Digital Intermediates

So you’ve got this idea for the “great American indie film” and all this digital talk seems like it would benefit you. Everyone is doing it, but what is it? Let’s look at the traditional approach first. When you shoot film, the finishing process involves actually cutting the negative, adding optical titles and effects, color-correction and printing. There are countless physical and photochemical steps from camera original negative to the release prints you watch at the multiplex. This process involves the creation of several intermediate positive and negative film copies, each of which incrementally reduces the quality and resolution of the final product that gets to the theater.


The Digital Intermediate process replaces most of these in-between optical and film lab stages with electronic alternatives. The negative is scanned frame-by-frame into a computer in a procedure analogous to capturing a photo or 35mm transparency with a desktop scanner. Once in a data format, these files can be edited, manipulated and color-corrected in a nearly lossless form, until this new “digital negative” is recorded back to a film internegative, from which theater release prints are struck. Fewer physical steps and photochemical layers equal a better product for moviegoers. But Digital Intermediate finishing comes in all flavors. The most common process used these days – referred to as 2K scanning – provides results roughly equivalent to half the resolution of the film negative. The horizontal dimension of a scanned 35mm frame at half resolution is approximately 2,000 pixels, hence the term 2K. Some blockbusters, like Spiderman II have used a more expensive 4K process, which is closer to full film resolution. 4K files are twice the horizontal and vertical pixel dimensions of 2K files, which means that data rates, file sizes, render times and storage costs increase in an exponential rather than linear fashion.


On the opposite end is the so-called “poor man’s” DI process. High-definition video equipment is used in place of 2K or 4K scanning methods. HD post gear generally runs in real-time whereas higher resolution scanning methods don’t, so costs are lower using these HD video techniques. Since a 2K image file is about the same size as an HD video frame – after the film frame is cropped for a widescreen theatrical format – HD post for film release can be acceptable for many movies, even if the original production was on film and not videotape. For instance, this technique might provide better results and afford lower cost to the 16mm documentary producer than making a 35mm “blow up” from his 16mm negative for the theaters. Of course, if your original production uses a standard or high definition digital video format rather than film, then you will invariably go the HD route for finishing before mastering to a film internegative for printing and distribution. Films like 28 Days Later, Once Upon A Time In Mexico and Collateral are notable examples.


The right approach for you boils down to cost. Traditional 35mm film finishing on a movie with few effects and standard titles will cost about the same as the HD workflow, yet will probably give you better results on screen. Simple 2K scanning is better but more expensive than HD. 4K is at the top end – currently reserved for a handful of Hollywood blockbusters. On the other hand if your vision is the next Sky Captain, then HD methods might be the only way in which your film can even be made. So if you are lucky enough to have a movie to produce – do your homework. Remember that all things “digital” are not a panacea.


Written by Oliver Peters for Create Magazine