检索结果-内蒙古大学图书馆

conference on image reconstruction from incomplete data vii

作者： Vafadar, Bahareh Bones, Philip J. Univ Canterbury Dept Elect & Comp Engn Computat Imaging Grp Christchurch 1 New Zealand

ISBN: (纸本)9780819492173

There is a strong motivation to reduce the amount of acquired data necessary to reconstruct clinically useful MR images, since less data means faster acquisition sequences, less time for the patient to remain motionless in the scanner and better time resolution for observing temporal changes within the body. We recently introduced an improvement in image quality for reconstructing parallel MR images by incorporating a data ordering step with compressed sensing (CS) in an algorithm named 'PECS'.(1) That method requires a prior estimate of the image to be available. We are extending the algorithm to explore ways of utilizing the data ordering step without requiring a prior estimate. The method presented here first reconstructs an initial image x(1) by compressed sensing (with scarcity enhanced by SVD), then derives a data ordering from x(1), R'(1), which ranks the voxels of x(1) according to their value. A second reconstruction is then performed which incorporates minimization of the first norm of the estimate after ordering by R'(1), resulting in a new reconstruction x(2). Preliminary results are encouraging.

关键词： Parallel Magnetic Resonance Imaging (pMRI) Compressed Sensing (CS)

来源：评论

学校读者我要写书评

暂无评论

High-dynamic range interferometric astronomical imaging in the presence of direction dependent effects

High-dynamic range interferometric astronomical imaging in t...

引用

conference on image reconstruction from incomplete data vii

作者： Bhatnagar, S. Natl Radio Astron Observ Socorro NM 87801 USA

ISBN: (纸本)9780819492173

Modern high sensitivity radio interferometric telescopes use ultra wide-band receivers on a large number of antenna elements to achieve the capability of imaging dynamic ranges in excess of 1:1,000,000. In practice, the imaging performance is limited by instrumental and ionospheric/atmospheric effects that corrupt the recorded data. Many of these effects are directionally dependent and vary with time and frequency. Correcting for them is therefore fundamentally more difficult and these effects have been ignored in classical image reconstruction algorithms. Few attempts in the past to correct for these effects in the image-domain did not deliver the required accuracy. Recent developments in new algorithms that can account for such direction dependent effects show promising results. In this paper I give a general mathematical description of these techniques, show that the resulting algorithms are more optimal in terms of imaging performance and computing requirements and show some results.

关键词： Interferometric imaging image reconstruction Radio Astronomy Direction-dependent effects

来源：评论

学校读者我要写书评

暂无评论

Superresolved image reconstruction from incomplete data

Superresolved Image Reconstruction from Incomplete Data

引用

conference on image reconstruction from incomplete data vii

作者： Chuang, Yi-Chen Dudley, Richard Fiddy, Michael A. Nanyang Technol Univ Sch Elect & Elect Engn 50 Nanyang Ave Singapore 639798 Singapore Univ N Carolina Dept Phys & Opt Sci Charlotte NC 28223 USA Univ N Carolina Ctr Optoelect & Opt Commun Charlotte NC 28223 USA

ISBN: (纸本)9780819492173

A finite thickness slab of a metamaterial having a refractive index close to n = -1, can be used for sub-wavelength scale imaging. In the image domain, the measured fields contain evanescent wave contributions from subwavelength scale features in the object but these have to be related to the intrinsic parameters describing the scatterer such as refractive index or permittivity. For weak scatterers there can be a simple relationship between the field distribution and the permittivity profile. However for strong (multiple) scatterers and, more importantly, for objects for which subwavelength features contribute to the scattered (near) field, there is no simple relationship between the measured data and the permittivity profile. This is a significant inverse scattering problem for which no immediate solution exists and given the metamaterial slab's limitations one cannot assume that either angle or wavelength diversity will be available to apply an inverse scattering algorithm. We consider wavelength diversity in this paper to acquire the measured data necessary to estimate a superresolved solution to the inverse scattering problem.

关键词： Metamaterials superresolution scattering inverse scattering algorithm

来源：评论

学校读者我要写书评

暂无评论

Determining wind fields in atmospheric mountain waves using sailplane flight data

Determining wind fields in atmospheric mountain waves using ...

