Patent ID: 6891640

Claim:
A method of printing new information on a printed medium, on which old information has been printed, by using a printing apparatus with printing ink or toner, said method comprising the steps of: detecting a printing region on said printed medium where said old information is printed; calculating a printed surface area of said printed region equal to the surface area of the printed medium covered by the old printed information; calculating a total surface area of said printed medium; responsive to said printed surface area being less than a predetermined portion of said total surface area, reusing said printed medium, comprising: identifying, as an erasing region, a region related to the printed region; erasing printed information on said identified erasing region by printing a pattern corresponding to said erasing region on said erasing region with erasing ink or toner of a different color from said printing ink or toner; and printing said new information with said printing ink or toner on said printed medium from which said printed information has been erased.