In order to perform pseudo-three-dimensional display for analyzing color distribution, there are provided a color-distribution-information input step of inputting color-distribution information indicating color coordinate values that sample points in a first color system can have in a second color system, a user's-instruction input step of inputting an instruction of a user relating to an operation of generating object-surface information, and a generation step of generating three-dimensional-object-surface information in accordance with the instruction of the user, based on the color-distribution information.