Watermarks encrypted in the cascaded Fresnel digital hologram

A cascaded Fresnel digital hologram (CFDH) is proposed, together with its mathematical derivation. Its application to watermarking has been demonstrated by a simulation procedure, in which the watermark image to be hidden is encoded into the phase of the host image. The watermark image can be deciphered by the CFDH setup, the reconstructed image shows good quality and the error is almost closed to zeros. Compared with previous technique, this is a lensless architecture, which minimizes the hardware requirement.     

A novel chaos-based image encryption algorithm using DNA sequence operations

An image encryption algorithm based on chaotic system and deoxyribonucleic acid (DNA) sequence operations is proposed in this paper. First, the plain image is encoded into a DNA matrix, and then a new wave-based permutation scheme is performed on it. The chaotic sequences produced by 2D Logistic chaotic map are employed for row circular permutation (RCP) and column circular permutation (CCP). Initial values and parameters of the chaotic system are calculated by the SHA 256 hash of the plain image and the given values. Then, a row-by-row image diffusion method at DNA level is applied. A key matrix generated from the chaotic map is used to fuse the confused DNA matrix; also the initial values and system parameters of the chaotic system are renewed by the hamming distance of the plain image. Finally, after decoding the diffused DNA matrix, we obtain the cipher image. The DNA encoding/decoding rules of the plain image and the key matrix are determined by the plain image. Experimental results and security analyses both confirm that the proposed algorithm has not only an excellent encryption result but also resists various typical attacks.     

The measurement of 3-D asymmetric temperature field by using real time laser interferometric tomography

A real time nondestructive temperature measurement technique based on laser holographic interference tomography technique is presented. An He–Ne laser is used as light source, and a CCD video camera is used to grab the interferogram. This laser holographic tomography technique is applied to the measurement of the temperature fields generated by two heated rods. Since data error is inevitable in engineering measurement, it is necessary to study the reconstruction techniques for reconstructing the temperature field. Three techniques including convolution back projection (CBP), algebra reconstruction technique (ART) and simultaneous iterative reconstruction technique (SIRT) are studied. Based on the reconstruction techniques and experimental situation, ART is used to reconstruct the asymmetric temperature fields. The thermocouples are used to measure the temperatures of the two heated rods. Comparing the reconstructed result with the measured temperature value, a satisfactory result is obtained.     

ZnO纳米棒阵列基-芴类共轭聚合物膜的制备及对TNT的检测评价

将共轭芴类荧光聚合物涂覆在纳米Zn O棒阵列上,制成荧光传感膜检测痕量TNT。通过水热法生长的Zn O纳米棒阵列具有较好的取向性,作为衬底可有效增大荧光膜荧光强度,同时,Zn O纳米棒阵列的高比表面积可提高膜对TNT气体的响应效率,使20s内的荧光猝灭率可达72%。     

基于分色校正的大像差光学成像系统图像处理技术

为解决传统大视场高分辨相机光学系统复杂、成本高昂等问题,利用同心多尺度计算成像系统,通过图像处理方式校正简化的光学结构残留的球差和倍率色差.分析光学系统的像差特性,得到不同波长的成像数据,并根据系统参量和像差表现,用红、绿、蓝三通道分别校正方案对图像进行处理.首先采用非线性图像缩放法,统一不同色光的放大倍率,完成倍率色差的校正;然后针对光学系统的点扩散函数随空间位置变化的特性,对各通道模糊图像进行分块,用Lucy-Richardson算法对每一个图像块进行图像复原,完成单色像差校正;最后融合三通道获得校正图像.用均方误差、峰值信噪比和结构相似度等方法进行图像质量评价,结果表明本文方法能够有效校正计算成像系统中的残留像差,提升图像质量.     

细胞工厂光学显微成像与图像处理技术

针对细胞工厂监控系统长工作距和大倾斜角的观测需求,设计了一种结构简单、成像清晰的光学显微成像系统.由于获得的细胞图像光照和色彩不均、样本浑浊、细胞重叠、边界粘连较多、细胞间距不明显,采用单尺度Retinex算法进行图像预处理,并结合Otsu阈值分割法与     

基于FPGA的高分辨率航空数码图像自适应增强

高分辨率航空数码成像具有数据量大、目标内容复杂多变且图像质量易受影响的特点,为了改善成像质量,需要进行图像增强处理.提出基于灰度直方图统计信息的自适应图像增强方法,达到了在不同拍摄条件下自适应改善图像视觉效果的目的.利用FPGA可并行实时处理海量图像数据的特点,构造了高速图像增强预处理器,实现了航空数码相机图像增强的快速运算,实验结果表明增强后的图像能更好的满足计算机视觉和人眼的需求.     

纳米流体研究的新动向

纳米流体近年来成为多个领域内的研究热点,特别是在流体物性测试、机理分析及新的应用上均取得长足进展.文章以该方向上最新完成的几类富有启发性的工作,如纳米流体热管、基于纳米液滴的纳米流体、纳米金属流体及借助于纳米颗粒控制纳米流体流动等进展予以剖析,归纳出了其中有待解决的一些重要科学问题,并指出一些可能的新应用.     

基于图象差距分割的快速目标匹配识别算法

本文在模板匹配的算法基础上,引入图象差距度量的思想,以最大图象距离差选取好的阈值,实现目标与背景的有效分离,以减少模板匹配的计算区域为手段,减少算法的计算量,并提高模板匹配算法的识别精度.实验证明,该算法实现简单且行之有效.