The Experts below are selected from a list of 174 Experts worldwide ranked by ideXlab platform
Nasir M Rajpoot - One of the best experts on this subject based on the ideXlab platform.
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2006 Birkhäuser Verlag Basel/Switzerland Directional Wavelet Analysis with Fourier-Type Bases for Image Processing
2016Co-Authors: Tao Qian, Zhen Yao, Mang I. Vai, Xu Yuesheng, Nasir M RajpootAbstract:Abstract. Motivated by the fact that in natural images, there is usually a pres-ence of local strongly oriented features such as Directional textures and linear discontinuities, a representation which is both well-localised in frequency and orientation is desirable to efficiently describe those oriented features. Here we introduce a family of multiscale trigonometric bases for image processing using Fourier-type constructions, namely, the multiscale Directional Cosine transform and the multiscale Fourier transform. We also show that by seek-ing an adaptive basis locally, the proposed bases are able to capture both oriented harmonics as well as discontinuities, although the complexity of such adaptiveness varies significantly. We conducted denoising experiments with the proposed bases and the results show great promise of the proposed direc-tional wavelet bases
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image denoising using multiscale Directional Cosine bases
International Conference on Image Processing, 2005Co-Authors: Zhen Yao, Nasir M RajpootAbstract:Motivated by the fact that in images, there is usually a presence of local strongly oriented harmonics, a representation which is both well-localised in frequency and orientation is desirable to efficiently describe such oriented harmonic features. Here we introduce a family of multiscale trigonometric bases for a bi-variate function called the multiscale Directional Cosine bases for image denoising tasks. Our results show the promise of the new bases which almost consistently outperform other image representation bases on natural images.
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ICIP (3) - Image denoising using multiscale Directional Cosine bases
IEEE International Conference on Image Processing 2005, 2005Co-Authors: Zhen Yao, Nasir M RajpootAbstract:Motivated by the fact that in images, there is usually a presence of local strongly oriented harmonics, a representation which is both well-localised in frequency and orientation is desirable to efficiently describe such oriented harmonic features. Here we introduce a family of multiscale trigonometric bases for a bi-variate function called the multiscale Directional Cosine bases for image denoising tasks. Our results show the promise of the new bases which almost consistently outperform other image representation bases on natural images.
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Directional Wavelet Analysis with Fourier-type Bases for Image Processing
Wavelet Analysis and Applications, 1Co-Authors: Zhen Yao, Nasir M Rajpoot, Roland WilsonAbstract:Motivated by the fact that in natural images, there is usually a presence of local strongly oriented features such as Directional textures and linear discontinuities, a representation which is both well-localised in frequency and orientation is desirable to efficiently describe those oriented features. Here we introduce a family of multiscale trigonometric bases for image processing using Fourier-type constructions, namely, the multiscale Directional Cosine transform and the multiscale Fourier transform. We also show that by seeking an adaptive basis locally, the proposed bases are able to capture both oriented harmonics as well as discontinuities, although the complexity of such adaptiveness varies significantly. We conducted denoising experiments with the proposed bases and the results show great promise of the proposed Directional wavelet bases.
Zhen Yao - One of the best experts on this subject based on the ideXlab platform.
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2006 Birkhäuser Verlag Basel/Switzerland Directional Wavelet Analysis with Fourier-Type Bases for Image Processing
2016Co-Authors: Tao Qian, Zhen Yao, Mang I. Vai, Xu Yuesheng, Nasir M RajpootAbstract:Abstract. Motivated by the fact that in natural images, there is usually a pres-ence of local strongly oriented features such as Directional textures and linear discontinuities, a representation which is both well-localised in frequency and orientation is desirable to efficiently describe those oriented features. Here we introduce a family of multiscale trigonometric bases for image processing using Fourier-type constructions, namely, the multiscale Directional Cosine transform and the multiscale Fourier transform. We also show that by seek-ing an adaptive basis locally, the proposed bases are able to capture both oriented harmonics as well as discontinuities, although the complexity of such adaptiveness varies significantly. We conducted denoising experiments with the proposed bases and the results show great promise of the proposed direc-tional wavelet bases
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ICIP (1) - Image Denoising with Directional Bases
2007 IEEE International Conference on Image Processing, 2007Co-Authors: Heechan Park, Graham R. Martin, Zhen YaoAbstract:Directional information is an important component of both natural and synthetic images, and it is exploited in many image processing applications. Directional basis analysis is used to capture significant structural information. This paper presents an empirical study of image denoising with Directional bases. We consider two distinct approaches. One involves the multi-resolution Fourier transform (MFT) facilitated with a multi-Directional selective filter. The other is based on statistics, independent component analysis (ICA) that adaptively decomposes an image into a set of Directional bases. We then present a combined approach that benefits from the computational efficiency of the MFT and the data adaptiveness of ICA. Experimental results are compared with those from other recent Directional transforms such as the curvelet and Directional Cosine transform.
