一种相移键控数字图像水印算法

根据相移键控原理．提出了一种不可逆DWT域二相相位键控数字图像水印算法．水印信号为二值图像，用不同相位的正弦信号将水印调制后嵌入到数字图像DWT变换系数中；用提取的同频率正弦信号的相位进行水印提取；该方法嵌入的水印具有非常好的安全性，且水印提取不需要原始未加水印的图像．实验结果表明该方法具有很好的不可见性；对JPEG压缩、图像加噪声和图像滤波等常见的图像处理具有极强的鲁棒性．

Digital Image Watermarking Algorithm Based on Phase Shift Keying

As an effective technique of copyright protection, digital watermarking has become a new focus of research in recent years. In this paper, a noninvertible digital image watermarking algorithm is proposed based on phase shift keying (PSK). The watermark used is a binary image. In watermark embedding, the sine signals with different phase are used to modulate watermark bits and embedded in the host image wavelet coefficients that act as signal carrier. In watermark extraction, the sine signal with same frequency is picked up from watermarked wavelet coefficients and its phase is used to extract watermark bits. The method has very good watermark security and the watermark is extracted without using original unwatermarked image. The experiments show that the quality of watermarked images is guaranteed. The algorithm is very robust against image manipulations such as JPEG compression, the image filtering and the noise addition.