An image processing apparatus includes an acceptance unit that accepts an image of an original from an image reader having a conveying unit that conveys an original in sequence along a conveying path passing through a read position and an image read unit that reads the image of the original at the read position at read speed responsive to conveying speed of the original; an acquisition unit that acquires information concerning a stable read range in which the read speed in the conveying direction in the original becomes a stable state from storage in which the information is previously stored; and a registration unit that extracts feature information concerning a microscopic pattern that a surface of the original has from a registration area in the image of the original accepted by the acceptance unit and registers the feature information in association with position information concerning a position of the registration area.