| Video Noise July 2007
Changing Film-Production Methods Improve Home Video
Traditional film production relies on the following steps
to get a movie from the camera into a movie-theater projector:
- Original negative produced in camera
- The workprint -- a positive copy of the original negative
without the orange base color -- is used during the editing process
- Original camera negative is cut to match the edited
workprint and spliced together into reels
- Interpositive is printed from edited original reels,
orange-tint base color is added
- Internegative is printed from interpositive; during this
stage, the color is corrected so that different shots and scenes match
- Release prints are created from internegative
- Release prints are sent to theaters
(Note: This summary is greatly simplified. If special
effects are to be inserted into the film, an entire additional stage of work must be done
to create the master from which interpositives can be printed.)
Prints made using this process are three generations
removed from the original camera negative. That’s three generations of lost image
quality. It’s like using a photocopier to make a copy of a copy of a copy of an
original document -- that third copy is clearly not as good as the original. In the
process of preparing a film for release, great care is taken to minimize how often the
original negative is handled, to lessen the chance of damaging it. Several interpositives
may be made from the edited original to ensure that all needed internegatives can be
produced, and multiple internegatives are then made to ensure that enough release prints
can be run off.
Telecine machines are used to make a DVD (or VHS tape or
laserdisc) of a film produced in this traditional way. A positive or a negative of the
film can be run through the Telecine to convert the 24-frames-per-second optical image to
a 30fps electronic signal. You probably remember watching films in these various formats
whose reissues looked better than the original releases. That was often because, in
addition to other enhancement techniques, a print was used for the Telecine stage that was
a generation closer to the original camera negative.
Today, things are different. Now, most films shot on a
significant budget include a Digital Intermediate (DI) stage. DI eliminates working
prints, interpositives, and internegatives, which means that the release prints shown in
theaters are two generations of duplication closer to the original camera negative. That
original negative is scanned by a "4K" scanner that has a little more than twice
the resolution of high-definition video. Once in digital form, the film is edited,
color-corrected, special effects are inserted, and work can be done frame by frame to
eliminate unwanted elements, such as altering a stunt double to more accurately represent
the actor, or removing wrinkles from the faces of older actors. Once the final version of
the film exists in digital form, release prints can be produced directly from the digital
source -- as can the DVD, HD DVD, and Blu-ray editions. This eliminates the Telecine
stage; transfers to video formats are made more or less directly from the original camera
negative. DI is thus able to provide better-looking films and video transfers than is
possible with traditional film-duplication processes. Even if a film was originally
produced with film duplication, the original camera negative can be scanned to DI, then
re-released with better image quality than ever before, for theater revivals or for
reissue on digital optical disc formats.
Digital Intermediate has created a veritable revolution in
the production of release prints, DVDs, HD DVDs, and Blu-ray Discs. A representative
of Sony Pictures estimated that of the 25 or so films that Sony will produce "in
house" in 2007 (i.e., films shot by Sony Pictures themselves rather than
acquired from other sources), an estimated 20 will go the DI route.
However, all is not perfect in the DI arena, or with
"films" originally shot digitally. Already, there have been problems with the
storing of digital "footage" produced with some mediums. Computer technology
changes so fast that it’s difficult to keep archival data in reliably retrievable
forms without converting it to more recently developed storage formats every three to five
years. The industry is well aware of the issue and is pursuing solutions.
But until a solution is found, the future of film archiving
seems to be in the past. One of the most viable solutions seems to be transferring the
digital data to color-separation film: three black-and-white prints, each print
representing a color -- red, green, or blue. These B&W prints store well and last many
decades. There will be a slight loss in image quality if the separation prints ever need
to be rescanned, but that’s better than losing the entire film.
...Doug Blackburn
db@hometheatersound.com |
