【作者】 刘薇；

【导师】 顾济华；

【作者基本信息】 苏州大学 ， 光学， 2006， 硕士

【摘要】 傅里叶变换数字全息术是借助透镜的傅里叶变换性质，以CCD等光电探测器件记录全息图，用数值方法再现全息图的数字全息术。它是综合光学全息原理和计算机技术、电子技术以及数字图像处理技术发展起来的一种新型全息成像技术。 本文从理论和实验两方面探讨了傅里叶变换数字全息及其在信息隐藏方面的应用。 (1) 阐述傅里叶变换数字全息的记录与再现基本原理，比较了傅里叶变换数字全息与菲涅耳数字全息再现算法的不同。 (2) 提出了实验方案，记录实验结果，结合图像处理的方法消除零级直透光与共轭像，并进行去噪处理。由于焦平面的光强过于集中，按照信息存储理论进行适当离焦，采集不同离焦量下的全息图，并计算重构图的相似度及峰值信噪比，得出在本实验条件下的最佳离焦量。当适当增加物体尺寸时，仍然可得到再现像，但是再现质量有所下降。 (3) 利用光学全息的抗撕毁性，研究它在信息隐藏方面的应用。通过计算机来模拟傅里叶数字全息图的记录与再现过程，将模拟的数字全息图与水印嵌入算法相结合，提出了一种基于数字全息技术的盲音频水印算法，仿真实验可以看出该算法对一般的信号破坏如低通滤波、噪声干扰特别是剪裁具有一定的稳健性。更多还原

【Abstract】 Fourier-transformed digital holography is a digital holography that uses the Fourier transformation characteristics of lens, a charge coupled device (CCD) camera for hologram recording and a numerical method for hologram reconstruction. It is a new imaging technique that combines optical holography, computer technology, electronic technology and digital image processing techniques.This paper presents the concept and underlying theory of Fourier-transformed digital holography, its experiment and its applications in information hiding.(1) Basic recording and reconstruction theory of Fourier-transformed digital holography is described. The reconstruction algorithms of Fourier-transformed digital holography and Fresnel-transformed digital holography are compared.(2) The experiment is designed. The results of the experiment are recorded. The digital image processing techniques are used to remove the zero-order diffraction, the conjugate image and the noise. Due to the intensive light at the focal plane, defocusing technique is used to improve the recording condition. Different digital holograms of different defocus distances are recorded. Corresponding similarity ratio and peak signal-to-noise ratio are calculated. The optimal defocus distance is acquired according to the maximum similarity ratio and peak signal-to-noise ratio under the condition of this experiment. The object size increases properly. The reconstruction image can still be acquired, although the quality of the image is degraded.(3) Based on the characteristics of the holography, its application in information hiding is researched. A blind audio watermark embedding algorithm by a holographic technique is proposed. The process of constructing and reconstructing a digital hologram are described on the basis of the theory of Fourier optics and simulated by the computer. The watermark, in the form of Fourier-transformed digital hologram, is embedded into the audio signal by quantification process. Experimental results show that the更多还原