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Conference on applications of Digital image processing xxx

作者： Zlokolica, Vladimir Jovanov, Ljubomir Pizurica, Aleksandra De Keyser, Paul Dhaenens, Frans Philips, Wilfried Univ Ghent Dept Telecommun & Informat Proc TELIN IPI Sint Pietersnieuwstr 41 B-9000 Ghent Belgium Agfa Gevaert NV B-2640 Mortsel Belgium

ISBN: (纸本)9780819468444

Optical coherence tomography produces high resolution medical images based on spatial and temporal coherence of the optical waves backscattered from the scanned tissue. However, the same coherence introduces speckle noise as well;this degrades the quality of acquired images. In this paper we propose a technique for noise reduction of 3D OCT images, where the 3D volume is considered as a sequence of 2D images, i.e., 2D slices in depth-lateral projection plane. In the proposed method we first perform recursive temporal filtering through the estimated motion trajectory between the 2D slices using noise-robust motion estimation/compensation scheme previously proposed for video denoising. The temporal filtering scheme reduces the noise level and adapts the motion compensation on it. Subsequently, we apply a spatial filter for speckle reduction in order to remove the remainder of noise in the 2D slices. In this scheme the spatial (2D) speckle-nature of noise in OCT is modeled and used for spatially adaptive denoising. Both the temporal and the spatial filter are wavelet-based techniques, where for the temporal filter two resolution scales are used and for the spatial one four resolution scales. The evaluation of the proposed denoising approach is done on demodulated 3D OCT images on different sources and of different resolution. For optimizing the parameters for best denoising performance fantom OCT images were used. The denoising performance of the proposed method was measured in terms of SNR, edge sharpness preservation and contrast-to-noise ratio. A comparison was made to the state-of-the-art methods for noise reduction in 2D OCT images, where the proposed approach showed to be advantageous in terms of both objective and subjective quality measures.

关键词： 3D OCT wavelets denoising

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Inspection of defects in fabrics using Gabor wavelets and principle component analysis

Inspection of defects in fabrics using Gabor wavelets and pr...

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International Symposium on signal processing and Its applications (ISSPA)

作者： Alper Basturk Halil Ketencioglu Zeki Yugnak M. Emin Yuksel Department of Computer Engineering Erciyes University Kayseri Turkey Department of Electrical and Electronics Engineering Erciyes University Kayseri Turkey

ISBN: (纸本)9781424407781;1424407796

In this paper, a new method for inspection of textile defects in fabrics is presented. The method is based upon the extraction of fabric features by Gabor wavelets. The Gabor wavelets transform provides an effective way to analyze images and extract features of textures. Principal component analysis using singular value decomposition is used to reduce the dimension of feature vectors. Performance of the method has been tested with defective fabric images taken from TILDA textile texture database. Experiments show that these defects are detected accurately.

关键词： Inspection Fabrics Wavelet analysis Textiles Feature extraction Wavelet transforms image analysis image texture analysis Principal component analysis Singular value decomposition

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Stéphane Mallat: A Wavelet Tour of signal processing, 2nd Edition

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Computer Music Journal 2007年第3期31卷 83-85页

作者： Bob L. Sturm

A Wavelet Tour of signal processing(AWT) is a complete guide to not only the important results and applications of wavelets—also known as multiresolution analysis—but also many of their lesser-known aspects. It contains eleven well-written chapters, two appendixes, and 361 references. Each chapter, except for the first, contains several theorems—most accompanied by thorough proofs—and concludes with a set of problems for students and further exploration. Stéphane Mallat, having made seminal contributions to the theory behind and application of wavelets to signal processing, is certainly qualified to be an official tour guide to the world of *** history of multiresolution analysis is quite diverse, extending from contributions made by mathematicians, physicists, statisticians, and engineers. As such, it has found application in a broad range of disciplines, of which signal processing is only one. In fact, it is especially applicable to signal processing, whether working with sounds, images, or higher-dimensional data. Mr. Mallat makes this clear in his first chapter, where he motivates the utility of wavelets by discussing problems difficult to approach using Fourier methods, but easier using wavelets. He writes, "If we are interested in transient phenomena—a word pronounced at a particular time, an apple located in the left corner of an image—the Fourier transform becomes a cumbersome tool" (p. 2). wavelets provide an intuitive means of analyzing signals at various scales for, among other things, segmenting and representing these transient *** formal definition of the wavelet transform (WT) is no different from the Fourier transform, save for the fact that the signal is correlated with a basis created by scaling and translating a single zero-mean time-localized function. In contrast, the Fourier transform basis consists of a set of infinite duration sinusoids, and the short-time Fourier transform (STFT) uses a basis of windowed sinusoids at a fix

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Urban road network extraction from SAR image

