Javier Herná Ndez-André’s research while affiliated with University of Granada and other places

We have analyzed the performance of simulated multispectral systems for the spectral recovery of reflec-tance of printer inks from camera responses, including noise. To estimate reflectance we compared the perform-ance of four algorithms which were not comparatively tested using the same data sets before. The criteria for selection of the algorithms were robustness against noise, amount of data needed as inputs (training set, spectral responsivities) and lacking of use of dimensionality reduc-tion techniques. Three different sensor sets and training sets were used. We analyzed the differences in the span-ning of the subspaces found for the three training sets, concluding that the ink reflectances have characteristic features. The best performance was obtained using the kernel and the radial basis function neural-net-based algorithms for the training set composed of printer inks reflectances, whereas for the other two training sets (com-posed of samples from the ColorChecker DC and Vhrel's reflectances' set) the quality of the recovered samples was more uniform among the algorithms. We also have per-formed an optimization to choose the best sensor set for the multispectral system with a reduced number of sensors.

We propose an easy and inexpensive laboratory experiment to obtain equal-thickness optical interference using a flatbed scanner and a personal computer to produce Fizeau fringes. Valuable discussions about multiple-beam interference, Fresnel equations, the theory of partial coherence, and colorimetry arise naturally from the interference-fringe results. © 2002 American Association of Physics Teachers.