystal material; there are no individual pixels. (And you really had to concentrate to find them, they were that small.) The system color balance was calibrated, so my suggestion that reds might be a bit hot was again attributed to the source.

The nearly invisible intensity banding brought a response that was my biggest surprise of the day. It was an interlace artifact. I had been watching 1080i30 HDTV, 1920 pixels wide by 1080 pixels high, just like the HDTV now available for the home. Now, I've seen many HDTV demonstrations, and 1080i30 resolution has always been claimed to be equivalent to 35mm film. But this was the very first time I had seen it blown up to the size of projected 35mm theatrical film, and I have to say it was actually better.

Since high-resolution theatrical video projection is in its infancy, the small flaws I noticed will be resolved. The best is yet to come. So what can we expect in the future? Encrypted satellite feeds of film directly to the theaters where the digital transmission will be stored for playback. Studios will be able to avoid the expense of having to strike thousands of prints. Film grain, dirt, and wear will be a thing of the past. And what's the relevance to our home theaters? The most exciting impact is that all films will be digitized at high resolution for theatrical projection. So the films will be ready for down-conversion to 16x9 enhanced video DVDs or encoded directly onto HDTV DVDs at full resolution. The cost of the transfer and compression will be amortized during the theatrical release, reducing the financial pressure on the DVD market. Most exciting of all, within five to ten years you may be enjoying theatrical quality at home.

And avoiding the jerks who insist on talking during the film. Like Sunday ... just behind me ... at The Digital Phantom Menace.

»» Visit Part Two, for a more in-depth look at the rival Texas Instruments DP technology

You can read more about this impressive projector (and see a photo), an explanation of the Image Light Amplifier, and read an article discussing various projection methods.