Urban road network extraction from SAR image

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MIPPR 2007: Remote Sensing and GIS Data processing and applications;and Innovative Multispectral Technology and applications

作者： Cheng, Pengxue Hu, Maolin Lab. of Intelligent Computing and Signal Processing Anhui University Hefei Anhui 230039 China Key Laboratory of Wireless Sensor Network and Communication Institute of Microsystem and Information Technology Chinese Academy of Sciences Shanghai 200050 China

ISBN: (纸本)9780819469540

In this paper, a technique for the extraction of roads in a high resolution synthetic aperture radar (SAR) image is presented. And a three-step method is developed for the extraction of road network from space borne SAR image: the process of the feature points, road candidate detection and connection. Roads in a high resolution SAR image can be modeled as a homogeneous dark area bounded by two parallel boundaries. Dark areas, which represent the candidate positions for roads, are extracted from the image by a Gaussian probability iteration segmentation. Possible road candidates are further processed using the morphological operators. And the roads are accurately detected by Hough Transform, and the extraction of lines is achieved by searching the peak values in Hough Space. In this process, to detect roads more accurately, post-processing, including noisy dark regions removal and false roads removal is performed. At last, Road candidate connection is carried out hierarchically according to road established models. Finally, the main road network is established from the SAR image successfully. As an example, using the ERS-2SAR image data, automatic detection of main road network in Shanghai Pudong area is presented.

关键词： Feature extraction

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Adaptive filtering and feedforward control for suppression of vibration and jitter

Adaptive filtering and feedforward control for suppression o...

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Conference on Acquisition, Tracking, Pointing and Laser Systems Technologies xxI

作者： Anderson, Eric H. Blankinship, Ross L. Fowler, Ross Leslie P. Glaese, Roger M. Janzen, Paul C. CSA Engn Inc Mountain View CA 94043 USA CSA Engn Inc Albuquerque NM 87123 USA

ISBN: (纸本)9780819466914

This paper describes the use of adaptive filtering to control vibration and optical jitter. Adaptive filtering is a class of signal processing techniques developed over the last several decades and applied since to applications ranging from communications to image processing. Basic concepts in adaptive filtering and feedforward control are reviewed. A series of examples in vibration, motion and jitter control, including cryocoolers, ground-based active optics systems, flight motion simulators, wind turbines and airborne optical beam control systems, illustrates the effectiveness of the adaptive methods. These applications make use of information and signals that originate from system disturbances and minimize the correlations between disturbance information and error and performance measures. The examples incorporate a variety of disturbance types including periodic, multi-tonal, broadband stationary and non-stationary. Control effectiveness with slowly-varying narrowband disturbances originating from cryocoolers can be extraordinary, IN reaching 60 dB of reduction or rejection. In other cases, performance improvements are only 30-50%, but such reductions effectively complement feedback servo performance in many applications.

关键词： adaptive filtering signal processing vibration control jitter control beam control active optics cryocoolers stabilization

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An efficient approach technique for dynamical infrared/visible images fusion

An efficient approach technique for dynamical infrared/visib...

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2007 IEEE International Symposium on Intelligent signal processing, WISP

作者： Demuynck, Olivier Lázaro, José Luis Spain Spain

ISBN: (纸本)142440830X

In this paper, we present a novel approach for a real time dynamical Infrared/Visible images fusion. The advantage of the proposed system compared with previous studies are its huge flexibility and probably lowest cost, since that it only employ both an infrared and a conventional visible cameras. A lot of external applications like security, surveillance..., etc. need this kind of alternative to complete the visible information in some cases like a sudden illumination variation from a bright image to an almost dark situation, or a foggy or smoked environment, where usual computer vision algorithm are not robust anymore. In all those cases, the further image treatments depending on the application are not detailed in this paper, since we just focus this study on the way to make both images fitting in a resulting image and to render the image for a user to easily observe a warm area. warm area. We describe in the following paragraphs each step of this treatment, and show the results of this image fusion. ©2007 IEEE.

关键词： image fusion

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imagery-derived modulation transfer function and its applications for underwater imaging - art. no. 669622

Imagery-derived modulation transfer function and its applica...

