Color prediction models are of high interest for color printing industry. Our previous work proposed a simple color prediction model which used an effective coverage map based on CIEXYZ. By applying the model to different printers and halftoning methods we verified the good performance of the method. Considering the requirement of accurate spectral or reflectance match in the digital printing industry, an investigation to extend our basic color prediction model form CIEXYZ to spectral data is presented in this paper. The whole procedure is simple to understand and easy to be carried out. The experiments show that the extended model works well in predicting the spectrum of a specific combination of printed inks.