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6th European conference on Antennas and Propagation, EuCAP 2012

作者： Mikhnev, v. vainikainen, P. Department of Radio Science and Engineering School of Science and Technology Aalto University Espoo Finland

ISBN: (纸本)9781457709180

Results of further development of a new two-parameter microwave imaging method for both detection and discrimination of subsurface targets are presented. The method is based on the derivation of two B-scans from the initial B-scan data, separately for amplitude and phase. Then, these two B-scans are combined in a common image using a rule that the amplitude data governs intensity of the pixels whereas phase data determines their colors. In this work, a modified technique of building the B-scan in phase is presented. The modified technique accounts better for the frequency dependence of the wave reflected from buried object that may be caused by dispersion of surrounding medium or variation of directivity of the antenna system versus frequency. Advantages of the modified method are demonstrated in experimental examples. © 2012 IEEE.

关键词： Radar target recognition

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Light field optical flow for refractive surface reconstruction

Light field optical flow for refractive surface reconstructi...

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conference on Applications of Digital image Processing XXXv

作者： Iffa, Emishaw Wetzstien, Gordon Heidrich, Wolfgang Univ British Columbia Dept Comp Sci Vancouver BC V6T 1W5 Canada MIT Media Lab Cambridge MA 02139 USA

ISBN: (纸本)9780819492166

This paper discusses a method to reconstruct a transparent flow surface from single camera shot with the aid of a Micro-lens array. An intentionally prepared high frequency background which is placed behind the refractive flow is captured and a curl-free optical flow algorithm is applied between pairs of images taken by different micro-lenses. The computed raw optical flow vector is a blend of motion parallax and background deformation vector due to the underlying flow. Subtracting the motion parallax, which is obtained by calibration, from the total op- optical flow vector yields the background deformation vector. The deflection vectors on each images are used to reconstruct the flow profile. A synthetic data set of fuel injection was used to evaluate the accuracy of the proposed algorithm and good agreement was achieved between the test and reconstructed data. Finally, real light field data of hot air created by a lighter flame is used to reconstruct and show a hot air plume surface.

关键词： Div-Curl algorithm light field optical flow parallax refractive surface transparent flow

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Preliminary investigations of three-dimensional microwave tomography using different data sets

Preliminary investigations of three-dimensional microwave to...

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6th European conference on Antennas and Propagation, EuCAP 2012

作者： Lui, Hoi-Shun Fhager, Andreas Persson, Mikael Department of Signals and Systems Chalmers University of Technology Gothenburg Sweden

ISBN: (纸本)9781457709180

Owing to the extensive amount of computing resources required for solving the non-linear microwave inverse scattering problems, previous numerical studies have mainly been focus on two-dimensional inverse scattering problemw. In three-dimensional cases, the vectorial nature of electromagnetic waves has to be properly handled. In this paper, preliminary investigations of using vertical and horizontal components of the scattered near-field are considered. The forward data is first evaluated quantitatively and image reconstruction using the two different sets of data from the same scattering problem is performed. © 2012 IEEE.

关键词： Tomography

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Limited Angle reconstruction Utilizing Improved Particle Swarm Optimization

Limited Angle Reconstruction Utilizing Improved Particle Swa...

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International conference on Biomedical Engineering and Biotechnology (iCBEB)

作者： Chenlin Du Junhai Wen Donghao Shi Rui Yang Department of Biomedical Engineering School of Life Science Beijing Institute of Technology Beijing China

Computed tomography technology has wide applications in industrial non-destructive tests, medical fields, and public security. In practice, incomplete projection is often acquired because of limitations on the detection environment, time and cost. Iterative reconstruction algorithm has a major potential to achieve superior results on the reconstruction with incomplete projection data. In this paper, we presented an iterative approach utilizing improved Particle Swarm Optimization, which can efficiently reconstruct the image from incomplete projection data by solving global optimization problem. Simulation results showed that the proposed algorithm has better convergence speed and reconstruction quality.

