Removing noise from original image is a challenging problem for researchers. There have been several published algorithms and each approach has its assumptions, advantages and limitations In this paper, we propose a m...
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Multi-scale transforms have got a lot of applications in imageprocessing, in recent years. wavelet transform is a powerful multiscale transform for denoising noisy signals and images, but the usual two-dimensional se...
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ISBN:
(纸本)0819464236
Multi-scale transforms have got a lot of applications in imageprocessing, in recent years. wavelet transform is a powerful multiscale transform for denoising noisy signals and images, but the usual two-dimensional separable wavelets are sub-optimal. These separable wavelet transforms can successfully identify zero dimensional singularities in images, but can weakly identify one dimensional singularities such as edges, curves and lines. In this sense, non-separable transforms such as Ridgelet and Curvelet transforms are proposed by Candes and Donoho. The coefficients produced by these non-separable transforms have shown to be sparser than wavelet coefficients. This fact results in better denoising capabilities than wavelet transform. These new non-separable transforms can identify direction in lines and curves, because of special structure of their basis elements. Basically, Magnetic Resonance images are probable to have Rician noise. In some special cases, this kind of noise can be supposed to be white Gaussian noise. In this paper, a new method for denoising MR images is proposed. This method is based on Monoscale Ridgelet transform. It is shown that this transform can successfully denoise MR images embedded in white Gaussian noise. The results are better in comparison with usual wavelet denoising methods, based on both visual perception and signal-to-noise ratio.
wavelet-based techniques for an automated classification of magnifying endoscope images with respect to pit patterns of colon lesions are discussed and compared. Algorithms classically used for wavelet-based classific...
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ISBN:
(纸本)0863416586
wavelet-based techniques for an automated classification of magnifying endoscope images with respect to pit patterns of colon lesions are discussed and compared. Algorithms classically used for wavelet-based classification but developed originally for texture classification applications provide encouraging results but still lack of the accuracy required for sensible clinical usage.
This paper presents a novel method for automatic segmentation of blood vessel in coronary angiographic images. The proposed algorithm composed of two steps, coronary angiogram enhancement process and entropy based thr...
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ISBN:
(纸本)0863416586
This paper presents a novel method for automatic segmentation of blood vessel in coronary angiographic images. The proposed algorithm composed of two steps, coronary angiogram enhancement process and entropy based thresholding. In the first step, a set of directional basis filters based on dyadic wavelet transform is designed to enhance blood vessels. Gaussian wavelet is used to fix the blood vessel directional information and its associated changes in coronary angiogram and a gradient image is obtained. Secondly the thresholding approach that evaluates 2-D entropy based on gray level gradient co-occurrence matrix is used to segment blood vessel from the background. The result of this method promises the simpleness and flexibility in many image enhancement and segmentation applications.
For nonseparable bidimensional wavelet transforms, the choice of the dilation matrix is all-important, since it governs the downsampling and upsampling steps, determines the cosets that give the positions of the filte...
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ISBN:
(纸本)3540446303
For nonseparable bidimensional wavelet transforms, the choice of the dilation matrix is all-important, since it governs the downsampling and upsampling steps, determines the cosets that give the positions of the filters, and defines the elementary set that gives a tesselation of the plane. We introduce nonseparable bidimensional wavelets, and give formulae for the analysis and synthesis of images. We analyze several dilation matrices, and show how the wavelet transform operates visually. We also show some distorsions produced by some of these matrices. We show that the requirement of their eigenvalues being greater than 1 in absolute value is not enough to guarantee their suitability for imageprocessingapplications, and discuss other conditions.
State-of-the-art signal compression and reconstruction techniques utilize wavelets. However, recently published research demonstrated that a genetic algorithm (GA) is capable of evolving non-wavelet inverse transforms...
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ISBN:
(纸本)0819462845
State-of-the-art signal compression and reconstruction techniques utilize wavelets. However, recently published research demonstrated that a genetic algorithm (GA) is capable of evolving non-wavelet inverse transforms that consistently outperform wavelets when used to reconstruct one- and two-dimensional signals under conditions subject to quantization error. This paper summarizes the results of a series of three follow-on experiments. First, a GA is developed to evolve matched forward and inverse transform pairs that simultaneously minimize the compressed file size (FS) and the squared error (SE) in the reconstructed file. Second, this GA is extended to evolve a single set of coefficients that may be used at every level of a multi-resolution analysis (MRA) transform. Third, this GA is expanded to achieve additional SE reduction by evolving a different set of coefficients for each level of an MRA transform. Test results indicate that coefficients evolved against a single representative training image generalize to effectively reduce SE for a broad class of reconstructed images.
