1. An image processing apparatus comprising: a data obtaining unit configured to obtain data representing a sheet of document; a calculating unit configured to determine an area where it is possible to obtain a paper fingerprint from the obtained data representing the sheet of document, and to calculate a paper fingerprint intensity of the sheet of document based on a number of areas of one or more paper fingerprint obtaining patterns allocated in the area where it is possible to obtain a paper fingerprint; and a paper fingerprint intensity reporting unit configured to report a result of the calculation.