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Spatially adaptive image denoising using inter-scale dependence in directionlet domain

IET image processing 2015年第2期9卷 142-152页

作者： Sethunadh, R. Thomas, Tessamma Indian Space Res Org ISRO Vikram Sarabhai Space Ctr Trivandrum Kerala India Cochin Univ Sci & Technol CUSAT Image & Video Proc Lab Cochin Kerala India

The performance of image processing algorithms can be significantly improved by the application of multi-resolution image representation with directional features. Directionlet transform (DT) is one such representation which has gained popularity over the past few years as an anisotropic, perfect reconstruction and critically sampled basis function with directional vanishing moments along any two directions. In this study, the authors propose a spatially adaptive image denoising scheme for Gaussian noise based on DT by considering the dependences of the directionlet coefficients across different scales. The image is first decomposed using DT and the coefficients so obtained are modelled using a bivariate heavy tailed pdf' with a local variance parameter to account for inter- and intra-scale dependencies of the coefficients. The DT is made adaptive to the local dominant directions in the image by identifying the dominant directions in the spatially segmented image through the computation of a parameter called directional variance'. Bayesian maximum a posteriori' estimator is then used to compute the noise free coefficients from the bivariate models of the signal and noise. The denoised image is obtained from the transform coefficients, which were modified using the bivariate shrinkage function, using directional information and inverse DT. Experimental results show that the bivariate shrinkage in directionlet domain achieves better performance than that in wavelet domain, in terms of numerical and perceptual quality.

关键词： image denoising image resolution image representation Gaussian noise image segmentation transforms spatially adaptive image denoising interscale dependence directionlet domain image processing algorithms multiresolution image representation directional features DT sampled basis function directional vanishing moments Gaussian noise directionlet coefficients image segmentation directional variance noise free coefficients bivariate models transform coefficients bivariate shrinkage function

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Recent advances in holographic 3D particle tracking

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ADVANCES IN OPTICS AND PHOTONICS 2015年第4期7卷 713-755页

作者： Memmolo, Pasquale Miccio, Lisa Paturzo, Melania Di Caprio, Giuseppe Coppola, Giuseppe Netti, Paolo A. Ferraro, Pietro CNR ISASI Inst Appl Sci & Intelligent Syst E Caia I-80078 Pozzuoli NA Italy Ist Italiano Tecnol Ctr Adv Biomat HealthCare CRIB I-80125 Naples Italy CNR Inst Microelect & Microsyst Unit Naples I-80121 Naples Italy

Particle tracking is a fundamental technique for investigating a variety of biophysical processes, from intracellular dynamics to the characterization of cell motility and migration. However, observing three-dimensional (3D) trajectories of particles is in general a challenging task in classical microscopy owing to the limited imaging depth of field of commercial optical microscopes, which represents a serious drawback for the analysis of time-lapse microscopy image data. Therefore, numerous automated particle-tracking approaches have been developed by many research groups around the world. Recently, digital holography (DH) in microscopy has rapidly gained credit as one of the elective techniques for these applications, mainly due to the uniqueness of the DH to provide a posteriori quantitative multiple refocusing capability and phase-contrast imaging. Starting from this paradigm, a huge amount of 3D holographic tracking approaches have been conceived and investigated for applications in various branches of science, including optofluids, microfluidics, biomedical microscopy, cell mechano-trasduction, and cell migration. Since a wider community of readers could be interested in such a review, i.e., not only scientists working in the fields of optics and photonics but also users of particle-tracking tools, it should be very beneficial to provide a complete review of state-of-the-art holographic 3D particle-tracking methods and their applications in bio-microfluidics. (C) 2015 Optical Society of America

关键词： Diffractive optical elements Digital holographic imaging image processing algorithms Imaging techniques Laser velocimetry Spatial light modulators

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Polarization sensitive optical frequency domain imaging system for endobronchial imaging

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OPTICS EXPRESS 2015年第3期23卷 3390-3402页

作者： Li, Jianan Feroldi, Fabio de Lange, Joop Daniels, Johannes M. A. Grunberg, Katrien de Boer, Johannes F. Vrije Univ Amsterdam Dept Phys & Astron Inst Lasers Life & Biophoton Amsterdam NL-1081 HV Amsterdam Netherlands Vrije Univ Amsterdam Med Ctr Dept Pulm Dis NL-1081 HV Amsterdam Netherlands Vrije Univ Amsterdam Med Ctr Dept Pathol NL-1081 HV Amsterdam Netherlands

A polarization sensitive endoscopic optical frequency domain imaging (PS-OFDI) system with a motorized distal scanning catheter is demonstrated. It employs a passive polarization delay unit to multiplex two orthogonal probing polarization states in depth, and a polarization diverse detection unit to detect interference signal in two orthogonal polarization channels. Per depth location four electro-magnetic field components are measured that can be represented in a complex 2x2 field matrix. A Jones matrix of the sample is derived and the sample birefringence is extracted by eigenvalue decomposition. The condition of balanced detection and the polarization mode dispersion are quantified. A complex field averaging method based on the alignment of randomly pointing field phasors is developed to reduce speckle noise. The variation of the polarization states incident on the tissue due to the circular scanning and catheter sheath birefringence is investigated. With this system we demonstrated imaging of ex vivo chicken muscle, in vivo pig lung and ex vivo human lung specimens. (C)2015 Optical Society of America

