A study of biorthogonal wavelets in digital watermarking

A study of a family of biorthogonal wavelet filters for use in digital watermarking is presented. The filters are explicitly parametrized by two free parameters and can be used to provide diversity in watermarking. Diversity can be used to improve the security of the watermarking system from hostile attacks. Each filter has at least two vanishing moments, which is important for ensuring some degree of smoothness in the resulting wavelet function. Along with robustness and security, other factors, which impact upon the successful implementation of the filters in a watermarking application are analysed. The relationship between the strength of the inserted watermark and wavelet energy is also discussed.