共查询到20条相似文献,搜索用时 31 毫秒
1.
V. A. Tkal M. N. Petrov 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2011,5(3):419-425
A simple procedure for quantitative estimation of the quality and efficiency of digital processing based on discrete wavelet
transform (DWT) of X-ray topographic and polarization-optical images for single crystal structure defects is proposed. Digital
processing of theoretical and experimental images of defects in a 6H-SiC single crystal has been performed using different
wavelet types. It is shown that the brightness characteristics of the analyzed image and differential contrast may be used
as a quantitative criterion of the processing quality and efficiency for the chosen wavelet. Theoretical images of typical
defects in a single crystal structure calculated by the modified Indenbom-Chamrov equations have been used as a reference
object. 相似文献
2.
V. A. Tkal’ M. N. Petrov N. A. Voronin I. V. Dzyuba 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2010,4(1):25-31
The procedure for eliminating the background nonuniformity of the polarization-optical contrast of a 6H-SiC single crystal
by digital processing based on the frequency analysis of images is considered in this paper. This procedure involves separating
the signal produced only by the background nonuniformity and subtracting it from the initial experimental contrast during
the wavelet processing. It is shown that, in the analyzed contrast, it is possible to decrease the intensity fluctuation induced
by the aliasing phenomenon. A good detailed elaboration of the images of structural defects, including low-frequency specific
features, and a good correspondence to the theoretical contrast calculated using the modified Indenbom—Chamrov equations were
obtained as a result of digital processing. 相似文献
3.
V. A. Tkal A. O. Okunev M. N. Petrov 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2008,2(6):931-933
The possibility of detecting growth striations by digital processing based on analysis of the brightness and frequency characteristics of images has been demonstrated by the example of x-ray topographic contrast of a GaSb(Si) single crystal. It has been shown that a higher efficiency of detecting growth striations in topograms is obtained by wavelet processing of the analyzed contrast. 相似文献
4.
基于小波包和偏最小二乘支持向量机的多光谱纹理图像的大米分类研究 总被引:4,自引:2,他引:2
提出了一种利用多光谱图像纹理特征进行大米分类的新方法。图像由MS3100-3CCD光谱成像仪获得,光谱成像仪提供3个波段的图像,由近红外(NIR)、红色(R)和绿色(G)组成,因此它能够获取普通数码照相机所不能获取的信息。对3CCD近红外波段图像进行二层小波包分解,得到16个子频带,因为纹理图像的特征信息主要集中在中频,因此提取8个中频频带(带通频带)的熵值,并且作为支持向量机的特征值输入。最后应用支持向量机技术分别对有和没有经过小波包分解的NIR波段纹理图像的熵值进行建模,建模样本和预测模型各为80个,每种各为20个。对四种大米进行处理,结果表明,经过小波包分解的纹理图像的识别率达到了100%,而没有经过小波包分解的纹理图像的识别率只有93.75%,说明结合小波包和支持向量机进行多光谱图像的纹理识别是种非常有效的技术,同时也为大米的分类提供一种快速和无损的新方法。 相似文献
5.
V. N. Kukin 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2014,8(4):748-753
Electron microscopy studies of nanoparticles in pyroboroncarbon reveal the pentagonal symmetry of their structure. The nanoparticles consisting of crystal individuals separated by twinning boundaries have icosahedral faceting (habit). As a result of the analysis of experimental high-resolution microphotographs of the nanoparticles via the digital processing of images based on fast Fourier transform, the conditions of phase conjugation in pyroboroncarbon are determined. 相似文献
6.
Digital image processing has been applied on various fields such as classification and qualitative analysis. In this work, a very simple quantitative approach was proposed for the first time. Based on the digital grayscale images of three-dimensional fluorescence spectra, several wavelet moment invariants were calculated, and used to establish the linear models for the quantitative analysis. This approach was applied to the quantitative analysis of Tryptophan, Tyrosine and Phenylalanine in mixture samples, and the correlation coefficients R(2) of the obtained linear models were more than 0.99, which were supported by the strict statistical parameters as well as leave-one-out and Jackknife cross-validations. Our study indicates that the selected wavelet moment invariants are immune from the noise and background signals, and the quantitative analysis can be performed accurately based on the overlapping peaks of compounds in mixture. This proposed approach provides a novel pathway for the analysis of three-dimensional spectra. 相似文献
7.
Digital holographic imaging fusion for a larger size object using compressive sensing is proposed. In this method, the high frequency component of the digital hologram under discrete wavelet transform is represented sparsely by using compressive sensing so that the data redundancy of digital holographic recording can be resolved validly, the low frequency component is retained totally to ensure the image quality, and multiple reconstructed images with different clear parts corresponding to a laser spot size are fused to realize the high quality reconstructed image of a larger size object. In addition, a filter combing high-pass and low-pass filters is designed to remove the zero-order term from a digital hologram effectively. The digital holographic experimental setup based on off-axis Fresnel digital holography was constructed. The feasible and comparative experiments were carried out. The fused image was evaluated by using the Tamura texture features. The experimental results demonstrated that the proposed method can improve the processing efficiency and visual characteristics of the fused image and enlarge the size of the measured object effectively. 相似文献
8.
9.
