Motion estimation plays an important role in video coding schemes by removing temporal redundancies that exist in image sequences. Motion information that is required in motion compensated prediction is transmitted as...
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Motion estimation plays an important role in video coding schemes by removing temporal redundancies that exist in image sequences. Motion information that is required in motion compensated prediction is transmitted as side information, as in forward motion estimation, or can be computed at the receiver in backward motion estimation. The former method has the advantage of more accurate prediction but, suffers in that the motion information is transmitted as side information. We introduce the motion transform (MT), a new motion estimation and compensation technique that does not require the transmission of motion vectors yet, performs well under a variety of conditions. In the proposed method, motion information is obtained in a bottom-up hierarchical fashion using a two-dimensional wavelet-like decomposition. By using a nonlinear non-expansive filter bank a hierarchical decomposition of the image allows coarse-to-fine motion compensation at the decoder without motion vector transmission.
The growth of networked multimedia systems has magnified the need for image copyright protection. One approach used to address this problem is to add an invisible structure to an image that can be used to seal or mark...
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The growth of networked multimedia systems has magnified the need for image copyright protection. One approach used to address this problem is to add an invisible structure to an image that can be used to seal or mark it. These structures are known as digital watermarks. We describe two techniques for the invisible marking of images. We analyze the robustness of the watermarks with respect to linear and nonlinear filtering, and JPEG compression. The results show that our watermarks detect all but the most minute changes to the image.
We present a control scheme for a rate scalable video codec. We describe a wavelet based video codec with motion compensation used to reduce temporal redundancy. The prediction error frames are encoded using an embedd...
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We present a control scheme for a rate scalable video codec. We describe a wavelet based video codec with motion compensation used to reduce temporal redundancy. The prediction error frames are encoded using an embedded zerotree wavelet (EZW) approach which allows data rate scalability. Since motion compensation is used in the algorithm, the duality of the decoded video may decay due to the propagation of errors in the temporal domain. An adaptive motion compensation scheme is proposed to address this problem. We show that using our control scheme the quality of the decoded video can be maintained at any data rate.
This paper presents a new multiple-exchange ascent algorithm for designing optimal Chebyshev digital FIR filters with arbitrary magnitude and phase specifications. Compared to existing Chebyshev design techniques, the...
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This paper presents a new multiple-exchange ascent algorithm for designing optimal Chebyshev digital FIR filters with arbitrary magnitude and phase specifications. Compared to existing Chebyshev design techniques, the new design algorithm exhibits faster convergence while maintaining high accuracy, and is guaranteed to converge to the optimal solution. In addition, the proposed algorithm reduces to the classic second Remez (Parks-McClellan) algorithm when real-only or imaginary-only filters are designed and is, therefore, a true generalization of the classic Remez algorithm to the complex case.
In ATM networks cell loss causes data to be dropped in the channel. When digital video is transmitted over these networks one must be able to reconstruct the missing data so that the impact of these errors is minimize...
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In ATM networks cell loss causes data to be dropped in the channel. When digital video is transmitted over these networks one must be able to reconstruct the missing data so that the impact of these errors is minimized. In this paper we describe a Bayesian approach to conceal these errors. Assuming that the digital video has been encoded using the MPEG1 or MPEG2 compression scheme, each frame is modeled as a Markov random field. A maximum a posteriori estimate of the missing macroblocks and motion vectors is described based on the model.
Existing algorithms for filtering noise from contaminated chaotic signals require relatively high signal-to-noise ratios (SNRs). A preprocessing method to be used in conjunction with existing algorithms is proposed fo...
Existing algorithms for filtering noise from contaminated chaotic signals require relatively high signal-to-noise ratios (SNRs). A preprocessing method to be used in conjunction with existing algorithms is proposed for initial noise reduction in severe SNRs. This preprocessing method is applicable to noisy data from any nonlinear dynamical system because no knowledge of the system dynamics is required.
Just a few years ago, parallelcomputers were tightly-coupled SIMD, VLTW, or MIMD machines. Now, they are clusters of workstations connected by communication networks yielding ever-higher bandwidth (e.g., Ethernet, FD...
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A new technique is presented for the characterization of impulsive interference with a-stable processes. The proposed model is constructed by estimating the a-stable distribution parameters using the empirical charact...
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We show that an archtypal nonlinear chaotic system can be interpreted as a first order anticausal IIR filter stimulated by iid Bernoulli noise. Based on this interpretation, we develop and characterize a number of est...
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Conceptually, an SIMD machine has the capability to overlap operation of the control unit (CU) with the operation of the processing elements (PEs). Computation of a single program is most efficient when the work load ...
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Conceptually, an SIMD machine has the capability to overlap operation of the control unit (CU) with the operation of the processing elements (PEs). Computation of a single program is most efficient when the work load of the CU and the PEs is balanced. Load balancing between the CU and PEs is accomplished by migrating certain computations (e.g., PE-common array index calculations, loop index variable manipulation) from the PEs to the CU and vice versa. The goal of this research is to develop some of the techniques needed for the automatic specification of CU/PE overlap at compile time. As a proof of concept, the ELP compiler has been modified to support experimentation with CU/PE overlap.< >
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