A dot pattern source image stored in a pattern memory is moved to a specified location in the pattern memory in an angle of n.times.90.degree. (n=0, 1, 2, or 3) with respect to the source image. First, area definition is made for a rectangular source area including the source image to be moved and a rectangular destination area where the source area is to be positioned after the move processing. Then, the positions of four sides of the source and destination areas are compared to determine, for each side, whether there is a processable side region which is included in the destination area but not included in the source area. When such a processable side region is found along one side, the image data in a corresponding region of the source area is moved to the processable side region with a specified angle relative to the source image data. After the move processing, the source and destination areas exclusive of the moved-processed portions are redefined as new source and destination areas, and similar steps are repeated. This technique permits the use of common program control for a basic control portion of move processing regardless of whether or not the move accompanies rotation, the positional relationship between the source and the destination areas, or the rotation angle.