An image processing system comprises an image providing apparatus which provides an image file, from which a digital watermark information can be extracted by using a watermark key that includes an authentication information which authenticates the image file provided by an valid provider, and the watermark key of the image file; and an image utilizing apparatus which extracts the digital watermark information from the image file provided by the image providing apparatus using the watermark key provided by the image providing apparatus, verifies whether the watermark key has been tampered or not using the authentication information in the watermark key, verifies whether the image file has been tampered or not using the verified watermark key, and displays the verified image file.