Mastering the digital intermediate - Special Report - Industry Overview

Post,  Dec, 2002  by Claudia Kienzle

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We hear the term "digital intermediate" frequently, especially connection with digital cinema projects. But what exactly is a digital intermediate?

While it's difficult to get agreement on a precise definition, the digital intermediate is basically an electronic alternative to the conventional film process where color timing is done photochemically at the film lab in preparation for theatrical release.

Enabled by the advancement of video to near-film resolutions, the digital intermediate brings film finishing into the electronic environment where directors and DPs gain real-time, interactive and accurate creative control over color and other picture attributes, with the ultimate objective being to shoot it back to 35mm film for theatrical release. Once produced, the digital intermediate can also serve as a "universal master" from which all video deliverables can be derived.

While most agree that 4K data is the ideal format for the digital intermediate -- because of its rich filmic color and picture representation -- they also agree that 4K's 48 MB per frame puts increased demands on processing time and storage, making it cost prohibitive for most clients.

So, many consider 2K data to be more practical because it reduces the data load to 12 MB per frame while preserving a filmic color space -- but it's still very expensive.

Then there are those that feel that 1080/24p HD, with its pared down color information, is easier to handle and more affordable, with just enough resolution to allow that content to be output to film.

Given the budget-challenged economy and relationship between resolution and cost, our sources for this article all agreed that it's difficult to determine what resolution, colorimetery, bit depth and format best constitute a digital intermediate today But they graciously agreed to step into this veritable quagmire to help illuminate this very complex subject.

SUNSET DIGITAL

"Whenever I get a call from someone who wants to discuss a digital intermediate, it's absolutely all over the board, with different meanings to different people," says Ron Burdett, chairman and CEO of Sunset Digital (www.sunsetdigital.net) in Glendale, CA. "The reason it's so hard to define is that the digital intermediate is truly a process, not a standard. When you step back and look at the big picture, what you are talking about is creating a digital master that is destined for theatrical release or film archive -- something that will see its life as a film."

With every advancement -- from D-I ,to 1080/60i HD, to 24p HD, 2K, 4K data and beyond, Burdett says, "What we've been striving to do is to make video look as good as film. Is it technically possible to do today? Yes. Is it cost effective given the depressed world economy and the time constraints facing our clients? Sorry, guys. Maybe it will be practical in three to five years." the main hitch for a feature film is storage, both at the facility and in the number of data tapes for archive.

While there's only a slight increase in pixels between 24p HD and 2K, Burdett cautions there's a tremendous jump in colorimetery going from HD 709's (sub-sampled chroma) color space to 2K's RGB 4:4:4 full-bandwidth color space, and the possibility of a higher bit depth up to 16-bits -- a quality level Sunset Digital produces with its Cintel C-Reality film scanning telecine.

For Tomb Raiders and Jurassic Pork 3, Sunset Digital produced HD digital intermediates that Burdett says compare favorably with color-timed film answer prints. But a digital intermediate does not necessarily require film origination. For the HBO docudrama The Laramie Project, Sunset Digital pulled together 4-by-3 video from every conceivable tape format, then delivered a 16-day-9 24p HD master and a 4-by-3 SD master for HBO to broadcast, as well as a 35mm film for projection at the Sundance 2002 Film Festival. He said, "This project put everything we know about digital intermediates to the test."

POST LOGIC STUDIOS

"We view the digital intermediate and the universal master as one and the same," says Barry Snyder, president of Post Logic Studios (www.postloginc.com) in Hollywood. "Once you have a high-quality digital intermediate, you can shoot it to film for the theatrical release. And that same digital intermediate can also be used to derive the other versions, including the HDTV, standard broadcast, in-flight market and DVD releases downstream. However, the digital intermediate and subsequent versions must all be properly color corrected and formatted according to the unique needs of each particular application."

Rather than relying solely on Look-Up Tables (LUTs) that convert the colorimetery and gamma of one format to another, Post Logic's colorists also use their artistic judgment to ensure high-quality imagery regardless of which medium it's ultimately viewed on.

Post Logic colorists Lou Levinson, Bryan McMahan, John Persichetti and Michael Underwood have shared the benefits of digital color timing with Hollywood's top directors and DPs, including Steven Spielberg, Robert Rodriguez, William Friedkin, Alan Daviau and Sam Mendes, among others.