Abstract —The design and analysis of nearly-orthogonal symmetric wavelet filter banks has been studied. Methods for analyzing the correlation of the nearly-orthogonal filter banks are proposed. The basic idea is to impose multiple zeros at the aliasing frequency to a symmetric filter, minimize the deviation of the filter satisfying the orthogonal condition, and a nearly orthogonal filter bank can be obtained. Since multiple zeros are imposed, a scaling function may be generated from the minimized filter. The integer translates of the wavelet and the scaling functions are nearly orthogonal. The integer translates of the wavelet at different scale are completely orthogonal. We will construct a perfect reconstructed semi-orthogonal filter bank. Detailed analysis of correlation of the nearly- orthogonal filter banks are given in this paper.
10 Read more
The wavelet transform is rapidly used for image cod- ing. Because in it has the progressive image transmis- sion concept features like quality or resolution scaling. Wavelets are crucial component of different systems like JPEG2000 system, MPEG-4. Discrete wavelet trans- forms (DWT) can draw favorable attention due the main features of disintegrating the image or signal onto explode ofbasic functions that are with the apparition- al properties.Many signal processing systems relays on wavelet filter banks .Wavelets are employed innu- merical analysis also Wavelets can beutilized , , real-time commutations , image enhancement and compression , , pattern
A new family of multiplier-less two-channel low-delay wavelet filter banks using the PR structure in  and the SOPOT representation is presented. The functions α ( z ) and β (z ) in the structure are chosen as nonlinear-phase FIR and IIR filters, and the design of such multiplier-less filter banks is performed using the genetic algorithm. It was found that GA is able to find very good solution to this problem. The proposed design method is very simple to apply, and is sufficiently general to construct low- delay wavelet bases with flexible length, delay, and number of zero at π (or 0) in their analysis filters. Several design examples are given to demonstrate the usefulness of the proposed method.
Content based image retrieval (CBIR) is an imperative and testing errand in numerous fields, for example, military, common, restorative and even in web applications. Here, we introduced novel content based medical image retrieval with decimated bi- orthogonal spline wavelet filter banks. Proposed algorithm is an extension for the existing low level feature extraction method done by using spline wavelet filters, also utilized iterative partitioning (IP) for extracting the similar patterns of query and database images. Simulation results shows that the proposed method has performed superior to the existing scheme in terms of precision and recall. Key words: CBIR, Bi-orthogonal spline wavelets, DWT, segmentation, iterative partitioning and precision
a shift of the natural frequencies due to damage. In this regard, it is natural to expect that the use of wavelet bases (or, equivalently, wavelet analysis filter banks) capable of resolving fine differences in the signal energy distribution in the frequency domain, or among the wavelet analysis scales, renders the RWE more effective for stationary damage detection. However, the Haar (non-smooth Daubechies) wavelet filter bank employed by Ren and Sun (2008) to compute the RWE is known to have significant overlapping between the frequency bands corresponding to different wavelet analysis scales (e.g., Vetterli and Herley 1992). Indeed, Yun et al. (2011) reported the problem of signal energy leakage among wavelet scales (spectral leakage) in using Haar wavelets for RWE-based damage detection, which renders the interpretation of the RWE values a challenging task. Further, in the above work, limited results using a smooth (higher-order) Daubechies wavelet filter bank, which attains improved frequency resolution attributes compared to the Haar wavelet basis, were provided and the authors noted that the use of different analysis wavelets influences the obtained RWE values. However, the authors neither did they attempt any direct comparison between different wavelet filter banks, nor did they provide recommendations to indicate a preferable wavelet filter bank. Moreover, despite being computationally efficient, the standard dyadic (octave) frequency domain discretization of the DWT used in Ren and Sun (2008) and Yun et al. (2011) does not facilitate a detailed characterization of high frequency content. This limitation may hinder damage detection and localization based on changes to the energy of response acceleration signals related to the higher modes of vibration (e.g., Yen and Lin 2000). The continuous wavelet transform (CWT) considered by Lee et al. (2014) may overcome the latter limitation, but at the expense of significant computational cost which may not be cost-efficient to be accommodated by wireless sensors.
