1. A method of generating a multidimensional lookup table for color processing of an image photographed by an image sensing device, comprising steps of: inputting color data of color patches photographed by the image sensing device and target data representing target colors of the color patches; performing color processing of the color data by using a color processing condition; optimizing the color processing condition on the basis of the color-processed color data and the target data; preparing the multidimensional lookup table by using the color processing condition; and providing a user interface which expresses a positional relationship between the color-processed color data and the target data and accepts a change in the target data.