1. A method of producing a profile defining correspondence between colorimetric value data and ink amount data representing a set of ink amounts of plural inks usable by a printer, comprising the steps of (a) providing a spectral printing model converter configured to convert ink amount data to spectral reflectance of a color patch to be printed according to the ink amount data; (b) providing a plurality of sample ink amount data each representing a set of ink amounts of plural inks; (c) converting each sample ink amount data into spectral reflectance of a virtual sample patch to be printed with the ink amounts represented by the sample ink amount data using the spectral printing model converter; (d) calculating an evaluation index for each sample ink amount data, the evaluation index including a color difference index representing a color difference between a sample color which is calculated from the spectral reflectance and a comparative color which is selected as a basis for comparison; (e) selecting plural sample ink amount data based on the evaluation index; and (f) producing a profile defining correspondence between colorimetric value data and ink amount data based on the selected plural sample ink amount data.