Abstract:
There is described a method for controlling the quality of printed documents (1 ), such as banknotes and other similar documents, in an environment where only part of the surface of the printed documents is available for inspection, the method comprising the steps of (i) storing a reference image (6); (ii) acquiring a sample image (5) of a sample printed document to be controlled, which sample image covers only a limited portion of the sample printed document; (iii) selecting a search pattern (7) within the acquired sample image; (iv) searching the reference image (6) for a match with the selected search pattern (7), (v) determining control parameters linked to the position of the search pattern (7) within said sample image (5) and within said reference image (6), (vi) comparing the control parameters linked to the position of the search pattern (7) within the sample image (5) with the control parameters linked to the position of the search pattern (7) within the reference image (6); and (vii) based on the results of the comparison of the control parameters, accepting or rejecting the sample printed document.