We propose a hybrid method to efficiently represent spectral BRDFs. We first perform Fourier transform to the spectrum for given incident and outgoing directions, and then decompose the Fourier coefficients into a smooth background and a sharp peak. The smooth background will be represented with a linear combination of spherical harmonics, and the sharp peak with a Gaussian function. The errors of representation are studied. This method has a potential of applications in color synthesis and analysis.
Huiying Xu, Yinlong Sun, "Efficient Representation of Spectral BRDFs" in Proc. IS&T 12th Color and Imaging Conf., 2004, pp 276 - 281, https://doi.org/10.2352/CIC.2004.12.1.art00049