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Signal Processing and Its Applications, 2007. ISSPA 2007. 9th International Symposium on

Date 12-15 Feb. 2007

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Displaying Results 1 - 25 of 366
  • Determination of the group velocity using the time-varying autoregressive TVAR

    Publication Year: 2007 , Page(s): 1 - 4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (236 KB) |  | HTML iconHTML  

    A time-varying autoregressive ldquoTVARrdquo approach is used for modeling nonstationary signals, and frequency information is then extracted from the TVAR parameters. In this study, we present the application of the TVAR spectrum on the acoustic signal backscattered by an elastic tube. The parameters of this model are determined by the adaptive algorithm. The adaptive methods may be sufficient for the TVAR parameter estimation, if the nonstationay part of a signal changes slowly. The time-varying spectrum ldquoTVARSrdquo (power spectral density) is applied to the analysis of the dispersion of symmetric S0 and antisymmetric A1 circumferential waves propagating around a tube with a radii ratio equal to 0.95. From the TFAR representation obtained, we have estimated the group velocity with precision. These velocities are compared with those computed by the proper mode theory given in the scientific literature. A good agreement is obtained. View full abstract»

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  • High resolution SAR imaging with enhanced focusing capabilities using the fractional fourier transform

    Publication Year: 2007 , Page(s): 1 - 4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (212 KB) |  | HTML iconHTML  

    The fractional Fourier transform (FrFT), which is a generalized form of the well-known Fourier transform, has only started to appear in the field of signal processing decade ago. This has opened up the possibility of a new range of potentially promising and useful applications. In this paper we apply the new FrFT-based Chirp Scaling Algorithm (CSA) to a high resolution small target imaging and compare its performance with the classical CSA based on the Fast Fourier Transform (FFT). Simulation results show that the FrFT-based CSA can offer significantly enhanced features compared to the classical FFT-based approach. View full abstract»

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  • Perception-based fingerprint image enhancement

    Publication Year: 2007 , Page(s): 1 - 4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (671 KB) |  | HTML iconHTML  

    People can easily recognize and correct discontinuities in images of regular patterns, such as broken ridges in fingerprint images. By utilizing this idea of human perception, we present in this paper a new fingerprint image enhancement method. The proposed method includes pattern partitioning and blockwise enhancement suitable for fingerprint images. In particular, we divide the fingerprint image into blocks of variable sizes and then apply on each block our pattern partitioning, which uses 20 log-Gabor filters and nearest neighbor clustering. Experimental results show that the proposed method successfully enhances the test fingerprint images, especially from the viewpoint of connecting broken ridges. View full abstract»

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  • Image retrieval based on texture and color method in BTC-VQ compressed domain

    Publication Year: 2007 , Page(s): 1 - 4
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (864 KB) |  | HTML iconHTML  

    Because of high volume of graphic information, the retrieval of compressed images is one of the needs of information era. One of the rapid methods for image compression which has the capability to maintain important information of images for retrieval is Block Truncation Coding (BTC). In this article a new method for retrieval of images compressed by BTC has been provided. This method has been examined on a database consisting of 9983 images with different contents and its results have been compared with similar methods. View full abstract»

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  • Cirols: Codec independent recovery of lost speech packets

    Publication Year: 2007 , Page(s): 1 - 4
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (454 KB) |  | HTML iconHTML  

    In this paper, we have focused on finding an error resilient method for discontinuity-less transmission of speech signals in the Internet. Our proposed method creates artificial correlation between speech samples that pre-distorts the speech signal. The receiver uses this correlation to reconstruct the lost speech packets. A discrete Fourier transform (DFT)-based speech enhancement technique is designed for the reduction of the processing error in the recovered speech caused by the speech codecs. The SegSNR results show the superiority of our proposed method over a proposed speech enhancement technique. View full abstract»

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  • Fractal based classification of Colon cancer tissue images

    Publication Year: 2007 , Page(s): 1 - 4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (193 KB) |  | HTML iconHTML  

    An attempt has been made to classify the histopathological images of colon cancer tissues from the normal tissues based only on fractal features. The tissue images are modelled as fractal sets in E3 euclidian space. A new fractal feature estimation algorithm has been used. We call it true box counting method. It is seen that lacunarity features are important parameters and are more important in classification or segmentation than other fractal features like fractal dimension and mass dimension. View full abstract»

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  • Block-shanno MBER beamforming

    Publication Year: 2007 , Page(s): 1 - 4
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1183 KB) |  | HTML iconHTML  

    We formulate a block processing objective function for the bit error rate (BER) cost function and present a nonlinear optimization strategy for its rapid minimization. The resulting algorithm is called the block Shanno minimum BER (BSMBER), which is conducted in the context of DS-CDMA with beamforming applications. Simulation analyses show the enhancements in convergence rate and BER performance of the proposed BSMBER over the popular MMSE and other minimum BER (MBER) based algorithms. In addition, the proposed algorithm has faster convergence rate over the gradient Newton algorithms while maintaining linearity in complexity. View full abstract»

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  • The defect of wavelet based image compression method and the way of improvement

    Publication Year: 2007 , Page(s): 1 - 4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (352 KB) |  | HTML iconHTML  

    From the aspect of the human visual system (HVS), the wavelet based image compression algorithm is analyzed first. A conclusion is drawn that such algorithm has an inherent defect when used for the images with rich details, such as remote sensing city images. A different kind of image compression algorithm based on spatial structure description is introduced and proved which is superior to wavelet based one on reserving image details. The compression result is more conform to the human visual system. View full abstract»

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  • A hybrid model for face recognition using facial components

    Publication Year: 2007 , Page(s): 1 - 4
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (321 KB) |  | HTML iconHTML  

    It is generally agreed that faces are not recognized only by utilizing some holistic search among all learned faces, but also through a feature analysis that aimed to specify more important features of each specific face. This paper addresses a novel decision strategy that efficiently uses both holistic and facial component (eye, nose and mouth) feature analysis to recognize faces. The proposed algorithm first performs a holistic search using the whole image features and selects probable candidates for further processing. Then the facial features of these probable candidates are compared and classified with the stored patterns in the train set. Finally the classification results are fused with a weighted majority voting to form the final decision. Simulation studies justify the superior performance of the proposed method as compared to that of Eigenface method. View full abstract»

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  • A sufficient condition for infinite connectivity in two dimensional ad-hoc wireless sensor networks

    Publication Year: 2007 , Page(s): 1 - 4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (319 KB) |  | HTML iconHTML  

    In this paper connectivity problem in wireless ad-hoc sensor networks is discussed. Asymptotic cases are considered. A relationship between coverage and connectivity in these networks is stated, generalized and used to find some upper bounds for transmitting capability of sensors. We introduce some concepts as multiconnectivity, infinite-connectivity and discuss their relation to fault tolerance in a sensor network. A sufficient condition for the order of connectivity to grow faster than the number of nodes is declared and proven. View full abstract»

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  • A novel technique for words reordering based on N-grams

    Publication Year: 2007 , Page(s): 1 - 4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (300 KB) |  | HTML iconHTML  

    This paper presents an approach for repairing word order errors in English text by reordering words in a sentence and choosing the version that maximizes the number of trigram hits according to a language model. The novelty of this method concerns the use of an efficient confusion matrix technique for reordering the words. For further reducing the number of permutations the use of unigramspsila probability is used. The comparative advantage of this method is that works with a large set of words, and avoids the laborious and costly process of collecting word order errors for creating error patterns. View full abstract»

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  • Asymptotic computation in mode decision for H.264/AVC video coding

    Publication Year: 2007 , Page(s): 1 - 4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (288 KB) |  | HTML iconHTML  

    In this paper asymptotic computation in intermode decision as a function of the quantization parameters (QPs) is defined and statistically calculated. The computation cost in several mode decision algorithms, is investigated and compared with the asymptotic computation. The experimental results reveal that the investigated algorithms are only suitable for high bit rate coding. To reduce the computation cost and maintain coding performance in low bit rate coding, a zero-block detection algorithm is proposed. The result indicates that the proposed algorithm is more suitable for low bit rate coding. View full abstract»

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  • Computationally efficient fine grained scalability for low bit rate video coding

    Publication Year: 2007 , Page(s): 1 - 4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (266 KB) |  | HTML iconHTML  

    Real time transmission of video contents of optimal quality over a varying bandwidth network like Internet is a challenging task. A codec, in this scenario, should be able to cope with the packet loss and bandwidth variation for the transmitted stream. Fine Granular Scalability (FGS) has been adopted in MPEG-4 standard to provide optimal video quality over a range of bandwidths. FGS is well suited to coping with varying bandwidths but it has the drawbacks of involving expensive computations and the fact that the enhancement layer adds considerably to the overall size of the coded bit stream. This may lead to congestion in a low bit rate connection. This paper suggests structural improvements in FGS codec so that it can be efficiently used for low bit rate connections in real time applications. The proposed scheme is based on open loop and closed loop enhancement predictions that can provide up to 35 times reduction in coding time. View full abstract»

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  • A novel AGC scheme for QAM demodulator applications

    Publication Year: 2007 , Page(s): 1 - 4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (320 KB) |  | HTML iconHTML  

    The performance of traditional approaches of automatic gain control (AGC) will be seriously degraded by intersymbol interference (ISI). This could result in slow convergence and possible instability problems. In this paper, we propose an equalizer-based AGC scheme to overcome the ISI interference and it uses the error signal of the equalizer output to control the AGC loop direction. Simulation results demonstrate good acquisition and tracking performances of the new scheme under large ISI circumstances. Our equalizer-based AGC is already silicon-proven for the application of QAM demodulator using charter 0.25 um cell libraries. View full abstract»

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  • Image compression based on color morphological pyramidal decomposition

    Publication Year: 2007 , Page(s): 1 - 4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (275 KB) |  | HTML iconHTML  

    In this work, a pyramidal technique designed for color image compression is introduced, and, is based on a combination of a modified morphological pyramid and adaptive Vector Quantizer. This hierarchical structure gives an ability to produce high color image quality (35-48 dB) at low bit rates (0.1-0.9 bpp). The proposed scheme contains a multi-level pyramid based on modified morphological filters; then, the resulting pyramid levels are applied to a suitable 3D VQ encoder. View full abstract»

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  • Statistical mesh distributions for 3D object topology

    Publication Year: 2007 , Page(s): 1 - 4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (936 KB) |  | HTML iconHTML  

    In this paper we introduce several statistical distributions to analyze the topological properties of 3D graphics. The proposed statistical measures include the mesh degree, the mesh assortativity, the mesh clustering coefficient, and the mesh geodesic distance distributions. These probabilistic distributions provide useful information about the way 3D mesh models are connected. Illustrating experimental results show the effectiveness of the proposed measures in quantifying the topological features of 3D objects. View full abstract»

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  • A novel conjugate gradient-based source localization algorithm

    Publication Year: 2007 , Page(s): 1 - 4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (411 KB) |  | HTML iconHTML  

    A new method for the subspace-based direction of arrival (DOA) estimation procedure without eigenvector computation is proposed. From the residual vectors of the conjugate gradient (CG) method which form a Krylov subspace basis, we build a test spectrum for DOA estimation. This approach is based on the same recently developed procedure which uses a non-eigenvector basis derived from the auxiliary vectors (AV). The AV basis calculation algorithm is replaced by the residual vectors of the CG algorithm. The initial conditions of the CG algorithm start with the linear transformation of the array response search vector by the input covariance matrix. Then, successive orthogonal gradient vectors are derived to form a basis of the signal subspace. The proposed CG-based method outperforms its counterparts in term of resolution of closely spaced-sources with a small number of snapshots and a low signal-to-noise ratio (SNR). View full abstract»

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  • A high-performance architecture for irregular LDPC decoding algorithm using input-multiplexing method

    Publication Year: 2007 , Page(s): 1 - 4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (266 KB) |  | HTML iconHTML  

    A new high-performance architecture for decoding the irregular Low-Density Parity-Check (LDPC) codes with respect to the iterative message-passing decoding algorithm is explored. The proposed method is based on reducing the logic delays in the iterative processing of the bit nodes and check nodes leading to the increment of maximum possible frequency. The simulations show the efficiency of the proposed method in low/high-complexity graph matrices, though it is more effective in high-complexity ones. About 28% reduction of the combinational delay in the bit/check processors is explored without much impacting the area consumption. View full abstract»

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  • Noise and speaker robustness in a Persian continuous speech recognition system

    Publication Year: 2007 , Page(s): 1 - 4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (247 KB) |  | HTML iconHTML  

    In this paper VTLN speaker normalization, MLLR and MAP adaptation methods are investigated in a Persian HMM-based speaker independent large vocabulary continuous speech recognition system. Speaker and environmental noise robustness are achieved in real world applications for this system. A search-based method is used in VTLN to find speaker relative warping factors. The warping factors are applied to signalpsilas spectrum to normalize the variation effect of VTL between speakers. In the MLLR framework, Gaussian mean and covariance transformations in global and full adaptation are experienced. In this method, regression tree based adaptation in batch-supervised fashion is used. Also the standard MAP is experienced as an adaptation method. Combinations of these approaches with CMN robust feature method are evaluated on 4 different tasks. Significant improvement is achieved in the recognition performance in noisy environments such that it makes the system operational in real applications. View full abstract»

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  • Prototype waveform optimization for an OFDM/OQAM system with hexagonal time-frequency lattice structure

    Publication Year: 2007 , Page(s): 1 - 4
    Cited by:  Papers (1)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (426 KB) |  | HTML iconHTML  

    This paper deals with the optimization of the time-frequency localization of the prototype waveform for OFDM/OQAM with hexagonal time-frequency lattice. The set of orthonormal waveforms among which the optimally localized one should be searched are obtained as the orthonormalization of mother functions well localized in time-frequency. To preserve as much as possible the good localization of the original mother functions, the canonical form of the orthonormalization procedure is used. For an easy and systematic way to generate well localized mother functions, we use the orthonormal base of Hermite functions, which are known to provide, in decreasing order, the best time-frequency localization. To preserve the pi/3 rotational invariance of the hexagonal lattice in the ambiguity function of each candidate prototype function, only Hermite functions with indices multiple of 6 are allowed. The obtained numerical results show that the optimized prototype waveform outperforms in localization the best localized waveform for OFDM/OQAM with square time-frequency lattice. View full abstract»

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  • Periodic/aperiodic decomposition for improving coherence based multi-channel speech denoising

    Publication Year: 2007 , Page(s): 1 - 4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (250 KB) |  | HTML iconHTML  

    In this paper, we are interested in bi-channel speech denoising by exploiting the ldquosimilarityrdquo between the observations expressed in term of spectral coherence function. Periodic/aperiodic decomposition, a powerful tool for speech analysis is used to improve speech denoising. More precisely, instead of applying coherence based filter to the couple of observations, we refine noisy observations by decomposing them into two sub-signals. Moreover, we adapt the coherence functions of each couple of sub-signals according to their properties. Experiments carried out on artificially and naturally noisy signals indicate that, relatively to the classical coherence denoising technique, significant gains are achieved by the proposed method. View full abstract»

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  • Super-resolution construction of IRIS images from a visual low resolution face video

    Publication Year: 2007 , Page(s): 1 - 4
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (249 KB) |  | HTML iconHTML  

    Iris became an important biometric in the last decade, due to its uniqueness and richness of features. In this paper, a novel super-resolution and image registration technique for visual (non-infra-red) iris images is presented. In the proposed technique a full face, 3 second long, 90 frames, visual video is captured with a digital camera located 3 feet away from each subject. Iris images are segmented from the full face image. A cross correlation model is applied for the registration/alignment of full gray scale iris images. A high resolution iris image, that is 4 times higher in terms of size and resolution, is constructed from every 9 low resolution images. This process of building a high resolution image is based on an auto_regressive signature model between consecutive low resolution images in filling the sub pixels in the constructed high resolution image. Then this process is iterated until a 16 times higher resolution iris image is constructed. Illustrative images are shown that prove the effectiveness of the proposed technique. View full abstract»

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  • Automated parking slot allocation using RFID technology

    Publication Year: 2007 , Page(s): 1 - 4
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (318 KB) |  | HTML iconHTML  

    One of the challenging problems for many vehicle owners in big metropolitan cities is where to park their vehicles. If the parking slot availability is known in advance one can save precious time and fuel wastage. In this paper we would like to propose an RFID based parking slot allocation system wherein an intended user is informed about the parking slot availability at a particular parking location via Short Messaging Service. The slot availability details are collected using an RFID system and are updated periodically into a Web server via Internet for a registered user. If needed, the user can reserve his parking slot via SMS. View full abstract»

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  • Comparison of a signal subspace tracking algorithm VIA LMS-type procedure with high resolution DOA estimation methods

    Publication Year: 2007 , Page(s): 1 - 4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (265 KB) |  | HTML iconHTML  

    In this paper, we present some new investigations on a robust adaptive beamforming via LMS-type procedure which has been proposed recently. This beamformer self-corrects and tracks desired source location errors or variations regardless of the eigenstructure of the input correlation matrix and array shape. This algorithm and MUSIC show an identical asymptotic variance in localization for immobile sources, whereas for the mobile case, the former is more efficient. Simulations show the proper performance of the aforementioned algorithm for resolving targets in low SNR and even for few number of snapshots in comparison with other high resolution methods. Also surveys show its efficiency in tracking moving sources. View full abstract»

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  • SNR and BER derivation and analysis of downlink OFDM systems with noisy fading Doppler channels

    Publication Year: 2007 , Page(s): 1 - 4
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (700 KB) |  | HTML iconHTML  

    In this paper, we investigate the SNR and BER performance of an OFDM system under imperfect synchronization which is caused due to noise, Doppler shift and frequency selective fades in the channel. An analytical expression for BER is derived assuming BPSK modulation and numerical results are presented to show the effect and extent of the above channel impairments in OFDM downlinks. View full abstract»

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