Automated color control in film-to-digital transfer

Abstract

A system and method for automatically adjusting color parameters during a film-to-digital transfer. An operator uses standard telecine equipment to preview scenes in order to determine a natural clustering of fields or scenes. Each cluster is processed separately. All the fields in a cluster are treated as one unit in the sense that color adjustments for the cluster are based on the cluster color histogram, which is computed by aggregating the colors from all pixels in the cluster. Constraints are specified for the cluster. Variables of a constraint may be automatically specified or determined by an operator based on observing sample frames from the cluster. In addition, the operator can nullify a constraint if desired. Within each cluster, the system adjusts red, green and blue intensities of the digitizing device, gains for each of these color channels, and other parameters. The system first determines which settings respect the constraints and then optimizes the solution. The solution is optimized such that the digital color distribution is as faithful as possible to the film color distribution subject to the constraints. This is achieved by adjusting the settings to maximize the entropy of the empirical, digital color histogram among all settings respecting the constraints.