检索结果-内蒙古大学图书馆

Application of transform algorithms to high-resolution image reconstruction in optical diffusion tomography of strongly scattering media

引用

JOURNAL OF ELECTRONIC IMAGING 2003年第4期12卷 602-612页

作者： Konovalov, AB Lyubimov, VV Kutuzov, II Kravtsenyuk, OV Murzin, AG Mordvinov, GB Soms, LN Yavorskaya, LM Russian Fed Nucl Ctr Inst Tech Phys Snezhinsk 456770 Chelyabinsk Reg Russia Russian Fed Nucl Ctr Inst Tech Phys Snezhinsk 456770 Chelyabinsk Reg Russia Res Inst Laser Phys St Petersburg 199034 Russia

The applicability of transform algorithms generally used in projection-computed tomography is substantiated for the, case of medical optical diffusion tomography (ODT). To reconstruct tissue optical inhomogeneities, a new method based on a concept of an average statistical trajectoty for transfer of light energy [photon average trajectory (PAT)] is proposed. By this method, the inverse problem of ODT is reduced to a solution of an integral equation with integration along a PAT Within the internal zone of the object, well away from the boundaries, PATs tend to a straight line, and standard integral algorithms based on the inverse Radon transform may be used to restore diffuse optical images. To demonstrate the capabilities of the PAT method, a numerical experiment on cross sectional reconstruction of cylindrical strongly scattering objects with low-contrast absorbing inhomogeneities is conducted. To solve the time-domain ODT inverse problem, two filtered backprojection algorithms (of Radon and Vainberg) are used. The reconstruction results are compared with those obtained by a well-known software package for temporal optical absorption and scattering tomography, based on multiple solutions of a diffusion equation. It is shown that in important cases of low-contrast absorbing inhomogeneities, the PAT method using the Vainberg algorithm allows reconstruction of tissue optical inhomogeneities with a 20% gain in spatial resolution. (C) 2003 SPIE and IST.

关键词： Acquisition tracking and pointing reconstruction algorithms Receivers Image restoration Spatial resolution Diffusion Fluctuations and noise Inverse optics Tissue optics Tomography

来源：评论

学校读者我要写书评

暂无评论

ITERATIVE CONVOLUTION BACKPROJECTION algorithms FOR IMAGE-reconstruction FROM LIMITED DATA

引用

JOURNAL OF THE OPTICAL SOCIETY OF AMERICA 1983年第11期73卷 1493-1500页

作者： MEDOFF, BP BRODY, WR NASSI, M MACOVSKI, A STANFORD UNIV DEPT RADIOLSTANFORDCA 94305

Image-reconstruction algorithms implemented on existing computerized tomography (CT) scanners require the collection of line integrals that are evenly spaced over 360 deg. In many practical situations, some of the line integrals are inaccurately measured or are not measured at all. In these limited-data situations, conventional algorithms produce images with severe streak artifacts. Recently, several other image-reconstruction algorithms were suggested, each tailored to a specific type of limited-data problem. These algorithms make minimal use of a priori knowledge about the image; only one has been demonstrated with real x-ray data. We present a new operator framework that treats all types of limited-data image-reconstruction problems in a unified way. From this framework we derive iterative convolution backprojection algorithms that make no restrictions on the location of missing line integrals. All available a priori information is incorporated by constraint operators. The algorithm has been implemented on a commercial CT scanner. We present examples of images reconstructed from real x-ray data in two limited-data situations and demonstrate the use of additional a priori information to reduce streak artifacts further.

