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 80s 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
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
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.