三维物体多重菲涅耳计算全息水印与无干扰可控重建方法

提出了一种基于三维物体的多重菲涅耳计算全息水印方法.将水印信号作为虚拟三维物体的层面,首先结合分区复用层析法和菲涅耳双随机相位编码方法产生复噪声形式的水印信号;然后对水印信号的频谱作共轭对称处理实现实值编码;为减小对宿主全息图数字重建的影响,将水印信号的频谱设置于对宿主数字重建影响小的频谱非感兴趣区域;编码后的信号以一定强度叠加于宿主全息图,水印信号恢复无需原始宿主全息图信息,可实现盲提取,对宿主全息图重建像面的二维码可扫描识别.仿真测试结果表明,所提出的方法具有较好的透明性和稳健性,在宿主全息图遭受滤波、JPEG(联合图像专家小组)压缩、高斯噪声、剪切、旋转等各种攻击的情况下,不论对宿主还是水印信号仍具有良好的数字重建质量,对重建像面的二维码仍可扫描识别;而重建像面水印信号的无干扰可控重建后处理操作解决了不同层面水印信号之间的衍射干扰问题,提高了水印信号的重建质量.虚拟光学手段的应用丰富了水印信号设计方法并提升了算法的安全性.

Multiple Fresnel computer-generated hologram watermark of three-dimensional object and its adjustable reconstruction without interference

This paper presents a novel method of generating multiple Fresnel hologram watermarks of three-dimensional objects. Firstly, the original watermark signal is used as the layers of the virtual three-dimensional object, and the encrypted watermark signal is generated in the form of complex noise by using both the region multiplexing tomography and the Fresnel double random phase coding method. Then, the spectrum of the watermark signal is conjugate symmetrically arranged and inverse Fourier transform is performed to obtain the real-valued watermark. The spectrum of the watermark signal is set to be in a non-interested region of the host spectrum to reduce their influence on the digital reconstruction of the host hologram. Finally, the encoded watermark signal is superimposed on the host hologram with a certain intensity. The original host hologram is not required during watermark reconstruction, and blind extraction is achieved. The reconstructed quick response (QR) code from the host hologram can be scanned and identified. The simulation results show that the proposed scheme has good invisibility and robustness to various types of image attacking operations such as filtering, joint photographic experts group (JPEG) compression, Gaussian noise, cropping, and rotation. The proposed method has good digital reconstruction quality for both host hologram and watermark when suffering attacks, and the QR code in the reconstruction plane has good scan recognition. Diffraction interference problem among different watermark layers is solved by the controllable post-processing of the watermarks with adjustable reconstruction and no interference, and the watermark restruction quality is improved. Furthermore, the application of virtual optics enriches the watermarking signal design method and enhances the security of the algorithm.