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Conference on applications of Digital image processing xxx

作者： Hou, Weilin Weidemann, Alan D. Gray, Deric J. USN Res Lab Stennis Space Ctr MS 39529 USA

ISBN: (纸本)9780819468444

The main challenge working with underwater imagery results from both rapid decay of signals due to absorption, which leads to poor signal to noise returns, and the blurring caused by strong scattering by the water itself and constituents within, especially particulates. The modulation transfer function (MTF) of an optical system gives the detailed and precise information regarding the system behavior. Underwater imageries can be better restored with the knowledge of the system MTF or the point spread function (PSF), the Fourier transformed equivalent, extending the performance range as well as the information retrieval from underwater electro-optical system. This is critical in many civilian and military applications, including target and especially mine detection, search and rescue, and diver visibility. This effort utilizes test imageries obtained by the Laser Underwater Camera Imaging Enhancer (LUCIE) from Defense Research and Development Canada (DRDC), during an April-May 2006 trial experiment in Panama City, Florida. Imaging of a standard resolution chart with various spatial frequencies were taken underwater in a controlled optical environment, at varying distances. In-water optical properties during the experiment were measured, which included the absorption and attenuation coefficients, particle size distribution, and volume scattering function. Resulting images were preprocessed to enhance signal to noise ratio by averaging multiple frames, and to remove uneven illumination at target plane. The MTF of the medium was then derived from measurement of above imageries, subtracting the effect of the camera system. PSFs converted from the measured MTF were then used to restore the blurred imageries by different deconvolution methods. The effects of polarization from source to receiver on resulting MTFs were examined and we demonstrate that matching polarizations do enhance system transfer functions. This approach also shows promise in deriving medium optical prop

关键词： image restoration ocean optics polarization MCM MTF

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Pupil shape description using Fourier series

Pupil shape description using Fourier series

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IEEE Workshop on signal processing applications for Public Security and Forensics

作者： Rakshit, Soumyadip Monro, Donald M. Univ Bath Dept Elect & Elect Engn Claverton Down Bath BA2 7AY Avon England

ISBN: (纸本)9781424412259

In this work, improved performance is obtained in human iris matching systems using a Fourier-based description to approximate non-circular pupil boundaries in human eyes. The study also leads an analysis of pupil shape. Excellent fitting is obtained for non-ideal cases such as oblong, irregular, off-centre and dilated pupils, and improved iris normalization is obtained compared to best fit circles. The method is applied to 1912 eye images of 478 eyes from the Bath database and the effect of increasing the number of Fourier coefficients on the pupil outline accuracy is studied. The RMS pixel error between the outline and actual edge points is seen to decrease from 1.48 (for circles) to 0.34 (for 9 coefficients). Only 21 cases are found to produce low deviations from a circular boundary, indicating that a majority of pupils (98.9%) are non-circular. The Equal Error Rate (EER) in verification using the new method is estimated to be significantly reduced, at 7.5x10(-5) compared to 1.2x10(-4) for pupils fitted as circular.

关键词： biometrics iris image segmentation

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An orthogonal subspace projection-based for estimation of virtual dimensionality for hyperspectral data exploitation

An orthogonal subspace projection-based for estimation of vi...

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Conference on Algorithms and Technologies for Multispectral, Hyperspectral, and Ultraspectral imagery xIII

作者： Liu, Weimin Wu, Chao-Cheng Chang, Chein-, I Univ Maryland Baltimore Cty Dept Comp Sci & Elect Engn Remote Sensing Signal & Image Proc Lab Baltimore MD 21250 USA

ISBN: (纸本)9780819466877

A recently introduced concept, virtual dimensionality (VD) has been shown promise in many applications of hyperspectral data exploitation. It was originally developed for estimating number of spectrally distinct signal sources. This paper explores utility of the VD from various signal processing perspectives and further investigates four techniques, Gershgorin radius (GR), orthogonal projection subspace (OSP), signal subspace estimation (SSE), Neyman-Pearson detection (NPD), to be used to estimate the VD. In particular, the OSP-based VD estimation technique is new and has several advantages over other methods. In order to evaluate their performance, a comparative study and analysis is conducted via synthetic and real image experiments.

关键词： Gershgorin radius (GR) Neyman-Pearson detection (NPD) orthogonal projection subspace (OSP) signal subspace estimation (SSE) virtual dimensionality (VD).

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Steerable Filters Generated with the Hypercomplex Dual-Tree Wavelet Transform

Steerable Filters Generated with the Hypercomplex Dual-Tree ...

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IEEE International Conference on signal processing and Communications, ICSPC

作者： J. Wedekind B. Amavasai K. Dutton MMVL Materials and Engineering Research Institute Sheffield Hallam University UK

The use of wavelets in the image processing domain is still in its infancy, and largely associated with image compression. With the advent of the dual-tree hypercomplex wavelet transform (D-HWT) and its improved shift invariance and directional selectivity, applications in other areas of image processing are more conceivable. This paper discusses the problems and solutions in developing the DHWT and its inverse. It also offers a practical implementation of the algorithms involved. The aim of this work is to apply the DHWT in machine vision. Tentative work on a possible new way of feature extraction is presented. The paper shows that 2-D hypercomplex basis wavelets can be used to generate steerable filters which allow rotation as well as translation.

关键词： Wavelet transforms image processing Discrete wavelet transforms Wavelet analysis Optical filters Biomedical signal processing Feature extraction Filter bank Equations Wavelet domain

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