空间编码复用散斑多信息融合关联成像(特邀)

提出空间编码复用散斑技术来实现单个单像素探测器对多个物体信息的同时探测获取。使用空间编码复用散斑对多个物体信息进行照明,使用单像素探测器对回波信号进行探测,利用关联算法获取混叠多物体信息,然后用空间编码信息对随机采样的多个物体信息进行解码,最后采用压缩感知技术对完整的多个物体信息进行复原。使用该技术分别实现了对多空间、多光谱和多偏振信息的同时探测获取,实验结果证实了该技术的有效性,该技术可有效降低系统数据量,提高关联成像系统的成像效能。     

新型四通道计算全息图

提出了一种新的制作四通道计算全息的方法,它在双通道计算全息的基础上通过在一个抽样单元中放置两个宽度和高度均可变化的矩形,实现在u方向和v方向各记录两个物体的信息,从而可以一次性记录四个物体.该方法已经在实验中得到了印证,文中给出了相应的原理和实验结果.     

基于光学全息和半色调技术的二维条码

描述了一种利用光学全息及半色调技术的二维条码的编解码方法。与传统的二维条码编码方法相比,该方法是利用光学全息的方法对信息进行编码和解码, 避免了传统二维条码复杂的编解码流程,而且可以利用全息固有的特征提高其数据存储能力和纠错能力。此外,在编码过程中引入半色调技术减少二维条码在打印过程中的信息丢失。根据上述原理,本文实现了全息二维条码的编解码,计算仿真和实验均证明了该方法的可行性。     

分离物体三维测量的彩色结构光编码新方法

提出了一种结合颜色、格雷码和正弦光栅的编码新方法,用于测量空间分离物体的三维面形。该彩色格雷码正弦条纹图案表现为用颜色信息编码的正弦条纹图案,利用此条纹图案来记录物体的三维面形数据。首先投射一幅彩色格雷码正弦条纹来调制被测物体的三维信息,摄像机拍得物体表面的变形条纹图,然后应用傅里叶变换方法获取截断相位,根据编码特征进行解码来指导截断相位的展开,获得展开相位,进而恢复出物体的三维面形。该方法编码稳定,解码方法可靠,只需要拍摄一幅图,就可以较好地重建空间分离物体的三维面形。空间分离物体的实验结果以及与基于调制度排序的截断相位二维空间展开结果的对比,均证明了该方法的正确性和可行性。     

颜色编码正弦条纹实现孤立动态物体3维测量

采用常规条纹投影与相位分析方法,对动态物体,尤其是空间存在孤立区域、分布不连续的动态物体进行3维面形测量时,很难得到可靠的展开相位。为了解决这一问题,提出一种用颜色编码正弦条纹光栅投影测量的新方法。该方法使用二级编码的颜色信息来标记待投影的正弦条纹,从另一角度拍摄记录带有颜色信息的变形条纹图,根据编码特征进行解码获取颜色级次来确定条纹级次,并指导截断相位的展开,重建空间孤立动态物体的3维面形数据。结果表明,该算法的编码稳定、解码方式可靠,只需要拍摄1幅图就可以较好地重建空间孤立物体的3维面形。     

再现二维图像的"莫阿锁"

给出了用莫阿（Moire原理再现多灰阶二维图像技术的步骤：用半色调屏对二维图像进行第一次编码,得到半色调屏图像fA（u,v）,然后分别对fA（u,v）图像和1一fA（u,v）反转图像用同空间频率为ξ0的基栅进行第二次编码,图像与反转图像之间基栅位相差为π,两次编码的方向夹角为45°。本技术可用于防伪。     

点阵合成体视动感全息图

首先获取三维物体不同视角的透视图,并对这些视图上的不同单元的光强信息用计算机分别收集、编码,得到一组编码片,依次在同一张全息片的不同点区域上记录编码片的信息.当普通灯光照明全息片时,双眼能同时分别接收到反映物体两个侧面的清晰再现像,构成体视像,而且像会随着人眼的移动而产生动感效应.本方法的优点是利用计算机对信息处理的精确性,再结合全息记录、再现的准确性,制作了一张点阵合成动感全息图样品,能看见清晰立体再现像,观察方便,人眼移动时再现像的动态效果逼真.     

