Application of Spectral Estimation Methods to the Design of a Multispectral 3D Camera

摘要

This article reports on the colorimetric improvement of a multispectral 3D digitizer through scanning at a small number of near-optimal wavelengths. Optimal wavelengths were first investigated theoretically based on the criterion of minimal color differences over some sets of reflectance curves using PCA-based and spline-based spectral estimation methods. Sets of three, four and five optimal sampling wavelengths were derived to within ±5 nm for each one based on the spread of variation for different combinations of the method and the data set used for the derivation. This provided a basis for the selection of HeCd, ArKr, HeNe and DPSS commercial laser lines for which the colorimetric performance was predicted. This was then tested in the laboratory, where color rendition charts were scanned with the camera at seven wavelengths, after which the charts were computer rendered on a CRT display. Both the theoretical prediction and the experimental observation indicate that four well-chosen wavelengths are adequate for proper rendition of the charts.