A method for an image forming apparatus includes scanning a document containing a copy-forgery-inhibited pattern having a latent-image part to be highlighted when the copy-forgery-inhibited pattern is copied and copy restriction information for restricting the number of times of copying, decoding the copy restriction information contained in the document image scanned, removing the copy-forgery-inhibited pattern from the document image scanned, updating the decoded copy restriction information, and forming, on a sheet, the updated copy restriction information with the image which the copy-forgery-inhibited pattern has been removed from the document image.