Chromatic Callier Effect and its Repercussions on the Digitization of Early Film Colors

The projection on screen has always been the supreme result of cinematography. Thus the digitization of a motion picture should seek to recreate the visual impression in the cinema. The image-forming particles contained in early color films can generate remarkable differences between a film directly observed with diffuse backlighting and its image projected on screen. In the recent decades this discrepancy has been largely overlooked by the film preservation community (film curators, scanner manufacturers, colorists, etc.). This paper re-establishes the importance of referring to the visual impression in the cinema, and describes the spectral variation of the Callier effect that can significantly alter early film colors when digitized. We have introduced the term “chromatic Callier effect” and described its repercussions on film digitization reporting case studies of tinted and toned film prints. The experimental results highlight that important changes are required in the optical design of film scanners to improve the digitization of motion pictures.