When a whole input gamut is mapped into an output gamut, even a gamut range which is not used in practice is mapped into the output gamut. This causes a saturation drop or tone loss. In order to solve this problem, image data obtained by the first device is input and an obtaining condition of the input image data is obtained. On the basis of the obtaining condition, the first gamut information of the input image data is obtained from a table showing the relationship between the output gamut of the first device and the obtaining condition. On the basis of the first gamut information and the second gamut information which indicates the gamut of the second device, the input image data is mapped into the gamut indicated by the second gamut information.