1. A printing system for use with a copier which cannot resolve an image including dots occupying a predetermined percentage of a predetermined portion of an image, the printing system comprising: a processor to generate image data including a main image including character data represented by a group of dots which corresponds to an acquired image, the group of dots being equal to the predetermined percentage of the predetermined portion; and a printer to print the main image including the character data represented by the group of dots which are equal to the predetermined percentage of the predetermined portion, the printed group of dots being visible to a human through a visual integration effect, wherein the processor to generate image data converts the acquired image to the group of dots comprised of dots arranged such that only two dots are included in an 8×8 matrix at a resolution of 600 dpi.