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IEEE Region 10 International conference TENCON

作者： Wing-Pong Choi Siu-Hong Tse Kwok-Wai Wong Kin-Man Lam Centre for Signal Processing Department of Electronic and Information Engineering Hong Kong Polytechnic University Hong Kong China

Gabor wavelets (GWs) are commonly used for extracting local features for various applications like object detection, recognition and tracking. However, extracting Gabor features is computationally intensive, so the features are impractical for real-time applications. In this paper, we propose a simplified version of Gabor wavelets (SGWs) and an efficient algorithm for extracting the features based on an integral image. We evaluate the performance of the SGWs for face recognition. Experimental results show that SGWs can achieve a performance level similar to GWs, while the runtime for feature extraction using SGWs is about 4.39 times faster than that of GWs, implemented by using fast Fourier transform (FFT).

关键词： Feature extraction Quantization Face recognition Computational complexity Data mining Object detection Fast Fourier transforms signal processing signal processing algorithms Runtime

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Registration of 2D to 3D joint images using phase-based mutual information

Registration of 2D to 3D joint images using phase-based mutu...

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Medical Imaging 2007 conference

作者： Dalvia, Rupin Abugharbieh, Rafeef Pickering, Mark Scarvell, Jennie Smith, Paul Univ British Columbia Biomed Signal & Image Comp Lab Vancouver BC V5Z 1M9 Canada Australian Def Force Acad Sch Info Tech & Elect Engn Canberra ACT Australia Univ Canberra Sch Hlth Sci Canberra ACT Australia Canberra Hosp Trauma & Orthopaed Res Unit Canberra ACT Australia

ISBN: (纸本)9780819466303

Registration of two dimensional to three dimensional orthopaedic medical image data has important applications particularly in the area of image guided surgery and sports medicine. Fluoroscopy to computer tomography (CT) registration is an important case, wherein digitally reconstructed radiographs derived from the CT data are registered to the fluoroscopy data. Traditional registration metrics such as intensity-based mutual information (MI) typically work well but often suffer from gross misregistration errors when the image to be registered contains a partial view of the anatomy visible in the target image. Phase-based MI provides a robust alternative similarity measure which, in addition to possessing the general robustness and noise immunity that MI provides, also employs local phase information in the registration process which makes it less susceptible to the aforementioned errors. In this paper, we propose using the complex wavelet transform for computing image phase information and incorporating that into a phase-based MI measure for image registration. Tests on a CT volume and 6 fluoroscopy images of the knee are presented. The femur and the tibia in the CT volume were individually registered to the fluoroscopy images using intensity-based MI, gradient-based MI and phase-based MI. Errors in the coordinates of fiducials present in the bone structures were used to assess the accuracy of the different registration schemes. Quantitative results demonstrate that the performance of intensity-based MI was the worst. Gradient-based MI performed slightly better, while phase-based MI results were the best consistently producing the lowest errors.

关键词： registration multiresolution and wavelets other (2D-3D registration)

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Motion-compensated orthogonal transforms for multiview video coding

Motion-compensated orthogonal transforms for multiview video...

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European signal processing conference (EUSIPCO)

作者： Markus Flierl Max Planck Center for Visual Computing and Communication Stanford University California

This paper discusses coding of multiview video with motion-compensated orthogonal transforms. These transforms have recently been introduced to generate strictly orthonormal decompositions of image sequences. Orthonormality is maintained for arbitrary motion compensation among the images. This is of particular interest for coding applications as motion compensation is inaccurate due to quantization of motion information. This is in contrast to the well known motion-compensated lifted wavelets where the properties of the decomposition are motion-dependent. This disadvantage affects compression efficiency and in particular that of multiview video signals. Multiview video coding schemes utilize motion and disparity compensation when decomposing the multiview imagery into view-temporal subbands. Usually decompositions in time and view direction are cascaded. Motion-compensated lifted wavelets suffer from their motion-dependent decomposition and in particular if cascaded for multiview video coding. On the other hand motion and disparity compensated orthogonal transforms offer the advantage that the overall decomposition is still strictly orthonormal. This paper investigates the advantages of strict orthonormality that is offered by motion-compensated orthogonal transforms.

关键词： Video coding Encoding Motion compensation Wavelet transforms Radiation detectors image sequences

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wavelets: a Versatile Tool for the High Frequency Surface Wave Radar

Wavelets: a Versatile Tool for the High Frequency Surface Wa...