34 Read more
Copyright © 2010 Guoan Yang et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The contourlet transform can deal eﬀectively with images which have directional information such as contour and texture. In contrast to wavelets for which there exists many good filters, the contourlet filter design for image processing applications is still an ongoing work. Therefore, this paper presents an approach for designing the contourlet filter based on the Chebyshev best uniform approximation for achieving an eﬃcient image denoising applications using hidden Markov tree models in the contourlet domain. Here, we design both the optimal 9/7 wavelet filter banks with rational coeﬃcients and new pkva 12 filter. In this paper, the Laplacian pyramid followed by the direction filter banks decomposition in the contourlet transform using the two filter banks above and the image denoising applications in the contourlet hidden Markov tree model are implemented, respectively. The experimental results show that the denoising performance of the test image Zelda in terms of peak signal-to-noise ratio is improved by 0.33 dB than using CDF 9/7 filter banks with irrational coeﬃcients on the JPEG2000 standard and standard pkva 12 filter, and visual eﬀects are as good as compared with the research results of Duncan D.-Y. Po and Minh N. Do.
10 Read more
Maximum regular wavelet filter banks have received much attention in the literature, and it is a general conception that they enjoy some type of optimality for image coding purposes. To investigate this claim, this article focuses on one particular biorthogonal wavelet filter bank, namely, the 2-channel 9/7. As a comparison, we generate all possible 9/7 filter banks with perfect reconstruc- tion and linear phase while having a diﬀerent number of zeros at z = − 1 for both analysis and synthesis lowpass filters. The best performance is obtained when the filter bank has 2/2 zeros at z = − 1 for the analysis and synthesis lowpass filters, respectively. The competing wavelet 9/7 filter bank, which has 4/4 zeros at z = − 1, is thus judged inferior both in terms of objective error measure- ments and informal visual inspections. It is further shown that the 9/7 wavelet filter bank can be obtained using gain-optimized 9/7 filter bank.
The first filter banks with two channels were introduced by Croisier, Esteban, and Galand  in 1976 when they compressed speech signal by subband coding schemes, which decomposes a discrete signal into two signals of half its size by using a filtering and subsampling procedure. These research showed that the signal can be recovered from these subsampled signals by canceling the aliasing terms with a particular class of filters called conjugate mirror filters (CMF). This breakthrough motivated an active
The computer-based lung respiratory sound analysis, which can provide more information about the condition of lung station, has achieved a great development in recent years. However, the external noise in respiratory sound signal is a large restriction to the further promotion of this technique. In this paper, a kind of serial integrated de-noising algorithms which consist of a FIR band-pass filter and a modified wavelet filter and an adaptive filter, is proposed to suppress the noise in respiratory sound signals. The design of this kind of filter and its practical application are studied. The practical application in de-noise of the lung sound shows that this filter has a good de-noising effect and a good performance in outstanding the acoustic characteristics.
12 Read more
There are various techniques developed by researchers to design filter banks used for different applications   . Filter banks are used in receiver systems in communications where the signals encoded with different carrier frequencies are required to be extracted. Filter banks are also used in compression of signals which contains some frequencies that are more important than others. Here, after decomposition, the important frequencies can be coded with a fine resolution. On the other hand, for less important frequencies coarser coding scheme will be used.
This study explored the potential of computed tomography (CT) textural feature analysis for the stratification of single large hepatocellular carcinomas (HCCs) > 5 cm, and the subsequent determination of patient suitability for liver resection (LR) or transcatheter arterial chemoembolization (TACE). Wavelet decomposition was performed on portal-phase CT images with three bandwidth responses (filter 0, 1.0, and 1.5). Nine textural features of each filter were extracted from regions of interest. Wavelet-2-H (filter 1.0) in LR and wavelet-2-V (filter 0 and 1.0) in TACE were related to survival. Subsequently, LR and TACE patients were divided based on the wavelet- 2-H and wavelet-2-V median at filter 1.0 into two subgroups (+ or -). LR+ patients showed the best survival, followed by LR-, TACE+, and TACE-. We estimated that LR+ patients treated using TACE would exhibit a survival similar to TACE- patients and worse than TACE+ patients, with a severe compromise in overall survival. LR was recommended for TACE- patients, whereas TACE was preferred for LR- and TACE+ patients. Independent of tumor size, CT textural features showed positive and negative correlations with survival after LR and TACE, respectively. Although further validation is needed, texture analysis demonstrated the feasibility of using HCC patient stratification for determining the suitability of LR vs. TACE.
