A generalised model for distortion performance analysis of wavelet based watermarking

A model for embedding distortion performance for wavelet based watermarking is presented in this paper. Firstly wavelet based watermarking schemes are generalised into a single common framework. Then a mathematical approach has been made to find the relationship between distortion performance metrics and the watermark embedding parameters. The derived model shows that for wavelet based watermarking schemes the sum of energy of the selected wavelet coefficients to be modified is directly proportional to the distortion performance (the mean square error) measured in the pixel domain. The propositions are made using the energy conservation theorem between input signal and transform domain coefficients for orthonormal wavelet bases. Such an analysis is useful to choose the wavelet coefficients during watermark embedding procedure and to find suitable input parameters such as wavelet kernel or the choice of subband.