A dual watermaking scheme based on Sobolev type orthogonal moments for document authentication

A dual watermarking scheme based on Sobolev type orthogonal moments, Charlier and Meixner, is proposed based on different discrete measures. The existing relation through the connection formulas allows to provide with structure and recurrence relations, together with two difference equations satisfied by such families. Weighted polynomials derived from them are being applied in an embedding and extraction watermarking algorithm, comparing the results obtained in imperceptibly and robustness tests with other families of polynomials.