共查询到20条相似文献,搜索用时 171 毫秒
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We propose a new approach for the direct estimation of the unwrapped phase from a single closed fringe pattern. The fringe analysis is performed along a given row/column at a time by approximating the phase with a weighted linear combination of linearly independent basis functions. Gaussian radial basis functions with equally distributed centers and a fixed variance are considered for the phase approximation. A state space model is defined with the weights of the basis functions as the state vector elements. Extended Kalman filter is effectively utilized for the accurate state estimation. A fringe density estimation based criteria is established to select whether the phase estimation is performed in a row by row or column by column manner. In the seed row/column decided based on this criteria, the optimal basis dimension is computed. The proposed method effectively renders itself in the simultaneous estimation of the phase and the phase derivative. The proposed phase modeling approach also allows us to successfully demodulate the low density fringe patterns. Simulation and experimental results validate the practical applicability of the proposed method. 相似文献
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H. Golnabi 《Optics & Laser Technology》2006,38(3):152-161
The goal of this paper is to describe essential criteria for image analysis of planar laser-induced fluorescence (PLIF) signals. A new image file conversion method is introduced and some typical illustrative examples showing the potential applications of the method in PLIF experiments are presented. Analysis of row, column, and total pixel counts, and the dark noise related to an image are discussed. Image segmentation, averaging and background correction can be easily done by the reported method. In our analysis it is straightforward to inspect the pixel counts and check for saturation of the camera sensors. It is also feasible to obtain a particular row or column for interpretation and it offers an easy way to check the validity of the captured images. Furthermore, the method offers a sensitive technique to check pulse-to-pulse variation of the excitation laser by using frame-to-frame fluorescence image data comparison, which is more illustrative than power checking by other means. The overall results show that the developed conversion method reported here can be effectively used to obtain more in-depth and quantitative information out of the raw data for the PLIF experiments. 相似文献
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结合相位恢复和像素行、列循环移动置乱技术, 本文提出了一种基于复振幅场信息复用和RSA算法的非对称多幅图像认证方法, 通过菲涅耳域的相位恢复算法, 依次恢复并生成多幅图像各自所对应的输入平面的复振幅信息, 通过各自的行、列向量随机数对原始二值振幅模板进行行、列循环移动置乱操作来获得每幅图像的采样模板, 认证系统将多个复振幅场信息采样、叠加并空间复用, 同时, 行向量随机数和列向量随机数被RSA算法公钥编码成密文. 系统认证时, 认证方利用自己持有的私钥将密文解码成行向量随机数和列向量随机数, 通过行、列循环移动置乱变换后获得各自的采样模板, 合成的复振幅信息和采样模板等认证信息均放置在各自正确位置, 当认证系统被正确波长的平面波照射时, 在输出平面能获得输出图像, 通过计算、显示输出图像和对应认证图像的非线性相关系数峰值来判断认证是否成功. 相似文献
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A novel blind color images watermarking based on SVD 总被引:1,自引:0,他引:1
Shao-li Jia 《Optik》2014
