Spread spectrum watermark based on wavelet transform for still digital image
Shao Hai-mei, Mei Tian-can, Qianqing Qin · Wuhan University Journal of Natural Sciences · 2004
The proposed method inserts a watermark into the spectral components of the data using techniques analogous to spread spectrum communications, hiding a narrow band signal in a wideband channel. The watermark is difficult for an attacker to remove. It is also robust to common signal and geometric distortion such as JPEG compression, cropping and scaling. In addition, the watermark can be extracted accurately without source host image at the receiver.