Improved Pixel-Wise Masking for Image Watermarking

Perceptual watermarking in the wavelet domain has been proposed for a blind spread spectrum technique, taking into account the noise sensitivity, texture and the luminance content of all the image subbands. In this paper, we propose a modified perceptual mask that models the human visual system behavior in a better way. The texture content is appreciated with the aid of the local standard deviation of the original image, which is further compressed in the wavelet domain. Since the approximation image of the last level contains too little information, we choose to appreciate the luminance content using a higher resolution level approximation subimage. The effectiveness of the new perceptual mask is appreciated by comparison with the old watermarking system.