A NEW WAVELET-BASED DIGITAL WATERMARKING USING THE HUMAN VISUAL SYSTEM AND SUBBAND ADAPTIVE THRESHOLD

摘要

A wavelet-based digital watermarking algorithm using the human visual system (HVS) and subband-adaptive threshold is proposed in this paper. The proposed algorithm is performed in the WT (wavelet transform) domain by slightly modifying the perceptually significant coefficients in all the subbands excluding them of the lowest level for the robustness to a series of attack. This is because lossy compression such as JPEG and MPEG eliminate the high frequency components. The perceptually significant coefficients for each subband are selected by the subband-adaptive threshold. Then, for each selected coefficient in the high frequency subbands, the maximum amount of the watermark is embedded in the extense of satisfying the invisibility according to the HVS of that coefficient. And the constant amplitude of the watermark is embedded to each coefficient in the baseband considering invisibility. The experimental results show that the proposed algorithm represents the better invisibility and robustness to the attacks than the conventional algorithm.