12 Read more
are used instead of D c t matrices in the ELT structure, the impulse response of the prototype filter obtained from this structure is a reversed version of the one which can be ob- tained from the direct ELT structure. If the DST-IV replaces the flipped DCT-IV, the resulting impulse responses of the channel filters are reversed versions of the corresponding fil- ters obtained from the original ELT structure. Moreover, ev- ery other channel filter is multiplied by − 1, that is, every channel is multiplied by ( − 1) k depending on the channel number k . Now everything is fine when K is even, but when K is odd the extra multiplication by − 1 is needed for every channel filter due to the factor ( − 1) K . This multiplication can be included in every butterfly matrix D s t and this results in the following butterfly matrices:
10 Read more
There are many ultrasound image enhancement techniques are suggested as spatial domain and frequency domain based techniques. In this paper, ultra sound image enhancement techniques based on Wiener filter, Median filter, Wavelet filter and Gaussian low pass filter are implemented and analyzed. The quality is evaluated by using MSE and PSNR. From the experimental result, it is found that wavelet filter gives better PSNR value. Hence more researchers are focusing on wavelet filtering.
diversity of prediction and update operators as linear, non- linear or spatially variable, we thus design corresponding adaptive filters via lifting to make them data-dependent, as a result, optimal image representation and accordingly, improved retrieval performance may be achieved. The rest of this paper is organized as follows. In Section 2, we introduce image decomposition approaches via general lifting and its adaptive version as well as classical wavelets. Section 3 provides image feature extraction and similarity criteria based on F-norm theory. Section 4 describes a progressive CBIR strategy. Section 5 presents the implementation and experimental results of above wavelet approaches applied in CBIR. Finally, conclusions and future research are provided
Low-pass Fourier filter, wavelet filter, as well as matched filter detection methods were used to detect baleen whale signals in northern Gulf of Mexico data collected by the Littoral Acoustic Demonstration Center (LADC) consortium. Some potential low frequency signals appeared on the matched filter output figure. The shape of the signals is in line with one of the typical signal shapes of fin whales--vertical down-sweeps with 18s-time interval. Another shape of the signals is in line with one of the call type shapes of Bryde's whales--down-sweeps with 7s-time interval. A high-pass Fourier filter was also used to find toothed whale high frequency sounds in the Gulf of Mexico data. The sounds featuring click trains and codas belonging to sperm whales have been clearly identified.
75 Read more
The TSAF uses multiple filters and each filter is adapted for filtering a particular portion of the interval between regeneration times, and is suitable for tracking signals whose statistical properties recur at various points in time. The filters are trained and the filter weights are obtained via an adaptive algorithm. Fig 3 shows the conceptual realization of TSAF. The averaged TSAF is shown in Fig 4 together the EA using 2000 trials. TSAF and EA are very similar and their correlation coefficient is 0.983, and the measurement time greatly reduced using TSAF. The tracking ability of TSAF makes it possible for the clinician to observe the signal variation trace in every single ensemble .
A novel technique for fault detection, classification and location in series compensated transmission lines is proposed. WT used to extract information from three phase current signals and to process the high frequency details to derive information about the fault. The salient features of this proposed logic are single “dB5” high pass wavelet filter is enough for each phase, need for multipliers avoided using karrenbaur transformation, simple transient energy calculation required for fault detection, classification and location is done. For ground fault adaptive threshold calculation is employed. The logic is fully deterministic, easy to understand, and also the classifier operation is fast and reliable. Simulation results are verified under various fault cases using EMTP.
Abstract:- Wavelets, filter banks and multi-resolution analysis have been used independently in the fields of applied mathematics, signal processing and image processing. It is shown that the wavelets are closely related to filter banks and there is a direct analogy between multi-resolution analysis in continuous time and a filter bank in discrete time. A two-channel filter bank has a low-pass and a high-pass filter in the decomposition phase and another low-pass and a high-pass filter in the reconstruction phase.
The performance of the proposed filter is tested with the image of size 512*512 by adding the salt and pepper noise with the variance 0.01, 0.03, 0.05, 0.07 and 0.1. The PSNR value of the proposed method is found to be improved and MSE value gets decreased than the previous soft thresholding method. The graphical analysis of comparison of PSNR, MSE values of various proposed filters.
In this study we implemented a wavelet transform based multicarrier system which comprised of perfect reconstruction Quadrature mirror filter banks and compared its performance against the conventional Fast Fourier transform based multicarrier system in the Rayleigh multipath fading environment with additive white Gaussian noise using zero forcing channel equalization algorithm which was implemented in time domain just before the DWT process. Results obtained showed slightly better BER performance in favor of the wavelet transform modulation. As no cyclic prefix or guard band was inserted spectral efficiency was improved in DWT as compared to the conventional FFT- OFDM system where in order to counter the degrading effects of ISI cyclic prefixing is required. Consequently, further multicarrier modulation studies can be possible using the DWT-OFDM.