1. An image processing apparatus comprising: a read-out means for reading out image data on which image processing has been performed and to which supplementary information including image processing information regarding the image processing has been attached; an intention judgment means for judging whether the image processing has been intentionally performed, based on the image processing information and information other than the image processing information, included in the supplementary information; a processing means for obtaining processed image data by performing at least one kind of further image processing on the image data; and a control means for controlling the processing means so that the processing means performs the further image processing on the image data by canceling or reducing a processing amount of the image processing which has already been performed on the image data in the further image processing if the judgment by the intention judgment means is YES, or so that the processing means performs the further image processing on the image data, including the image processing which has already been performed if the judgment by the intention judgment means is NO.