There is provided a dither pattern capable of reducing deterioration in image quality caused due to beading by suppressing the occurrence of grains in printing images using a plurality of color inks. If among threshold dots, for which repulsive force potentials are totalized, a threshold dot Do has the largest total, a change in repulsive force potential is obtained between before and after the movement of dot Do. The threshold dot Do is moved to a dot with the smallest total of repulsive force potentials between before and after its movement. By repeating this process, the total energy of all the three planes can be reduced, achieving a dot distribution, in which the number of low frequency components is reduced and the dots are appropriately dispersed, for superposed dither patterns.