that is characteristic to error diffusion fig2 is a view for illustrating an image output when only the dither method is used in the figure the area surrounded by the wide line corresponds to one dither matrix as is apparent from the figure when the dither method is employed dots are printed periodically thus any mechanical noise generated will be noticeable fig2 represents an image output from an ink jet printer of the present embodiment as a matrix of eight by eight and fig2 shows the fig2 pattern with the density increased by one stage for the dither method increasing the number of tones to output a low density intermediate tone requires a larger dither matrix and this disadvantageously results in a lower resolution by contrast the present embodiment basically employing error diffusion can be free from such a problem and also achieve fine changes in density that is when a dither matrix of four by four in size is used according to the dither method an image having its density increased from that shown in fig2 by one stage in density is as shown in fig2 this shows that when the dither method is employed increasing a density by one stage doubles the density the present embodiment is free from such a disadvantage fig2 shows an exemplary image output from an ink jet printer according to the present embodiment and.