Further, the print data generation apparatus 100 performs an overprint prediction process for predicting a color obtained by overprinting inks of a plurality of colors (typically, predicting a color of a portion where a plurality of spot color inks are overprinted or a portion where a spot color ink and a process color ink are overprinted). In the overprint prediction process, results of the spectral reflect antes prediction process (that is, prediction values of spectral reflectances) are used according to needs. Moreover, the print data generation apparatus 100 performs a process for converting data, which is obtained by the overprint prediction process, into print data in format capable of printed output in the digital printing apparatus 350. Note that, as a specific method of the overprint prediction process, the above-mentioned Deshpande et al. method may be adopted, or another method may be adopted.

<1.2 Configuration of Print Data Generation Apparatus>

FIG. 3 is a diagram showing a hardware configuration of the print data generation apparatus 100 in the present embodiment. The print data generation apparatus 100 is implemented by a personal computer, and includes a CPU 11, a ROM 12, a RAM 13, an auxiliary storage device 14, an input operation unit 15 such as a keyboard, a display unit 16, an optical disk drive 17, and a network interface unit 18. The submitted data transmitted through the communication line CL is inputted into the print data generation apparatus 100 via the network interface unit 18. Print data generated by the print data generation apparatus 100 is sent to the digital printing apparatus 350 through the communication line CL via the network interface unit 18.