First, a general procedure for constructing a variety of orthogonal wavelets which are compactly supported in frequency domain is presented. These orthogonal wavelets, as a result of the method of Multiresolution Anal...
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ISBN:
(纸本)0780336798;0780336801
First, a general procedure for constructing a variety of orthogonal wavelets which are compactly supported in frequency domain is presented. These orthogonal wavelets, as a result of the method of Multiresolution Analysis(MRA), share the same space structure. This property makes it possible to construct a ''combined'' orthonormal base of L-2(R) which contains more than one wavelet functions. This kind of combined orthonormal wavelet bases are more flexible and are expected to be more efficient than the conventional wavelet bases in data compression, speech coding and image coding.
In this paper speckle reduction is approached as a Wiener-like filtering performed in the wavelet domain by means of an adaptive shrinkage of the detail coefficients of an undecimated decomposition. The amplitude of e...
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ISBN:
(纸本)0819441929
In this paper speckle reduction is approached as a Wiener-like filtering performed in the wavelet domain by means of an adaptive shrinkage of the detail coefficients of an undecimated decomposition. The amplitude of each coefficient is divided by the variance ratio of the noisy coefficient to the noise-free one. All the above quantities are analytically calculated from the speckled image, the speckle variance, and the wavelet filters. On the test image Lenna corrupted by synthetic speckle, the proposed method outperforms Kuan's LLMMSE filtering by almost 3 dB SNR. Experiments carried out on true and synthetic speckled images demonstrate that the visual quality of the results is excellent in terms of both background smoothing and preservation of edge sharpness and textures. The absence of decimation in the wavelet decomposition avoids the typical ringing impairments produced by critically-subsampled wavelet-based denoising.
Hidden Markov models have been used in a wide variety of wavelet-based statistical signalprocessingapplications. Typically, Gaussian mixture distributions are used to model the wavelet coefficients and the correlati...
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ISBN:
(纸本)0780370414
Hidden Markov models have been used in a wide variety of wavelet-based statistical signalprocessingapplications. Typically, Gaussian mixture distributions are used to model the wavelet coefficients and the correlation between the magnitudes of the wavelet coefficients within each scale and/or across the scales is captured by a Markov tree imposed on the (hidden) states of the mixture. This paper investigates correlations directly among the wavelet coefficient amplitudes (sign x magnitude), instead of magnitudes alone. Our theoretical analysis shows that the coefficients display significant correlations in sign as well as magnitude, especially near strong edges. We propose a new wavelet-based HMM structure based on mixtures of one-sided exponential densities that exploits both sign and magnitude correlations. We also investigate the application of this for denoising the signals corrupted by additive white Gaussian noise. Using some examples with standard test signals, we show that our new method can achieve better mean squared error, and the resulting denoised signals are generally much smoother.
Poor directional selectivity, a major disadvantage of the separable 2D discrete wavelet transform (DWT), has previously been circumvented either by using highly redundant, nonseparable wavelet transforms or by using r...
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ISBN:
(纸本)0819437646
Poor directional selectivity, a major disadvantage of the separable 2D discrete wavelet transform (DWT), has previously been circumvented either by using highly redundant, nonseparable wavelet transforms or by using restrictive designs to obtain a pair of wavelet. trees. In this paper, we demonstrate that superior directional selectivity may be obtained with no redundancy in any separable wavelet transform. We achieve this by projecting the wavelet coefficients to separate approximately the positive and negative frequencies. Subsequent decimation maintains nonredundancy. A novel reconstruction step guarantees perfect reconstruction within this critically-sampled framework. Although our transform generates complex-valued coefficients, it may be implemented with a fast algorithm that uses only real arithmetic. We also explain how redundancy may be judiciously introduced into our transform to benefit certain applications. To demonstrate the efficacy of our projection technique, we show that it achieves state-of-the-art performance in a seismic image-processing application.
Efficient image watermarking techniques have been developed in the wavelet domain. Similar to other wavelet-based imageprocessing, the choice of wavelet filters generally affects the performance of a wavelet-based wa...
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Efficient image watermarking techniques have been developed in the wavelet domain. Similar to other wavelet-based imageprocessing, the choice of wavelet filters generally affects the performance of a wavelet-based watermarking system. In this paper, we evaluate the performance of a set of biorthogonal integer wavelets under a multiresolution-watermarking framework. Biorthogonal integer wavelets have been extensively used for imageapplications because they possess the linear-phase property and can be efficiently implemented. We find that the widely adopted 9/7-F wavelet achieves the best robustness performance. Further investigation is conducted to show that the superiority of the 9/7-F wavelet is primarily owing to its being nearly orthogonal.
A perspective invariant function has been derived. It is based on analyzing the object boundary using the dyadic wavelet transform. Five dyadic wavelet transform levels are used to define the invariant function. The s...
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ISBN:
(纸本)0819437646
A perspective invariant function has been derived. It is based on analyzing the object boundary using the dyadic wavelet transform. Five dyadic wavelet transform levels are used to define the invariant function. The selection of the dyadic levels is discussed. Experimental results test the recognition power of the proposed invariant function. In addition: the stability of the invariant function is examined.
The objective of this investigation is to apply waveletimageprocessing to Four-Wave Mixing (FWM) for the purpose of defining beam interaction both within and outside the nonlinear crystal. This will allow a better u...
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ISBN:
(纸本)0819443670
The objective of this investigation is to apply waveletimageprocessing to Four-Wave Mixing (FWM) for the purpose of defining beam interaction both within and outside the nonlinear crystal. This will allow a better understanding of beam quality and allow for better performance of potential devices.
Combined use of the X-ray (Radon) transform and the wavelet transform has proved to be useful in application areas such as diagnostic medicine and seismology. In the present paper, the wavelet X-ray transform is intro...
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ISBN:
(纸本)0819425915
Combined use of the X-ray (Radon) transform and the wavelet transform has proved to be useful in application areas such as diagnostic medicine and seismology. In the present paper, the wavelet X-ray transform is introduced. This transform performs one-dimensional wavelet transforms along lines in R-n, which are parameterized in the same fashion as for the X-ray transform. It is shown that the transform has the same convenient inversion properties as the wavelet transform. The reconstruction formula receives further attention in order to obtain usable discretizations of the transform. Finally, a connection between the wavelet X-ray transform and the filtered backprojection formula is discussed.
This paper provides an overview of subband and wavelet theories. It emphasizes their strong relations. The practical merits of these decomposition techniques in signalprocessing are examined. The current status of th...
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ISBN:
(纸本)0819412236
This paper provides an overview of subband and wavelet theories. It emphasizes their strong relations. The practical merits of these decomposition techniques in signalprocessing are examined. The current status of this active research field is summarized and it concludes with the discussion of potential extensions for future study.
We introduce a pose estimation method for synthetic aperture radar (SAR) imagery using the 2-D continuous wavelet transform (CWT). The computational complexity of the new approach is comparable to other image-based ap...
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ISBN:
(纸本)0819437646
We introduce a pose estimation method for synthetic aperture radar (SAR) imagery using the 2-D continuous wavelet transform (CWT). The computational complexity of the new approach is comparable to other image-based approaches such as ones that incorporate principle component analysis (PCA). Using the public domain MSTAR database, we show that the CWT-based method provides a better pose estimate than the PCA method.
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