PURPOSE: To display a three-dimensional(3D) image without forcing or forcing the use of glasses to an observer by separating the 3D image into depth components and displaying the separated images on correct depth positions ao as to recall the observer to a sense of visual depth.

CONSTITUTION: When N input images are separated by multi-image resolution expression indicated by images 1' to N', each of the multi-image resolution coefficients of images 1' to N" indicates how much energy is included in the frequency/position of an image photographed by a specific focal distance and whether the image is focused on the specific position in the best state or not can be judged by comparing the coefficient with the values of multi-image resolution coefficients generated from the remaining (N-1) images. When the process is repeatedly applied to all coefficients of the multi-image resolution expression, the allocation of the multiimage resolution coefficients of N images only to one image can be obtained. Consequently a 3D picture can be displayed without forcing or restricting the use of glasses to an observer.