1. An information processing method of generating print data in a printing apparatus for printing an image on a printing medium by using a plurality of kinds of printing materials, comprising: an acquisition step of acquiring characteristic data representing a metallic luster characteristic of each of the plurality of kinds of printing materials to be used by the printing apparatus; a determination step of determining, on the basis of a stimulus value represented by the characteristic data acquired in the acquisition step in correspondence with each of the plurality of kinds of printing materials, an overlay order to form an image on the printing medium by overlaying a printing material having a smaller stimulus value on a printing material having a large stimulus value; and a generation step of generating the print data in accordance with the overlay order determined in the determination step.