【作者】 冯升同；

【导师】 王大勇；

【作者基本信息】 北京工业大学 ， 光学， 2005， 硕士

【摘要】 随着社会信息量“爆炸”似的增长,原来的存储器件和存取速度越来越不够用。体全息存储适时而生,它有着高冗余度、高存储容量、极高的数据传输速率以及极快的存取时间等优点,因而得到越来越多的关注。本论文以体全息相关器为基础进行图像识别。本论文介绍了体全息存储原理及技术,包括体光栅的形成和布拉格衍射、衍射效率、水平角度选择性,还介绍了相干光学信息处理系统、Vander Lugt 滤波器的形成过程,给出了多重匹配滤波器相关的运算过程,最后介绍了子波变换的定义以及光学子波变换。本论文构建了一个与北京市车辆牌照密切相关的牌照图像库。从仿真和实验两方面比较了空域滤波与频域滤波、一般高通滤波器与子波滤波器的优缺点。实验表明子波滤波器的引入大大提高了相关器的识别能力。为了解决旋转不变识别,本论文采用综合判别函数方法,对每一个畸变训练集,综合出一个综合判别函数。在光路引入子波滤波器后,利用角度复用技术将综合判别函数依次存入晶体,然后输入任意一个训练集的任意一幅图像,都被精确地识别。本论文尝试着采用圆谐展开方法来实现旋转不变识别。选取一幅图像的圆谐二级分量,将其生成纯位相滤波器,然后存入晶体。输入任意旋转角度的图像,都被准确地识别出来。为了减少滤波器的个数和计算量,结合圆谐展开和综合判别函数方法生成圆谐—综合判别函数滤波器。利用该滤波器可以识别多类任意旋转角度的图像。本论文还研究了三维物体相关识别,发现三维物体的相关输出对旋转角度极为敏感,这一特点可以应用于机器人视觉识别。本论文最后总结了取得的成果,并指明了以后的研究方向。更多还原

【Abstract】 Due to the “information explosion”, Memory capacity and its access speed have not satisfied our need in the last decade. More attention are attached on volume holographic storage for its high redundancy, capacity, fast data transfer rate and short access time. Image recognition is carried out based on volume holographic storage. In this paper, principle and technique of volume holographic storage are presented such as volume grating formation, Bragg diffraction, and horizontal angle selectivity. Also optical information processing system and Vander Lugt filter are presented, as well as correlation procedure based on matched-filter. Finally optical wavelet transform is presented. In this paper, an image set is constructed according to registration mark in Beijing District. From computer simulation and experiments comparison results are presented between spatial and frequency , high-pass and wavelet filtering. And it is suggested that the discrimination is greatly improved owing to the wavelet filter. To achieve rotation-invariance, Synthetic Discriminant Function(SDF) is introduced . A SDF is synthesized using a更多还原