Recovery of Reflectance Spectra Based on Minimizing Color Inconstancy

Despite the importance of reflectance spectra data of a color, it is not simply available and most of the color devices measure colorimetric values. Transferring the colorimetric values to corresponding spectral reflectance considers as an important issue in mulispecral imaging and color reproduction. Consequently, several efforts have been made to describe spectral information using various statistical and mathematical methods. Considering that the dimension of spectra is much further than three, most of the time these methods lead to a metameric pair of the original sample even in the best condition. In this study, we introduce a method to recover spectra with more color constancy from colorimetric values. To this end, we consider the retaliation between color constancy and metamerism phenomena to enhance the reconstruction process. Metameric pairs are two samples with different color constancies but the same color coordinates under reference illuminant, the introduced procedure is based on achieving a metamer pair with more color constancy. Accordingly, the corresponding fundamental metamer (N*) of tristimulus values (CIEXYZ) is calculated by Cohen and Kappauf decomposition technique. The desirable spectra is defined as N* and a black metamer (B) in which the black meter component is comprised of a multiplication of a scalar coefficient and a basis black. Several methods are employed to define and achieve the most proper basis black which minimizes the color inconstancy. For each sample, the scalar coefficient is achieved in the way that the sample color coordinates after adaptation under second illuminant is the same as its coordinates under reference illuminant. So we can recover a spectral reflectance which is more color constant.

Keywords:

Spectral reflectance , Recovery , Tristimulus values , Color constancy