Colour Characterisation of a Digital Cine Film Scanner

Abstract

This study presents a solution to the problem of characterising a cinema film scanner, used in the field of digital film postproduction. The scanner digitises negative films, and produces a digital positive version of each frame so that special effects can be added by computer. Negatives are scanned because they provide the most appropriate medium from the point of view of preserving the integrity of the artistic intent, they are however meaningless in colorimetric terms and this complicates the characterisation issue. Since Analytical models of the film printing process are impractical because of the commercially sensitive nature of some of the data required, the solution presented uses a multi-stage interpolation that characterises the different stages of the film printing process. The first consists of identifying the relationship between negative and positive densities. The second consists of identifying the relationship between positive (or print) density and colorimetry. The results show that the distance weighted interpolation technique yields the most satisfactory results.