An apparatus takes in a plurality of still image frames, to generate an interpolated image frame. Next, moving addition of the still image frame and an interpolated image frame is performed in time-axis direction, to generate a superimposed image frame. At this time, high spatial frequency components in the superimposed image frame are suppressed strongly as alienation of motion between the still image frames becomes larger. Movie is reproduced by sandwiching these superimposed image frames between the still image frames. As a result of this, the movie reproduction with smooth motion is made possible even from a group of the still images photographed by an electronics still camera and the like.