Common, tri-chromatic, RGB colour-acquisition devices capture spectral signals by a coarse sampling through three broad colour filters. Due to metamerism, a single response from a RGB device corresponds to an infinite set of possible surface spectral reflectances. In order to acquire higher quality surface colour descriptors that reduce metamerism in the acquisition process, multi-spectral imaging devices are used. These sample the spectral signals more finely through > 3 colour filters, enabling better estimation of surface spectral reflectance and consequently mitigating the problem of metamerism.In this paper the performance of a 6-channel digital video camera is evaluated in terms of it's accuracy to capture surface spectral reflectances. A number of known techniques to estimate reflectance from device response are examined, such as linear least squares, the Wiener estimation technique, Tikhonov regularised estimation as well as the Metamer Set Maximum Likelihood method.The performance of each algorithm is compared under different training and testing conditions. The experiments show that there estimation accuracy is significantly increased by using multi-spectral acquisition and furthermore that there is benefit in using more advanced estimation techniques still.
Peter Morovič, Hideaki Haneishi, "Estimating reflectances from multi-spectral video responses" in Proc. IS&T 14th Color and Imaging Conf., 2006, pp 131 - 137, https://doi.org/10.2352/CIC.2006.14.1.art00024