关键词： algorithms Attenuation coefficient Fourier transforms Image reconstruction reconstruction algorithms Temporal resolution

来源：评论

学校读者我要写书评

暂无评论

Integration of robust filters and phase unwrapping algorithms for image reconstruction of objects containing height discontinuities

引用

OPTICS EXPRESS 2012年第10期20卷 10896-10920页

作者： Weng, Jing-Feng Lo, Yu-Lung Natl Cheng Kung Univ Dept Mech Engn Tainan 70101 Taiwan

For 3D objects with height discontinuities, the image reconstruction performance of interferometric systems is adversely affected by the presence of noise in the wrapped phase map. Various schemes have been proposed for detecting residual noise, speckle noise and noise at the lateral surfaces of the discontinuities. However, in most schemes, some noisy pixels are missed and noise detection errors occur. Accordingly, this paper proposes two robust filters (designated as Filters A and B, respectively) for improving the performance of the phase unwrapping process for objects with height discontinuities. Filter A comprises a noise and phase jump detection scheme and an adaptive median filter, while Filter B replaces the detected noise with the median phase value of an N x N mask centered on the noisy pixel. Filter A enables most of the noise and detection errors in the wrapped phase map to be removed. Filter B then detects and corrects any remaining noise or detection errors during the phase unwrapping process. Three reconstruction paths are proposed, Path I, Path II and Path III. Path I combines the path-dependent MACY algorithm with Filters A and B, while Paths II and III combine the path-independent cellular automata (CA) algorithm with Filters A and B. In Path II, the CA algorithm operates on the whole wrapped phase map, while in Path III, the CA algorithm operates on multiple sub-maps of the wrapped phase map. The simulation and experimental results confirm that the three reconstruction paths provide a robust and precise reconstruction performance given appropriate values of the parameters used in the detection scheme and filters, respectively. However, the CA algorithm used in Paths II and III is relatively inefficient in identifying the most suitable unwrapping paths. Thus, of the three paths, Path I yields the lowest runtime. (c) 2012 Optical Society of America

关键词： Digital image correlation Image reconstruction Nonlinear spatial filtering Phase unwrapping reconstruction algorithms Speckle noise

来源：评论

学校读者我要写书评

暂无评论

COMPARISON BETWEEN ML-EM AND WLS-CG algorithms FOR SPECT IMAGE-reconstruction

引用

IEEE TRANSACTIONS ON NUCLEAR SCIENCE 1991年第6期38卷 1766-1772页

作者： TSUI, BMW ZHAO, XD FREY, EC GULLBERG, GT UNIV UTAH DEPT RADIOL SALT LAKE CITY UT 84112 USA UNIV UTAH DEPT BIOMED ENGN SALT LAKE CITY UT 84112 USA

We have studied the properties of two iterative reconstruction algorithms, namely, the maximum likelihood with expectation maximization (ML-EM) and the weighted least squares with conjugate gradient (WLS-CG) algorithms, for use in compensation for attenuation and detector response in cardiac SPECT imaging. A realistic phantom, derived from a patient X-ray CT study to simulate 201T1 SPECT data, was used in the investigation. Both algorithms are effective in compensating for the nonuniform attenuation distribution in the thorax region and the spatially variant detector response function of the imaging system. At low iteration numbers, the addition of detector response compensation provides improvement in both spatial resolution and image noise when compared with attenuation compensation alone. However, at higher iteration numbers, there is a more rapid increase in image noise when detector response compensation is included, and the increase is more dramatic for the WLS-CG algorithm. In general, the convergence rate of the WLS-CG algorithm is about ten times that of the ML-EM algorithm. Also, the WLS-CG exhibits a faster increase in image noise at large iteration numbers than the ML-EM algorithm. This study is valuable in the search for useful and practical reconstruction methods for improved clinical cardiac SPECT imaging.

关键词： Image reconstruction Iterative algorithms Least squares methods Gaussian noise Bayesian methods Maximum likelihood estimation Pixel Character generation Entropy reconstruction algorithms

来源：评论

学校读者我要写书评

暂无评论

Modal wavefront reconstruction based on Zernike polynomials for lateral shearing interferometry: comparisons of existing algorithms

引用

APPLIED OPTICS 2012年第21期51卷 5028-5037页

作者： Dai, Fengzhao Tang, Feng Wang, Xiangzhao Sasaki, Osami Feng, Peng Chinese Acad Sci Shanghai Inst Opt & Fine Mech Lab Informat Opt & Optoelect Technol Shanghai 201800 Peoples R China Chinese Acad Sci Grad Sch Beijing 100039 Peoples R China Niigata Univ Fac Engn Niigata 9502181 Japan