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IEEE National conference on Radar

作者： Florent Jangal Stephane Saillant Marc Helier Office National d'Etudes et de Recherches Aérospatiales The French Aerospace Laboratory Palaiseau France Université Pierre et Marie Curie Ivry-sur-Seine France

Widely used in image processing, wavelets seem to be a promising versatile tool for the high frequency surface wave radar (HFSWR). HFSWR is based on the ability of HF waves (3 MHz to 30 MHz) to propagate along the earth curvature. HFSWR can detect targets up to few hundred kilometers beyond the horizon. The two main applications of the HFSWR are the maritime surveillance of the exclusive economic zone (EEZ) and the remote sensing of the sea. Beside the classical noise which affects all radar signals, the detection capabilities of HFSWR suffer from two limitations: the sea clutter and the ionospheric clutter which are target masks. However sea clutter can be used to perform remote sensing of the sea. In this paper we are studying how wavelets may contribute to the improvement of radar signal processing. We consider general de-noising feature for radar signals, we carry out a wavelet-based improvement of remote sensing of oceanographic parameters and we show the first results of a wavelet-based processing for ionospheric clutter mitigation.

关键词： Frequency Surface waves Remote sensing Sea surface Radar imaging Radar detection Radar clutter Radar remote sensing Radar signal processing image processing

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An Optimal Wavelet Filter for Despeckling Echocardiographic images

An Optimal Wavelet Filter for Despeckling Echocardiographic ...

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International conference on Computational Intelligence and Multimedia applications

作者： P.S. Hiremath Prema T. Akkasaligar Sharan Badiger Department of P.G. Studies & Research in Computer Science Gulbarga University Gulbarga Karnataka India Engineering College B.L.D.E.A's Dr P.G.H. Bijapur Karnataka India Departmentof Medicine Sri B. M. Patil Medical College Bijapur Karnataka India

The major difficulty concerning echocardiograph image processing is speckle noise. In this paper, we present wavelet based algorithm for denoising echocardiograph images and then determine an optimal wavelet filter that yields good quality images. The log transformed input is represented in multiscale wavelet domain. Global hard thresholding of subband coefficients is performed to achieve lossy compression of image. The inverse wavelet transformed image is free from speckle noise. The image quality is assessed in terms of objective and statistical measures, namely, peak-signal-to-noise ratio (PSNR), compression ratio, variance, mean square error (MSE). The experiments are performed using different wavelets at various levels of decomposition. The results show that bior6.8 with 2- level decomposition yields better quality despeckled images.

关键词： Filters image quality Speckle image coding PSNR image reconstruction Biomedical imaging Noise reduction Educational institutions Wavelet domain

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Biorthogonal wavelets of maximum coding gain through pseudoframes for subspaces

Biorthogonal wavelets of maximum coding gain through pseudof...

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conference on Mathematics of Data/image Pattern Recognition, Compression and Encryption with Application ix

作者： Herman, Matthew A. Li, Shidong Univ Calif Davis Dept Math 1 Shields Ave Davis CA 95616 USA San Francisco State Univ Dept Math San Francisco CA 94132 USA

ISBN: (纸本)0819463949

A method for designing a signal-adapted, two-channel biorthogonal wavelet filter bank that maximizes coding gain is presented using the technique of Pseudoframes for Subspaces (PFFS). At the same time the PFFS model is able to incorporate the requirements of regularity and perfect reconstruction into this design. The coding gain achieved for AR(2) signals can result in a reduction in bit rate of more than 0.66 bits per sample as compared to traditional biorthogonal wavelet filter banks of the same length. The ability for PFFS to combine all of these design elements using an unconstrained optimization parameter makes pursuing this technique worthwhile.

关键词： subband coding gain biorthogonal wavelets signal-adapted filter banks pseudoframes frames

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applications of non-orthogonal filter banks to signal and image analysis

Applications of non-orthogonal filter banks to signal and im...

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IEEE/PES Transmission and Distribution conference and Exposition Latin America

作者： Soares, Luciana R. de Oliveira, H. M. Cintra, Renato J. S. Univ Fed Pernambuco Dept Elect & Syst Signal Proc Grp CP 7800 BR-50711970 Recife PE Brazil Univ Fed Pernambuco Dept Stat Recife PE Brazil

ISBN: (纸本)9781424402878

A non-orthogonal wavel ET-based multiresolution analysis was already provided by scaling and wavelet filters derived from Gegenbauer polynomials. Allowing for odd n (the polynomial order) and a value (a polynomial parameter) within the orthogonality range of such polynomials, scaling and wavelet functions are generated by frequency selective FIR filters. These filters have compact support and generalized linear phase. Special cases of such filter banks include Haar, Legendre, and Chebyshev wavelets. As an improvement, it has been achieved that for specific a values it is possible to reach a filter with flat magnitude frequency response. We obtain a unique closed expression for a value for every n odd value. The main advantages in favor of Gegenbauer filters are their smaller computational effort and a constant group delay, as they are symmetric filters. Potential applications of such wavelets include fault analysis in transmission lines of power systems and image processing.

