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International conference on Communications and Electronics, ICCE

作者： D.-v. Nguyen Tao Jiang Lars Kuhnert K.-D. Kuhnert Research School Moses University of Siegen Siegen Germany Institute for Real-Time-Learning Systems University of Siegen Siegen Germany

The work presented in this paper deals with the poor performance of depth image generation given by Tyzx stereo vision system under different lighting conditions in both indoor and outdoor environments. For that aim, we introduce a fitting plane algorithm to correct distance information as well as fulfill the missing points in the original depth. First, the color image is over-segmented into many small homogeneous regions of interest. Those small regions can be approximately considered as planar surfaces which form the 3-d scene. While 3D points inside each small region should found a plane, this insight is then used to enhance the depth image. Assuming that the environment is made up of a number of small planes, we certainly make no explicit assumptions about the structure of the scene; this enables the algorithm to cope up with many different scenes even with significant non-vertical structure. The algorithm has been confirmed to be easily implemented and robust throughout many experiments in different lighting conditions and different scenarios in both indoor and outdoor environments. Concretely, the proposed approach enables a 3-d reconstruction capability using Tyzx DeepSea G3 vision system which is infeasible from the raw depth data. Moreover, the proposed algorithm improves more than 48% of 3-d reconstruction accuracy compared with the original result given by the stereo vision system over testing 611 scenes under real-time constraint.

关键词： image color analysis image segmentation Machine vision Stereo image processing Lighting Three dimensional displays

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Use of the Fisher Information Matrix to Optimize the Acquisition Protocol for a D-SPECT System

Use of the Fisher Information Matrix to Optimize the Acquisi...

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IEEE Nuclear Science Symposium and Medical Imaging conference

作者： Niccolo Fuin Stefano Pedemonte Simon Arridge Sebastien Ourselin Brian F Hutton Institute of Nuclear Medicine University College London Hospitals London NW1 2BU United Kingdom. S.Pedemonte S.Arridge S.Ourselin are with the Center for Medical Image Computing University College London London NW1 9EE United Kingdom.

ISBN: (纸本)9781467320283

The design of the D-SPECT system is based on compact CZT solid state detectors units that permit movements that would not be achievable with conventional gamma cameras. This new design permits to overcome some inherent SPECT limitations allowing for a region-centric acquisition. By choosing to spend more time directing the detector heads towards a region of interest (ROI), one can allocate more time to collect data from this region at the expense of collecting fewer data from less important regions. However, changing the detector angular movements allowing for a non uniform scanning pattern, the interdependence in the information changes and the D-SPECT system response may be highly shift-variant. In order to be able to compare a set of candidate scanning patterns (for a given activity distribution) a method is needed, that quantifies the information gain. The Fisher Information Matrix (FIM) formalism can be employed to characterise the uncertainty of the reconstruction. Unfortunately, computing, storing and inverting the FIM is not feasible with a 3D imaging system. To tackle this problem we introduce a new approximated expression that relies on a subsampled version of the FIM. This formulation reduces the the computational complexity in inverting the FIM but nevertheless accounts for the global interdependence between the variables. In this paper we adopt this novel algorithm, to investigate the effect of the presence of activity outside the ROI, in determining the optimal D-SPECT acquisition protocol. We perform a set of experiments to determine the optimal scanning pattern for different levels of background. If the activity in the ROI is significantly high with respect to the activity in the background, an acquisition protocol that spends more time acquiring data from the ROI is preferable. Whereas for high levels of activity in the background, an acquisition that scans uniformly the whole field of view may give better results in terms of reconstructed image qua

关键词： reconstruction image Quality Fisher Information D-SPECT Emission Tomography System Design

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REDUCTION OF vIBRATION-INDUCED ARTIFACTS IN SYNTHETIC-APERTURE-RADAR imageRY USING THE FRACTIONAL FOURIER TRANSFORM

REDUCTION OF VIBRATION-INDUCED ARTIFACTS IN SYNTHETIC-APERTU...

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IEEE International conference on image Processing

作者： Qi Wang Matthew Pepin Ralf Dunkel Tom Atwood Armin W. Doerry Balu Santhanam Walter Gerstle Majeed M. Hayat Department of Electrical and Computer Engineering University of New Mexico Albuquerque NM USA General Atomics Aeronautical Systems Inc. San Diego CA USA Sandia National Laboratories Albuquerque NM USA Department of Civil Engineering University of New Mexico Albuquerque NM USA Department of Electrical and Computer Engineering Center for High Technology Materials University of New Mexico Albuquerque NM USA

In synthetic aperture radar (SAR) images of objects exhibiting low-level vibrations are accompanied by localized artifacts, or ghost targets, caused by the micro-Doppler present in the returned SAR signals. Conventional Fourier-transform-based SAR processing techniques are not fit to remove ghosting effects prior to image formation due to the non-stationary nature of the returned signals from vibrating objects. Recently, a method based on the discrete fractional Fourier transform (DFrFT) has been developed for estimating the instantaneous vibration accelerations and vibrating frequencies from returned SAR signals. Here, a novel image de-ghosting algorithm for vibrating targets in SAR imagery is proposed by employing the DFrFT-based vibration-estimation algorithm. The proposed de-ghosting method is applied to SAR data collected by the Lynx SAR system. Experimental results show a substantial reduction in ghosting caused by a 1.5-cm amplitude, 0.8-Hz vibration present in a test target.

