Color Cross Talk Correction for Digital Image Printing System

摘要

On color photographic media the image is formed in three different layers of the photographic emulsion. Ideally each layer is only sensitive to a single primary color; Red, Green and Blue, (R, G and B, respectively). However, due to the band structure of the molecular excitation level found in the embedded dyes, there is cross talk between the different light sensitive layers. Red exposure not only creates density in the red sensitive layer, it also creates small but measurable contributions in the green and blue sensitive layers. Similar effects can be seen for green and blue exposures. To achieve the desired density on the final print it is necessary to compensate for the density contribution arising from cross talk. In digital printing equipment this is conventionally accomplished through either a closed loop or iterative calibration process. Both of these are cumbersome and wasteful in time and media usage. This paper puts forth a novel method that corrects for the cross talk contribution. This method is based on measuring the densities that are printed at different light exposure values. From these measured densities one can obtain the correlation between the printed grayscale densities and the light exposure values over a wide range for each of the complimentary and non-complimentary light. In comparison to the conventional methods, this method provides quick and satisfactory results for cross talk correction. Taking the cross talk contribution into account, a linearization method has been developed to achieve equal perceptual steps of gray. This method enables us to calibrate printers from scratch in a single attempt.