The Digital Intermediate Process
By Freddy Goeske 11/23/2002

For over a century the filmmaking process has been constantly evolving. The growing sophistication of filmmakers and the influence of technology is ever increasing the benchmark of the quality expected by the audience. In the past ten years alone digital technologies have brought us visual effects that would have been too expensive, too dangerous or just outright impossible before. Since the late 80’s nonlinear editing systems have replaced cutting on film and become so inexpensive almost anyone can have one now. Innovation has given filmmakers more control over the budget, look and feel of motion pictures.
Today every aspect of film production is becoming more and more influenced by digital technology. The latest ground swell to hit filmmaking is the Digital Intermediate process. In simplest terms the Digital Intermediate process or DI is the conversion of film to digital bits and then back to film again. While that might sound simple in reality this is a bleeding edge process that will evolve over many years and has great potential to revolutionize the postproduction process. This process will influence everything from on set production to the delivery of content to consumers and everything in between. To see its full potential the Digital Intermediate process will require combining the skill sets of Film, Video and Information Technology professionals.

Ideally the process begins in preproduction with the production team finding a post house they are comfortable with and testing with them. The team should test looks and understand the workflow requirements for this new process. The Director of Photography should be well aware of how to best exploit the advantages of the process. Additionally, the producer should understand how the process would affect the budget and scheduling. Because this process is new each post house will have its own workflow requirements and recommended best practices.

Once the editorial process has been completed and the picture is locked to sound an over cut negative is scanned into digital bits. This scanning process varies from facility to facility but in general the trend is to scan the film in at a 2k resolution at 10bits per color channel. The resolution and color bit depths will inevitability improve as scanner technology improves, storage gets cheaper and networks get faster. Today the Thomson Spirit Data Cine and Imagica film scanners are the most popular.

Just as the scanning equipment varies between facilities so does the scanning methodology. Some facilities will color grade the film on the scanner before converting it to bits and some will scan the negative and then color grade. While it is much more convenient to scan first and then color grade some experts insist that due to the limitations of today scanners you must grade the film on the scanner to maximize the color detail being converted into data. Still other suggest a logarithmic 10bit RGB film scan is sufficient to capture the full 9 1/2 stops of dynamic range of advanced film stocks. This argument should become moot as scanner technology improves.

The Director of Photography will spend about two weeks with a colorist grading the film and setting the overall final look for the project. From scene to scene color consistency to advanced skip bleach looks, in the digital lab a great colorist has the ability too create almost any look imaginable. In most facilities the colorist will use a Pandora Megadef or a Da Vinci 2k color correction console with a film color calibrated CRT or projector. These advanced consoles give the operator the ability to manipulate everything from basic RGB color control to advanced secondary color correction in specific regions of a frame. Once completed the color corrected data is moved onto a powerful workstation for conformation. On the workstation, usually a Discreet Logic Inferno or other real-time 2k workstations, the data is conformed to the edit decision list (EDL) and compared to the locked offline output for editorial consistency. During this process things like dust busting, scratch removal, speed changes, transitions, title graphics and end credits are added. Additionally, simple effects, wire removal and boom removal can be performed. If the film includes visual effects or other digital elements they will be imported into the project while on the workstation. On most projects the conforming and cleanup process only takes a few days.

After conforming and cleanup the Digital Intermediate process allows for a digital answer print will be created. The digital answer print can be played back in a digital cinema and approved before committing the project to film out. While not yet perfected the latest digital projectors can give you a very good idea of what the film will look like at the cinema. In addition to the advanced color control advantages of Digital Intermediate, the process also avoids many of the conventional optical printing steps in the film delivery process. Because the original camera negative is scanned and all subsequent processing is done digitally it is possible to eliminate the inter-positive to inter-negative process all together. During the film out process you can directly create an inter-negative or inter-positive on polyester or acetate base to allow release prints to be reproduced. In the case of mass duplication several polyester inter-negatives can be digital recoded totally eliminating the inter-positive step.

Once the digital answer print has been approved it will be filmed out to meet the requirements for film distribution. The film recording process gives you the ability to select different film stocks with different grain and look characteristics. The output from the film recorder will create a distribution master that will require only one light printing with no further color or printer light changes greatly simplifying the printing process. The end result is higher quality print in the cinema and a digital master ready to be delivered to any tape or other distribution medium without re-mastering.

Today the cost of a Digital Intermediate is around $180,000 to $240,000 USD. This might sound steep to the independent producer but as more postproduction facilities offer this service and technology gets cheaper market forces will drive the cost down. It is also important to look at the big picture when looking at the costs. This process substantially reduces the cost to create HD, SD & DVD deliverables. If the film was shot on 16mm the process allows delivery to 35mm at no additional cost. Other cost saving can come from ability to combine digital dailies and 3 perforation 35mm in the camera reducing by 25% the amount of film used per minute on the set. The point is the price of DI is coming down and savvy producers will find ways to leverage this technique to reduce costs while increasing the quality of the viewing experience.

-----Freddy Goeske