An input chromaticity data calculation unit 113 calculates input chromaticity data rg from device-dependent color data RGB. A chromaticity data transformation unit 114 transforms the input chromaticity data rg into output chromaticity data xy by referring to an LUT stored by an LUT storage unit 13. A total amount calculation unit 115 refers to the LUT of the LUT storage unit 13 to calculate a total amount Σ′XYZ of the device-independent color data XYZ from the color data RGB. An output color data calculation unit 116 uses the total amount Σ′XYZ to calculate color data XYZ from the output chromaticity data xy.