The work presented deals with the possibilities of synthesizing white color, which is of great interest for diffractive image devices. The method of additive mixing is utilized for synthesizing arbitrary nonspectral colors using diffracted light. The suggested solution is based on employing only two complementary colors as primaries for additive mixing, which is simpler and offers better energy efficiency than color-mixing models using three or more primaries. For comparison, two different two-component mixing models are considered together with a three-component RGB model. First, the theory of additive color mixing is modified for the case of diffracted light, and equations for relative areas of primary gratings are derived. Using colorimetry, a method of measurement and determination of diffracted light color is proposed and practically tested. Finally, a set of available primary gratings was used for experimental preparation of white color, and results of the two approaches to color mixing models are compared.