Herein, concerning the present embodiment, we focus on the case in which the prediction target gradation values include the gradation value other than the gradation values for which the spectral reflectances are obtained regarding the reference color. In this case, for example, if only the gradation value of 0.5 is the characteristics-acquired gradation value, then prediction values of the spectral reflectances of the gradation value for which the spectral reflectances are obtained regarding the reference color among the prediction target gradation values between the maximum gradation value and the characteristics-acquired gradation value are obtained by applying the spectral reflectances of the maximum gradation value for the prediction target color to the corresponding second relational equation; and prediction values of the spectral reflectances of the gradation value for which the spectral reflectances are obtained regarding the reference color among the prediction target gradation values between the characteristics-acquired gradation value and the minimum gradation value are obtained by applying the spectral reflectances of the characteristics-acquired gradation value for the prediction target color to the corresponding second relational equation. That is, with the maximum gradation value or the characteristics-acquired gradation value being taken as a reference gradation value, the prediction values of the spectral reflectances of the gradation value for which the spectral reflectances are obtained regarding the reference color among two or more prediction target gradation values are obtained by applying the spectral reflectances of the reference gradation value for the prediction target color to the corresponding second relational equation. In this manner, in the present embodiment, in Step S162 in FIG. 10, the prediction values of the spectral reflectances are calculated by applying, to the second relational equation, the spectral reflectances of the maximum gradation value or the characteristics-acquired gradation value for the prediction target color. Then, in Step S164 in FIG. 10, the prediction values of the spectral reflectances of the gradation value for which the spectral reflectances are not obtained regarding the reference color among the prediction target gradation values are obtained by the spline interpolation (for example, cubic spline interpolation) based on the prediction values obtained in Step S162. At this time, the prediction values of the spectral reflectances of the prediction target gradation value between the maximum gradation value and the characteristics-acquired gradation value are obtained not by performing spline interpolation based on prediction values for only three or more gradation values between the maximum gradation value and the characteristics-acquired gradation value, but by performing spline interpolation based on prediction values for three or more gradation values including a gradation value between the maximum gradation value and the characteristics-acquired gradation value and a gradation value between the characteristics-acquired gradation value and the minimum gradation value. The same also applies to the prediction values of the spectral reflectances of the prediction target gradation values between the characteristics-acquired gradation value and the minimum gradation value. Note that, though linear interpolation can also be used in place of the spline interpolation, the prediction values are obtained more accurately by the spline interpolation than the linear interpolation.