Abstract: Print data composed of a multiplicity of dot information is supplied to a printing head having a plurality of dot forming elements arrayed along a sub-scanning direction. The printing head and the printing medium relatively move in main scanning direction and sub-scanning direction each other, and an image is printed on the surface of the printing medium. In the print data supplied by every main scanning action of the printing head, a deformed data portion of concave and convex shapes of waveform are formed, for example, so that dots may not be arrayed parallel continuously in the main scanning direction of the printing head, at the joint of the ends of the sub-scanning direction. The concave and convex shapes at the joint side of the print data, and the concave and convex shapes at the joint side of other print data adjacent to the print data are printed in mutually fitted state.

Abstract: The present invention is intended to prevent appearance of streaks in head scanning direction at the joint of print data of the image to be printed. Print data composed of a multiplicity of dot information is supplied to a printing head having a plurality of dot forming elements arrayed along a sub-scanning direction. The printing head and the printing medium relatively move in main scanning direction and sub-scanning direction each other, and an image is printed on the surface of the printing medium. In the print data supplied by every main scanning action of the printing head, a deformed data portion of concave and convex shapes of waveform are formed, for example, so that dots may not be arrayed parallel continuously in the main scanning direction of the printing head, at the joint of the ends of the sub-scanning direction.