http://asp.eurasipjournals.com The most accessed research articles published by EURASIP Journal on Advances in Signal Processing 2012-05-04T00:00:00Z Recent work in the computational modeling of visual attention has demonstrated that a purely bottom-up approach to identifying salient regions within an image can be successfully applied to diverse and practical problems from target recognition to the placement of advertisement. This paper proposes an application of a combination of computational models of visual attention to the image retrieval problem. We demonstrate that certain shortcomings of existing content-based image retrieval solutions can be addressed by implementing a biologically motivated, unsupervised way of grouping together images whose salient regions of interest (ROIs) are perceptually similar regardless of the visual contents of other (less relevant) parts of the image. We propose a model in which only the salient regions of an image are encoded as ROIs whose features are then compared against previously seen ROIs and assigned cluster membership accordingly. Experimental results show that the proposed approach works well for several combinations of feature extraction techniques and clustering algorithms, suggesting a promising avenue for future improvements, such as the addition of a top-down component and the inclusion of a relevance feedback mechanism. http://asp.eurasipjournals.com/content/2007/1/043450 EURASIP Journal on Advances in Signal Processing 2007, null:043450 2006-11-19T00:00:00Z doi:10.1155/2007/43450 /content/figures/1687-6180-2007-043450-toc.gif EURASIP Journal on Advances in Signal Processing 1687-6180 ${item.volume} 043450 2006-11-19T00:00:00Z XML No description available http://asp.eurasipjournals.com/content/2012/1/79 Alexei Nikitin Marc Epard John Lancaster Robert Lutes Eric Shumaker EURASIP Journal on Advances in Signal Processing 2012, null:79 2012-04-10T00:00:00Z doi:10.1186/1687-6180-2012-79 /content/figures/1687-6180-2012-79-toc.gif EURASIP Journal on Advances in Signal Processing 1687-6180 ${item.volume} 79 2012-04-10T00:00:00Z PDF In this article, we introduce MATLAB-based link and system level simulation environments for UMTS Long-Term Evolution (LTE). The source codes of both simulators are available under an academic non-commercial use license, allowing researchers full access to standard-compliant simulation environments. Owing to the open source availability, the simulators enable reproducible research in wireless communications and comparison of novel algorithms. In this study, we explain how link and system level simulations are connected and show how the link level simulator serves as a reference to design the system level simulator. We compare the accuracy of the PHY modeling at system level by means of simulations performed both with bit-accurate link level simulations and PHY-model-based system level simulations. We highlight some of the currently most interesting research questions for LTE, and explain by some research examples how our simulators can be applied. http://asp.eurasipjournals.com/content/2011/1/29 Christian Mehlfuhrer Josep Colom Ikuno Michal Simko Stefan Schwarz Martin Wrulich Markus Rupp EURASIP Journal on Advances in Signal Processing 2011, null:29 2011-07-25T00:00:00Z doi:10.1186/1687-6180-2011-29 /content/figures/1687-6180-2011-29-toc.gif EURASIP Journal on Advances in Signal Processing 1687-6180 ${item.volume} 29 2011-07-25T00:00:00Z XML A strong digital communication transmitter located in close physical proximity to a receiver of a weak signal can noticeably interfere with the latter even when the respective channels are tens or hundreds of megahertz apart. When time domain observations are made in the signal chain of the receiver between the first mixer and the baseband, this interference is likely to appear impulsive. Understanding the mechanism of this interference is important for its effective mitigation. In this article, we show that impulsiveness, or a high degree of peakedness, of interchannel interference in communication systems results from the non-smooth nature of any physically realizable modulation scheme for transmission of a digital (discontinuous) message. Even modulation schemes designed to be 'smooth', e.g., continuous-phase modulation, are, in fact, not smooth because their higher order time derivatives still contain discontinuities. When observed by an out-of-band receiver, the transmissions from these discontinuities may appear as strong transients with the peak power noticeably exceeding the average power, and the received signal will have a high degree of peakedness. This impulsive nature of the interference provides an opportunity to reduce its