This invention converts input color data into output color data using a table which has been created based on spectral data generated by an appropriate generation method and indicates the correspondence between an input chromaticity and an output chromaticity. To do this, an input color data acquisition unit converts input color data into input chromaticity data. An output chromaticity data calculating unit converts the input chromaticity data into output chromaticity data by referring to an LUT indicating the correspondence between an input chromaticity and an output chromaticity. An output color data calculating unit converts the output chromaticity data into output color data using a conversion coefficient calculated from the input color data. The table indicating the correspondence is created based on spectral data generated by a generation method different for each of a low chroma color and a high chroma color.