非相干全息术成像特性及研究进展

非相干光照明的物体或者自发光物体可以认为是由无数多个点源构成,任意两点发出的光波之间不具有相干性,但同一物点发出的光被分束后是空间自相干的。非相干全息术通过某种光学技术将来源于非相干物体上同一点的光波分为两束,由于这两束光是空间自相干的,因而两束光可以干涉实现点源全息图的记录,所有点源全息图的非相干叠加构成物体的全息图。对全息图进行光学或数值重建可以恢复原始物体的三维信息。近年来,非相干全息术已经在非扫描荧光显微成像、非相干彩色全息显示和自适应光学领域展示了其应用的潜力。阐明了非相干全息术记录和再现的基本原理,介绍了记录非相干数字全息图的系统与方法,重点分析和讨论了基于自参考光的同轴数字全息成像系统的成像特性、应用的优势和局限,并介绍了这些方面的研究进展。     

位相编码计算全息在防伪中的应用

提出一种计算全息位相编码防伪方法。它用迂回位相法对波面进行位相编码,然后用编码的波面与参考波面干涉,从干涉图样中该出记录的物本信息。物体信息由计算机产生或用ＣＣＤ记录,可以是有一定灰阶的物体。这种编码方法与全息干涉术相结合,可制作防伪功能极高的全息图。     

双通道计算全息及仿真再现

本文在单通道罗曼Ⅲ型计算全息的基础上 ,介绍了双通道计算全息的编码原理和制作技术 ,并用计算机仿真得到了双通道计算全息图的再现像 ,实现了双通道计算全息制作再现全过程计算机处理 ,为评价编码方案和再现像像质提供了有效的方法     

Two-color storage tube

A direct-view storage tube has been developed which is capable of displaying stored information in either of two colors or in intermediate hues. The operating principle is based on the fact that flood electrons which pass through the holes in the storage mask when the storage-surface potential is near cutoff fall within small areas on the viewing screen opposite the storage-mask holes; whereas flood electrons which pass through the holes when the potential is near its maximum, i.e., flood-gun-cathode potential, fall on larger overlapping areas on the viewing screen. The viewing screen consists of a pattern of two phosphors: one occupies small areas in register with the storage-mask holes, and the other occupies areas surrounding the first. The tube, which has a 10-inch diameter, can be operated with simple circuitry, essentially the same as that required for conventional half-tone storage tubes. When the performance of this tube is compared with that of conventional half-tone storage tubes, it can be seen that a moderate sacrifice in resolution was made in order to replace the half-tone monochromatic range with a system of two primary colors and intermediate hues. This system permits the color coding of stored information that provides a vivid qualitative or semiquantitative representation of a variable in the display. The design and performance considerations for the tubes are discussed and future investigations for this type of tube are outlined.     

Coded overlapped code division multiplexing system with Turbo product structure

Coded overlapped code division multiplexing system with Turbo product structure (TPC-OVCDM) is introduced, and trellis coded modulation (TCM) code is employed as error correcting code for uncoded overlapped code division multiplexing (OVCDM) system. In such a scheme, row code and column code are TCM and OVCDM spreading code, respectively. Data bits are only encoded directly by TCM and transformed into a matrix. Each column of this matrix is then permuted by symbol interleaver before being encoded by OVCDM spreading code. During iterative decoding process in the receiver, two constituent decoders use symbol by symbol BCJR algorithm in the log domain. The order of decoding two sub-codes is determined by the encoding order. The proportion of TCM coding and OVCDM coding affects system performance. For fixed coding structure and symbol interleaver, the performance of TPC-OVCDM systems of different proportions of additive white Gaussian noise (AWGN) channel have been simulated. The results show that TPC-OVCDM system of reasonable proportion can achieve significant coding gain, compared with uncoded OVCDM system under the condition of same spectral efficiency at bit error rate (BER) level of 10-5 .     

