In this work, we introduce an efficient hidden Markov field model for waveletimage coefficients and apply it to the image denoising problem. Specifically, we propose to model waveletimage coefficients within subband...
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ISBN:
(纸本)0780362934
In this work, we introduce an efficient hidden Markov field model for waveletimage coefficients and apply it to the image denoising problem. Specifically, we propose to model waveletimage coefficients within subbands as Gaussian random variables with parameters determined by underlying hidden Markov-type process. Our model is inspired by the recent Estimation-Quantization image coder [1] and the work in [2]. To reduce the computational complexity we apply the novel factor graph [3] framework to combine two 1-D chain models to approximate a hidden Markov field (HMF) model. We then apply the proposed models for waveletimage coefficients to perform an approximate Minimum Mean Square Error (MMSE) estimation procedure to restore an image corrupted by additive white Gaussian noise. Our results are among the state-of-the-art in the field and they indicate the promise of the proposed modeling techniques.
An automated pavement inspection system consists of image acquisition and distress imageprocessing. The former is accomplished with imaging sensors, such as video cameras and photomultiplier tubes. The latter include...
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An automated pavement inspection system consists of image acquisition and distress imageprocessing. 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.
Deconvolution in blind digital images is a common issue in image enhancement techniques, which basically was a notion of many researches. In this study, spatial varying blind deconvloution is stated and implemented. I...
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ISBN:
(纸本)9781728133775
Deconvolution in blind digital images is a common issue in image enhancement techniques, which basically was a notion of many researches. In this study, spatial varying blind deconvloution is stated and implemented. In addition, image noise removal approach which utilizes the normalized platform of second-generation wavelet transform is applied as pre-processing step. The low and high frequencies are decomposed in this step in order to be extracted. Practically, the main merit of wavelet transform is its efficiency in reduction of data redundancy in digital images. This feature helps a lot in terms of data classification where it is easy to distinguish the signal from its noisy counterpart. The second step, a recursive deep convolutional neural network (R-DbCNN) is implemented to suppress any image blur affected by second-generation wavelet transform to further remove the blur of noisy image. The experimental results depict that the suggested method outperforms recent blur removal techniques for different bluer image types in terms of image quality and time consumption.
Recent years have seen the development of signal denoising algorithms based on wavelet transform. It has been shown that thresholding the wavelet coefficients of a noisy signal allows to restore the smoothness of the ...
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ISBN:
(纸本)0780370414
Recent years have seen the development of signal denoising algorithms based on wavelet transform. It has been shown that thresholding the wavelet coefficients of a noisy signal allows to restore the smoothness of the original signal. However, wavelet denoising suffers of a main drawback : around discontinuities the reconstructed signal is smoothed, exhibiting pseudo-Gibbs phenomenon. We consider the problem of denoising piecewise smooth signals with sharp discontinuities. We propose to apply a traditional wavelet denoising method and to restore the denoised signal using a total variation minimization approach. This second step allows to remove the Gibbs phenomena and therefore to restore sharp discontinuities, while the other structures are preserved. The main innovation of our algorithm is to constrain the total variation minimization by the knowledge of the remaining wavelet coefficients. In this way, we make sure that the restoration process does not deteriorate the information that has been considered as significant in the denoising step. With this approach we substantially improve the performance of classical wavelet denoising algorithms, both in terms of SNR and in terms of visual artifacts.
Kirchhoff migration operator is a highly oscillatory integral operator. In our previous work (see "Seismic Imaging in wavelet Domain", Wu and Yang [1], 1997), we have shown that the matrix representation of ...
