An image processing apparatus decides a grid point coordinate on a lookup table corresponding to a predetermined color; calculates, based on association between a signal of the predetermined color in the uniform color space designated by a first color space information and the decided grid point coordinate, a first matrix for converting each signal in the uniform color space into a grid point coordinate; calculates, based on association between the signal of the predetermined color in the uniform color space designated by a second color space information and the decided grid point coordinate, a second matrix for converting each grid point coordinate into a signal in the uniform color space; and generates a lookup table for converting each grid point coordinate into a signal in the second color space by using the second matrix and the second color space information.