power by nonlinear filtering, thus improving quality of the receiver channel. http://asp.eurasipjournals.com/content/2011/1/137 Alexei Nikitin EURASIP Journal on Advances in Signal Processing 2011, null:137 2011-12-21T00:00:00Z doi:10.1186/1687-6180-2011-137 /content/figures/1687-6180-2011-137-toc.gif EURASIP Journal on Advances in Signal Processing 1687-6180 ${item.volume} 137 2011-12-21T00:00:00Z XML In high resolution computed tomography (CT) using flat panel detectors (FPDs), imperfect or defected detector elements cause stripe artifacts in sinogram which results in concentric ring artifacts in the image. Such ring artifacts obscure image details in the regions of interest of the image. In this paper, novel techniques are proposed for the detection, classification and correction of ring artifacts in the sinogram domain. The proposed method is suitable for multislice CT with parallel or fan beam geometry. It can also be employed for ring artifact removal in 3D cone beam volume CT by adopting a sinogram by sinogram processing technique. The detection algorithm is based on applying data driven thresholds on the mean curve and difference curve of the sinogram. The ring artifacts are classified into three types and a separate correction algorithm is used for each class. The performance of the proposed techniques is evaluated on a number of real micro-CT images. Experimental results corroborate that the proposed algorithm can remove ring artifacts from micro-CT images more effectively as compared to other recently reported techniques in the literature. http://asp.eurasipjournals.com/content/2012/1/93 Sabrina Rashid Soo Yeol Lee Md. Kamrul Hasan EURASIP Journal on Advances in Signal Processing 2012, null:93 2012-04-27T00:00:00Z doi:10.1186/1687-6180-2012-93 /content/figures/1687-6180-2012-93-toc.gif EURASIP Journal on Advances in Signal Processing 1687-6180 ${item.volume} 93 2012-04-27T00:00:00Z PDF In this article, we propose a weighted l2,1 minimization algorithm for jointly-sparse signal recovery problem. The proposed algorithm exploits the relationship between the noise subspace and the overcomplete basis matrix for designing weights, i.e., large weights are appointed to the entries, whose indices are more likely to be outside of the row support of the jointly sparse signals, so that their indices are expelled from the row support in the solution, and small weights are appointed to the entries, whose indices correspond to the row support of the jointly sparse signals, so that the solution prefers to reserve their indices. Compared with the regular l2,1 minimization, the proposed algorithm can not only further enhance the sparseness of the solution but also reduce the requirements on both the number of snapshots and the signal-to-noise ratio (SNR) for stable recovery. Both simulations and experiments on real data demonstrate that the proposed algorithm outperforms the l1-SVD algorithm, which exploits straightforwardly l2,1 minimization, for both deterministic basis matrix and random basis matrix. http://asp.eurasipjournals.com/content/2012/1/98 Chundi Zheng Gang Li Yimin Liu Xiqin Wang EURASIP Journal on Advances in Signal Processing 2012, null:98 2012-05-02T00:00:00Z doi:10.1186/1687-6180-2012-98 /content/figures/1687-6180-2012-98-toc.gif EURASIP Journal on Advances in Signal Processing 1687-6180 ${item.volume} 98 2012-05-02T00:00:00Z PDF This study presents an appearance-based face recognition scheme called the nonparametric-weighted Fisherfaces (NW-Fisherfaces). Pixels in a facial image are considered as coordinates in a high-dimensional space and are transformed into a face subspace for analysis by using nonparametric-weighted feature extraction (NWFE). According to previous studies of hyperspectral image classification, NWFE is a powerful tool for extracting hyperspectral image features. The Fisherfaces method maximizes the ratio of between-class scatter to that of within-class scatter. In this study, the proposed NW-Fisherfaces weighted the between-class scatter to emphasize the boundary structure of the transformed face subspace and, therefore, enhances the separability for different persons' face. The proposed NW-Fisherfaces was compared with Orthogonal Laplacianfaces, Eigenfaces, Fisherfaces, direct linear discriminant analysis, and null space linear discriminant analysis methods for tests on five facial databases. Experimental results showed that the proposed approach outperforms other feature extraction methods for most databases. http://asp.eurasipjournals.com/content/2012/1/92 Dong-Lin Li Mukesh Prasad Sheng-Chih Hsu Chao-Ting Hong Chin-Teng Lin EURASIP Journal on Advances in Signal Processing 2012, null:92 2012-04-26T00:00:00Z