引用

conference on image reconstruction from incomplete data vii

作者： Zhang, Ni Millane, Rick P. Enevoldson, Einar Murray, James E. Univ Canterbury Dept Elect & Comp Engn Computat Imaging Grp Christchurch 1 New Zealand NASA Dryden Flight Res Ctr Edwardsville IL 93523 USA

ISBN: (纸本)9780819492173

The problem of estimating wind velocities from limited flight data recordings is considered, with application to sailplane flights in high-altitude atmospheric mountain waves. Sailplane flight recorders routinely measure only GPS position and the problem is highly underdetermined. The nature of this problem is studied and a maximum a posteriori estimator is developed using prior information on the wind velocity and the sailplane airspeed and heading. The method is tested by simulation and by application to sailplane flight data.

关键词： Maximum a posteriori wind velocity aircraft sailplane mountain wave atmospheric wave

来源：评论

学校读者我要写书评

暂无评论

Single image Spatially Variant Out-of-focus Blur Removal

Single Image Spatially Variant Out-of-focus Blur Removal

引用

conference on image reconstruction from incomplete data vii

作者： Chan, Stanley H. Nguyen, Truong Q. Harvard Univ SEAS 33 Oxford St Cambridge MA 02138 USA UCSD Dept ECE La Jolla CA 92093 USA

ISBN: (纸本)9780819492173

This paper addresses the problem of two-layer out-of-focus blur removal from a single image, in which either the foreground or the background is in focus while the other is out of focus. To recover details from the blurry parts, the existing blind deconvolution algorithms are insufficient as the problem is spatially variant. The proposed method exploits the invariant structure of the problem by first predicting the occluded background. Then a blind deconvolution algorithm is applied to estimate the blur kernel and a coarse estimate of the image is found as a side product. Finally, the blurred region is recovered using total variation minimization, and fused with the sharp region to produce the final deblurred image.

关键词： Blind deconvolution spatially variant total variation alpha-matting kernel estimation depth

来源：评论

学校读者我要写书评

暂无评论

Maximum subarray algorithms for use in optical and radio astronomy

Maximum subarray algorithms for use in optical and radio ast...

引用

conference on image reconstruction from incomplete data vii

作者： Weddell, S. J. Takaoka, T. Read, T. Candy, R. Univ Canterbury Dept Elect & Comp Engn Christchurch 1 New Zealand Univ Canterbury Dept Comp Sci & Software Engn Christchurch 1 New Zealand

ISBN: (纸本)9780819492173

The maximum sub-array algorithm has been implemented within a field programmable gate array as an efficient centroiding method for wavefront slope estimation. However, a convenient platform for this work is a graphics processor unit (GPU). Translation of the maximum subarray algorithm to a GPU has been performed and shows significant performance gains compared to a single-core CPU. Recently, this algorithm has been applied to radio telescope images acquired for the Australian square kilometer array pathfinder project. This paper provides an overview of the maximum subarray algorithm and shows how this can be utilized for optical and radio telescope applications

关键词： graphics processing unit maximum subarray problem astronomical image processing

来源：评论

学校读者我要写书评

暂无评论

Study of optical micro-scanning reconstruction

Study of optical micro-scanning reconstruction

引用

conference on image reconstruction from incomplete data vii

作者： Zhao, Xunjie Li, Chengjin Soochow Univ Sch Phys Sci & Technol Suzhou 215006 Peoples R China Sci & Technol ElectOpt Secur Lab Sanhe 065201 Peoples R China

ISBN: (纸本)9780819492173

Infrared images provide valuable information for many applications. However, compared to a visible image, the image quality is poor and its spatial resolution is limited due to the focal plane arrays cannot be made dense enough to yield a sufficiently high spatial sampling frequency, which consequently leads to image blurring. Optical micro-scanning technique has been proven to be an effective method to increase the resolution of images. This technique is able to produce high resolution (HR) images from a set of optically shifted images of low-resolution (LR). Over the last decade, optical micro-scanning technique has become one of the active topics of research, among this, the super-resolution (SR) reconstruction algorithms are the focus. This paper starts with the basic principle of SR reconstruction. Then several methods of high-precision movement registration algorithm and SR reconstruction algorithms were introduced. This study particularly focuses on the more recent development in motion estimation methods. Furthermore, an algorithm based on sub-pixel image registration that estimates the displacements of the LR image is presented. The critical steps in image registration are collecting feature points and estimating a spatial transformation especially when outliers are present. In this paper, the Harris corner detector is used to find the feature points and then the point feature is described by the neighborhood difference in order to reduce the sensitivity to illumination variations. Moreover, the Random Sample Consensus(RANSAC) algorithm is employed to build a transformation model. Simulation results demonstrate that the method can estimate the displacements accurately.