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ISBN:
(纸本)0819429139
Kirchhoff migration operator is a highly oscillatory integral operator. In our previous work (see "Seismic Imaging in wavelet Domain", Wu and Yang [1], 1997), we have shown that the matrix representation of Kirchhoff migration operator for homogeneous background in space-frequency domain is a dense matrix, while the compressed beamlet-operator, which is the wavelet decomposition of the Kirchhoff migration operator in beamlet-frequency (space-scale-frequency) domain, is a highly sparse matrix. Using the compressed matrix for imaging, we can obtain high quality images with high efficiency. We found that the compression ratio of the migration operator is very different for different wavelet basis. In the present work, we study the decomposition and compression of Kirchhoff migration operator by adapted wavelet packet transform, and compare with the standard discrete wavelet transform (DWT). We proposed a new maximum sparsity adapted wavelet packet transform (MSAWPT), which differs from the well-known Coifman-Wickerhauser's best basis algorithm, to implement the decomposition of Kirchhoff operator to achieve the maximum possible sparsity. From the numerical tests, it is found that the MSAWPT can generate a more efficient matrix representation of Kirchhoff migration operator than DWT and the compression capability of MSAWPT is much greater than that of DWT.
We address a well known problem of nonlinear image diffusion techniques, namely the loss of texture information. We do so by first determining that it is due to unaccounted correlation structure in the image which we ...
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ISBN:
(纸本)0780370414
We address a well known problem of nonlinear image diffusion techniques, namely the loss of texture information. We do so by first determining that it is due to unaccounted correlation structure in the image which we subsequently mitigate by proposing a wavelet frame-based technique. This, by the same token establishes a theoretical bridge between the scale space methodology and the multiscale analysis approach. We provide examples to illustrate the effectiveness of the proposed approach.
ECG recordings were obtained from 21 healthy subjects aged between 13 and 65 years, over a range of heart rate extending from 46 to 184 beats/min (bpm). A wavelet transform method, based on the Mexican Hat wavelet was...
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ISBN:
(纸本)0780370414
ECG recordings were obtained from 21 healthy subjects aged between 13 and 65 years, over a range of heart rate extending from 46 to 184 beats/min (bpm). A wavelet transform method, based on the Mexican Hat wavelet was then used to precisely locate the positions of the onset, peak and termination of individual components in the ECG signal. These times were then classified according to the heart rate associated with the cardiac cycle to which the component belonged. Second order equations in the square root of the cardiac cycle time, TR-R Of the form ***(R-R) + ***-R + C were fitted to the data obtained for each component to characterize its timing variation.
In this paper, we propose a new wideband bearing estimation method based on wavelet transform. By analyzing the relationship between the wavelet transform of the frequency invariant beam's output and the array'...
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ISBN:
(纸本)9781479902699;9781479902675
In this paper, we propose a new wideband bearing estimation method based on wavelet transform. By analyzing the relationship between the wavelet transform of the frequency invariant beam's output and the array's beampattern, we derived spatial power spectrum based on wavelet transform (SPS-WT). The method has good performance on noise suppression by utilizing the statistical uncorrelation character between signals and noise, and also has high resolution on bearing estimation. The performance of the proposed method is illustrated in simulation results.
The theory of signal-adapted filter banks has been developed in signal compression in recent years and only rarely be applied to other applications fields such as machine learning. In this paper, we propose lattice st...
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ISBN:
(纸本)0780376633
The theory of signal-adapted filter banks has been developed in signal compression in recent years and only rarely be applied to other applications fields such as machine learning. In this paper, we propose lattice structure based signal-adapted filter banks and time-scale atoms, respectilvely, for the construction of morphological local discriminant bases and hybrid wavelet-support vector classifiers. The first mentioned method is a more powerful construction of the recently introduced local discriminant bases algorithm which employs, additionally to the conventional wavelet-packet tree adjustment, an adaptation of the analyzing time-scale atoms. The latter mentioned method utilizes adapted wavelet decompositions which are tailored for support vector classifiers with radial basis functions as kernels. For both methods, we present applications in biomedical signalprocessing.
25 years after the seminal work of Jean Morlet, the wavelet transform, multiresolution analysis, and other space frequency or space scale approaches are considered standard tools by researchers in imageprocessing, an...
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ISBN:
(纸本)9780819464514
25 years after the seminal work of Jean Morlet, the wavelet transform, multiresolution analysis, and other space frequency or space scale approaches are considered standard tools by researchers in imageprocessing, and many applications have been proposed that point out the interest of these techniques. This paper proposes a review of the recent published works dealing with industrial applications of wavelet and, more generally speaking, multiresolution analysis. More than 180 recent papers are presented.
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