Predicting simultaneously the spectral reflectance and transmittance of halftone prints is now possible thanks to a recently developed model based flux-transfer matrices, called Duplex Primary Reflectance-Transmittance model, valid for single-face printing as well as duplex printing. The model can be calibrated from either spectral reflectance measurements or spectral transmittance measurements; but it can also be calibrated from both measurements by minimizing the distance between the theoretical transfer matrices and experimental transfer matrices. According to the test carried out with paper printed in inkjet, the predictive performances of DPRT model, coupled with the new calibration method, are good enough to permit interesting applications in graphical arts, such as the display of multiple images depending on whether the light source is in front of the duplex color print or beside it.