关键词： Synthetic aperture radar vibrations Fourier transforms Acceleration Chirp image reconstruction Frequency estimation

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reconstruction of Gated Dynamic Cardiac SPECT data Using Spatiotemporal Basis Functions

Reconstruction of Gated Dynamic Cardiac SPECT Data Using Spa...

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IEEE Nuclear Science Symposium and Medical Imaging conference

作者： Uttam Shrestha Fares Alhassen Youngho Seo Elias H. Botvinick Grant T. Gullberg Department of Radiology and Biomedical Imaging University of California San Francisco

ISBN: (纸本)9781467320283

Modeling of data from a dynamic acquisition is complicated by the combination of camera motion, organ motion, and the time-varying nature of the radionuclide distribution being imaged which results in inconsistent projection data sets. Our approach is to estimate the time varying radionuclide distribution directly from projection data. Entire tomographic slices or volumes are represented by a multiresolution spatiotemporal parameterization. The heart is modeled using spatiotemporal model that takes into account changes in the deformation of the heart as well as changes in the intensity of the signal caused by uptake and washout of the radiopharmaceutical from the heart and motion of the camera. We have developed an algorithm to reconstruct the continuous kinetics of the radiopharmaceutical by using spatiotemporal basis functions when the cardiac cycle of the heart is uniformly gated. The temporal basis functions are chosen to reflect the optimal tracer dynamics while the gate basis functions are assumed to be periodic with respect to the beating of the heart. Our preliminary results show that the fast gantry rotation of the SPECT camera can delineate the proper positioning of the myocardium in the reconstructed image while the 'out of phase' slow camera rotation smear out the motion of the heart.

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Augmenting monocular motion estimation using intermittent 3D models from depth sensors

Augmenting monocular motion estimation using intermittent 3D...

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International conference on Pattern Recognition

作者： M v Rohith Chandra Kambhamettu University of Delaware Newark DE US Dept. of Computer and Information Sciences University of Delaware Delaware USA

Estimation of human motion has been improved by recent advances in depth sensors such as the Microsoft Kinect. However, they often have limited range of depths and a large number of such sensors are necessary to estimate motion in large areas. In this paper, we explore the possibility of estimating motion from monocular data using initial and intermittent 3D models provided by the depth sensor. We use motion segmentation to divide the scene into several rigidly moving components. The orientation of individual components are estimated and these reconstructions are synthesized to provide a coherent estimate of the scene. We demonstrate our algorithm on three sequences from a real video sequence. Quantitative comparison with depth sensor reconstructions show that the proposed method can accurately estimate motion even with a single 3D initialization.

关键词： Motion segmentation image reconstruction Sensors Trajectory Solid modeling Humans Cameras

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Efficient MR image reconstruction for compressed MR imaging

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MEDICAL image ANALYSIS 2011年第5期15卷 670-679页

作者： Huang, Junzhou Zhang, Shaoting Metaxas, Dimitris Dept Comp Sci Piscataway NJ 08854 USA

In this paper, we propose an efficient algorithm for MR image reconstruction. The algorithm minimizes a linear combination of three terms corresponding to a least square data fitting, total variation (Tv) and L1 norm regularization. This has been shown to be very powerful for the MR image reconstruction. First, we decompose the original problem into L1 and Tv norm regularization subproblems respectively. Then, these two subproblems are efficiently solved by existing techniques. Finally, the reconstructed image is obtained from the weighted average of solutions from two subproblems in an iterative framework. We compare the proposed algorithm with previous methods in term of the reconstruction accuracy and computation complexity. Numerous experiments demonstrate the superior performance of the proposed algorithm for compressed MR image reconstruction. (C) 2011 Elsevier B.v. All rights reserved.

关键词： Convex optimization Compressive sensing MR image reconstruction

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Evaluation of 2D image reconstruction using fan-beam FBP algorithm with no backprojection weight from WLP completed truncated projection data

Evaluation of 2D image reconstruction using fan-beam FBP alg...

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2011 4th International conference on Biomedical Engineering and Informatics, BMEI 2011

作者： Sumith, K. Narasimhadhan, A.v. Rajgopal, Kasi Dept. of Electrical Engg Indian Institute of Science Bangalore India

ISBN: (纸本)9781424493524

This paper presents the image reconstruction using the fan-beam filtered backprojection (FBP) algorithm with no backprojection weight from windowed linear prediction (WLP) completed truncated projection data. The image reconstruction from truncated projections aims to reconstruct the object accurately from the available limited projection data. Due to the incomplete projection data, the reconstructed image contains truncation artifacts which extends into the region of interest (ROI) making the reconstructed image unsuitable for further use. data completion techniques have been shown to be effective in such situations. We use windowed linear prediction technique for projection completion and then use the fan-beam FBP algorithm with no backprojection weight for the 2-D image reconstruction. We evaluate the quality of the reconstructed image using fan-beam FBP algorithm with no backprojection weight after WLP completion. © 2011 IEEE.

