CURRENCY VERIFICATION

A method for verifying authenticity of a certificate under test, wherein an authentic version of the certificate has a known watermark in a predetermined watermark region thereof. The method includes capturing an image of at least a portion of the watermark region of the certificate under test. A correlation is found between the image of the watermark region and the known watermark. Responsive to the correlation, a portion of the image of the watermark region is registered with the known watermark, and a range of intensity values in the registered portion of the image is measured. A vector is defined in a decision space, the vector having coordinates given by the range of the intensity values and by a value of the correlation between the image of the watermark region and the known watermark. The certificate under test is determined to be authentic if the vector falls within a predefined area of the decision space.