Image processing apparatus and its method

Since many ICC profile generation tools print and measure a large number of color patches and then make profile generation calculations, profile re-generation requires a long time. Hence, patch data are generated, calorimetric values corresponding to the patch data are obtained. Reference values of an Lab color space, which correspond to the patch data, are calculated using a conversion lookup table from a CMYK color space to the Lab color space, which is included in a profile. A conversion lookup table from the Lab color space to the CMYK color space, which is included in the profile, is updated using the calorimetric values and reference values.