Electronic Design

TI Takes Lead In Digital Camera

One year ago, I reported that the digital cinema era began at the ShoWest Exhibition in Las Vegas. At that same event last March, several producers of large-venue projection platforms announced plans for products tailored to the needs of digital cinema. They promised that all would be based upon the digital light processing (DLP) technology from Texas Instruments (Dallas, Texas). The first of these should be ready this summer. But, don't expect a rapid replacement of film-based theaters. That will likely take 10 to 20 years.

Digital cinema offers many benefits. It provides consistent image quality which, unlike film, won't degrade over time. Plus, it significantly reduces duplication and distribution costs, and grants greater flexibility to the theater owners. For example, owners can easily allocate more theaters for "hot" movies and potentially, rent the theater for pay-per-view events. Still, to make this transition, some thorny issues need to be resolved. Digital cinema developers must first prove that the image quality is as good, or better than film. The infrastructure to copyright, protect, and deliver content must also be agreed upon because someone has to pay to renovate the 108,000 worldwide movie theaters that currently use 35-mm film projection.

Last year, The Victor Company of Japan (JVC, Yokohama, Japan) featured prototype digital cinema projectors using their Image Light Amplifier technology. Since then, they discontinued all but one model. Now they will focus on a more promising replacement technology called the Direct-Drive Image Light Amplifier, sometimes known as liquid crystal on silicon. It places a liquid crystal layer on the surface of a CMOS chip that's augmented with a reflective electrode matrix on top. As a result of this redirection, there was no major news from JVC at ShoWest this year.

In contrast, Texas Instruments had a flurry of new announcements. The company's DLP technology consists of three silicon chips with 1.3 million moveable mirrors on each. Large-venue projection applications, like the recent Oscar ceremonies, have proven this technology to be a winner.

The needs of digital cinema, however, difffer from the requirements for most large-venue applications. Cinematographers agreed that the black levels were too high, or bright, and that the contrast was too low for cinema using TI's early digital cinema projectors. Further, they wanted more processing bits for a wider dynamic range, especially in the dark regions. And they desired better control of the colorspace to achieve a more film-like gamma correction.

In conclusion, TI developed a new chip set, referred to as the DLP Cinema. Its resolution is SXGA or 1280 by 1024. But, an added dark metal layer lowers black levels and increases contrast. Contrast has been improved to over 1000:1 verses the large-venue projectors that usually offer only 400-500:1.

New support ASICs have also been developed for the DLP Cinema chip set. With these, data processing is performed with 14 bits of depth/color at 24 frames per second, an alternative to the 12+ bits/color and 30-Hz frame rate of typical large-venue projectors. TI notes that they additionally process the data differently "because the eye perceives colors differently in a dark environment." The color processing was designed to replicate the visual experience of film, but apparently it's still a work in progress. The current crop of DLP Cinema prototype projectors are able to couple to lamp console units used in standard film projection.

At ShoWest, Christie Systems (Cypress, Calif.) and Barco Projection Systems (Kuurne, Belgium), agreed to adopt the new DLP Cinema chip set for use in digital cinema projection products. Both companies worked with TI through the last year in trial installations testing TI prototypes in real theaters. Today, 17 worldwide digital cinema installations use the DLP Cinema technology. New products from these companies could arrive by late summer.

Another notice came from Imax (Mississauga, Canada) and its subsidiary Digital Projection Inc. (Kennesaw, Ga.), regarding DLP-based digital cinema. TI laid out its plan to work with three companies. Imax is the most likely third candidate, but negotiations aren't final. Presently 205 Imax theaters operate in 25 countries. Pricing for the new digital systems may run up to $300K.

Meanwhile, NEC Technologies (Itasca, Ill.) has opted against the DLP Cinema chip and selected TI's less expensive standard SXGA DLP chip set in digital cinema products. The optimized presentation of film-based material will be achieved via their home-grown TriDigital Image Processing technology in an upgraded platform called the MultiSync XT5000-DC. TriDigital Image Processing entails three key steps to optimally decode film transfer material for digital projection.

First, the ColorBit Pre-Processor decodes incoming signals. This is to satisfy the unique requirements for film-based materials as opposed to a conventional video processor. Then, the Deep BlackBit Decoder extracts the maximum dynamic range of the original filmed image to produce deep, dark blacks that still exhibit the contrast and detail of the original film material. Finally, the Wide ColorBit Post-Processor manufactures an image that overcomes the RGB characteristics of the projector which would otherwise make the image appear like video.

All of these developments bode well for replicating or surpassing the visual experience of film. Yet, there are many hurdles to overcome before digital cinema is a mainstream technology.

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