Four modal methods of reconstructing a wavefront from its difference fronts based on Zernike polynomials in lateral shearing interferometry are currently available, namely the Rimmer-Wyant method, elliptical orthogonal transformation, numerical orthogonal transformation, and difference Zernike polynomial fitting. The present study compared these four methods by theoretical analysis and numerical experiments. The results show that the difference Zernike polynomial fitting method is superior to the three other methods due to its high accuracy, easy implementation, easy extension to any high order, and applicability to the reconstruction of a wavefront on an aperture of arbitrary shape. Thus, this method is recommended for use in lateral shearing interferometry for wavefront reconstruction. (C) 2012 Optical Society of America

关键词： Laser beam characterization Numerical simulation reconstruction algorithms Shearing interferometry Wavefront aberrations Zernike polynomials

来源：评论

学校读者我要写书评

暂无评论

FAST algorithms FOR PHASE AND MAGNITUDE reconstruction FROM BISPECTRA

引用

OPTICAL ENGINEERING 1990年第5期29卷 504-512页

作者： DIANAT, SA RAGHUVEER, MR Rochester Institute of Technology (United States)

Techniques are developed for signal reconstruction from sampIes of the bispectrum of a 1-D or 2-D signal. The phase and magnitude of the Fourier transform of a signal as well as those of the bispectrum are expanded into a series using a set of appropriate basis functions. reconstruction is achieved by equating coefficients of like terms of these two expansions. The algorithms derive their speed by using a restricted portion of the bispectrum space and by being based on the use of the fast Fourier transform. In addition to detailed theoretical derivations, results of computer simulation are provided.

关键词： reconstruction algorithms Algorithm development Fourier transforms Signal to noise ratio Electronic filtering Statistical analysis Computer simulations Image filtering Image transmission Interference (communication)

来源：评论

学校读者我要写书评

暂无评论

Analytical evaluation of algorithms for point cloud surface reconstruction using shape features

引用

JOURNAL OF ELECTRONIC IMAGING 2013年第4期22卷

作者： Cao, Lu Verbeek, Fons J. Leiden Univ Leiden Inst Adv Comp Sci Sect Imaging & BioInformat NL-2333 CA Leiden Netherlands

In computer vision and graphics, reconstruction of a three-dimensional surface from a point cloud is a well-studied research area. As the surface contains information that can be measured, the application of surface reconstruction may be potentially important for applications in bioimaging. In the past decade, a number of algorithms for surface reconstruction have been developed. Generally speaking, these algorithms can be separated into two categories: explicit representation and implicit approximation. Most of these algorithms have a sound basis in mathematical theory. However, so far, no analytical evaluation between these algorithms has been presented. The straightforward method of evaluation has been by convincing through visual inspection. Therefore, we design an analytical approach by selecting surface distance, surface area, and surface curvature as three major surface descriptors. We evaluate these features in varied conditions. Our ground truth values are obtained from analytical shapes: the sphere, the ellipsoid, and the oval. Through evaluation we search for a method that can preserve the surface characteristics best and which is robust in the presence of noise. The results obtained from our experiments indicate that Poisson reconstruction method performs best. This outcome can now be used to produce reliable surface reconstruction of biological models. (C) 2013 SPIE and IS&T

关键词： Error analysis reconstruction algorithms Optical spheres Clouds 3D modeling Shape analysis Biological research Algorithm development 3D image processing Statistical modeling

来源：评论

学校读者我要写书评

暂无评论

Practical algorithms for simulation and reconstruction of digital in-line holograms

引用

APPLIED OPTICS 2015年第9期54卷 2424-2434页

作者： Latychevskaia, Tatiana Fink, Hans-Werner Univ Zurich Dept Phys CH-8057 Zurich Switzerland

Here we present practical methods for simulation and reconstruction of in-line digital holograms recorded with plane and spherical waves. The algorithms described here are applicable to holographic imaging of an object exhibiting absorption as well as phase-shifting properties. Optimal parameters, related to distances, sampling rate, and other factors for successful simulation and reconstruction of holograms are evaluated and criteria for the achievable resolution are worked out. Moreover, we show that the numerical procedures for the reconstruction of holograms recorded with plane and spherical waves are identical under certain conditions. Experimental examples of holograms and their reconstructions are also discussed. (c) 2015 Optical Society of America

关键词： Digital holographic imaging Fast Fourier transforms Fourier transforms Holographic recording Optical elements reconstruction algorithms

来源：评论

学校读者我要写书评

暂无评论

Implicit Neural Representations for End-to-End PET reconstruction

Implicit Neural Representations for End-to-End PET Reconstru...

