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A method for restoration of low-resolution document images

International Journal on Document Analysis and Recognition 2000年第4期2卷 200-210页

作者： Thouin, Paul D. Chang, Chein-I Department of Defense Fort Meade MD 20755 United States Remote Sensing Signal and Image Processing Laboratory Department of Computer Science and Electrical Engineering University of Maryland Baltimore County 1000 Hilltop Circle Baltimore MD 21250 United States

Image restoration using resolution expansion is important in many areas of image processing. This paper introduces a restoration method for low-resolution text images which produces expanded images with improved definition. This technique creates a strongly bimodal image with smooth regions in both the foreground and background, while allowing for sharp discontinuities at the edges. The restored image, which is constrained by the given low-resolution image, is generated by iteratively solving a nonlinear optimization problem. Low-resolution text images restored using this technique are shown to be both quantitatively and qualitatively superior to images expanded using the standard methods of linear interpolation and cubic spline expansion. Experimental results demonstrate that text images created by this new algorithm improve optical character recognition accuracy more than images obtained by existing expansion methods. © 2000 Springer-Verlag Berlin Heidelberg.

关键词： Restoration

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An area-time-efficient residue-to-binary converter

An area-time-efficient residue-to-binary converter

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Midwest Symposium on Circuits and Systems (MWSCAS)

作者： Wei Wang M.N.S. Swamy M.O. Ahmad Centre for Signal Processing and Communications Department of Electrical and Computer Engineering Concordia University Montreal QUE Canada

In this paper, a new residue-to-binary conversion algorithm, that reduces the size of modulo operation required by the Chinese remainder theorem, is introduced. Based on this algorithm, an efficient residue-to-binary converter is proposed for a general residue number system. The proposed converter achieves a significantly better performance in terms of area, time, and power consumption than existing devices. For the case of the 28-bit dynamic range, the proposed converter is about 20% faster while requiring only 70% of the area, compared to the best existing converter (Srikanthan et al, IEE Proc. Comput. Digit. Tech., vol. 145, no. 3, pp. 229-235, 1998). Also, the power consumption is reduced by 16% in high speed situations and 50% in low voltage situations.

关键词： signal processing algorithms Energy consumption Very large scale integration Cathode ray tubes Low voltage Dynamic range Digital signal processing Algorithm design and analysis Arithmetic

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Joint bit-allocation for MPEG encoding of multiple video sequences with minimum quality-variation

Joint bit-allocation for MPEG encoding of multiple video seq...

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IEEE International Symposium on Circuits and Systems (ISCAS)

作者： H. Sorial W.E. Lynch A. Vincent Centre for Signal Processing and Communications Department of Electrical & Computer Engineering Concordia University Montreal QUE Canada

This paper addresses the problem of multi-program video transmission over a single communication channel. We present a joint bit-allocation for MPEG encoding of multiple video sequences with a minimum quality-variation. The proposed method uses a picture-complexity measure based on the actual coding distortion in encoded frames, then allocates accordingly the available bits to explicitly reduce the variation in quality between the sequences. We compare the performance of the proposed method to independent encoding of the sequences at constant bit rates and to encoding with a joint bit-allocation scheme that uses a TM5-like picture-complexity measure. Results show that the proposed bit-allocation method is superior in terms of minimizing the quality variation between the video sequences and within the individual sequences. The method also provides better minimum picture quality than the other encoding schemes mentioned above. Applications of the joint bit-allocation method include multi-program transmission such as video on demand (VOD) services and digital TV broadcasting.

关键词： Encoding Video sequences Telecommunication control Communication channels Bit rate Video on demand Layout Bandwidth Streaming media Equations

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Statistically optimal null filters: Kalman equivalence

Statistically optimal null filters: Kalman equivalence

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International Conference on Acoustics, Speech, and signal processing (ICASSP)

作者： R. Agarwal E.I. Plotkin M.N.S. Swamy Stellate Systems Montreal Canada Department of Electrical & Computer Engineering Center for Signal Processing and Communications Montreal Canada

A new approach in the enhancement/suppression of narrowband signals, based on the combination of the maximum output SNR and the least-squares optimizing criteria, has been presented previously. The resulting statistically-optimal null filters (SONFs) have also been presented as recursive filters. Because of their time-varying nature, optimality under the MSE criterion and the similarity to the RLS method, it is anticipated that the SONFs may be related to the well known Kalman filter. In this paper, we show the SONFs to be an alternate implementation of the Kalman filter. For the first order case we show this analytically. Due to mathematical intractability, for the higher order case we set up the mathematical formulations and use simulations for verification.

关键词： Kalman filters signal processing Additive noise Matched filters State estimation Narrowband Resonance light scattering Gaussian noise Noise level signal analysis

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Groupwise successive interference cancellation for multirate CDMA based on MMSE criterion

Groupwise successive interference cancellation for multirate...

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IEEE International Conference on communications (ICC)

作者： Jinwen Ma Hongya Ge Center for Communications and Signal Processing Department of Electrical and Computer Engineering New Jersey Institute of Technology Newark NJ USA

In this work, groupwise successive interference cancellation scheme for multirate CDMA signals is proposed. The proposed detector operation is based on the minimum mean square error (MMSE) criterion. It has the promise of decision feedback interference cancellation for superior performance compared to the linear MMSE detection at the cost of a moderate increase in complexity. In groupwise detection, users are grouped according to their processing gain or data rate, i.e., users with the same processing gain or data rate are grouped together, then detected. Users with the lowest processing gain or highest data rate are detected first, neglecting the presence of the other users in the system. Interference between the groups is cancelled in a successive order. The BER of the groupwise successive MMSE interference canceler is compared with the BER multirate linear MMSE detector and multirate decorrelating detector. The results show that the groupwise successive MMSE interference canceler yields better performance than the multirate linear MMSE detector and multirate decorrelating detector. When the system is highly loaded, the groupwise successive MMSE interference canceler can offer a better performance than the multirate linear MMSE detector and the multirate conventional detector.

