In order to predict a color obtained by overprint of inks of a plurality of colors, which include ink of a spot color, a colorimetric value for a color to be referred to at the time of prediction (hereinafter, the color will be referred to as a “reference color”) is required. More specifically, for the reference color, required are: information (colorimetric values) on spectral reflectances of the maximum gradation value; information (colorimetric values) on spectral reflectances of the minimum gradation value; and information (colorimetric values) on spectral reflectances of at least one intermediate gradation value. Further, in each of the following embodiments, also for a prediction target color, required are: information (colorimetric values) on spectral reflectances of the maximum Gradation value; information (colorimetric values) on spectral reflectances of the minimum gradation value; and information (colorimetric values) on spectral reflectances of at least one intermediate gradation value. Incidentally, for the maximum gradation value and the minimum gradation value, the spectral reflectances can be acquired relatively easily. Note that the description will be given below on the assumption of a case in which the spectral reflectances are obtained in increments of 10 nm in a wavelength range of 380 nm to 730 nm (that is, a case in which one color is specified by 36 spectral reflectances). However, not only this but also, for example, to a case in which spectral reflectances with the number obtained by dividing a wavelength range including a range of 400 nm to 700 nm by unit wavelength ranges with an appropriate size, each of the embodiments (including modified examples) which will be described later can be applied.