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image denoising using multiscale Directional Cosine bases
International Conference on Image Processing, 2005Co-Authors: Zhen Yao, Nasir M RajpootAbstract:Motivated by the fact that in images, there is usually a presence of local strongly oriented harmonics, a representation which is both well-localised in frequency and orientation is desirable to efficiently describe such oriented harmonic features. Here we introduce a family of multiscale trigonometric bases for a bi-variate function called the multiscale Directional Cosine bases for image denoising tasks. Our results show the promise of the new bases which almost consistently outperform other image representation bases on natural images.
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ICIP (3) - Image denoising using multiscale Directional Cosine bases
IEEE International Conference on Image Processing 2005, 2005Co-Authors: Zhen Yao, Nasir M RajpootAbstract:Motivated by the fact that in images, there is usually a presence of local strongly oriented harmonics, a representation which is both well-localised in frequency and orientation is desirable to efficiently describe such oriented harmonic features. Here we introduce a family of multiscale trigonometric bases for a bi-variate function called the multiscale Directional Cosine bases for image denoising tasks. Our results show the promise of the new bases which almost consistently outperform other image representation bases on natural images.
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Directional Wavelet Analysis with Fourier-type Bases for Image Processing
Wavelet Analysis and Applications, 1Co-Authors: Zhen Yao, Nasir M Rajpoot, Roland WilsonAbstract:Motivated by the fact that in natural images, there is usually a presence of local strongly oriented features such as Directional textures and linear discontinuities, a representation which is both well-localised in frequency and orientation is desirable to efficiently describe those oriented features. Here we introduce a family of multiscale trigonometric bases for image processing using Fourier-type constructions, namely, the multiscale Directional Cosine transform and the multiscale Fourier transform. We also show that by seeking an adaptive basis locally, the proposed bases are able to capture both oriented harmonics as well as discontinuities, although the complexity of such adaptiveness varies significantly. We conducted denoising experiments with the proposed bases and the results show great promise of the proposed Directional wavelet bases.
Cheong Rim Choi - One of the best experts on this subject based on the ideXlab platform.
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Obliquely propagating solitary kinetic Alfven wave in a collisional dusty plasma
Physics of Plasmas, 2010Co-Authors: M. H. Woo, C.-m. Ryu, Cheong Rim ChoiAbstract:An obliquely propagating solitary kinetic Alfven wave in a low beta dusty plasma (β⪡me/mi) is studied by considering the ion motion along the magnetic field and the collisional effect of electrons. The existence condition for a solitary wave for a collisionless dusty plasma is re-examined. It is found that there is an upper limit of the possible Alfvenic Mach velocity, imposed by dust particles. The Mach number lies between lz and lz/Nd, where lz is the Directional Cosine and Nd is the dust particle charge density. In the collisional case, the same upper limit of the Mach velocity is found, and the solitary wave turns into an oscillating double layer. The damping scale and the size of the oscillation structure increase with increasing dust particle charge density. The damping scale and the size of the oscillation structure are estimated by using the virial theorem.
