共查询到19条相似文献,搜索用时 109 毫秒
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绝对式光学编码器串行编码方法的研究 总被引:1,自引:0,他引:1
针对传统绝对式光学编码器各编码码道沿径向分布、结构复杂的缺点,提出了一种绝对式光学编码器的串行编码方法。在码盘上仅刻划一圈存储多位二值信息的编码码道,沿码盘圆周方向按一定位置布置的光敏元件并行读取的二进制数具有唯一性,对此二进制数查表译码,就可以实现绝对位置测量。与传统绝对式光学编码器相比,码盘直径小、光学图案简单,有利于绝对式编码器实现小型化和提高精度。 相似文献
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提出一种新的基于信息光学的数字水印方法。该方法将水印信息隐藏于半色调编码的计算全息图之中。通过相位复原技术将需隐藏的水印信息编码为相位函数嵌入在复波前中,其振幅定义为宿主图像,通过计算全息记录复波前并对全息图进行半色调编码完成水印信息的嵌入。水印的提取过程只需对含有水印信息的半色调图像进行光学或数字的傅里叶变换即可完成。并给出了算法有效性的理论分析和仿真实验结果。结果证明这种水印技术对于各种数字图像处理操作具有很高的稳健性,且半色调编码图的二值特性使嵌入水印具有很强的抗打印、抗复印、抗扫描的能力。 相似文献
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基于现有的相位空间光调制器,提出并实现了计算机制相位彩虹全息近眼显示.指出带限条件下物光在全息面上相位分布的计算及高频闪耀光栅纵向色散的控制是实现相位彩虹全息的关键要素.在计算相位彩虹全息图时,首先利用带限条件下的角谱衍射算法获取全息面上物光的复振幅分布,并利用双向误差扩散算法将复振幅分布编码为相位分布.然后,对参考光对应的高频闪耀光栅的相位进行编码,得到计算机制相位彩虹全息图.最后,设计了包含白色点光源、准直透镜、空间光调制器、4f滤波系统及目镜的全息彩色近眼显示系统,并通过光学再现获得了相位彩虹全息近眼显示效果,证明了所提方法的有效性. 相似文献
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Kuang Tsan Lin 《Optics Communications》2009,282(4):527-248
An encoding method is used to encrypt the Fourier-transformed information of a hidden (covert) digital image in an overt image, while the Fourier-transformed information must be encoded with binary codes. All of the pixels in an overt image are classified into five groups that are called identification, type, tracing, dimension, and information codes. Identification codes are used to judge if the overt image contains codes that belong to the proposed encoding method or not; type codes are used to judge the encoding type; tracing codes are used to judge the encoding trace; dimension codes are used to judge the size of the hidden information; and information codes are used to decode the hidden information. Applying the proposed encoding method is rather easy, and host images corresponding to overt images are not needed for decoding work. The experiment has demonstrated four types of encoding for the proposed encoding method to reconstruct covert images without any distortion or only with a little distortion. 相似文献
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Spin (polarization) is widely used in free-space optics, while in photouic integrated circuits (PICs), infor- mation is usually encoded in optical route. So a practical way to connect these two encoding methods is necessary for information communication. In this letter, an encoding convertor is designed to connect spin encoding and route encoding. Finite element method is used to calculate the conversion efficiency and extinction ratio of the encoding convertor and the theoretical analyses are also given. Our protocol shows a friendly way to convert optical spin information to route information, which will promote the compatibility of free-space optics and PICs. 相似文献
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Dey KK Bhattacharyya R Kumar A 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2004,171(2):259-363
NMR photography has gained significant attention as a method of storing and retrieving information using NMR spectroscopy. Among the commonly practiced methods the most important is the frequency encoding by use of a multi-frequency pulse on a liquid crystal molecule. We propose and demonstrate another robust method which relies on spatial encoding. Spatial information is mapped onto the spectrum, if excited and recorded in the presence of a gradient. The encoding is performed by applying a multi-frequency pulse in the presence of a gradient. The subsequent acquisition, under a gradient, helps storing this spatial information on a one-dimensional spectrum. Series of such spectra can also store two-dimensional patterns. This procedure is described and exemplified in this paper. 相似文献
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基于级联分数傅里叶变换系统的数字水印技术 总被引:1,自引:0,他引:1
提出一种基于分数傅里叶变换和随机相位编码的光学加密数字水印技术,可成为一种信息隐藏及保护的有效方案.该数字水印技术对于噪音叠加和常见的图像处理操作具有较强的稳健性.该技术根据光学级联分数傅里叶变换系统,利用两个随机相位分布函数对水印信息编码并经过迭代分数傅里叶变换嵌入到变换域的载体图像中.在水印检测和提取过程中,两个相位分布函数作为密钥.随机相位编码技术的引入,进一步提高了数字水印系统的密钥空间.增强了系统的安全性.该数字水印技术基于光学分数傅里叶变换原理,可以利用光学变换系统方便地实现. 相似文献
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Kuang Tsan Lin 《Optics Communications》2008,281(13):3447-3453
This paper proposes a new type of encoding methods to encrypt hidden (covert) information in host images. The encrypted information can be plot, fax, word, or network data, and it must be encoded with binary codes. All the pixels in an encoded (overt) image modulated from a host image are classified into three groups. The first group of pixels is called identification codes, used to judge whether the overt image is encoded by a method proposed in this paper or not. The second group of pixels is called type codes, used to judge the encoding type. The third group of pixels is called information codes, used to decode the encoded information. Applying the proposed encoding methods is quite convenient, and host images are not needed for decoding. Decoding covert information from overt images is rather difficult for un-authorized persons, whereas it is very easy for designers or authorized persons. Therefore, the proposed methods are very useful. 相似文献
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由于虹膜自身的稳定性、非侵犯性、不可更改性等优点,虹膜识别已经成为生物特征身份鉴别领域中的研究热点。但虹膜丰富的纹理和复杂的结构给特征提取和编码带来了很大困难。为尽可能地简化特征提取和编码方法,提高虹膜识别效率,提出了一种基于局部信息统计的虹膜分块编码方法。对原始人眼图像进行虹膜定位等预处理操作,得到归一化的虹膜纹理图像;分别根据虹膜局部信息与全局信息、局部信息与局部信息之间的比较关系进行分块编码;计算了不同虹膜代码之间的汉明(Hamming)距离。根据汉明距离给出识别结果。实验证明该方法有效、可行,具有较高的识别率和识别速度。 相似文献
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In this paper, Arnold transformation and double random-phase encoding technique widely used in digital image information hiding are introduced to digital audio information hiding. The digital audio is transformed into a 2-D image called sound map and then the sound map will be divided into many windows and each window will be encrypted based on the Arnold transformation. Finally sound map will be re-encrypted based on double random-phase encoding technique. This method offers many advantages for digital audio information hiding: improve security and high attack immunity. 相似文献
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Lu Xi Zhou Xin Yuan Sheng Li Xiao-feng Lu Pei Chen Yao-yao 《Optics & Laser Technology》2009,41(6):751-754
A new method based on statistical hypothesis detection for information hidden using the double random-phase encoding technique is introduced. According to this method, a series of windows are opened on the lowest bit-plane of image, and an exclusive OR (XOR) operation is performed between different pixels in every window. The results of XOR operation are then analyzed. Using this method, we can judge whether an image contains secret information encrypted by the double random-phase encoding technique. The result of the judgment may be influenced by two parameters, namely the size of the window and the threshold value. A further study is also made to determine the optimal parameters. 相似文献