1. An image processing apparatus comprising: a searching unit configured to search for an area where dots are to be put on by an area ratio that is greater than a first area ratio and less than a second area ratio based on input image data, from a sheet on which the image data is to be printed; and an obtaining unit configured to obtain sheet fingerprint information from the area found from the sheet as a result of searching by the searching unit; wherein the second area ratio is greater than the first area ratio.