Today's silent-era film restoration starts with high-definition digital scan of a nitrate print. In the case of "The Trail to Yesterday" (1918), the only surviving print at the eyeFILM Museum in Amsterdam was scanned at 2K resolution in 10-bit DPX digital format.
Nitrate based film stock of the silent era was the first transparent plasticized medium with a photosensitive emulsion that first became commercially available by Eastman in 1889 and the was primary film stock for motion picture until 1951 when the movie industry transitioned to cellulose acetate film, or safety film.
My restoration work flow is a 2-pass process. The first pass uses VivaPRO software by Algosoft, that uses mathematically-based artificial intelligence models to precisely measure, analyze and correct levels of grain, noise, flicker, color representation, luminescence, chromatic properties, artifacts and other imperfections in every frame.
The second-pass is a manual process to remove any remaining artifacts or imperfections, using additional software tools.
A side-by-side comparison is presented below. The film frame on the left is the starting point - the high-definition scan of the original nitrate film stock. The frame on the right is a result of both the first and second-pass processes.
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The attention or emphasis in the 'cleaned' frame is not only artifact removal, but the resulting texture of the AI-driven process to reduce noise and provide a more lucid image.
Film restorers must ask the question as to whether to add realistic film grain back into the images after cleaning. For this film, that is still an open question.
The image below is an extreme close-up the actor Anna Q Nilsson. Here is where the noise removal and other processing from the VivaPRO software is effective in providing a restored look to the image.
Thus the result of the AI-driven analysis and corrective action, is a both a pleasing and cinematic look for the restored film.