A major drawback of block-based still image or video compression methods at low rates are the visible block boundaries that are also known as blocking artifacts. Several methods have been proposed in the literature to...
详细信息
ISBN:
(纸本)0780370414
A major drawback of block-based still image or video compression methods at low rates are the visible block boundaries that are also known as blocking artifacts. Several methods have been proposed in the literature to reduce these artifacts for video sequences. However, most are simply adaptations of still image blocking artifact reduction methods, which do not exploit temporal information. In this paper, we propose a novel multi-frame blocking artifact reduction method that incorporates temporal information effectively. This method uses the spatial correlations that exist between the successive frames to define constraint sets at multiple frames and provides a Projections Onto Convex Sets (POCS) solution. The proposed method operates solely on transform domain (DCT) data, and hence provides a solution that is compatible with the observed video. It does not need to make any spatial smoothness assumptions, which are typical with blocking artifact reduction algorithms for still images.
Hardware in the loop simulation (HILS) is used in the evaluation of various IR seeker systems. To perform IR HILS testing a number of costly peripheral systems are required. The most important of these are the motion ...
详细信息
ISBN:
(纸本)0819440612
Hardware in the loop simulation (HILS) is used in the evaluation of various IR seeker systems. To perform IR HILS testing a number of costly peripheral systems are required. The most important of these are the motion simulation table, the IR scene generator, the IR scene projector, the dynamics simulator and the simulation controller. The cost of IR image projectors prohibits a number of scientists with access to the remaining equipment from preforming HILS testing of IR seekers. Simulating the reticle and calculating the detector signal in real-time allows the evaluator to bypass the IR scene projector and to do signal injection into the unit under test (UUT). The use of a commercial off the shelf personal computer permits the testing of single detector reticle seekers at a fraction of the cost of ail IR image projector. This paper will deal with the development of the algorithms required to realize a real-time simulation of a conical scan FM reticle. The simulation makes use of imageprocessing techniques which are computationally intensive. This paper will investigate methods to decrease the simulation time in order to generate real-time signals for the UUT. The implementation of the various techniques as well as the effect on the simulation time will be presented. The disadvantages and problems associated with these methods will also be explored. The algorithms that were developed will be presented along with the fastest simulation times achieved.
Deblocking and deringing are two video post-processing techniques largely used to remove coding artifacts and improve the visual quality when rendering low bit rate coded video. The algorithms used to achieve these ta...
详细信息
ISBN:
(纸本)0780370414
Deblocking and deringing are two video post-processing techniques largely used to remove coding artifacts and improve the visual quality when rendering low bit rate coded video. The algorithms used to achieve these tasks are computationally intensive and usually require high speed processors to be able to run in real time. Efficient implementations of signal adaptive filters for video post-processing can be obtained using the specialized features of the parallel BOPS(R) DSP cores. The performance achieved by deblocking and deringing CIF and SDTV size video sequences on the MANTA(TM) prototype chip are illustrated. It is shown that such complex tasks may be executed at low clock rates using the BOPS ManArray(TM) technology.
作者：
Keshava, NMIT
Lincoln Lab Lexington MA 02420 USA
In this paper, we explore the role of best bands algorithms in the context of maximizing the performance of hyperspectral algorithms. Specifically, we first focus on creating art intuitive framework for how metrics qu...
详细信息
ISBN:
(纸本)0780370414
In this paper, we explore the role of best bands algorithms in the context of maximizing the performance of hyperspectral algorithms. Specifically, we first focus on creating art intuitive framework for how metrics quantify the distance between two spectra. Focusing on the Spectral Angle Mapper (SAM) metric, we demonstrate how the separability of two spectra can be increased by choosing the bands that maximize the metric. This intuition about best bands analysis for SAM is extended to the Generalized Likelihood Ratio Test (GLRT) for a practical target/background detection scenario. Results are shown for a scene imaged by the HYDICE sensor demonstrating that the separability of targets and background can be increased by carefully choosing the bands for the test.
Evolving networks of ad-hoc, wireless sensing nodes rely heavily on the ability to establish position information. The algorithms presented herein rely on range measurements between pairs of nodes and the a priori coo...