关键词： image reconstruction

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Qualitative model of spatio-temporal radiation pattern of GPR antenna

Qualitative model of spatio-temporal radiation pattern of GP...

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Proceedings of the International conference on Ground Penetrating Radar, GPR

作者： F. D. Edemskiy A. v. Popov S. A. Zapunidi Department of radio wave propagation Ionosphere and Radio Wave Propagation Pushkov Institute of Terrestrial Magnetism Troitsk Moscow Russia

In our recent work, a simple qualitative model of a dipole GPR antenna radiation pattern has been developed. Replacing the real resistively-loaded dipole by an infinite line current source stretched along the ground-air interface reduces derivation to a 2D boundary value problem for a scalar wave equation which admits an exact analytical solution. Using the complex variable technique we express the Green function in terms of elementary functions and obtain the spatio-temporal radiation pattern for an arbitrary current pulse form by Duhamel integral. In spite of this simplification, the constructed solution describes quite well the ultra-wideband (UWB) pulse emitted by a realistic GPR antenna. These analytical results are useful for the interpretation of GPR raw data by giving a full description of the pulse amplitude and waveform dependence on the radiation angle. Moreover, an inverse problem can be solved: to find the unknown antenna current pulse from the signal measured in the air half-space. Two cases are considered: the surface wave and the aerial wave propagating upwards. This information gives the possibility to deconvolve the subsurface probing data thus increasing the GPR resolution.

关键词： Ground penetrating radar Antenna radiation patterns Antenna measurements Green function image reconstruction Dipole antennas

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A compact dynamic phantom to assess the effect of motion in cardiac PET and SPECT studies

A compact dynamic phantom to assess the effect of motion in ...

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IEEE Symposium on Nuclear Science (NSS/MIC)

作者： L. Presotto v. Bettinardi P. Petta M.C. Gilardi Department of physics Milano Bicocca University Milano Italy San Raffaele Hospital Milano Italy IBFM-CNR Institute for Molecular Bioimaging and Physiology Milan Italy IBFM-CNR Institute for Molecular Bioimaging and Physiology Segrate Milan Italy

Purpose: Cardiac PET and SPECT images are known to suffer from degradation due to cardiac and respiratory motion. In this work we describe a dynamic heart phantom, that we designed and built, to simulate both these movements. The phantom can be used: (i) to study the degradation effects due to the heart motion on PET/SPECT images and (ii) to evaluate and optimize motion corrections/compensation techniques for PET/SPECT heart studies. Methods: The phantom consists of two main parts. The first one simulates the left ventricle and its contraction while the second one (a moving platform) simulate the respiratory motion. The phantom has been tested in a number of different acquisition configurations (no motion, with only respiratory or cardiac motion, with both cardiac and respiratory motion) to study the effects of heart motion on the reconstructed PET images. On the same set of data we tested the capability of single and double gated, acquisition and reconstruction techniques, to account and compensate for the heart motion. Results: The phantom was able to simulate well both cardiac and/or respiratory motion. In the PET studies we were able to assess the effects of motion on the image quality as well as on the quantitative accuracy of PET data. We found that double gated PET acquisition and reconstructions techniques were effective in recovering the true radioactivity distribution compared to that of the reference static condition (no motion). Conclusions: We have successfully designed and built a compact heart dynamic phantom capable of cardiac and respiratory motion. The phantom can be useful in the assessment of motion degradation on cardiac PET/SPECT images. Furthermore, the phantom can also be used in the evaluation and optimization of gating acquisition and reconstruction techniques as well as in the evaluation of corrections techniques aiming to account and compensate for heart motion.

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image reconstruction by Prioritized Incremental Normalized Convolution 1

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17th Scandinavian conference on image Analysis (SCIA)

作者： Landstrom, Anders Nellros, Frida Jonsson, Hakan Thurley, Matthew Lulea Univ Technol Dept Comp Sci Elect & Space Engn S-97187 Lulea Sweden

ISBN: (数字)9783642212277

ISBN: (纸本)9783642212277

A priority-based method for pixel reconstruction and incremental hole filling in incomplete images and 3D surface data is presented. The method is primarily intended for reconstruction of occluded areas in 3D surfaces and makes use of a novel prioritizing scheme, based on a pixelwise defined confidence measure, that determines the order in which pixels are iteratively reconstructed. The actual reconstruction of individual pixels is performed by interpolation using normalized convolution. The presented approach has been applied to the problem of reconstructing 3D surface data of a rock pile as well as randomly sampled image data. It is concluded that the method is not optimal in the latter case, but the results show an improvement to ordinary normalized convolution when applied to the rock data and are in this case comparable to those obtained from normalized convolution using adaptive neighborhood sizes.

关键词： image reconstruction hole filling normalized convolution

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