Adaptive filters are important application in the signalprocessing field. This paper discusses the adaptive local noise removal algorithm proposed by Professor Rafael C. Gonzalez and points out its shortcomings. To i...
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ISBN:
(纸本)9812700420
Adaptive filters are important application in the signalprocessing field. This paper discusses the adaptive local noise removal algorithm proposed by Professor Rafael C. Gonzalez and points out its shortcomings. To improve the algorithm, a new method, geometric mean based adaptive local noise removal algorithm, has been proposed. The simulation results indicate that the new algorithm is more satisfactory. The mean square error e(mse) is reduced by 1/4. The signals to noise ratios (i.e., SNR, SNRm, PSRN) are raised by 1/10. This algorithm has been shown promise for applications.
The goal of this paper is to present a quantitative study about Telco churn analysis and the inherent problems of its application and computer processing. An independent customer characterizes the approach and the pre...
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ISBN:
(纸本)1845641787
The goal of this paper is to present a quantitative study about Telco churn analysis and the inherent problems of its application and computer processing. An independent customer characterizes the approach and the pre-processing step uses the wavelet transform concept;the pattern classification problem is solved by an artificial neural network (RBF- Radial Basis Function). The signal representation considers different levels of resolution (multi-resolution). This idea is frequently used in image/video processing where general image versions with a low resolution are stored in different levels of resolution. The concepts of multi-resolution have been implemented by a digital filter bank, Hi-pass and Low-pass. Each sub-band will give the best resolution, for each spectral region. The idea is to look for a spectral transient. A scalable Daubechies' function db 2 and db 3 were tested for this study and the results were used as input for the RBF neural network. Daubechies' function has shown important properties as for instance, orthogonality and scalability, which are not presented by Morlet's function. Some results of the experiment were presented to point out the performance of the wavelet pre-processing approach.
In many parts of the world, breast cancer is the leading cause mortality among women and it is the major cause of cancer death, next only to lung cancer. In recent years, microwave imaging has shown its potential as a...
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ISBN:
(纸本)0819461865
In many parts of the world, breast cancer is the leading cause mortality among women and it is the major cause of cancer death, next only to lung cancer. In recent years, microwave imaging has shown its potential as an alternative approach for breast cancer detection. Although advances have improved the likelihood of developing an early detection system based on this technology, there are still limitations. One of these limitations is that target responses are often obscured by surface reflections. Contrary to ground penetrating radar applications, a simple reference subtraction cannot be easily applied to alleviate this problem due to differences in the breast skin composition between patients. A novel surface removal technique for the removal of these high intensity reflections is proposed in this paper. This paper presents an algorithm based on the multiplication of adjacent wavelet subbands in order to enhance target echoes while reducing skin reflections. In these multiscale products, target signatures can be effectively distinguished from surface reflections. A simple threshold is applied to the signal in the wavelet domain in order to eliminate the skin responses. This final signal is reconstructed to the spatial domain in order to obtain a focused image. The proposed algorithm yielded promising results when applied to real data obtained from a phantom which mimics the dielectric properties of breast, cancer and skin tissues.
A new method for image compression based on Morphological Associative Memories (MAM) is proposed. We used MAM at the transformation stage of image coding, thereby replacing the traditional methods such as Discrete Cos...
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ISBN:
(纸本)3540465561
A new method for image compression based on Morphological Associative Memories (MAM) is proposed. We used MAM at the transformation stage of image coding, thereby replacing the traditional methods such as Discrete Cosine Transform or wavelet Transform. After applying the MAM, the informative image data are concentrated in a minimum of values. The next stages of image coding can be obtained by taking advantage of this new representation of the image. The main advantage offered by the MAM with respect to the traditional methods is the speed of processing, whereas the compression rate and the obtained signal to noise ratios compete with the traditional methods.
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