Estimating Spectral Absorption Coefficients of Semitransparent Liquids Based on NMF

Abstract

A part of the light transmitted through semitransparent liquids is absorbed by the liquids and its energy is attenuated. The change in light energy due to the absorption depends on the spectral absorption coefficients of liquids and the optical path lengths of light rays, and is described by the Lambert-Beer's law. In general, spectral absorption coefficients of liquids are often unknown in real-world applications, because they depend not only on liquid media themselves but also on dissolved materials. Accordingly, in this paper, we propose a method for estimating the spectral absorption coefficients of a semitransparent liquid from the hyperspectral images of objects immersed in the liquid. Specifically, our proposed method estimates spectral absorption coefficients on the basis of Non-negative Matrix Factorization, since the observed spectral radiance values, spectral absorption coefficients, optical path lengths, and Fresnel terms are all non-negative.