Since the color image watermark has more bit information, it is a challenging problem to design a robust and blind color watermarking scheme for copyright protection. In this paper, a blind watermarking scheme based on singular value decomposition (SVD) is proposed. By analyzing the orthogonal matrix U via SVD, it is found that there exists a strong similarity correlation between the second row first column element and the third row first column element. Hence, this paper utilizes this property for image watermarking. Firstly, the 4 × 4 non-overlapping pixels block of each component in color host image is processed by SVD. And then, the color watermark is embedded by slightly modifying the value of the second row first column element and the third row first column one of U matrix, and the modified relation can be utilized to extract watermark. Experimental results, compared with the related existing methods, show that the proposed color image scheme has stronger robustness against most common attacks such as image compression, filtering, cropping, noise adding, blurring, scaling and sharpening et al. 相似文献
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无源驱动对高分子发光显示屏质量要求较高,每个像素都应具有完好的二极管特性。为了在选通像素时,消除D.Braun串扰,无源驱动必须断绝选通像素与非选通像素之间的关联,所以需空闲行列上加以反向偏压。但研究表明,对于整流特性比较低的像素,在行扫描的空闲时间内,使驱动IC的VDD与VEE短路,产生相当大的漏电流并在显示屏的电阻网络上形成异常的压降,从而改变空闲行列上的原有电位。这样也就改变了非选通像素的偏置状态,使之正偏导通发光,形成了新的串扰。其表现为两种亮线:一是列串扰。亮度分布与阳极ITO及金属引线电阻有关;二是行串扰。从实验上讨论此两种串扰的产生原因,并提出减缓串扰的可能性。 相似文献
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Jae-Seung Lee 《辐射效应与固体损伤》2013,168(11-12):886-899
ABSTRACTWe proposed a new, optimised scanning parameter that can reduce the patient’s radiation dose while maintaining image quality in a head computed tomography (CT) scan. We evaluated the clinical CT scan parameters (tube voltage, tube current, slice thickness pitch, scan range, rotation time, and CT dose index) for brain CT examination in a total of 52 multi-detector row spiral CTs (SOMATOM Definition AS+, Siemens Healthcare, Germany). The data were analysed, and the range of valid scan parameters was determined clinically using quartile distribution within the 95% confidence interval. The American Association of Physicists in Medicine performance evaluation phantom was used to acquire images using these scan parameters, and new, optimised CT scan parameters were proposed by analysing CT number accuracy, noise, uniformity, spatial resolution, and contrast resolution. The new CT scan parameters proposed were determined as tube voltage 100?kVp and tube current 300?mAs. Compared with conventional clinical scan parameters, tube voltage was reduced by 16.7% and tube current was decreased by 33.3%. Loss in imaging accuracy and uniformity of CT number was less than 20%, loss in noise was less than 40%, and no change in resolution was observed. Conversely, the CT dose index and effective dose was 20%–50%. A new systematic method for clinically assessing the optimised CT scan parameters were proposed, and the effective dose was decreased, with changing exposure conditions. 相似文献
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在考察多种二值图像连通区域标记方法的基础上,提出了一种新的基于图像填充和游程码的二值图像孔洞连通域的标记和表达方法。对二值图像进行一次扫描,得到所有可能构成孔洞的游程码,并将游程对应的区域基于特定标记值进行填充。通过判断每个游程与图像上一行像素点标记值的对应关系完成新连通域的建立、游程数据存储和连通区域的合并,判断每个游程与图像下一行像素点标记值的对应关系完成孔洞的筛选。由于仅需扫描图像一次,且对每个游程只须进行单独处理,标记算法的效率较高、复杂度较低。结果表明,可以快速有效地完成二值图像孔洞连通域的标记。同时,它还给出孔洞之间的包含关系,能够有效地实现二值图像的拓扑结构表达。 相似文献
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研究了基于Gabor滤波器组的人民币图像识别方法。针对纸币图像特点,设计了适合于其特征提取的Gabor滤波器组参数,得到了纸币图像多尺度多方向上的纹理特征,然后对纹理图像进行网格划分,并计算网格中像素灰度均值行列投影和,最后采用网格投影特征模板匹配法进行纸币识别。实验表明该法抗干扰能力较强,能够较大提高旧币和污染纸币识别率,并且耗时不长。 相似文献
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非制冷红外焦平面阵列(UFPA)不可避免地存在无效像元, 这对UFPA的成像效果造成了极坏的影响。为解决这一问题, 在分析并总结各种非制冷红外焦平面无效像元识别算法优缺点的基础上, 提出一种新的无效像元识别与实时补偿方法。根据像元响应特性, 采用循环迭代法以搜索最优的无效像元判别阈值, 并据此标识出无效像元的位置。在硬件实现阶段, 对于M×N的UFPA器件, 在任意采样时刻, 利用移位寄存器保存当前采样点之前的M个响应值, 使其输出可实时更新为与采样点同列的上一个数据; 同时, 利用一般的寄存器实时保存与采样点同行的前一个数据, 采用同帧行列间内插法实现无效像元的实时补偿。该算法有效地解决了无效像元识别阈值选取困难及不易实时补偿的问题。针对320×240的UFPA器件, 该算法在基于FPGA的红外图像处理系统上得以实时实现, 成功地消除了无效像元对UFPA成像效果的影响。 相似文献
