Scanner color accuracy is of growing importance as more and more people want to scan color photographs. Traditional three color scanners can suffer from color reproduction errors due to the significant mismatch between their spectral sensitivities and those of the human visual system. In this paper the authors describe some of the technology behind a novel six color scanner that combines data captured with two different light sources to produce an improved final scan. Specifically, they describe the selection of appropriate light sources and the tuning of the scan parameters for those lights. They also describe a color processing pipeline that avoids amplification of image noise, and data processing methods to overcome illumination problems with non-flat subjects and slightly misaligned scans.
Andrew Hunter, Jeffrey DiCarlo, Stephen Pollard, "Six Color Scanning" in Proc. IS&T CGIV 2008/MCS'08 4th European Conf. on Colour in Graphics, Imaging, and Vision 10th Int'l Symp. on Multispectral Colour Science, 2008, pp 570 - 574, https://doi.org/10.2352/CGIV.2008.4.1.art00122