Colorant-amount transforming method

A colorant-amount transforming method for transforming a first colorant amount for forming an image on a first medium into a second colorant amount for forming the image on a second medium whose colorimetric value differs from that of the first medium, comprising the steps of:

• (a) transforming the colorant amount subject to transformation into a colorimetric value by a first transformation for transforming the first colorant amount into a colorimetric value corresponding to one of a tristimulus value and a spectral reflectance in which a portion of contribution of one of the tristimulus value and the spectral reflectance of the first medium itself to one of the tristimulus value and the spectral reflectance of the image formed on the first medium with the first colorant amount is replaced by one of the tristimulus value and the spectral reflectance of some standard white in accordance with a contribution rate;
• and
• (b) transforming the colorimetric value obtained by the transformation in step (a) into a colorant amount targeted in the transformation by a second transformation for transforming into the second colorant amount a colorimetric value corresponding to one of a tristimulus value and a spectral reflectance in which a portion of contribution of one of the tristimulus value and the spectral reflectance of the second medium itself to one of the tristimulus value and the spectral reflectance of the image formed on the second medium with the second colorant amount is replaced by one of the tristimulus value and the spectral reflectance of the white used in step (a) in accordance with a contribution rate.