关键词： chebyshev wavelets discrete-time filters filter banks Gegenbauer polynomials Gegenbauer wavelets image analysis legendre wavelets multiresolution analysis signal analysis wavelet transform

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Wavelet-based pavement distress detection and evaluation

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OPTICAL ENGINEERING 2006年第2期45卷

作者： Zhou, J Huang, PS Chiang, FP SUNY Stony Brook Dept Mech Engn Stony Brook NY 11794 USA

An automated pavement inspection system consists of image acquisition and distress image processing. The former is accomplished with imaging sensors, such as video cameras and photomultiplier tubes. The latter includes distress detection, isolation, classification, evaluation, segmentation, and compression. We focus on wavelet-based distress detection, isolation, and evaluation. After a pavement image is decomposed into different-frequency subbands by the wavelet transform, distresses are transformed into high-amplitude wavelet coefficients and noise is transformed into low-amplitude wavelet coefficients, both in the high-frequency subbands, referred to as details. Background is transformed into wavelet coefficients in a low-frequency subband, referred to as approximation. First, several statistical criteria are developed for distress detection and isolation, which include the high-amplitude wavelet coefficient percentage (HAWCP), the high-frequency energy percentage (HFEP), and the standard deviation (STD). These criteria are tested on hundreds of pavement images differing by type, severity, and extent of distress. Experimental results demonstrate that the proposed criteria are reliable for distress detection and isolation and that real-time distress detection and screening is currently feasible. A norm for pavement distress quantification, which is defined as the product of HAWCP and HFEP, is also proposed. Experimental results show that the norm is a useful index for pavement distress evaluation. (c) 2006 Society of Photo-Optical Instrumentation Engineers.

关键词： wavelet transform automated pavement inspection pavement distress image processing distress detection and isolation distress evaluation

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Evolved transforms for signal compression and reconstruction under quantization

Evolved transforms for signal compression and reconstruction...

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conference on Modeling and Simulation for Military applications

作者： Moore, Frank W. Univ Alaska Anchorage Dept Math Sci Anchorage AK 99508 USA

ISBN: (纸本)0819462845

State-of-the-art signal compression and reconstruction techniques utilize wavelets. However, recently published research demonstrated that a genetic algorithm (GA) is capable of evolving non-wavelet inverse transforms that consistently outperform wavelets when used to reconstruct one- and two-dimensional signals under conditions subject to quantization error. This paper summarizes the results of a series of three follow-on experiments. First, a GA is developed to evolve matched forward and inverse transform pairs that simultaneously minimize the compressed file size (FS) and the squared error (SE) in the reconstructed file. Second, this GA is extended to evolve a single set of coefficients that may be used at every level of a multi-resolution analysis (MRA) transform. Third, this GA is expanded to achieve additional SE reduction by evolving a different set of coefficients for each level of an MRA transform. Test results indicate that coefficients evolved against a single representative training image generalize to effectively reduce SE for a broad class of reconstructed images.

关键词： wavelets genetic algorithms quantization multi-resolution analysis image processing

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2007 IEEE International conference on image processing, ICIP 2007 Proceedings

2007 IEEE International Conference on Image Processing, ICIP...

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14th IEEE International conference on image processing, ICIP 2007

ISBN: (纸本)1424414377

The proceedings contain 841 papers. The topics discussed include: scalable coding of high dynamic range video;bit-depth scalable video coding;the super hi-vision codec;inverse bit plane decoding order for turbo code based distributed video coding;encoder rate control for transform domain Wyner-Ziv video coding;image authentication based on distributed source coding;codec-independent scalable distributed video coding;a novel image re-indexing by self organizing motor maps;multichannel image decomposition by using pseudo-linear Haar wavelets;a feature analysis approach to mass detection in mammography based on RF-SVM;time reversal beamforming for microwave breast cancer detection;automatic quality analysis for film and video restoration;unscented kalman filter for image estimation in film-grain noise;detection and recovery of film dirt for archive restoration applications;and restoration of variable area soundtracks.

关键词： Video signal processing

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