详细信息
ISBN:
(纸本)0780370414
Evolving networks of ad-hoc, wireless sensing nodes rely heavily on the ability to establish position information. The algorithms presented herein rely on range measurements between pairs of nodes and the a priori coordinates of sparsely located anchor nodes. Clusters of nodes surrounding anchor nodes cooperatively establish confident position estimates through assumptions, checks, and iterative refinements. Once established, these positions are propagated to more distant nodes, allowing the entire network to create an accurate map of itself. Major obstacles include overcoming inaccuracies in range measurements as great as +/-50%, as well as the development of initial guesses for node locations in clusters with few or no anchor nodes. Solutions to these problems are presented and discussed, using position error as the primary metric. algorithms are compared according to position error, scalability, and communication and computational requirements. Early simulations yield average position errors of 5% in the presence of both range and initial position inaccuracies.
This paper analyzes the asymptotic performance of Maximum Likelihood (ML) channel estimation algorithms in wideband code division multiple access (WCDMA) scenarios. We concentrate on systems with periodic spreading se...
详细信息
ISBN:
(纸本)0780370414
This paper analyzes the asymptotic performance of Maximum Likelihood (ML) channel estimation algorithms in wideband code division multiple access (WCDMA) scenarios. We concentrate on systems with periodic spreading sequences (period larger than or equal to the symbol span) with high spreading factors, where the transmitted signal contains a code division multiplexed pilot for channel estimation purposes. Assuming randomized training and code sequences, we derive and compare the asymptotic covariances of the training-only (TO), semi-blind conditional ML (CML) and semi-blind Gaussian ML (GML) channel estimators.
In this paper two new adaptive equalizers are proposed which belong to the quasi-Newton (QN) algorithmic family. The first algorithm is a Linear Equalizer (LE) and the second one is a Decision Feedback Equalizer (DFE)...
详细信息
ISBN:
(纸本)0780370414
In this paper two new adaptive equalizers are proposed which belong to the quasi-Newton (QN) algorithmic family. The first algorithm is a Linear Equalizer (LE) and the second one is a Decision Feedback Equalizer (DFE). In the LE case the involved inverse Hessian matrix is approximated by a proper expansion consisting of powers of a Toeplitz matrix. Due to this formulation the algorithm can be efficiently implemented in the transform domain (TD) using FFT. The same idea is applied to the Feedforward part of the DFE. The derived algorithms enjoy the advantages of QN algorithms, that is, they exhibit faster convergence than their stochastic gradient counterparts and less computational complexity as compared to other Newton-type algorithms. These advantages are further enhanced due to TD implementation.
In this paper, we bring local phase and multiresolution analysis to the texture segmentation problem. A Markov random field characterization is still employed, except it is used to model phase correlations rather than...
详细信息
ISBN:
(纸本)0780370414
In this paper, we bring local phase and multiresolution analysis to the texture segmentation problem. A Markov random field characterization is still employed, except it is used to model phase correlations rather than intensity correlations. Since statistical characteristics of phase are typically quite different to those of intensity, there exists the potential for creating greater discrimination in its feature space. We apply the Wreath Product Transform and use the phase at higher scales to initiate the segmentation process. For textures defined by homogeneous regions of dominant local edges, we see that the new algorithm yields better segmentation than that obtained through conventional multiresolution algorithms based on lowpass data.
Two algorithms that can obtain more accurate estimate of the fractal dimension are proposed. One is the shifting DBC (SDBC) algorithm and the other one is the scanning BC (SBC) algorithm. It is theoretically proven th...
详细信息
ISBN:
(纸本)0780370414
Two algorithms that can obtain more accurate estimate of the fractal dimension are proposed. One is the shifting DBC (SDBC) algorithm and the other one is the scanning BC (SBC) algorithm. It is theoretically proven that the SDBC algorithm approaches the estimated value closer to the exact fractal dimension than the DBC method. Simulation results show that the proposed algorithms consistently give more satisfactory results on textured images.
This paper discusses several issues related to blind source separation in nonlinear models. Specifically, separability results show that separation in the general case is impossible, however, for specific nonlinear mo...
详细信息
ISBN:
(纸本)0780370414
This paper discusses several issues related to blind source separation in nonlinear models. Specifically, separability results show that separation in the general case is impossible, however, for specific nonlinear models the problem does have a solution. A specific set of parametric nonlinear mixtures is considered, this set has the Lie group structure. In the parameter set, a group operation is defined and a relative gradient is defined. The latter is applied to design stochastic algorithms for which the equivariance property is shown.
暂无评论