A new spectral reflectance estimation method based on CIE XYZ values under multi-illuminants was proposed to obtain multi-spectral images accurately by using digital still cameras. CIE XYZ values under multi-illuminants were initially predicted from raw RGB responses by using a polynomial model with local training samples. Then, spectral reflectance was constructed from the predicted CIE XYZ values via the pseudo-inverse method. Experimental results indicated that the new spectral reflectance estimation method significantly outperformed the traditional colorimetric characterization method without requiring extra training samples or greatly increasing computational complexities. (C) 2016 Wiley Periodicals, Inc. Published Online 2 February 2016 in Wiley Online Library (wileyonlinelibrary.com).