Patent ID: 6807634
Filing Date: 2004-10-19
Classification: G06T,H04N

Abstract:
A digital watermarking method, comprising the steps of:forming a first collection of masks; forming a second collection of masks, each mask in said second collection being different from said masks in said first collection; assigning to each of a plurality of customers Ci a plurality of pairs of masks (M(K(I,j, 1)), M(K(I,j, 2))), each pair of masks assigned per customer corresponding to a different one of a plurality of digital images Ij offered for use by a vendor, the first mask M(K(I,j, 1) in each pair being derived from said first collection and the second mask M(K(I,j, 2) in each pair being derived from said second collection; accepting a request to use one of said digital images from one of said customers; and encoding into said digital image requested for use by said one of said customers the pair of masks assigned to said one of said customers in said assigning step which corresponds to the requested digital image, wherein said pair of masks are used to perform a recognition among said plurality of customers so that at most the number of comparative computations is no more than two times the square root of a number of said plurality of customers.