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Ion thermal pressure effects on dust ion acoustic solitary waves in a dusty plasma obliquely propagating to an external magnetic field
Physics of Plasmas, 2005Co-Authors: Cheong Rim Choi, Chang-mo Ryu, Nam C. Lee, Dae-young Lee, Yonggi KimAbstract:Effects of the isothermal ion pressure on the dust ion acoustic solitary waves (DIASWs) in a dusty plasma, which are obliquely propagating to an external magnetic field, are investigated based on the Sagdeev potential. It is found that as the ion temperature increases the speed of the DIASW increases. The increase is more effective for a higher value of the Directional Cosine lz. The small amplitude solutions of the Sagdeev potential Ψ(n) expanded up to δn3 and δn4, as was done in the previous study [Choi et al., Phys. Plasmas 12, 022304 (2005)], exhibit different behaviors with respect to the change in the ion temperature. The width and height of a double layer are found to decrease with the increase in the ion temperature for both the small and the large amplitude solutions.
M Mahmoud - One of the best experts on this subject based on the ideXlab platform.
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On the higher-order solution of the dust-acoustic solitary waves in a warm magnetized dusty plasma with dust charge variation
Physics of Plasmas, 2004Co-Authors: S. K. El-labany, Waleed M. Moslem, W. F. El-taibany, M MahmoudAbstract:The higher-order contribution in reductive perturbation theory is studied for small-butfinite-amplitude dust-acoustic solitary waves in warm magnetized three-component dusty plasmas comprised of variational charged dust grains, isothermal ions, and electrons. The basic set of fluid equations is reduced to the Zakharov–Kuznetsov equation for the first-order perturbed potential and a linear inhomogeneous Zakharov–Kuznetsov-type equation for the second-order perturbed potential. Stationary solutions of both equations are obtained using a renormalization method. The effects of the higher-order contribution, external magnetic field, dust charge variation, dust grain temperature, ratios of temperature and density of positive ions to electrons, and Directional Cosine of the wave vector k along the x axis on the nature of the solitary waves are investigated.
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Kadomtsev-Petviashvili Equation for Dust Acoustic Solitary Waves in a Warm Dusty Plasma with Dust Charge Variation
Physica Scripta, 2004Co-Authors: S. K. El-labany, Waleed M. Moslem, W. F. El-taibany, M MahmoudAbstract:The properties and stability of nonlinear three-dimensional dust acoustic solitary waves are examined in a dusty plasma, having warm variational charged dust grains, hot ions and electrons, through the derivation of the Kadomtsev-Petviashvili equation using the reductive perturbation method. It is found that only rarefactive solitary waves can propagate in this system. To determine the stability of the waves, we used a method based on energy considerations to obtain a condition for stable solitary waves. It is found that this condition depends on dust charge variation, dust grains temperature, Directional Cosine of the wave vector k along the x-axis. Also, we study the dependance of the amplitude and the width on various plasma parameters. The findings of this investigation may be useful in understanding laboratory plasma phenomena and astrophysical situations.
Patrick D. Wolf - One of the best experts on this subject based on the ideXlab platform.
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An analytical comparison of the information in sorted and non-sorted Cosine-tuned spike activity.
Journal of neural engineering, 2007Co-Authors: Deborah S. Won, P H E Tiesinga, Craig S. Henriquez, Patrick D. WolfAbstract:Spike sorting is a technologically expensive component of the signal processing chain required to interpret population spike activity acquired in a neuromotor prosthesis. No systematic analysis of the value of spike sorting has been carried out, and little is known about the effects of spike sorting error on the ability of a brain–machine interface (BMI) to decode intended motor commands. We developed a theoretical framework to examine the effects of spike processing on the information available to a BMI decoder. We computed the mutual information in neural activity in a simplified model of Directional Cosine tuning to compare the effects of pooling activity from up to four neurons to the effects of sorting with varying amounts of spike error. The results showed that information in a small population of Cosine-tuned neurons is maximized when the responses are sorted and there is diverse tuning of units, but information was affected little when pooling units with similar preferred directions. Spike error had adverse effects on information, such that non-sorted population activity had 79–92% of the information in its sorted counterpart for reasonable amounts of detection and sorting error and for units with moderate differences in preferred direction. This quantification of information loss associated with pooling units and with spike detection and sorting error will help to guide the engineering decisions in designing a BMI spike processing system.