Fractographs are elevation maps of the fracture zone of some broken material. The technique employed to create these maps (confocal laser microscopy) often introduces noise composed of positive or negative 'spikes...
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ISBN:
(纸本)0819437646
Fractographs are elevation maps of the fracture zone of some broken material. The technique employed to create these maps (confocal laser microscopy) often introduces noise composed of positive or negative 'spikes' that must be removed before further analysis. Since the roughness of these maps contains useful information, it must be preserved. Consequently, conventional denoising techniques cannot be employed. We use continuous and discrete wavelet transforms of these images, and the properties of wavelet coefficients related to pointwise Holder regularity, to detect and remove the spikes.
This article presents two modelling methods using wavelet networks. Both methods are intended to be used for an acoustic pulse signal classifier. We present a few results obtained with signals coming from a recording ...
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ISBN:
(纸本)0818679204
This article presents two modelling methods using wavelet networks. Both methods are intended to be used for an acoustic pulse signal classifier. We present a few results obtained with signals coming from a recording of the percussive response of metal parts. The object of this application is the non-destructive testing of these parts, as defects perturb the acoustic signature. The first modelling method uses wavelet networks to perform a non-linear regression on the signal to be classified. The second consists of non-linear auto-recursive modelling of the signal by means of the networks. The use of wavelet networks enables us to combine the generalizing capacities of neural networks with the efficiency of wavelet analysis of pulse signals.
wavelet thresholding is a powerful tool for denoising images and other signals with sharp discontinuities. Using different wavelet bases gives different results, and since the wavelet transform is not time-invariant, ...
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ISBN:
(纸本)0819450804
wavelet thresholding is a powerful tool for denoising images and other signals with sharp discontinuities. Using different wavelet bases gives different results, and since the wavelet transform is not time-invariant, thresholding various shifts of the signal is one way to use different wavelet bases. This paper describes several denoising methods that apply wavelet thresholding or variations on wavelet thresholding recursively. (We previously termed one of these methods "recursive cycle spinning.") These methods are compared experimentally for denoising piecewise polynomial signals. Though similar, the methods differ in computational complexity, convergence speed, and sensitivity to threshold selection.
We address the problem of improving the performance of wavelet based fractal image compression by applying efficient triangulation methods. We construct iterative function systems (IFS) in the tradition of Barnsley an...
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ISBN:
(纸本)0819429139
We address the problem of improving the performance of wavelet based fractal image compression by applying efficient triangulation methods. We construct iterative function systems (IFS) in the tradition of Barnsley and Jacquin, using non-uniform triangular range and domain blocks instead of uniform rectangular ones. We search for matching domain blocks in the manner of Zhang and Chen, performing a fast wavelet transform on the blocks and eliminating low resolution mismatches to gain speed. We obtain further improvements by the efficiencies of binary triangulations (including the elimination of affine and symmetry calculations and reduced parameter storage), and by pruning the binary tree before construction of the IFS. Our wavelets are triangular Haar wavelets and "second generation" interpolation wavelets as suggested by Sweldens' recent work.
In this paper, Malvar wavelets defined on a unit sphere are introduced. They are constructed by using a similar technique of constructing 2D Malvar wavelets, where one dimension (theta) is periodic on (0, 2(pi) ) and ...
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ISBN:
(纸本)0819422134
In this paper, Malvar wavelets defined on a unit sphere are introduced. They are constructed by using a similar technique of constructing 2D Malvar wavelets, where one dimension (theta) is periodic on (0, 2(pi) ) and the other dimension (phi) is not periodic on (0, (pi) ).
We present a coder that yields good quality images at very high compression rates. It performs embedded coding and can carry out both lossy and lossless compression, properties which are suitable for progressive trans...
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ISBN:
(纸本)0819441929
We present a coder that yields good quality images at very high compression rates. It performs embedded coding and can carry out both lossy and lossless compression, properties which are suitable for progressive transmission;It is based on an integer to integer wavelet transform, and uses augmented zerotrees with a hybrid technique that incorporates bitplane coding as well.
We treat nonparametric estimation of a regression function defined on a 'tensor product irregular grid,' that is, a grid constructed as the Cartesian product of two irregular one-dimensional grids. Our wavelet...
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ISBN:
(纸本)0819450804
We treat nonparametric estimation of a regression function defined on a 'tensor product irregular grid,' that is, a grid constructed as the Cartesian product of two irregular one-dimensional grids. Our wavelet-type estimator is based on a wavelet transform which is the tensor product of two one-dimensional design-adapted wavelet transforms. We propose a denoising scheme and show the performance of the resulting estimator through a simulation study.
Density conditions have turned out to be a powerful tool for deriving necessary conditions for weighted wavelet systems to possess an upper or lower frame bound. In this paper we study different definitions of density...
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ISBN:
(纸本)0819450804
Density conditions have turned out to be a powerful tool for deriving necessary conditions for weighted wavelet systems to possess an upper or lower frame bound. In this paper we study different definitions of density and compare them with respect to their appropriateness and practicality.
We present here a technique to construct the general 9-7 wavelets whose coefficients contain free variables that include an interval by lifting scheme. Based on the developed 9-7 wavelets, wavelet filters with binary ...
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ISBN:
(纸本)0780374886
We present here a technique to construct the general 9-7 wavelets whose coefficients contain free variables that include an interval by lifting scheme. Based on the developed 9-7 wavelets, wavelet filters with binary coefficients, biorthogonality and perfect reconstruction are achieved. By selecting the simplest 9-7 wavelet filter coefficient and developing associated lifting scheme, we propose an efficient approach for image compression. The new method has characteristics that are close to the original irrational coefficients 9-7 wavelet filters of Cohen, Daubechies and Feauveau, but the proposed method provide a simple integer implementation technique, so,it is easily high, efficient realized by hardware.
In this paper, we propose a new algorithm for extracting a non smooth shape from its noisy observation. The key ideal is to project the noisy shape onto a set of orthogonal subspaces at different resolutions, and cons...
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ISBN:
(纸本)0819432997
In this paper, we propose a new algorithm for extracting a non smooth shape from its noisy observation. The key ideal is to project the noisy shape onto a set of orthogonal subspaces at different resolutions, and construct scale space representation gleaned from the locally smoothed shape. Using the curvature we proceed to filter the high resolution scale subspace by projecting it onto the scale which is in turn used for the reconstruction. Inspired by the conjugate mirror filter and the wavelet decomposition synergy, we propose a curvature based filter operating at different scales and with minimal knowledge about the noise statistics.
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