doi:10.1186/1687-6180-2012-92 /content/figures/1687-6180-2012-92-toc.gif EURASIP Journal on Advances in Signal Processing 1687-6180 ${item.volume} 92 2012-04-26T00:00:00Z XML This article deals with the application of Spatial Time Frequency Distribution (STFD) to the direction findingproblem using the Multiple Signal Classification (MUSIC) algorithm. A comparative performance analysis isperformed for the method under consideration with respect to that using data covariance matrix when the receivedarray signals are subject to calibration errors in a non stationary environment. An unified analytical expression ofthe Direction Of Arrival (DOA) error estimation is derived for both methods. Numerical results show the effectof the parameters intervening in the derived expression on the algorithm performance. It is particulary observedthat for low Signal to Noise Ratio (SNR) and high Signal to sensor Perturbation Ratio (SPR) the STFD methodgives better performance, while for high SNR and for the same SPR both methods give similar performance. http://asp.eurasipjournals.com/content/2012/1/94 Mohamed Khodja Adel Belouchrani Karim Abed-Meraim EURASIP Journal on Advances in Signal Processing 2012, null:94 2012-04-30T00:00:00Z doi:10.1186/1687-6180-2012-94 /content/figures/1687-6180-2012-94-toc.gif EURASIP Journal on Advances in Signal Processing 1687-6180 ${item.volume} 94 2012-04-30T00:00:00Z PDF The Kalman filter (KF) has been improved for a mobile robot to human tracking. The proposed algorithm combines a curve matching framework and KF to enhance prediction accuracy of target tracking. Compared to other methods using normal KF, the Curve Matched Kalman Filter (CMKF) method predicts the next movement of the human by taking into account not only his present motion characteristics, but also the previous history of target behavior patterns--the CMKF provides an algorithm that acquires the motion characteristics of a particular human and provides a computationally inexpensive framework of human-tracking system. The proposed method demonstrates an improved target tracking using a heuristic weighted mean of two methods, i.e., the curve matching framework and KF prediction. We have conducted the experimental test in an indoor environment using an infrared camera mounted on a mobile robot. Experimental results validate that the proposed CMKF increases prediction accuracy by more than 30% compared to normal KF when the characteristic patterns of target motion are repeated in the target trajectory. http://asp.eurasipjournals.com/content/2012/1/99 Suk Jin Lee Gaurav Shah Arka Aloke Bhattacharya Yuichi Motai EURASIP Journal on Advances in Signal Processing 2012, null:99 2012-05-03T00:00:00Z doi:10.1186/1687-6180-2012-99 /content/figures/1687-6180-2012-99-toc.gif EURASIP Journal on Advances in Signal Processing 1687-6180 ${item.volume} 99 2012-05-03T00:00:00Z PDF Monitoring physiological functions such as swallowing often generates large volumes of samples to be stored and processed, which can introduce computational constraints especially if remote monitoring is desired. In this paper, we propose a compressive sensing (CS) algorithm to alleviate some of these issues while acquiring dual-axis swallowing accelerometry signals. The proposed CS approach uses a time-frequency dictionary where the members are modulated discrete prolate spheroidal sequences (MDPSS). These waveforms are obtained by modulation and variation of discrete prolate spheroidal sequences (DPSS) in order to reflect the time-varying nature of swallowing acclerometry signals. While the modulated bases permit one to represent the signal behavior accurately, the matching pursuit algorithm is adopted to iteratively decompose the signals into an expansion of the dictionary bases. To test the accuracy of the proposed scheme, we carried out several numerical experiments with synthetic test signals and dual-axis swallowing accelerometry signals. In both cases, the proposed CS approach based on the MDPSS yields more accurate representations than the CS approach based on DPSS. Specifically, we show that dual-axis swallowing accelerometry signals can be accurately reconstructed even when the sampling rate is reduced to half of the Nyquist rate. The results clearly indicate that the MDPSS are suitable bases for swallowing accelerometry signals. http://asp.eurasipjournals.com/content/2012/1/101 Ervin Sejdic Azime Can Luis Chaparro Catriona Steele Tom Chau EURASIP Journal on Advances in Signal Processing 2012, null:101 2012-05-04T00:00:00Z doi:10.1186/1687-6180-2012-101 /content/figures/1687-6180-2012-101-toc.gif EURASIP Journal on Advances in Signal Processing 1687-6180 ${item.volume} 101 2012-05-04T00:00:00Z PDF