关键词： image reconstruction Particle swarm optimization Computed tomography Optimization Convergence Iterative methods Algorithm design and analysis

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Transcranial photoacoustic tomography of the monkey brain

Transcranial photoacoustic tomography of the monkey brain

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conference on Photons Plus Ultrasound - Imaging and Sensing/Photonics West BiOS Symposium

作者： Nie, Liming Huang, Chao Guo, Zijian Anastasio, Mark Wang, Lihong v. Washington Univ Dept Biomed Engn St Louis MO 63130 USA

ISBN: (纸本)9780819488664

A photoacoustic tomography (PAT) system using a virtual point ultrasonic transducer was developed for transcranial imaging of monkey brains. The virtual point transducer provided a 10 times greater field-of-view (FOv) than finite-aperture unfocused transducers, which enables large primate imaging. The cerebral cortex of a monkey brain was accurately mapped transcranially, through up to two skulls ranging from 4 to 8 mm in thickness. The mass density and speed of sound distributions of the skull were estimated from adjunct X-ray CT image data and utilized with a time-reversal algorithm to mitigate artifacts in the reconstructed image due to acoustic aberration. The oxygenation saturation (sO(2)) in blood phantoms through a monkey skull was also imaged and quantified, with results consistent with measurements by a gas analyzer. The oxygenation saturation (sO(2)) in blood phantoms through a monkey skull was also imaged and quantified, with results consistent with measurements by a gas analyzer. Our experimental results demonstrate that PAT can overcome the optical and ultrasound attenuation of a relatively thick skull, and the imaging aberration caused by skull can be corrected to a great extent.

关键词： Transcranial photoacoustic tomography time-reversal image reconstruction

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Fitting Plane Algorithm-based Depth Correction for Tyzx DeepSea Stereoscopic Imaging

Fitting Plane Algorithm-based Depth Correction for Tyzx Deep...

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4th International conference on Communications and Electronics (ICCE)

作者： Nguyen, D. -v. Jiang, Tao Kuhnert, Lars Kuhnert, K. -D. Univ Siegen Res Sch Moses D-57068 Siegen Germany Univ Siegen Inst Real Time Learning Syst D-57068 Siegen Germany

ISBN: (纸本)9781467324939;9781467324922

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： Stereo vision Fitting Plane Depth image Enhancement 3-D reconstruction

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reconstruction of Dose Distribution in In-beam PET for Carbon Therapy

Reconstruction of Dose Distribution in In-beam PET for Carbo...

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IEEE Nuclear Science Symposium / Medical Imaging conference Record (NSS/MIC) / 19th Room-Temperature Semiconductor X-ray and Gamma-ray Detector Workshop

作者： Kim, Kwangdon Bae, Seungbin Lee, Kisung Chung, Yonghyun An, Sujung Joung, Jinhun Korea Univ Dept Radiol Sci Seoul 136793 South Korea Yonsei Univ Dept Radiol Sci Wonju 220-710 South Korea Nucare Med Syst Inc Seoul 136693 South Korea

ISBN: (纸本)9781467320306;9781467320283

There are two main artifacts in reconstructed images from in-beam positron emission tomography(PET). Unlike generic PET, in-beam PET uses the annihilation photons which occur during heavy ion therapy. Therefore, the geometry of in-beam PET is not a full ring, but a partial ring in order for the hardrons to arrive the tumor without penetration of detector blocks. The partial ring, however, causes truncation in projection data, due to an absence of detector modules in the openings. The other is ring artifact caused by the gaps between detector modules which can be also founded in generic PET. In this study, we aim to investigate the effect of gaps in reconstructed images and propose possible solutions to compensate the artifacts. We acquired the data by GATE v6.1 with initial ion energies 170,290, 350AMev of carbon beams. Each detector module consists of a 13 by 13 LYSO crystal array. The dimension of a crystal was 4mm * 4mm * 20 mm and the radius of inner circle of the gantry was 15cm. In case of truncation error, we proposed to get prior knowledge of the location where annihilations occur. Similar to time-of-flight PET reconstruction, we applied a Gaussian distribution to system matrix, through the width of hardron beams in our back-projection routine. Then expectation maximization(EM) updates were performed iteratively. In case of the latter, to fill the gaps, we used the iterative discrete-cosine transform(DCT) domain method proposed by Uygar Tuna, Sari Peltonen, and Ulla Ruotsalainen. The results show that the proposed method can compensate to some extent the error caused by insufficient angle coverage and we can see the path of hardron beam by proposed method. However, we found other artifacts induced beyond the Bragg peak positions the number of iterations increased. We will improve the proposed algorithm to get more accurate dose distribution.