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D. Rayane A. R. Allouche R. Antoine I. Compagnon M. Broyer Ph. Dugourd 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,24(1-3):9-13
The permanent electric dipole moment of metal
atom-C60 compounds is measured. A column
(alkali) and a row (transition metals) of the periodic table are
systematically investigated. Most of the experimental results
are obtained at high temperature when the atom is mobile on the
C60 cage. For a given example
(NaC60), the dipole moment is also
measured by a different method at low temperature and both
results are consistent. For alkali, the results are compared to
ab initio calculations. A
good agreement is obtained, both for absolute values and for the
evolution of the bonding in the alkali column. For transition
metals, the relative values of the dipole moments are in
qualitative agreement with the ionic character of the compounds. 相似文献
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R.K.P. Zia 《Physics letters. A》1978,64(4):345-347
Duality transformations are used to derive a relationship between energies associated with interfaces between regions of different phases of one system and correlation functions of the dual system. For the two-dimensional Ising model, the relation is confirmed for the row/column and diagonal interfaces. 相似文献
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被动差分光学吸收光谱法监测污染源排放总量研究 总被引:6,自引:1,他引:6
研究了一种测量污染源污染气体(如SO2、NO2)排放总量的光学遥测方法,即采用被动差分光学吸收光谱(DOAS)系统在移动平台(如汽车)上对污染源排放烟羽进行扫描测量,利用被动差分光学吸收光谱处理方法对系统采集的天顶太阳散射光谱进行处理获取柱密度,在结合测量时段的气象(风场)信息后获得污染气体的排放通量,最终得到排放总量。着重描述了获得烟羽垂直柱密度的差分光学吸收光谱方法以及污染气体排放通量的计算方法,并利用车载被动差分光学吸收光谱系统对某一热电厂SO2排放进行了外场测量,实验结果与在线设备的对比表明:这种基于被动差分光学吸收光谱光学遥测方法能够用于污染源排放总量的快速测量。 相似文献
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针对数字图像传输时经常面临JPEG压缩和几何攻击,提出一种抗JPEG压缩和几何攻击的鲁棒零水印算法.将原始图像分割成互不重叠的子块,对每个子块进行奇异值分解,对奇异值矩阵进行harr小波变换,通过比较相邻两个子块奇异值矩阵小波低频逼近子带对角线元素的均值大小关系产生零水印序列.数学理论分析表明:通过比较相邻两个子块奇异值矩阵所有奇异值的均值大小关系产生零水印序列,算法实质上没有对原始图像做任何改动,具有非常好的不可见性.实验结果表明,该算法在抵抗JPEG压缩和旋转、尺寸缩放、随机删除行列、偏移行列、打印-扫描几种几何攻击表现出比较强的鲁棒性. 相似文献
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Zuo Qian Shao Changpeng Wu Nianci Xiang Hua 《International Journal of Theoretical Physics》2021,60(7):2592-2603
International Journal of Theoretical Physics - To solve the linear systems of equations Ax = b on a quantum computer, Shao and Xiang proposed a quantum version of row and column methods by... 相似文献
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In this paper, a blind dual color image watermarking scheme based on Schur decomposition is introduced. This is the first time to use Schur decomposition to embed color image watermark in color host image, which is different from using the binary image as watermark. By analyzing the 4 × 4 unitary matrix U via Schur decomposition, we can find that there is a strong correlation between the second row first column element and the third row first column element. This property can be explored for embedding watermark and extracting watermark in the blind manner. Since Schur decomposition is an intermediate step in SVD decomposition, the proposed method requires less number of computations. Experimental results show that the proposed scheme is robust against most common attacks including JPEG lossy compression, JPEG 2000 compression, low-pass filtering, cropping, noise addition, blurring, rotation, scaling and sharpening et al. Moreover, the proposed algorithm outperforms the closely related SVD-based algorithm and the spatial-domain algorithm. 相似文献