A new wavelet watermarking technique

A digital watermark technique based on the wavelet transform is proposed. To ensure the security of the watermark, the watermark is scrambled before embedding. As the watermark image is usually smaller than the original image, the watermark is extended to the same size of the original image. Then, according to the characteristics of the multiresolution decomposition of the wavelet transform, the watermark values in different directions and subbands are added by various intensity to the corresponding directions and subbands of the original image. Finally, when detecting the presence of the watermark, a similarity between the extracted watermark and the original watermark is defined using F norm.