RS-Turbo级联码的性能仿真及其在图像传输中的应用

RS码是一种纠突发错误能力很强的信道编码方式,Turbo码是一种巧妙的将卷积码和随机交织器结合在一起,同时采用软输出并通过不断迭代的方法译码来逼近最大似然编码的一种新的纠错能力很强的信道编码方式;本文分析了两种编码方式并研究了将二者级联后RS-Turbo的性能,给出了将其级联码在图像传输中的应用.     

Two-channel multithreshold decoding of the systematic convolutional code

A variant of the two-channel sequential multithreshold decoding of the non-recursive systematic convolutional code of rate R = 0.5 has been considered. The main operations of two-channel sequential multithreshold processing and correction of errors detected in the receiving channel were determined on the basis of the joint comparative analysis of two functionally-related syndrome sequences generated.     

信源平衡编码及其在流密码中的应用

本文对离散无记忆信源给出了一种编码方法，它使编码后信源输出有着最好的平衡性，即0与1的数目最大程度地接近．对等长编码，本文给出的方法是步优的；对基于Huffman码的平衡编码，在保持平均码长不变的情况下，本文给出的方法使0与1的平衡性达到最优．因为一般信源字符的频率是一个统计数字．这里的平衡性也是从统计角度来说的．最后我们还讨论了这种平衡编码对流密码中的非线性组合器在防止相关攻击方面的防护作用．     

Two-channel conjugate vector quantizer for noisy channel speechcoding

A two-channel conjugate vector quantizer is proposed in an attempt to reduce quantization distortion for noisy channels. In this quantization, two different codebooks are used. The encoder selects the channel code pair that generates the smallest distortion between the input and the averaged output vectors. These two codebooks are alternately trained by an iterative algorithm which is based on the generalized Lloyd algorithm. Coding experiments show that the proposed scheme has almost the same SNR as a conventional vector quantizer for an error-free channel. On the other hand, it has a significantly higher SNR than the conventional one for a 1% error rate. This scheme also has merits in computational complexity and storage requirements. The scheme is confirmed to be effective for a medium bit-rate speech waveform coder     

Discrete wavelet transform based on cyclic convolutions

A filterbank in which cyclic convolutions are used in place of linear convolutions will be referred to as a cyclic convolution filterbank (CCFB). A dyadic tree-structured CCFB can be used to perform a discrete wavelet transform suitable for coding based on symmetric extension methods. This paper derives two types of efficient implementation techniques for the tree-structured CCFB: one using complex arithmetic and one using only real arithmetic. In addition, the present paper analyzes in detail the perfect reconstruction (PR) condition for the two-channel CCFB and shows that this condition is much less restrictive than that of usual two-channel filterbanks. When each of the two-channel CCFBs constituting a tree-structured CCFB is designed to be PR, the whole system is PR. A quadrature mirror filter (QMF) CCFB having the PR property is demonstrated to be easily designed using a standard filter design subroutine. In contrast, designing a linear-phase PR FIR QMF bank that has good frequency response is not possible when filters are realized by linear convolutions.     

基于BF561的H.264并行编码的研究

基于H.264视频编码标准和多核DSP ADSP-BF561的结构特点,提出了一种H.264并行编码方案.这种方案将输入视频分为两个相对独立的Slice编码,适应该DSP的同构双核结构,充分发挥了DSP的处理性能.实验结果表明,该并行方案在几乎不降低图像质量的情况下,编码速度提高了40%左右.     

A new non-orthogonal space-time code with low decoding complexity

A full diversity block space-time code over two transmit antennas and two symbol periods is introduced. In this method, each code is equal to the addition of two matrices; A/sup m/ and DA/sup n/, where A and D are the two constant matrices and m and n are the two data symbols. A is selected such that the set A/sup m/, 0 /spl les/ m /spl les/ 2/sup b/ - 1 is closed under the matrix multiplication. This structure allows a simple maximum likelihood (ML) decoding method, and at the same time, simplifies the optimization of the coding advantage. Simulations show that the performance of the new code is very close to that of the Damen code (M. O. Damen et al., 2002) which is the best known block space-time code in terms of the coding advantage. Moreover, the decoding complexity of the proposed method is significantly lower than that of the Damen code.