针对多光谱图像存储和传输安全性问题,提出一种将混沌思想、小波变换和KL(karhunen-loeve)变换相结合的多光谱图像压缩加密算法。首先,采用K-means聚类方案将多光谱图像聚类为通用像素,通过选择合适的K值使算法的性能最优,同时便于后续处理;然后对通用像素进行二维离散9/7小波变换,对变换后的系数进行Arnold变换以及加密处理,消除多光谱图像大部分空间冗余,减少压缩过程中的块效应;之后对产生的小波系数进行改进的KL变换,消除残余空间冗余和光谱冗余;最后采用差分脉冲滤波器对系数进行编码,并采用Tent映射对码流进行混淆扩散加密。通过实验可知,本算法的信息熵达到11.794 3(选取12位多光谱图像),信息熵更接近最大值12,优于现有算法,可以更好的隐藏原图特征;该算法的像素变化率(NPCR)和归一化平均变化强度(UACI)分别为99.81%和34.19,优于现有的其他算法,本算法可以更好的抵御差分攻击;输出比特流变化率保持在47.62%~47.71%之间,密文比特流变化率保持在47.45%~47.52%,本算法具有较好的密钥敏感性;在压缩比为4∶1~32∶1范围内,系统PSN... 相似文献
10.
A new improved design of an all-optical processor that performs modular arithmetic is presented. The modulo-processor is based on all-optical circuit of interconnected semiconductor optical amplifier logic gates. The design allows processing times of less than 1 μs for 16-bit operation at 10 Gb/s and up to 32-bit operation at 100 Gb/s. 相似文献
11.
水声目标信号在发送、传播过程中,易受到环境噪声、系统自噪声等影响,因此水声监听过程中目标信号会掺杂大量噪声信息。为提高获取目标信号的准确性和可靠性,降低噪声,在已有小波分析基础上,提出小波包节点相对能量判断最优分解层,最优分解层节点系数分段阈值处理重构方法,实现水声监听信号分频段去噪。将0.1 kHz~8.4 k Hz实验数据按节点频率排序划分为5个强弱不同的频段信号实现消噪提取,结果表明该方法可将噪声信号与目标信号有效分离,与全局单一阈值相比,具有较好降噪能力。该方法打破了小波阈值去噪高频处理的局限性,提高了识别精度,改善了全局单一阈值去噪存在的短板,在鱼类分析识别、舰船监听、深海探测等方面具有一定的推广和应用价值。 相似文献
12.
Optical implementation of orthogonal phase-code multiplexing 总被引:1,自引:0,他引:1
We propose a new optical implementation of orthogonal phase-code multiplexing in which an arbitrary phase shift of theta or theta +pi is used in the reference beam instead of 0 or pi as in the conventional method. To compare the new and the conventional methods, we employ a 2-bit orthogonal phase code and store two binary-data images in a BaTiO(3) crystal with each method. We also employ numerical methods to simulate the 2-bit phase-code multiplexing and show that the signal-to-noise ratio in the restored images is improved by more than one order of magnitude in the new method in our experimental conditions. 相似文献
13.
14.
15.
针对利用液晶空间光调制器(LC-SLM)进行全息图光电再现过程中,再现像面存在多级衍射像造成单一像能量利用率低的问题,提出了一种在位相全息图中加载数字闪耀光栅的方法,以提高全息图光电再现中单一衍射像的衍射效率.分析了闪耀光栅作为衍射光学元件的特性及其对光波进行位相调制的原理,并阐述了在LC-SLM中加载数字闪耀光栅对位相全息图光电再现时像面能量分布的影响.搭建了基于LC-SLM的位相全息图光电再现实验系统.理论分析表明:在其他条件不变的情况下,加载竖直(或水平)槽向周期为2 pixels的数字闪耀光栅可使
关键词:
全息光电再现
位相全息图
数字闪耀光栅
液晶空间光调制器 相似文献
16.
An interface is described which links an ultrasonic B-scanner to a small digital computer. The interface digitizes the image signals from the scanner to 10 levels. The 10 levels are then converted to a four-bit binary word, four of which are packed into a 16-bit word. The 16-bit words are then transferred to the digital computer. 相似文献
17.
基于单片FPGA的磁共振成像梯度计算模块 总被引:2,自引:1,他引:1
提出了一种用于磁共振成像的高集成度的数字梯度计算模块. 它可以实时计算任意层面成像所需的梯度波形,并能对X、Y、Z三个通道做波形预增强处理. 该模块基于单片FPGA器件,梯度波形数据预存于FPGA内嵌的RAM中,波形更新时间最小为1 μs. 在FPGA内部通过复用一种快速IIR滤波器算法,能在1 μs时间内实现包含6组不同时间常数和幅度的预增强运算. 实验证明该系统具有通用性好、体积小和成本低等特点,为磁共振谱仪的研制提供了一种紧凑、灵活的梯度波形发生方案. 相似文献
18.
多路CCD成像非一致性动态校正新方法 总被引:4,自引:3,他引:1
在多路CCD成像结构中,由于影响各路成像参量不一致的因素较多,常规校正方法变得复杂和困难。在分析多路CCD成像机理的基础上,提出了一种利用小波变换的多路CCD成像非一致性动态校正新方法,即在分析同一目标成像中异路图像像元特性差异的基础上,利用小波变换构筑校正因子对后续的CCD捕获图像进行校正。为满足实时校正的需要,研究了动态条件下成像校正的时效性,分析了不同小波的动态校正效率。实验结果表明,校正后同一目标异路图像相关值为0.9975,Symlet3小波在两路及多路成像校正中均具有较高效率;在多路成像中,Symlet系列小波相对于其它类型小波校正效率相对突出。此方法为多路CCD成像非一致性在线校正提供了有效的途径。 相似文献
19.
Image processing procedures for noise reduction and image registration in the Pressure Sensitive Paint (PSP) experiments are
investigated. A several types of filter are examined for the removal of shot noise. An algorithm to detect a marker cell located
on the model surface is proposed and an appropriate marker size is discussed. The digital processing based on the wavelet
transform is effective to reduce the shot noise and to enhance the edge of the model. The algorithm to sharpen the edge of
the model using wavelet transforms is developed. The results indicate that the methods developed in this study effectively
remove the shot noise and correct the displacement of the model on the images taken during the wind-on. 相似文献