Digital cinema systems have been around for some time, even the high-end "4K" variant. Digital cinema upstart RED, however, is making the high-resolution format more accessible for both filmmakers and theaters. And its technological breakthroughs could trickle down to consumers in the not-too-distant future.

At the beginning of this decade, it became apparent that the resolution specifications for HDTV—even the pixel-dense 1080p mode—just weren't adequate to digitally project feature films in movie theaters. Both the Society of Motion Picture and Television Engineers as well as a new group, Digital Cinema Initiatives, began work to define standards for digital cinema playback. DCI, formed by several large Hollywood studios, released version 1.0 of the "Digital Cinema System Specification" in 2005; the current 1.2 version of the spec was formalized last March.

The spec defines both a 2K and 4K resolution, similar to HDTVs specification of 720 and 1080 formats. Unlike HDTV, which specifies the maximum vertical resolution, 2K and 4K refer specifically to the maximum horizontal pixel counts of 2048 and 4096, respectively.

The spec defines 2K as 2048x1080 (HDTV is 1920x1080, for comparison) and 4K as 4096x2160, both with 36-bit color. The actual pixel counts can vary depending on the aspect ratio a film is shot in, which usually isn't 16:9 (1.78:1).

To get some idea of these resolutions, 2K projectors can display 2.2 megapixels and 4K projectors can show 8.8 megapixels. That might not seem like much compared even to entry-level DSLRs that shoot as high as 12 megapixels, but movies run at 24 frames per second, so there isn't much time for hardcore pixel-peeping. To get an idea of the data requirements for these digital formats, uncompressed 2K needs 228MB/s and 4K needs 911MB/s (that's megabytes, not bits).

Given these data rates, it's understandable that the DCI spec allows for compression of the video data. Even with compression, though, current digital projection requires high-performance RAIDs, fiber optic connections, and loads of processing power, not to mention high-priced, top-of-the-line 2K or 4K digital projectors. Even now, most theaters might have just a screen or two capable of handling 2K resolutions.

Why bother?



With few theaters even equipped to project 2K, why even bother with 4K? Almost any digital photographer or audio engineer can tell you that it's always easier, and usually better, to start out with more resolution than needed and then resample down if necessary. So, a 4K source will look better sampled down to 1080p HDTV than direct 1080p HD video.

2K, and more commonly 4K, are also used as digital intermediates for post-production work. The film that was shot is digitally scanned for editing, color correction, effects work, etc. before being transferred back to film for projection or sampled to 2K for digital projection or sampled down to make DVDs or high-def Blu-ray discs.

All of this is great technology for studios and theaters. But RED, known for making great strides in moving the world of film into a fully digital realm with its 4K RED ONE digital cinema camera, is stepping up once more to make 4K resolution digital projection cheaper and more efficient with its RED RAY playback device. Announced in 2008, the company's Red Ray player is capable of 4K and 2K playback as well as 720 and 1080 HD formats from "standard DVDs." The feat is accomplished via wavelet compression encoding that is capable of getting 4K resolution down to as little as 10Mb/s (yes, that time I meant bits, not bytes).

HDTV is finally going mainstream and Blu-ray still hasn't reached the mass-adoption that studios been hoped for, but RED RAY tech makes real the possibility of home 4K players or relatively trivial network streaming of 4K resolution video. Such video will look great downsampled to playback on today's HDTVs, but future home theaters will be built around 4K flat panels or projectors. RED, with its RED RAY playback technology, as well as digital cinema cameras capable of 6K or higher resolution, plans to be ready for that future, well, today.