| 1. |
- Bengtsson, Tomas, 1983, et al.
(författare)
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Regularized Optimization for Joint Super-Resolution and High Dynamoc Range Image Reconstruction in a Percetually Uniform Domain.
- 2012
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Ingår i: ICASSP, IEEE International Conference on Acoustics, Speech and Signal Processing - Proceedings. - 1520-6149. - 9781467300469 ; , s. 1097-1100
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Konferensbidrag (refereegranskat)abstract
- This paper discusses resolution enhancement of a set of images with varying exposure durations, having a high combined dynamic range. So far, little has been said in relation to the Human Visual System when it comes to Super-Resolution and High Dynamic Range fusion, unlike the case for traditional Super-Resolution where errors are measured with respect to human perception in the pixel domain. We propose a Super-Resolution method in the L*a*b* domain to bridge the gap and present some image reconstruction results.
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| 2. |
- Henter, Gustav Eje, et al.
(författare)
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Gaussian process dynamical models for nonparametric speech representation and synthesis
- 2012
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Ingår i: Acoustics, Speech and Signal Processing (ICASSP), 2012 IEEE International Conference on. - : IEEE. - 9781467300469 ; , s. 4505-4508
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Konferensbidrag (refereegranskat)abstract
- We propose Gaussian process dynamical models (GPDMs) as a new, nonparametric paradigm in acoustic models of speech. These use multidimensional, continuous state-spaces to overcome familiar issues with discrete-state, HMM-based speech models. The added dimensions allow the state to represent and describe more than just temporal structure as systematic differences in mean, rather than as mere correlations in a residual (which dynamic features or AR-HMMs do). Being based on Gaussian processes, the models avoid restrictive parametric or linearity assumptions on signal structure. We outline GPDM theory, and describe model setup and initialization schemes relevant to speech applications. Experiments demonstrate subjectively better quality of synthesized speech than from comparable HMMs. In addition, there is evidence for unsupervised discovery of salient speech structure.
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| 3. |
- Huang, F., et al.
(författare)
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Transform-domain Wiener filter for speech periodicity enhancement
- 2012
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Ingår i: Acoustics, Speech and Signal Processing (ICASSP), 2012 IEEE International Conference on. - : IEEE. - 9781467300469 ; , s. 4577-4580
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Konferensbidrag (refereegranskat)abstract
- In this paper, we present a transform-domain Wiener filtering approach for enhancing speech periodicity. The enhancement is performed on the linear prediction residual signal. Two sequential lapped frequency transforms are applied to the residual in a pitch-synchronous manner. The residual signal is effectively represented by two separate sets of transform coefficients that correspond to the periodic and aperiodic components, respectively. A Wiener filter operating on the transform coefficients is developed to restore periodicity and reduce noise. Different filter parameters are designed for the transform coefficients of the periodic and aperiodic components. A template-driven method is used to estimate the filter parameters for the periodic component. For the aperiodic components, the filter parameters are computed based on a local SNR for effective noise reduction. Experimental results confirm that the harmonic structure of the signal can be effectively restored with the proposed approach.
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| 4. |
- Le Dortz, N., et al.
(författare)
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WiFi fingerprint indoor positioning system using probability distribution comparison
- 2012
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Ingår i: Acoustics, Speech and Signal Processing (ICASSP), 2012 IEEE International Conference on. - : IEEE. - 9781467300469 ; , s. 2301-2304
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Konferensbidrag (refereegranskat)abstract
- Positioning services are increasingly used for applications such as navigation, advertising and social media. While outdoor navigation based on GPS and/or cellular systems works well, indoor navigation is a much tougher challenge. This paper presents a new indoor positioning method based on Wi-Fi fingerprints, i.e. RSSI measurements from multiple Wi-Fi access points. During an offline phase, fingerprints are collected at known positions in the building. This database of locations and the associated fingerprints are called the radio map. In the online mode, the current Wi-Fi fingerprint probability distributions are compared with those of the radio map. The user location is estimated by calculating a weighted average of the three offline positions that best match the online measurements. Experiments show that our technique is superior to other proposed methods and reaches a median error of 2.4m.
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| 5. |
- Li, Haopeng, et al.
(författare)
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Sift-based multi-view cooperative tracking for soccer video
- 2012
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Ingår i: Acoustics, Speech and Signal Processing (ICASSP), 2012 IEEE International Conference on. - : IEEE. - 9781467300469 ; , s. 1001-1004
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Konferensbidrag (refereegranskat)abstract
- This paper presents a SIFT-based multi-view cooperative tracking scheme for multiple player tracking in soccer games. We assume that future sports events will be captured by an array of fixed high-definition cameras which provide multi-view video sequences. The imagery will then be used to provide a free-viewpoint networked experience. In this work, SIFT features are used to extract the interview and inter-frame correlation among related views. Hence, accurate 3D information of each player can be efficiently utilized for real time multiple player tracking. By sharing the 3D information with all cameras and exploiting the perspective diversity of the multi-camera system, occlusion problems can be solved effectively. The extracted 3D information improves the average reliability of tracking by more than 10% when compared to SIFT-based 2D tracking.
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| 6. |
- Li, Minyue, et al.
