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Improvements in the image quality of ventilatory tomograms by electrical impedance tomography

PHYSIOLOGICAL MEASUREMENT 2008年第6期29卷 S51-S61页

作者： Hahn, G. Dittmar, J. Just, A. Hellige, G. Univ Gottingen Dept Anaesthesiol Res D-37075 Gottingen Germany

We present an improved approach to image ventilation in functional electrical impedance tomography (f-EIT). It combines the advantages of the two established procedures of calculating standard deviation as a functional parameter of ventilation (SD method) and the so-called filling capacity (FC method). The SD method quantifies the local impedance variation over a series of tomograms for each pixel;the FC method is based on the slope of a linear fit of regional versus the global impedance change. Tidal volume v(T) is displayed linearly by the SD method in f-EIT;it is, however, sensitive to noisy data. The FC method is much more robust with respect to noise but does not display the tidal volume vT. We combined the advantages of both techniques in a new vT method which is based on raw data. It saves computing time and is suitable for both f-EIT and absolute EIT (a-EIT). We separated the raw data into two representative sets: end expiratory and end inspiratory. This was accomplished by calculating the global time course of the relative impedance changes from the raw data. In this time course, we determined all frame numbers (indices) of end expiration and end inspiration. These frame numbers were used to calculate one mean expiratory and one mean inspiratory raw data frame. reconstruction by difference imaging directly reflects the mean tidal volume v(T) during the acquired frame series. The effect of the improvement by the vT method was investigated at different noise levels by adding artificial noise from 0 to 100 mu v(rms) to a real raw dataset. The robustness with regard to noise of the vT method was similar to that of the FC method. The practical value of suppression of non-ventilatory impedance changes, artefacts and noise was tested by studying ten healthy subjects (four females, six males) during normal breathing. We found a highly significant improvement in the image quality (p < 0.001) of ventilation for this group of volunteers.

关键词： EIT ventilation functional EIT absolute EIT bioimpedance

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Aspects of binary image reconstruction from Fourier amplitude data

Aspects of binary image reconstruction from Fourier amplitud...

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2008 23rd International conference image and vision Computing New Zealand, IvCNZ

作者： Lo, v.L. Millane, R.P. Computational Imaging Group Department of Electrical and Computer Engineering University of Canterbury Private Bag 4800 Christchurch New Zealand

The reconstruction of a binary image from under sampled Fourier amplitude data is considered. Binary, connectivity, and compactness constraints are discussed and shown to he sufficient to enforce a unique solution. An... 详细信息

ISBN: (纸本)9781424425822

关键词： X ray crystallography

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Wiener Altering of aliased imagery

Wiener Altering of aliased imagery

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image reconstruction from incomplete data v

作者： Thurman, Samuel T. Fienup, James R. Institute of Optics University of Rochester Rochester NY 14627 United States

ISBN: (纸本)9780819472960

We analyze a Fourier-domain Wiener filter for the reconstruction of aliased imagery. The filter is designed to minimize the expected mean square error for the unaliased portion of the object Fourier transform. This analysis yields a net system transfer function, which characterizes the combined effects of the imaging system, sampling, and the reconstruction process, that is valid at both aliased and unaliased spatial frequencies. This transfer function provides insight into how aliasing artifacts are modified by the reconstruction process. Additionally, the net transfer function is useful for characterizing the combined performance of the imaging system and post processing. For example, the net system transfer function can be used to calculate the edge response for reconstructed imagery even in the presence of aliasing. Examples are used to illustrate these aspects of using the Wiener filter with aliased imagery.

关键词： image reconstruction

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A ROBUST FRAMEWORK FOR GEOTIME CUBE

A ROBUST FRAMEWORK FOR GEOTIME CUBE

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15th IEEE International conference on image Processing (ICIP 2008)

作者： Toujas, v. Donias, M. Jeantet, D. Guillon, S. Berthoumieu, Y. Univ Bordeaux 1 ENSEIRB ENSCPBGrp Signal Lab IMSUMR 5218 351 Cours Liberat F-33405 Talence France TOTAL CSTJF F-64018 Pau France

ISBN: (纸本)9781424417650

This paper presents a robust unsupervised framework for 3D seismic data flattening. The resulting volume, called GeoTime cube, brings to light history of sedimentary deposits which is a key issue in petroleum prospecting. The proposed method makes it possible to obtain the transformation by transcribing fundamental principles of geophysics in image processing. The first step is a sedimentary layer reconstruction, the second one consists in numbering them according to their relative geological age and the last one computes a transformation in order to clearly represent them in a flattened way. Finally, the results obtained by our method compared to an existing one show that many relevant information can be extracted from GeoTime cubes and the final flattened data enhances the seismic structures identification.

