提出了一种基于数字菲涅耳全息和离散余弦变换的数字水印技术。利用全息技术得到原始水印图像的菲涅耳全息图,之后将其嵌入宿主图像离散余弦变换域的中频系数,将水印添加位置和光学系统的几何结构参数作为恢复水印信息的密钥,并且算法属“盲数字水印技术”,从而该算法具有较好的安全性和实用性。对算法的测试结果也表明,该算法对噪声、滤波、剪切、旋转、有损压缩等常见的图像处理操作具有较高的稳健性。因此,该算法具有一定的实用价值。

The digital watermark technique is proposed based on Fresnel hologram and Discrete Cosine Transform (DCT). The Fresnel hologram of the original watermark is gotten by use of digital holography technique. Then the hologram is embedded in the median-frequency coefficients in the DCT domain. The position of watermark and geometric parameters of optical system are adopted to retrieve the watermark without the original host image. The algorithm has high security and practical value. Numerical experiments show that the embedded watermark is robust to usual image manipulations,such as superposing noise,cropping,filtering and lossy compression. Therefore,there is an application prospect for the algorithm.