Embedding distortion analysis in wavelet-domain watermarking

Abstract

Imperceptibility and robustness are two complementary fundamental requirements of any watermarking algorithm. Low strength watermarking yields high imperceptibility, but exhibits poor robustness. High strength watermarking schemes achieve good robustness but often infuse distortions resulting in poor visual quality in host image. This paper analyses the embedding distortion for wavelet based watermarking schemes. We derive the relationship between distortion, measured in mean square error (MSE), and the watermark embedding modification and propose the linear proportionality between MSE and the sum of energy of the selected wavelet coefficients for watermark embedding modification. The initial proposition assumes the orthonormality of discrete wavelet transform. It is further extended for non-orthonormal wavelet kernels using a weighting parameter, that follows the energy conservation theorems in wavelet frames. The proposed analysis is verified by experimental results for both non-blind and blind watermarking schemes. Such a model is useful to find the optimum input parameters, including, the wavelet kernel, coefficient selection and subband choices for wavelet domain image watermarking. CCS Concepts: • Security and privacy → Digital rights management.