1. An image processing apparatus, comprising: an input section for inputting an image having a unique image from an information medium; a management table that stores information on each type of information medium; a control section for performing image processing on the inputted image and outputting the image; an identification section for obtaining a size of the information medium based on the inputted image of the information medium, and identifying the type of the information medium by comparing the size of the information medium with the information stored in the management table; and an area determination section for determining a specific area in which the unique image exists based on the type of the information medium; and an authentication section for authenticating a user, wherein the area determination section determines the specific area to be masked according to a security level of the user, such that the higher the security level, the less of the specific area is to be masked, whereas the lower the security level, the more of the specific area is to be masked, and the control section performs image processing for masking the specific area.