Mathematically Based Algorithms for Film Digital Restoration

Since its invention in the nineteenth century, cinema has become one of the most important media of popular culture, becoming a fundamental part of our historical memory. Even with the advent of the digital, many directors prefer to shot movies on the analog support and in many festivals films are still projected using the traditional instruments. Unfortunately, the frequent projection of the film and the contact with dirt or worn rollers in the film path can cause film deterioration. Furthermore, damages can occur also outside the projector, if film is wound too tightly or loosely and stored in wrong conservation conditions, or also during the editing or restoration processes. Furthermore, films are subject to the aging of dyes contained in the emulsion and a fast decay of the support itself especially when the conservation conditions of temperature and humidity are not appropriated and controlled. The decay is an irreversible natural process that usually introduces a color dominant, loss of contrast and/or color desaturation. Dealing with the risks of losing the cinematographic heritage, the need to preserve moving images becomes more and more important, even though conservative practices are not yet defined or jointly approved by the film restoration community.