关键词： Seismic imaging GeoTime Flattening Surface reconstruction Partial Differential Equations

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WAvEFRONT reconstruction OF 3D CYLINDRICAL SUBSURFACE RADAR imageRY: A STUDY ON SYNTHETIC PHANTOMS

WAVEFRONT RECONSTRUCTION OF 3D CYLINDRICAL SUBSURFACE RADAR ...

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2008 IEEE Radar conference

作者： Flores-Tapia, Daniel Thomas, Gabriel Pistorius, Stephen Univ Manitoba Dept Elect & Comp Engn 75A Chancellors Circle Winnipeg MB R3T 5V6 Canada Univ Manitoba Dept Phys & Astron Winnipeg MB R3E 0V9 Canada Canc Care Manitoba Dept Med Phys Winnipeg MB R3E 0V9 Canada

ISBN: (纸本)9781424415380

In recent years, the use of radar technology has been proposed in a wide range of subsurface imaging applications. Traditionally, linear scan trajectories are used to acquire data in most subsurface radar scenarios. However, novel subsurface radar applications, such as breast microwave imaging and wood inspection, require the use of non linear scan trajectories in order to adjust to the geometry of the scanned area. This paper proposes a novel reconstruction algorithm for subsurface radar data acquired along 3D cylindrical scan trajectories. The spectrum of the collected data is processed in order to locate the spatial origin of the larger reflections and remove the spreading of the target reflections which results from the different signal travel times along the scan trajectory. The proposed algorithm was tested using experimental data sets, yielding promising results.

关键词： image reconstruction Microwave Imaging Near Field

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Markerless garment capture

Markerless garment capture

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ACM SIGGRAPH conference 2008

作者： Bradley, Derek Popa, Tiberiu Sheffer, Alla Heidrich, Wolfgang Boubekeur, Tamy Univ British Columbia Vancouver BC V5Z 1M9 Canada TU Berlin Berlin Germany

A lot of research has recently focused on the problem of capturing the geometry and motion of garments. Such work usually relies on special markers printed on the fabric to establish temporally coherent correspondences between points on the garment's surface at different times. Unfortunately, this approach is tedious and prevents the capture of off-the-shelf clothing made from interesting fabrics. In this paper, we describe a marker-free approach to capturing garment motion that avoids these downsides. We establish temporally coherent parameterizations between incomplete geometries that we extract at each timestep with a multiview stereo algorithm. We then fill holes in the geometry using a template. This approach, for the first time, allows us to capture the geometry and motion of unpatterned, off-the-shelf garments made from a range of different fabrics.

关键词： object scanning/acquisition cloth modeling image processing motion capture surface reconstruction

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DEPTH COMPUTATIONS USING data IN THE FORM OF INTENSITY OF PIXELS FOR ENHANCED COMPUTER vISION

DEPTH COMPUTATIONS USING DATA IN THE FORM OF INTENSITY OF PI...

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International conference on Computing, Communications and Networking

作者： Sandyaranil, N. vaithyanathan, v. Dr MGR Univ Dept MCA Madras Tamil Nadu India SASTRA Univ Dept CSE Tanjore Tamil Nadu India

ISBN: (纸本)9781424435944

Literature review on computer vision revealed that considerable work was carried out on making the computer to understand objects and their relative positioning using techniques such as shape from shading etc., No specific references were made on quantitative estimation of depth/depth reconstruction between two points in a given 2D image of a 3D environment. An attempt is made in this paper to address above issue by proposing a second order equation using numerical methods connecting the depth between two points in the given 2D image of a 3D environment and the corresponding difference in pixel intensity values between the same two points in the 2D image. The validity of the proposed equation is verified by comparing with existing methods. The major contribution of the present work is that the depth reconstructed using the proposed equation is in excellent agreement with the corresponding depth using existing methods.