引用

IEEE International Symposium on Biomedical Imaging

作者： Younès Moussaoui Diana Mateus Nasrin Taheri Saïd Moussaoui Thomas Carlier Simon Stute École Centrale Nantes LS2N CNRS UMR 6004 Nantes Université Nantes France Dépt. de Médecine Nucléaire Centre Hospitalier Universitaire de Nantes Nantes France CRCI2NA INSERM CNRS Université d'Angers Université de Nantes Nantes France

ISBN: (数字)9798331520526

ISBN: (纸本)9798331520533

Implicit neural representations (INRs) have demonstrated strong capabilities in various medical imaging tasks, such as denoising, registration, and segmentation, by representing images as continuous functions, allowing complex details to be captured. For image reconstruction problems, INRs can also reduce artifacts typically introduced by conventional reconstruction algorithms. However, to the best of our knowledge, INRs have not been studied in the context of PET reconstruction. In this paper, we propose an unsupervised PET image reconstruction method based on the implicit SIREN neural network architecture using sinusoidal activation functions. Our method incorporates a forward projection model and a loss function adapted to perform PET image reconstruction directly from sinograms, without the need for large training datasets. The performance of the proposed approach was compared with that of conventional penalized likelihood methods and deep image prior (DIP) based reconstruction using brain phantom data and realistically simulated sinograms. The results show that the INR-based approach can reconstruct high-quality images with a simpler, more efficient model, offering improvements in PET image reconstruction, particularly in terms of contrast, activity recovery, and relative bias.

关键词： Training Three-dimensional displays Pipelines Phantoms reconstruction algorithms Brain modeling Positron emission tomography Image reconstruction Biological neural networks Tuning

来源：评论

学校读者我要写书评

暂无评论

PD-SDF: Dynamic Surface reconstruction Based on Plane Decomposition for Single View RGB-D Videos

PD-SDF: Dynamic Surface Reconstruction Based on Plane Decomp...

引用

International Conference on Acoustics, Speech, and Signal Processing (ICASSP)

作者： Jinwen Li Weixing Xie Junfeng Yao Shaoqi Wu Youhong Peng Mengyuan Ge Xiao Dong Center for Digital Media Computing School of Film School of Informatics Xiamen University National Institute for Data Science in Health and Medicine Xiamen University Key Laboratory of Digital Protection and Intelligent Processing of Intangible Cultural Heritage of Fujian and Taiwan Ministry of Culture and Tourism Jiujiang Research Institute of Xiamen University Jiujiang China Guangdong Provincial/Zhuhai Key Laboratory of IRADS BNU-HKBU United International College Zhuhai China

ISBN: (数字)9798350368741

ISBN: (纸本)9798350368758

Surface reconstruction of dynamic scenes from single view videos is a challenging task due to the highly ill-posed and under-constrained nature. Existing single view reconstruction methods suffer from severe quality issues, such as surface distortion and mesh adherison. In this paper, we propose an efficient dynamic representation network, PD-SDF, which consists of a 4D motion field and a 3D geometry field. The explicit disentanglement of motion and geometry based on planar factorization guarantees the mesh consistency across frames. Specifically, to address the mesh adhesion problem, we design a depth-guided sampling strategy to focus on optimizing the SDF field near the object surface. Due to insufficient geometric cues, we design various regularization strategies to constrain smoothness and topological correcness of the scene geometry. Extensive experiments show that our method outperforms existing methods in both appearance and geometry reconstruction. The project page: https://***/

关键词： Geometry Training Surface reconstruction Three-dimensional displays Noise reconstruction algorithms Stability analysis Speech processing Surface treatment Videos

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：