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Digital old film scan restoration

Cellulose nitrate film rolls were used by filmmakers from its release in the 1880s to the 1950s. It's also known as the high flammable film. From the 1920s cellulose acetate started to take over as it was introduced as "safety" film. And from 1950s and onwards polyester film took over due to its superior dimensional stability and mechanical strength.

Old film stocks have both degraded due to its organic nature and how they were stored. Even if they are stored in climate controlled environments they still rotted in the film cans. But the very old scans also have a lot of technical artifacts due to camera and scan mechanics.

Restoration process

Digitally we can alter the visual appearance. Several steps can be automated by algoritms and AI, but also hand-painting is needed. The process can be divided in to the following steps:

  1. Stabilization of film frame jittering
  2. Removal of grain
  3. Removal of dust and scratches
  4. Removal of blobs (often caused by scan fluids)
  5. Removal of flickering and light variations (shutter artifacts)
  6. Colorization
  7. Correcting frame rate
  8. Add back film grain

This was shot in 1906 at Tegelbacken in Stockholm and was restored to be used in Lasse Hallströms feature HILMA. It's shot at ~18 fps and is converted to 24 fps by motion analysis.

All footage are from "HILMA" produced by Viaplay studios.

Two more examples: