We define and characterize a frame-like stable decomposition for subspaces in a separable Hilbert space. We call in pseudoframes for subspaces (PFFS). Properties of PFFS are discussed. A necessary and sufficient condi...
详细信息
ISBN:
(纸本)0819429139
We define and characterize a frame-like stable decomposition for subspaces in a separable Hilbert space. We call in pseudoframes for subspaces (PFFS). Properties of PFFS are discussed. A necessary and sufficient condition for the construction is provided. An analytical formula for the construction of PFFS is also derived. An example is studied both as a motivation of the theoretical study of such pseudoframes and as an actual construction. Potential applications of PFFS are discussed.
wavelet transform is an efficient way to perform multiresolution signal decomposition with a good time and frequency resolution and simple generation of families of functions to generate bases of the space of square s...
详细信息
ISBN:
(纸本)085296692X
wavelet transform is an efficient way to perform multiresolution signal decomposition with a good time and frequency resolution and simple generation of families of functions to generate bases of the space of square summable sequences. The basis functions used in the wavelet transform are all affine transformed versions of the original function. The compactly supported wavelets are defined from a scaling function that is the solution of a fractal-like equation. The multiresolution fractal coders lead to better results, both in terms of rate-distortion curves and visual quality.
We present a path-and motion-planning scheme that is "multiresolution" both in the sense of representing the environment with high accuracy only locally and in the sense of addressing the vehicle kinematic a...
详细信息
We present a path-and motion-planning scheme that is "multiresolution" both in the sense of representing the environment with high accuracy only locally and in the sense of addressing the vehicle kinematic and dynamic constraints only locally. The proposed scheme uses rectangular multiresolution cell decompositions, efficiently generated using the wavelet transform. The wavelet transform is widely used in signal and imageprocessing, with emerging applications in autonomous sensing and perception systems. The proposed motion planner enables the simultaneous use of the wavelet transform in both the perception and in the motion-planning layers of vehicle autonomy, thus potentially reducing online computations. We rigorously prove the completeness of the proposed path-planning scheme, and we provide numerical simulation results to illustrate its efficacy.
Sparse signal representations and compressed sensing have found use in a large number of applications including image compression. Compressed sensing exploits the sparsity of naturally occurring images to reduce the v...
详细信息
ISBN:
(纸本)9781467321976;9781467321969
Sparse signal representations and compressed sensing have found use in a large number of applications including image compression. Compressed sensing exploits the sparsity of naturally occurring images to reduce the volume of the data by using less number of measurements. Inspired by this, we propose a new framework for image compression that combines compressed sensing theory with wavelet and vector quantization. wavelet transform is used to sparsify the input image while measurement vectors generated from the sparse vectors are transmitted using vector quantization. Simulation experiments are carried out to analyze the effects of various parameters on the image reconstruction quality. Results obtained have been found to be quite promising.
Sleep Apnoea Syndromes (SAS) is a sleep disorder which caused breathing pauses during sleep at night. There is various method of analyzing sleep EEG signals can be found in the literature. In this paper both linear;Di...
详细信息
ISBN:
(纸本)9781509055593
Sleep Apnoea Syndromes (SAS) is a sleep disorder which caused breathing pauses during sleep at night. There is various method of analyzing sleep EEG signals can be found in the literature. In this paper both linear;Discrete wavelet Transform (DWT) and non-linear;Approximate Entropy (ApEn) extraction methods were performed to differentiate features of each sleep stages between apnoea and healthy person. The efficiency of both extraction methods was compared by using ANOvA. In our study, we observed the non-linear feature of ApEn improves the ability to discriminate healthy and sleep apnoea at different sleep stages.
wavelets provide an attractive method for efficient image compression. For transmission across noisy or bandwidth limited channels, a signal may be subjected to quantization in which the signal is transcribed onto a r...
详细信息
ISBN:
(纸本)9780819486332
wavelets provide an attractive method for efficient image compression. For transmission across noisy or bandwidth limited channels, a signal may be subjected to quantization in which the signal is transcribed onto a reduced alphabet in order to save bandwidth. Unfortunately, the performance of the discrete wavelet transform (DWT) degrades at increasing levels of quantization. In recent years, evolutionary algorithms (EAs) have been employed to optimize wavelet-inspired transform filters to improve compression performance in the presence of quantization. wavelet filters consist of a pair of real-valued coefficient sets;one set represents the compression filter while the other set defines the image reconstruction filter. The reconstruction filter is defined as the biorthogonal inverse of the compression filter. Previous research focused upon two approaches to filter optimization. In one approach, the original wavelet filter is used for image compression while the reconstruction filter is evolved by an EA. In the second approach, both the compression and reconstruction filters are evolved. In both cases, the filters are not biorthogonally related to one another. We propose a novel approach to filter evolution. The EA optimizes a compression filter. Rather than using a wavelet filter or evolving a second filter for reconstruction, the reconstruction filter is computed as the biorthogonal inverse of the evolved compression filter. The resulting filter pair retains some of the mathematical properties of wavelets. This paper compares this new approach to existing filter optimization approaches to determine its suitability for the optimization of image filters appropriate for defense applications of imageprocessing.
This paper describes an approach for accomplishing sub- octave wavelet analysis and its discrete implementation for noise reduction and feature enhancement. Sub-octave wavelet transforms allow us to more closely chara...
详细信息
This paper proposes an image steganography for hiding secret images. The objective of the proposed work is to increase the embedding capacity while ensuring the security of the image. This has been addressed using two...
详细信息
ISBN:
(纸本)9781509043811
This paper proposes an image steganography for hiding secret images. The objective of the proposed work is to increase the embedding capacity while ensuring the security of the image. This has been addressed using two levels of processing. First is the application of Genetic Algorithm (GA) as 'before embedding hiding technique' which tries to identify suitable places in cover image where embedding of secret image will not lead to much distortion in the image. Second process is improvement using Discrete Cosine Transform (DCT) and its wavelet (DCWT) to gain the advantage of their energy compaction property. The secret image is embedded in the lower energy transformed regions of the cover image. The paper makes a comparison between DCT and DCWT (with and without using GA). The experimental results are evaluated using various performance evaluation parameters such as Mean Square Error (MSE), Peak signal-to-Noise Ratio (PSNR) and Correlation. The overall comparison proves that both DCT and DCWT perform better when combined with genetic algorithm. This work also proves that the proposed two level processing contributes in improvement of both security as well as embedding capacity for the image steganography.
In this work we present a technique based on wavelet analysis for EEGs processing of epileptic patients explored with scalp electrodes. Our aims is to provide a contribution to the automatic treatment of EEGs in the f...
详细信息
ISBN:
(纸本)0819437646
In this work we present a technique based on wavelet analysis for EEGs processing of epileptic patients explored with scalp electrodes. Our aims is to provide a contribution to the automatic treatment of EEGs in the following areas of clinical applications: detection of transients, data reduction in long-term records and tracking of crisis propagation. We show the results obtained with the proposed method applied to several EEGs records.
We present a definition of wavelet-bicoherence based on wavelet-polyspectra. We propose a simple estimator for wavelet-bicoherence, and discuss its statistical properties. In particular it is shown that wavelet-bicohe...
详细信息
ISBN:
(纸本)0780370414
We present a definition of wavelet-bicoherence based on wavelet-polyspectra. We propose a simple estimator for wavelet-bicoherence, and discuss its statistical properties. In particular it is shown that wavelet-bicoherence estimates has a larger number of effective degrees of freedom than traditional Fourier-based bicoherence estimates. The proposed estimator is applied to detection of coherent couplings in rocket measurements from the ionospheric E-region. It is concluded that wavelet-bicoherence is a well suited toot for analysis of non-stationary mode coupling.
暂无评论