(författare)
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Audio coding with power spectral density preserving quantization
- 2012
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Ingår i: Acoustics, Speech and Signal Processing (ICASSP), 2012 IEEE International Conference on. - : IEEE. - 9781467300469 ; , s. 413-416
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Konferensbidrag (refereegranskat)abstract
- The coding of audio-visual signals is generally based on different paradigms for high and low rates. At high rates the signal is approximated directly and at low rates only signal features are transmitted. The recently introduced distribution preserving quantization (DPQ) paradigm provides a seamless transition between these two regimes. In this paper we present a simplified scheme that preserves the power spectral density (PSD) rather than the probability distribution. In a practical system the PSD must be estimated. We show that both forward adaptive and backward adaptive PSD estimation are possible. Our experimental results confirm that preservation of PSD at finite precision leads to a unified coding paradigm that provides effective coding at both high and low rates. An audio coding application shows the perceptual benefits of PSD preserving quantization.
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| 7. |
- Lundberg Nordenvaad, Magnus, et al.
(författare)
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A map based estimator for inverse complex covariance matricies
- 2012
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Ingår i: 2012 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP). - 1520-6149. - 9781467300469 ; , s. 3369-3372
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Konferensbidrag (refereegranskat)abstract
- A novel approach to estimate (inverse) complex covariance matrices is proposed. By considering the class of unitary invariant estimators, the main challenge lies in estimating the underlying eigenvalues from sampled versions. By exploiting that the distribution of the sample eigenvalues can be derived in closed form, a Maximum A Posteriori (MAP) based scheme is then derived. The performance of the derived estimator is simulated and results indicate that the proposed scheme shows performance similar to one of the best estimators known to date. The main advantage lies in that the proposed solution only requires numerical optimization over a P-dimensional space where P is the size of the covariance matrix.
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| 8. |
- Mohammed, Saif Khan, 1977-, et al.
(författare)
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Constant Envelope Precoding for Power-Efficient Downlink Wireless Communicationin Multi-User MIMO Systems Using Large Antenna Arrays
- 2012
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Ingår i: 2012 IEEE International Conference on Acoustics, Speech and Signal Processing. - : IEEE Press. - 9781467300445 - 9781467300452 - 9781467300469 ; , s. 2949-2952
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Konferensbidrag (refereegranskat)abstract
- We consider downlink cellular multi-user communication betweena base station (BS) having $N$ antennas and $M$ single-antenna users, i.e.,an $N \times M$ Gaussian Broadcast Channel (GBC).Under an average only total transmit power constraint (APC), large antenna arrays at the BS (having tens to a few hundred antennas) have been recently shown to achieve remarkablemulti-user interference (MUI) suppression with simple precoding techniques.However, building large arrays in practice, would require cheap/power-efficient Radio-Frequency(RF) electronic components. The type of transmitted signal that facilitates the use ofmost power-efficient RF components is a constant envelope (CE) signal (i.e.,the amplitude of the signal transmitted from each antenna is constant for every channel useand every channel realization).Under certain mild channel conditions (including i.i.d. fading), we analytically show that,even under the stringent per-antenna CE transmission constraint (compared to APC),MUI suppression can still be achieved with large antenna arrays. Our analysis also reveals that,with a fixed $M$ and increasing $N$, the total transmitted power can be reduced while maintaining a constant signal-to-interference-noise-ratio (SINR) level at each user.We also propose a novel low-complexity CE precoding scheme, using which,we confirm our analytical observations for the i.i.d. Rayleigh fading channel, through Monte-Carlo simulations.Simulation of the information sum-rate under the per-antenna CE constraint, shows that, for a fixed $M$ and a fixed desired sum-rate, the required total transmit powerdecreases linearly with increasing $N$, i.e.,an $O(N)$ array power gain.Also, in terms of the total transmit power required to achieve a fixed desired information sum-rate,despite the stringent per-antenna CE constraint, the proposed CE precoding scheme performs close to the GBC sum-capacity (under APC) achieving scheme.
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| 9. |
- Morelande, M., et al.
(författare)
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Optimal posterior density approximation for bearings-only tracking
- 2012
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Ingår i: ICASSP, IEEE International Conference on Acoustics, Speech and Signal Processing - Proceedings. - 1520-6149. - 9781467300469 ; , s. 3585-3588
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Konferensbidrag (refereegranskat)abstract
- The optimal homotopy filter is a nonlinear filtering approximation which seeks an optimal parameterisation for the posterior. The search for an optimal parameterisation is performed by constructing a homotopy between the prior and posterior and solving the resulting ordinary differential equation. Here the optimal homotopy filter is applied to the problem of bearings-only tracking. A simulation analysis shows that the performance of the optimal homotopy filter compares favourably to established algorithms.
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| 10. |
- Mysore Rama Rao, B. S., et al.
(författare)
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Detection of sparse random signals using compressive measurements
- 2012
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Ingår i: Acoustics, Speech and Signal Processing (ICASSP), 2012 IEEE International Conference on. - : IEEE. - 9781467300469 ; , s. 3257-3260
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Konferensbidrag (refereegranskat)abstract
- We consider the problem of detecting a sparse random signal from the compressive measurements without reconstructing the signal. Using a subspace model for the sparse signal where the signal parameters are drawn according to Gaussian law, we obtain the detector based on Neyman-Pearson criterion and analytically determine its operating characteristics when the signal covariance is known. These results are extended to situations where the covariance cannot be estimated. The results can be used to determine the number of measurements needed for a particular detector performance and also illustrate the presence of an optimal support for a given number of measurements.
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