نتایج جستجو برای: wavelet coefficients
تعداد نتایج: 138766 فیلتر نتایج به سال:
this article introduces a systematic study for computational aspects of classical wavelet transforms over finite fields using tools from computational harmonic analysis and also theoretical linear algebra. we present a concrete formulation for the frobenius norm of the classical wavelet transforms over finite fields. it is shown that each vector defined over a finite field can be represented as...
A new method based on principal component analysis (PCA) and artificial neural networks (ANN) is proposed for fault diagnosis of gearboxes. Firstly the six different base wavelets are considered, in which three are from real valued and other three from complex valued. Two wavelet selection criteria Maximum Energy to Shannon Entropy ratio and Maximum Relative Wavelet Energy are used and compared...
This paper concentrates on a new procedure which experimentally recognises gears and bearings faults of a typical gearbox system using a least square support vector machine (LSSVM). Two wavelet selection criteria Maximum Energy to Shannon Entropy ratio and Maximum Relative Wavelet Energy are used and compared to select an appropriate wavelet for feature extraction. The fault diagnosis method co...
In this paper, we propose an efficient method for rearranging the wavelet packet coefficients of an image to form hierarchical trees, by which the well known SPIHT algorithm can be applied. For images with textures, the high frequency wavelet coefficients are likely to become significant after several code passes of SPIHT, which degrades substantially the coding performance. As a result, the hi...
-In this paper, we propose an efficient method for rearranging the wavelet packet coefficients of an image to form hierarchical trees, by which the well known SPIHT algorithm can be applied. For images with textures, the high frequency wavelet coefficients are likely to become significant after several code passes of SPIHT, which degrades substantially the coding performance. As a result, the h...
in this paper, we try to find a particular combination of wavelet shrinkage and nonlinear diffusion for noise removal in dental images. we selected the wavelet diffusion and modified its automatic threshold selection by proposing new models for speckle related modulus. the laplacian mixture model and circular symmetric laplacian mixture models were evaluated and as it could be expected, the lat...
Many important problems in engineering and science are well-modeled by Poisson processes. A common technique for noise reduction is to use a filter. Wiener filter, which utilizes the second-order statistics of the Fourier decomposition, and the median filter which is based on the theory of order statistion, are normally used to denoise degraded images. Wavelet-based methods are powerful tools f...
A novel image coding scheme using wavelet transform is presented. The developed coding scheme prevents undesirable classifications of wavelet coefficients which arise from conventional quadtree based image coding. This is accomplished by pre-processing the wavelet coefficients. This pre-processing is based statistical distributions of the wavelet coefficients in subbands and the human visual sy...
Wavelet based image denoising methods have attracted extensive interests over the last decade. Donoho et. al. [3] first suggested to remove/suppress noise by thresholding of wavelet coefficients. The underlying assumption is simple and intuitive: a wavelet coefficient is treated as noise and set to zero if it is below a preset threshold. Otherwise, the coefficient is kept or slightly modified. ...
Wavelet based image denoising methods have attracted extensive interests over the last decade. Donoho et. al. [3] first suggested to remove/suppress noise by thresholding of wavelet coefficients. The underlying assumption is simple and intuitive: a wavelet coefficient is treated as noise and set to zero if it is below a preset threshold. Otherwise, the coefficient is kept or slightly modified. ...
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