关键词： Interference cancellation Multiaccess communication Detectors Decorrelation Quality of service Multiuser detection signal processing Feedback Bit error rate computer errors

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Minimal complexity hierarchical loop representations of SFG processors for optimal high level synthesis

Minimal complexity hierarchical loop representations of SFG ...

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International Conference on Application Specific Systems (ASAP), Architectures and Processors

作者： A. Stone E.S. Manolakos Communications and Digital Signal Processing CDSP Center Electrical and Computer Engineering Department Northeastern University Boston MA USA

In order to rapidly produce, using high level synthesis, quality silicon implementations of signal Flow Graphs (SFGs) for large size, real-world signal/image processing problems, the Hardware Description Language (HDL) representations of SFG nodes should possess certain desirable characteristics. We have embedded in DG2VHDL, a design tool developed by the authors which translates automatically an algorithm's Dependence Graph into synthesizable VHDL models for SFG arrays, an algorithm that formulates the minimal design complexity nested loop structure (to be defined herein) for each SFG processor. This representation will, in all but some pathological cases, produce post-synthesis hardware whose area scales near optimally with increasing problem size. Furthermore, the time and memory required for the synthesis of such models does not increase with the problem size. A polynomial time heuristic is presented which finds (almost always) the minimal design complexity loop representation of SFG nodes.

关键词： Hardware design languages Algorithm design and analysis High level synthesis Silicon Flow graphs signal processing Image processing signal synthesis Pathology Polynomials

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A new spread spectrum receiver for narrow-band interference suppression

A new spread spectrum receiver for narrow-band interference ...

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IEEE/AFCEA EUROCOMM Information Systems for Enhanced Public Safety and Security

作者： Kunjie Wang Y. Bar-Ness Center for Communications and Signal Processing Research Department of Electrical and Computer Engineering New Jersey Institute of Technology Newark NJ USA

A new spread spectrum receiver with narrow-band interference suppression is proposed. This receiver also considers information from previous bit samples beside those from current bit. Closed-form analytical expression for the output signal-to-interference ratio is derived under the condition of single tone interference. Analytical results show that the new spread spectrum receiver outperforms other previous NBI suppression techniques.

关键词： Spread spectrum communication Narrowband Interference suppression signal analysis Performance analysis Gaussian noise signal processing Multiple access interference Closed-form solution Band pass filters

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Data-aided nonlinear filter for narrowband interference rejection in DS-SS systems: closed-form analytical results

Data-aided nonlinear filter for narrowband interference reje...

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Asilomar Conference on signals, Systems & computers

作者： K. Wang Y. Bar-Ness Center for Communications and Signal Processing Research Department of Electrical and Computer Engineering New Jersey Institute of Technology Newark NJ USA

ISBN: (纸本)0780365143

The performance of the data-aided nonlinear filter (DNF), for combating narrowband interference (NBI) in direct sequence spread spectrum (DS-SS) systems, is analyzed. Closed-form analytical expressions for improvement in signal to interference-plus-noise ratio (SINR) are derived under the condition of single tone interference. Results show that the DNF structure outperforms conventional nonlinear prediction filter.

关键词： Nonlinear filters Narrowband Interference Spread spectrum communication Performance analysis signal analysis signal processing Random variables signal to noise ratio Bandwidth

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A space-time receiver for asynchronous DS-CDMA systems based on Kalman filter

A space-time receiver for asynchronous DS-CDMA systems based...

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Asilomar Conference on signals, Systems & computers

作者： Kun Wang Hongya Ge Center for Communications and Signal Processing Research Department of Electrical and Computer Engineering New Jersey Institute of Technology Newark NJ USA

ISBN: (纸本)0780365143

A new Kalman filter based space-time (S-T) receiver is proposed in this paper. By modeling an asynchronous CDMA system as a first-order state-space model, we can recursively obtain the finite-length linear minimum mean square error (LMMSE) receiver, which provides the best multiple access interference (MAI) cancellation among all the linear filters. Further interference suppression is provided by the spatial beam-former. The proposed receiver overcomes the near-far problem existing in the conventional joint S-T RAKE receiver. Simulation results demonstrate that the proposed Kalman filter based S-T receiver significantly outperforms the conventional joint S-T RAKE receiver.

关键词： Multiaccess communication Fading Multipath channels RAKE receivers Detectors Interference suppression Filters signal to noise ratio signal processing Multiple access interference

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The prediction MMSE receiver for joint multiple-access and narrow-band interference suppression in DS/CDMA channels

The prediction MMSE receiver for joint multiple-access and n...

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IEEE International Conference on communications (ICC)

作者： Kunjie Wang Yeheskel Bar-Ness Center for Communications and Signal Processing Research Department of Electrical and Computer Engineering New Jersey Institute of Technology Newark NJ USA

A new MMSE receiver, which is termed prediction MMSE (PMMSE) receiver, is proposed for joint multiple-access and narrow-band interference suppression in asynchronous DS/CDMA systems. Numerical results indicate that th... 详细信息

关键词： Narrowband Interference suppression Multiple access interference Multiaccess communication Delay Finite impulse response filter Covariance matrix Gaussian noise signal processing Performance analysis

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