关键词： super-resolution reconstruction optical micro-scanning sub-pixel registration Harris corner detector RANSAC image interpolation feature matching

来源：评论

学校读者我要写书评

暂无评论

Optical motion tracking to improve image quality in MRI of the brain

Optical motion tracking to improve image quality in MRI of t...

引用

conference on image reconstruction from incomplete data vii

作者： Maclaren, Julian Aksoy, Murat Ooi, Melvyn Bammer, Roland Stanford Univ Ctr Quantitat Neuroimaging Dept Radiol Stanford CA 94305 USA

ISBN: (纸本)9780819492173

Magnetic resonance imaging (MRI) of the brain is highly sensitivity to head motion. Prospective motion correction is a promising new method to prevent artifacts resulting from this effect. The image volume is continuously updated based on head tracking information, ensuring that the magnetic fields used for imaging maintain a constant geometric relationship relative to the object. This paper reviews current developments and methods of performing prospective correction. Optical tracking using cameras has major advantages over other methods used to obtain head pose information, as it does not affect the MR imaging process or interfere with the sequence timing. Results show that motion artifacts can be almost completely prevented for most imaging sequences. Despite this success, there are still engineering challenges to be solved before the technique becomes widely accepted in the clinic. These include improvements in miniaturization, marker fixation and MR compatibility.

关键词： MRI optical tracking prospective motion correction MR compatibility review

来源：评论

学校读者我要写书评

暂无评论

3-D reconstruction OF OBJECTS from incomplete data AND A-PRIORI KNOWLEDGE.

NATO Conference Series, (Series) 4: Marine Sciences

引用

NATO conference Series, (Series) 4: Marine Sciences 1980年 1卷 393-395页

作者： Tsikos, Constantinos J. Bajcsy, Ruzena K.

The authors are interested in the reconstruction of 3-D objects from various sources of incomplete data as well as apriori knowledge about the object under reconstruction. As data sources use is made of conventional Xray projections as well as CAT scans perpendicular to the Xray planes. These data sources were chosen because they are complementary to each other, in the sense that information not found in one set can be found in the other.

关键词： image PROCESSING

来源：评论

学校读者我要写书评

暂无评论

Kepler mission exoplanet transit data analysis using fractal imaging

Kepler mission exoplanet transit data analysis using fractal...

引用

conference on image reconstruction from incomplete data vii

作者： Dehipawala, S. Tremberger, G., Jr. Majid, Y. Holden, T. Lieberman, D. Cheung, T. CUNY Queensborough Community Coll New York NY 11364 USA

ISBN: (纸本)9780819492173

The Kepler mission is designed to survey a fist-sized patch of the sky within the Milky Way galaxy for the discovery of exoplanets, with emphasis on near Earth-size exoplanets in or near the habitable zone. The Kepler space telescope would detect the brightness fluctuation of a host star and extract periodic dimming in the lightcurve caused by exoplanets that cross in front of their host star. The photometric data of a host star could be interpreted as an image where fractal imaging would be applicable. Fractal analysis could elucidate the incomplete data limitation posed by the data integration window. The fractal dimension difference between the lower and upper halves of the image could be used to identify anomalies associated with transits and stellar activity as the buried signals are expected to be in the lower half of such an image. Using an image fractal dimension resolution of 0.04 and defining the whole image fractal dimension as the Chi-square expected value of the fractal dimension, a p-value can be computed and used to establish a numerical threshold for decision making that may be useful in further studies of lightcurves of stars with candidate exoplanets. Similar fractal dimension difference approaches would be applicable to the study of photometric time series data via the Higuchi method. The correlated randomness of the brightness data series could be used to support inferences based on image fractal dimension differences. Fractal compression techniques could be used to transform a lightcurve image, resulting in a new image with a new fractal dimension value, but this method has been found to be ineffective for images with high information capacity. The three studied criteria could be used together to further constrain the Kepler list of candidate lightcurves of stars with possible exoplanets that may be planned for ground-based telescope confirmation.

关键词： fractal imaging Kepler mission exoplanets time series

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：