关键词： Second order equation Depth reconstruction Attributes Object recognition 2D images

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image Restoration Using L₁-Norm Regularization and a Gradient-Based Neural Network with Discontinuous Activation Functions

Image Restoration Using <i>L</i><sub>1</sub>-Norm Regulariza...

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International Joint conference on Neural Networks

作者： Ferreira, Leonardo v. Kaszkurewicz, Eugenius Bhaya, Arnit Univ Fed Rio de Janeiro NACAD COPPE Dept Elect Engn Rio De Janeiro Brazil

ISBN: (纸本)9781424418206

The problem of restoring images degraded by linear position invariant distortions and noise is solved by means of a L-1-norm regularization, which is equivalent to determining a L-1-norm solution of an overdetermined system of linear equations, which results from a data-fitting term plus a regularization term that are both in L-1 norm. This system is solved by means of a gradient-based neural network with a discontinuous activation function, which is ensured to converge to a L-1-norm solution of the corresponding system of linear equations.

关键词： image reconstruction

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How much zoom is the right zoom from the perspective of Super-Resolution?

How much zoom is the right zoom from the perspective of Supe...

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6th Indian conference on Computer vision, Graphics and image Processing

作者： Arora, Himanshu Namboodiri, Anoop M. IIIT Ctr Visual Informat Technol Hyderabad 500032 Andhra Pradesh India

ISBN: (纸本)9781424442195

Constructing a high-resolution (HR) image from low-resolution (LR) image(s) has been a very active research topic recently with focus shifting from multi-frames to learning based single-frame super-resolution (SR). Multi-frame SR algorithms attempt the exact reconstruction of reality, but are limited to small magnification factors. Learning based SR algorithms learn the correspondences between. LR and HR patches. Accurate replacements or revealing the exact underlying information is not guaranteed in many scenarios. In this paper we propose an alternate solution. We propose to capture images at right zoom such that it has just sufficient amount of information so that further resolution enhancements can be easily achieved using an v off the shelf single-frame SR algorithm. This is true under the assumption that such a zoom factor is not very high, which is true for most man-made structures. The low-resolution. image is divided into small patches and ideal resolution is predicted for every patch. The contextual information is incorporated using a Markov Random Field based prior. Training data is generated from high-quality images and can use any single-frame SR algorithm. Several constraints are proposed to minimize the extent of zoom-in. We validate the proposed approach on synthetic data and real world images to show the robustness.

关键词： image enhancement

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DESCRIPTIvE EXPERIMENT DESIGN UNIFIED WITH WORST-CASE PERFORMANCE OPTIMIZATION-ADAPTED REGULARIZATION FOR HIGH-RESOLUTION RADAR/SAR IMAGING

DESCRIPTIVE EXPERIMENT DESIGN UNIFIED WITH WORST-CASE PERFOR...

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2008 IEEE Radar conference

作者： Shkvarko, Yuriy v. CINVESTAV IPN Guadalajara 45010 Jal Mexico

ISBN: (纸本)9781424415380

This paper considers the problem of high-resolution imaging of the environment formalized in terms Of a nonlinear ill-posed inverse problem of nonparametric estimation of the power spatial spectrum pattern (SSP) of the wavefield scattered from an extended remotely sensed scene (referred to as the scene image) via processing the discrete measurements of a finite number of independent realizations of the observed degraded radar data signals (one realization of the trajectory signal in the case of SAR). The model-level uncertainties are associated with unknown statistics of perturbations of the signal formation operator (SFO) in turbulent environment. The system-level uncertainties are attributed to the imperfect array calibration, finite dimensionality of measurements, uncontrolled antenna vibrations and random carrier trajectory deviations in the case of SAR. An effective method for SSP reconstruction is therefore proposed by incorporating into the minimum risk (AM) nonparametric spectral estimation strategy the experiment design-motivated constraints of SSP observability/identifiability for the finite-dimensional range continuous-to-discrete SFO algorithmically coupled with descriptive experiment design regularization (DEDR) and unified with worst-case statistical performance optimization approach. The MR objective functional is constrained by this information, and the robust DEDR reconstruction operator applicable to the scenarios with the low-rank uncertain estimated data correlation matrices is found We also show how this algorithm may be considered generalization of the robust MvDR and the regularized inverse spatial filtering techniques. The efficiency of the developed technique is illustrated via numerical simulations.

关键词： Descriptive experiment design regularization

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