关键词： image processing image processing algorithms Optical imaging Phase measurement Polarization Speckle noise

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Depth-based defocus map estimation using off-axis apertures

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OPTICS EXPRESS 2015年第17期23卷 21958-21971页

作者： Lee, Eunsung Chae, Eunjung Cheong, Hejin Jeon, Semi Paik, Joonki Chung Ang Univ Grad Sch Adv Imaging Sci Multimedia & Film Image Proc & Intelligent Syst Lab Seoul 156756 South Korea

This paper presents a depth-based defocus map estimation method from a single camera with multiple off-axis apertures. The proposed estimation algorithm consists of two steps: (i) object distance estimation using off-axis apertures and (ii) defocus map estimation based on the object distance. The proposed method can accurately estimate the defocus map using object distances that are well-characterized in a color shift model-based computational camera. Experimental results show that the proposed method outperforms the state-of-the-art defocus estimation methods in the sense of both accuracy and the estimation range. The proposed defocus map estimation method is suitable for multifocusing, refocusing, and extended depth of field (EDoF) systems. (C) 2015 Optical Society of America

关键词： Extended depth of field image enhancement image processing image processing algorithms image registration Imaging systems

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Fourier interpolation stochastic optical fluctuation imaging

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OPTICS EXPRESS 2015年第12期23卷 16154-16163页

作者： Stein, Simon C. Huss, Anja Haehnel, Dirk Gregor, Ingo Enderlein, Joerg Univ Gottingen Inst Phys 3 D-37077 Gottingen Germany BCCN Gottingen Germany DFG Res Ctr Nanoscale Microscopy & Mol Physiol Br Gottingen Germany

Stochastic Optical Fluctuation Imaging (SOFI) is a super-resolution fluorescence microscopy technique which allows to enhance the spatial resolution of an image by evaluating the temporal fluctuations of blinking fluorescent emitters. SOFI is not based on the identification and localization of single molecules such as in the widely used Photoactivation Localization Microsopy (PALM) or Stochastic Optical Reconstruction Microscopy (STORM), but computes a superresolved image via temporal cumulants from a recorded movie. A technical challenge hereby is that, when directly applying the SOFI algorithm to a movie of raw images, the pixel size of the final SOFI image is the same as that of the original images, which becomes problematic when the final SOFI resolution is much smaller than this value. In the past, sophisticated cross-correlation schemes have been used for tackling this problem. Here, we present an alternative, exact, straightforward, and simple solution using an interpolation scheme based on Fourier transforms. We exemplify the method on simulated and experimental data. (C) 2015 Optical Society of America

关键词： Fast Fourier transforms Fourier transforms image processing algorithms image quality Spatial resolution Three dimensional imaging

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image alignment of historical and current Cebu maps to determine river path changes and flooding pattern 8

Image alignment of historical and current Cebu maps to deter...

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2015 International Conference on Humanoid, Nanotechnology, Information Technology,Communication and Control, Environment and Management (HNICEM)

作者： Gallanosa, Phoebe B. Soriano, Maricor N. Univ Philippines Natl lnst Phys Quezon City Philippines

ISBN: (纸本)9781509003600

Two historical maps of Cebu City dated 1833 and 1873 were digitized and piecewise linearly transformed to align street maps with current Google Maps of the city. The calculated RMS errors of the transformed maps are established to be comparable with other studies. Disappearance of water basins and river path changes were observed in the current map. Overlaying a flood hazard map on the transformed historical maps reveals a correlation between sites of reclamation and river path changes with current flood prone areas. Old maps can inform land use planners about ancient water ways that can become flooding hazards if improperly managed.

关键词： image processing algorithms historical maps image transformation flooding hazards

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A New Shear Wave Imaging System for Ultrasound Elastography 37

A New Shear Wave Imaging System for Ultrasound Elastography

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37th Annual International Conference of the IEEE-Engineering-in-Medicine-and-Biology-Society (EMBC)

作者： Qiu, Weibao Wang, Congzhi Xiao, Yang Qian, Ming Zheng, Hairong Chinese Acad Sci Shenzhen Inst Adv Technol Paul C Lauterbur Res Ctr Biomed Imaging Shenzhen 518055 Peoples R China

ISBN: (纸本)9781424492701

Ultrasound elastography is able to provide a non-invasive measurement of tissue elasticity properties. Shear wave imaging (SWI) technique is a quantitative method for tissue stiffness assessment. However, traditional SWI implementations cannot acquire 2D quantitative images of tissue elasticity distribution. In this study, a new shear wave imaging system is proposed and evaluated. Detailed delineation of hardware and image processing algorithms are presented. Programmable devices are selected to support flexible control of the system and the image processing algorithms. Analytic signal based cross-correlation method and a Radon transform based shear wave speed determination method are proposed with parallel computation ability. Tissue mimicking phantom imaging, and in vitro imaging measurements are conducted to demonstrate the performance of the proposed system. The system has the ability to provide a new choice for quantitative mapping of the tissue elasticity, and has good potential to be implemented into commercial ultrasound scanner.

