可逆水印能将有用信息嵌入作品之后再无损地恢复原始作品。现今的大部分扩展嵌入方案均针对时域信号进行水印扩展嵌入,而本文提出一种在频域扩展嵌入的方法。该算法采用H.264编码中的整数离散余弦变换(IntDCT)对作品进行处理,然后在频域按照矢量差分扩展的方式嵌入水印。实验结果表明,该算法能获得高达0.8bit/像素的水印嵌入率,此时水印作品拥有较高的峰值信噪比达50dB以上,水印仍然满足不可见性。
A reversible watermark embedding algorithm based on frequency-field is proposed. This algoritlxm uses an integer DCT(IntDCT) of H. 264 encoding scheme on the work,then in the frequency-field the watermark is embedded according to the vector difference expansion. The results show that the algorithm can get as high as 0.8 bpp embedding rates, the watermarked work has a high peak signal-to-noise ratio (PSNR〉50 dB) and the watermark can still be imperceptible.