提出一种基于数字全息图的可控再现菲涅耳计算全息水印方法。对水印物平面光波计算离散菲涅耳变换获得全息面上的物光波复振幅分布，为提高安全性，对物平面水印信号和衍射面信号进行双随机相位编码加密处理；对加密后的数据进行预处理及载波调制和实值编码；将编码后的信号作离散余弦变换(DCT)后以一定强度叠加于宿主全息图的中频分量，水印信号恢复无需原始宿主全息图信息，可实现盲提取。结果表明，所提出的方法具有良好的透明性，通过放大率及重建光波的控制，重建像平面的水印信号可以实现大小和位置可调；并且宿主全息图在遭受剪切、联合照片专家组(JPEG)压缩、滤波、旋转、拉伸等各类攻击的情况下，对宿主和水印信号均具有良好的数字重建质量；宿主数字全息图的零级像抑制处理不影响水印信号的提取

A method on controllable reconstruction of Fresnel computer-generated hologram watermark for digital hologram has been proposed. Complex amplitude distribution is obtained by calculating discrete Fresnel transformation of the watermark object wave in the holographic plane, and the watermark and the diffraction distribution signal are double-random-phase modulated to improve security. The encryption data are reprocessed and modulated to get real-coded CGH watermark. The encoded signal after the discrete cosine transformation is added to medium frequency component with certain intensity. The watermark can be blind extracted without the host hologram signal. The results show that the approach behaves good invisibility and is robust to many attacks such as cropping, JPEG compression, filtering, rotation, scaling, etc. The method has good digital reconstruction quality for both the host hologram and the watermark. The size and position of the watermark can be easily adjusted by changing the magnification and the reconstructed wave. The zero-order image elimination of the host hologram does not affect the extraction of the watermark.