关键词： SWI Ultrasound Elastography image processing algorithms image processing algorithm SMARCA1 gene SEISMIC S WAVES ultrasound scanner Elasticity Imaging Techniques Imaging systems control systems correlation methods

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Automated Analysis of Line Plots in Documents 13

Automated Analysis of Line Plots in Documents

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13th IAPR International Conference on Document Analysis and Recognition (ICDAR)

作者： Nair, Rathin Radhakrishnan Sankaran, Nishant Nwogu, Ifeoma Govindaraju, Venu SUNY Buffalo Dept Comp Sci & Engn Buffalo NY 14260 USA

ISBN: (纸本)9781479918058

Information graphics, such as graphs and plots, are used in technical documents to convey information to humans and to facilitate greater understanding. Usually, graphics are a key component in a technical document, as they enable the author to convey complex ideas in a simplified visual format. However, in an automatic text recognition system, which are typically used to digitize documents, the ideas conveyed in a graphical format are lost. We contend that the message or extracted information can be used to help better understand the ideas conveyed in the document. In scientific papers, line plots are the most commonly used graphic to represent experimental results in the form of correlation present between values represented on the axes. The contribution of our work is in the series of image processing algorithms that are used to automatically extract relevant information, including text and plot from graphics found in technical documents. We validate the approach by performing the experiments on a dataset of line plots obtained from scientific documents from computer science conference papers and evaluate the variation of a reconstructed curve from the original curve. Our algorithm achieves a classification accuracy of 91 % across the dataset and successfully extracts the axes from 92 % of line plots. Axes label extraction and line curve tracing are performed successfully in about half the line plots as well.

关键词： document image processing feature extraction image classification information retrieval automatic information extraction axes label extraction classification accuracy document based information retrieval image processing algorithms line curve tracing line plots Accuracy image color analysis Three-dimensional displays image processing algorithm three-dimensional displays document image processing image colour analysis image classification Line graph information retrieval Feature extraction graphic images automatic analysis Information Extraction axe Axis, Cervical Vertebra Dataset

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In situ image processing capabilities of ARM-based micro-controllers

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JOURNAL OF REAL-TIME image processing 2014年第1期9卷 111-125页

作者： Taysi, Z. Cihan Yavuz, A. Gokhan Guvensan, M. Amac Karsligil, M. Elif Yildiz Tech Univ ISL Istanbul Turkey Yildiz Tech Univ Dept Comp Engn Istanbul Turkey

Dealing with visual data is the key for environmental monitoring tasks in Wireless Multimedia Sensor Networks (WMSNs). Tasks such as object detection, recognition, and/or tracking do require extracting and using the right information from the inherently large amount of visual data. The widely accepted solution of legacy WSNs, transmitting the acquired data to a central base station for further processing, would render a WMSN totally useless because of the unacceptable use of bandwidth and energy. Therefore, we consider the in situ processing as a viable solution for WMSNs. However, processing power and memory capacity restrictions of existing multimedia sensor nodes along with their power consumption are the limiting factors for wide-spread use of in situ processing. Nevertheless, recent technological improvements and introduction of the new ARM cores encourage us to evaluate the image processing capabilities of ARM7/ARM9/ARM11 based micro-controllers for in situ processing in WMSNs. In this work, we first discussed the architectural design differences among the various ARM cores. Then we classified image processing algorithms into three categories. Then, we evaluated the performance of each microcontroller by running a set of basic image processing algorithms necessary for object detection, recognition, and/or tracking. The test results show that ARM11 runs up to 6-30 times faster than ARM9 and ARM7, respectively. Besides, ARM11 consumes up to 5-7 times less energy than ARM9 and ARM7 for the same type of operations.

关键词： ARM-based micro-controllers Architectural enhancement image processing algorithms CPU time Energy consumption

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Real-time image edge enhancement with a spiral phase filter and graphic processing unit

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APPLIED OPTICS 2014年第19期53卷 4297-4300页

作者： Zhong, Zhi Gao, Pengjun Shan, Mingguang Wang, Ying Zhang, Yabin Harbin Engn Univ Coll Informat & Commun Engn Harbin 150001 Heilongjiang Peoples R China

Isotropic image edge enhancement with high contrast can be achieved using a spiral phase filter (SPF) in a 4f optical system. However, real-time application of edge enhancement with SPF has generally been limited due to the requirement of coherent light or complex phase-shifting operation. In this paper, we demonstrate a real-time image edge enhancement method using a SPF and a graphic processing unit (GPU). By implementing the process of virtual spiral phase filtering on GPU, we are able to speed up the whole procedure by more than 8.3x with respect to CPU processing, and ultimately achieve video rate for megapixel images. In particular, our implementation can achieve higher speedup for more multiple images. These developments are increasing the potential for image edge enhancement of moving objects. (C) 2014 Optical Society of America

关键词： image processing image processing algorithms image sharpening Spatial light modulators Spiral phase Wavelets

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