Roughly speaking, there are two kinds of the color mixing theories. One is formulated for the halftone printing process such as the Neugebauer equations (NE), Yule-Neilsen approximation (YN), and Clapper-Yule multiple internal reflections (CY). The other is based on the subtractive principle such as the Beer-Bouguer law (BB) for the homogeneous medium and the Kubelka-Munk theories (KM) for the turbid medium. In addition, we present an empiri-cal extension of the subtractive models for the halftone printings. We compare these models by applying them to a Canon color copier and an ink jet printer. Brief descrip-tions of these theories with regard to the basic assumptions, formulations, and comparison results, are given in this paper. The emphasis of this study is placed on the spectral modeling of the halftone prints.