关键词： Gaussian distribution carbon discrete cosine transforms dosimetry expectation-maximisation algorithm image reconstruction ion beam applications medical image processing positron emission tomography radiation therapy tumours

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Context-aware single image rain removal

Context-aware single image rain removal

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2012 13th IEEE International conference on Multimedia and Expo, ICME 2012

作者： Huang, De-An Kang, Li-Wei Yang, Min-Chun Lin, Chia-Wen Wang, Yu-Chiang Frank Research Center for Information Technology Innovation Academia Sinica Taipei Taiwan Department of Electrical Engineering National Taiwan University Taipei Taiwan Institute of Information Science Academia Sinica Taipei Taiwan Department of Computer Science and Information Engineering National Taiwan University Taipei Taiwan Department of Electrical Engineering National Tsing Hua University Hsinchu Taiwan

ISBN: (纸本)9781467316590

Rain removal from a single image is one of the challenging image denoising problems. In this paper, we present a learning-based framework for single image rain removal, which focuses on the learning of context information from an input image, and thus the rain patterns present in it can be automatically identified and removed. We approach the single image rain removal problem as the integration of image decomposition and self-learning processes. More precisely, our method first performs context-constrained image segmentation on the input image, and we learn dictionaries for the high-frequency components in different context categories via sparse coding for reconstruction purposes. For image regions with rain streaks, dictionaries of distinct context categories will share common atoms which correspond to the rain patterns. By utilizing PCA and SvM classifiers on the learned dictionaries, our framework aims at automatically identifying the common rain patterns present in them, and thus we can remove rain streaks as particular high-frequency components from the input image. Different from prior works on rain removal from images/videos which require image priors or training image data from multiple frames, our proposed self-learning approach only requires the input image itself, which would save much pre-training effort. Experimental results demonstrate the subjective and objective visual quality improvement with our proposed method. © 2012 IEEE.

关键词： Rain

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3D near-infrared imaging based on a single-photon avalanche diode array sensor

3D near-infrared imaging based on a single-photon avalanche ...

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conference on Biosensing and Nanomedicine v

作者： Pavia, Juan Mata Wolf, Martin Charbon, Edoardo Univ Spital Zurich Klin Neonatol Frauenklin Str 10 CH-8091 Zurich Switzerland Quantum Architecture Grp AQUA EPFL CH-1015 Lausanne Switzerland

ISBN: (纸本)9780819491770

Near-infrared light can be used to determine the optical properties (absorption and scattering) of human tissue. Optical tomography uses this principle to image the internal structure of parts of the body by measuring the light that is scattered in the tissue. An imager for optical tomography was designed based on a detector with 128x128 single photon pixels that included a bank of 32 time-to-digital converters. Due to the high spatial resolution and the possibility of performing time resolved measurements, a new contactless setup has been conceived. The setup has a resolution of 97ps and operates with a laser source with an average power of 3mW. This new setup generated an high amount of data that could not be processed by established methods, therefore new concepts and algorithms were developed to take advantage of it. Simulations show that the potential resolution of the new setup would be much higher than previous designs. Measurements have been performed showing its potential. images derived from the measurements showed that it is possible to reach a resolution of at least 5mm.

关键词： Near-infrared spectroscopy (NIRS) Near-infrared imaging NIRI Time-resolved imaging image reconstruction techniques Diffuse optical tomography Inverse problems CMOS SPAD Time-of-flight camera Single-photon detector

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Recovering structure from many low-information 2-D images of randomly-oriented samples

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Journal of Physics: conference Series 2013年第19期425卷

作者： H T Philipp K Ayyer M W Tate v Elser S M Gruner Laboratory of Atomic and Solid State Physics Cornell University Ithaca NY 14853 USA Cornell High Energy Synchrotron Source Cornell University Ithaca NY 14853 USA Laboratory for Elementary Particle Physics Cornell University Ithaca NY 14853 USA

New sources and detectors are allowing scientists to look at matter with finer spatial and temporal resolutions. These experiments can produce data that are a series of severely Poisson limited snap-shots of randomly oriented samples. An extreme case of this is destructive imaging of single particles with an x-ray free-electron laser – many frames are needed for a reconstruction, but there is no a priori information associated with the frames about particle orientation. We use Cornell's Pixel Array Detectors (PADs) to examine the practical limits of an expectation maximization (EM) algorithm designed to deal with extremely low-fluence data, having just a few photons per frame. We demonstrate image reconstruction of a high-contrast sample using hundreds of thousands of randomly oriented frames with an average x-ray photon occupancy as low as 2.5 photons per frame. Practical aspects of reducing low-fluence data, such as thresholding and noise limits, will be discussed for high- and low-contrast samples; and data collected in the presence of significant background signal.

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