Can I interest you in a DI?
The Digital intermediate (DI) is the process of digitizing a motion picture into high resolution data sequences. This allows for a greater degree of fine tuning to manipulate color and change other characteristics of the image. The DI is made possible by the formulation of look up tables (aka LUTs). The image sequences are processed through a film print emulation LUT in order to predict what the film will look like on print release stock.
Color-timed data sequences are recorded to inter-negative (IN) film stock on a laser recorder through a process known as film-out. After a digital negative is manufactured, this element will be used to develop contact prints or additional inter-positives (IP) and inter-negatives (IN) in order to fulfill distribution needs. A DI facility will provide side by side comparisons between the data and film prints to validate the accuracy of LUT calibration during the course of color-correction.
Besides the photochemical objectives of a DI, the process affords the latitude to master the digital cinema and DVD/home video versions of a release simultaneously with the film outputs. This is also achieved by LUTs geared to faithfully reproduce the integrity of the digital images on video and in a digital cinema viewing environment.
Digital intermediates have become a routine function of the theatrical post-production process, but like many inventions it didn’t really start out this way. DI’s were once big science projects with lots of black magic and voodoo being performed behind the scenes, or so it seemed. A wise colleague once described the initial methods as using a sledge hammer to cut down a tree. Eventually it worked, but it was crude.
The sledge hammer ultimately gave way to chainsaws and other more practical methodology. All of the painful lessons and diligent research and development have continued to establish viable procedures for the DI. This includes solutions for Red
camera management, 3D, greater image resolution and the evolving digital cinema initiative (DCI).
A notable advancement to the DI services has come with the rapid proliferation of digital acquisition. This is playing a pivotal role by driving new methodologies and innovation to the digital intermediate service. Instead of scanning rolls of film you may be recovering and rendering terabytes of r3d files from a Red One camera.
This does not imply that film is dead. This is only a barometer of the choices filmmakers have between acquisition tools. Film still remains the standard for worldwide distribution, but the DI has become a bouquet of methodology tailored to a project’s source materials, budget and distribution objectives. Many films are a hybrid of acquisition formats, utilizing 35mm 3perf, 4perf, P2, Genesis, Red, 16mm and list goes on. It’s not uncommon for three or more of these formats to be used during principle photography, even on a walk and talk picture.
Regardless of the acquisition choices, the finishing process still bundles all of these customizations into a methodology that resembles a video workflow, but instead of using videotape to facilitate the pipeline, the DI remains purely data-centric. You might even be conforming high resolution data within your own cutting room. With the proliferation of cost efficient NLE systems and storage solutions, it’s not unusual for the DI turnover to begin at the color-correction phase with fully conformed data sequences being delivered directly from the filmmakers.
In addition to the changes occurring in post-production methodology, the role and responsibility of the director of photography has changed with the advent of real time digital color-correction. The flexibility and power of color-correctors along with a seasoned digital intermediate colorist can easily accent, alter or just change the look of a film altogether. DP’s are learning that they can rely on the DI suite to achieve specific looks as opposed to spending extra time during production on costly set-ups. This type of production efficiency can allow the producers to save enough money to apply additional resources to more complicated shoot days.
The digital intermediate also affords tremendous latitude in other aspects of the finishing process. Laborious tasks of yesterday such as, dirt fixes, repositions, speed changes and de-saturating color images to black and white are easily resolved without scheduling special optical or visual effects sessions.
Besides the tremendous advantages a DI offers, there are obstacles that should not be overlooked. I have classified these as a Gotchas and there are three that frequently recur. When you are protecting a modest budget, it’s important to recognize these complications since DI tools often have a false perception of infinite boundaries.
First gotcha: Technical decisions made during principle photography will impact the DI finishing process. If you are shooting with digital acquisition such as, Red, Cannon HF10, XHA1, Sony HDV or Panasonic P2, you will require special handling to achieve
professional finishing results. It’s critical for the filmmakers to partner with a DI facility to devise a sustainable workflow prior to beginning the shoot. The camera may be inexpensive and easy to use, but the media recovery and mapping for DI integration is anything but simple. Often the promises of integrating the field masters directly into an NLE system does not actually allow for the correct EDL mapping back to the original camera masters. Although commercial and ENG productions can get away with this style of post, a feature film will not get the same leniency by borrowing this methodology.
Furthermore, this gotcha also gives way to NLE organization. Poor database management and poor organization will set the tone for the duration of the entire project. For example, the accuracy of the ALE database in the cutting room edit system will be decisive to current scanning, ingesting and conforming processes. Certainly some of these issues can be initiated by the transfer house so vigilance from the cutting room is critical to prevention. If you see errors in the first couple of days of dailies, be sure to sound off to your facility immediately. Avoiding these kinds of snags will craft a reliable course for post-production finishing.
Second gotcha: Don’t go optical crazy without testing the effect. Although it’s painless and tempting to address blow-ups and repos on the conform stations, you still have visual limitations in 2K, 4K and HD. Keep in mind it’s just as easy to compromise quality as it is to create it when using such powerful tools.
Third gotcha: Integration of visual effects shots. It’s critical to coordinate the file naming conventions between the cutting room and vfx vendors. In other words, the EDLs need to match the final comps. By auto-conforming your VFX shots instead of eye-matching leverages a more efficient approach for finishing a project.
An effective method to avoid the gotcha is by having the DI personnel involved with a project before principle photography begins. In addition to the pre-production meetings, you should have a DI production meeting to discuss the impending workflow and obtain specifications from the facility to lay the groundwork for the minimum requirements needed from the filmmakers. The key to realizing expectations is to alleviate as much confusion and any unforeseen blunders before they happen, even if the suggestions seem repetitive and obvious.
By and large, the digital intermediate experience can be a complete nightmare or a walk in the park. The work behind the scenes at a DI facility is anything but easy; however, skilled personnel that truly understand filmmaking, organization and the tools they are using can greatly influence the flexibility and quality of the digital intermediate product. Can I interest you in a DI?
- Devin Sterling
Executive Producer, Digital Intermediate
Riot / Ascent Media Group