Patent ID: 7137005

Claim:
A method of inserting a watermark into digital media data, the method comprising: calculating a working matrix X, each element of which is a predetermined function of each subset of source digital data; calculating a matrix C by C=XX T ; calculating eigen-values and an eigen-vector-matrix P of said matrix C; calculating a matrix of main components Y by Y=P T X; choosing k strings of said matrix Y; calculating coefficients a q , 1≦q≦k by using ∑ q = 1 k ⁢ a q ⁢ y i p ⁢ j q = w p , wherein a watermark is represented by a set of numbers w 1 ,w 2 ,K,w k , where 1≦p≦k with k and p being integers and where y i p j q is a string is matrix Y corresponding to an eigenvalue, with i and j signifying rows and columns with the matrix Y; calculating a marked string z j by z j = ∑ q = 1 k ⁢ a q ⁢ y i p ⁢ j , 1≦j≦n, with n being an integer, and replacing one of said chosen strings of Y with z j ; calculating a matrix {tilde over (Y)} orthogonalized from said matrix Y; calculating a watermarked working matrix {tilde over (X)} by {tilde over (X)}=P{tilde over (Y)}; and marking said source digital data using said watermarked working matrix {tilde over (X)}.