From The Art and Popular Culture Encyclopedia
The film preservation, or film restoration, movement is an ongoing project among film historians, archivists, museums, and non-profit organizations to rescue decaying film stock and preserve the images which they contain. In the widest sense, preservation nowadays assures that a movie will continue to exist, as close to its original form as possible.
For many years the term “preservation” used to be a synonym of “duplication” only. The preservationist’s goal was to create a durable copy without significant loss of quality. Film preservation now holds the concepts of handling, duplication, storage, and access. The archivist’s job these days is to protect the film and at the same time share the content with the public.
It should be distinguished from film revisionism, in which long-completed films are subjected to outtakes never previously seen being inserted, new music scores and/or sound effects being added, black-and-white film being colorized or converted to Dolby stereo, or minor edits or other cosmetic changes being made, regardless of reason.