A rate-distortion framework is used to define a very low bit-rate coding scheme based on quadtree segmentation and optimized selection of motion estimators, This technique achieves maximum reconstructed image quality ...
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A rate-distortion framework is used to define a very low bit-rate coding scheme based on quadtree segmentation and optimized selection of motion estimators, This technique achieves maximum reconstructed image quality under the constraint of a target bit rate for the coding of the vector field and segmentation information, First, a complete scheme is proposed for hybrid two-dimensional (2-D) and three-dimensional (3-D) motion estimation and compensation, The quadtree object segmentation is optimized for hybrid motion estimation in the rate-distortion sense, This scheme adapts to the depth of the quadtree and the technique used for motion estimation for each leaf of the tree. A more sophisticated technique, adapted to the requirements of a very low bit-rate coder, is also proposed which also considers the transmission of the prediction error corresponding to the particular choice of the motion estimator, Based on these coding schemes, two versions of a very low bit-rate image sequence coder are developed, Experimental results illustrating the performance of the proposed techniques in very low bit-rate image sequence coding application areas are presented and evaluated.
The domain of a global function is the set of all global states of an execution of a distributed program, We show how to monitor a program in order to determine if there exists a global state in which the sum x(1) + x...
The domain of a global function is the set of all global states of an execution of a distributed program, We show how to monitor a program in order to determine if there exists a global state in which the sum x(1) + x(2) +...+ x(N), exceeds some constant K, where x(i) is defined in process i. We examine the cases where x(i) is an integer variable for N = 2 and where x(i) is a boolean variable for general N, For both cases we provide algorithms, prove their correctness, and analyze their complexity. (C) 1997 Academic Press.
In this paper we propose an object-based stereo image coding algorithm. The algorithm relies on modeling of the object structure using 3D wire-frame models, and motion estimation using globally rigid and locally defor...
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In this paper we propose an object-based stereo image coding algorithm. The algorithm relies on modeling of the object structure using 3D wire-frame models, and motion estimation using globally rigid and locally deformable motion models. Algorithms for the estimation of motion and structure parameters from stereo images are described. Motion parameters are used to construct predicted images at subsequent time instances by mapping the image texture on the object surface. Coding of object parameters, appearing background regions and prediction errors is investigated and experimental results with video-conference scenes are presented. The proposed algorithm is very efficient for applications like stereoscopic video transmission, and is especially suited to advanced applications such as generation and transmission of intermediate views for multiview receiver systems, as well as applications in which an object-wise editing of the bit-stream is required, such as video-production using preanalysed scenes or virtual reality applications.
In this paper we integrate motion and structure estimation in order to exploit their coherence. We propose an algorithm that uses models for object surfaces and their motion and estimates the model parameters using th...
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In this paper we integrate motion and structure estimation in order to exploit their coherence. We propose an algorithm that uses models for object surfaces and their motion and estimates the model parameters using the image intensity matching criterion. The visible scene surface is represented with a parametrically deformable, spatially adaptive, wireframe model. Object motion is first modeled using the well-known rigid motion assumption along with the quaternion rotation representation. Nonrigid motion modeling using the finite element technique is also investigated as an alternative to rigid motion modeling or as a refinement of it. A functional containing image matching and surface smoothness constraints is minimized with respect to the unknown model parameters. A discontinuity detection scheme allowing deactivation of smoothness constraints across object boundaries, is investigated. A regularization scheme using a coarse to fine strategy is employed. (C) 1997 Academic Press.
The maturing of telecommunication technologies has ushered in a whole new era of applications and services in the health care environment. Teleworking, teleconsultation, multimedia conferencing and medical data distri...
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The maturing of telecommunication technologies has ushered in a whole new era of applications and services in the health care environment. Teleworking, teleconsultation, multimedia conferencing and medical data distribution are rapidly becoming commonplace in clinical practice. As a result, a set of problems arises, concerning data confidentiality and integrity. Public computer networks, such as the emerging ISDN technology, are vulnerable to eavesdropping. Therefore it is important for telemedicine applications to employ end-re-end encryption mechanisms securing the data channel from unauthorized access or modification. We propose a network access and encryption system that is both economical and easily implemented for integration in developing or existing applications, using well-known and thoroughly tested encryption algorithms. Public-key cryptography is used for session-key exchange, while symmetric algorithms are used for bulk encryption. Mechanisms for session-key generation and exchange are also provided.
A 1.5V resistive fuse for image smoothing and segmentation using bulk-driven MOSFETs is presented. The circuit switches on only if the differential voltage applied across its input terminals is less than a set voltage...
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A 1.5V resistive fuse for image smoothing and segmentation using bulk-driven MOSFETs is presented. The circuit switches on only if the differential voltage applied across its input terminals is less than a set voltage;it switches off if the differential voltage is higher than the set value. The useful operation range of the circuit is 0.4V with a supply voltage of 1.5V and threshold voltages of V-Tn = 0.828V and V-Tp = -0.56V for n and g channel MOSFETs, respectively.
Increasingly, feedback of measured run-time information is being used in the optimization of computation execution. Because of this, the need for a model relating the static view of a computation to its runtime varian...
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New shift-invariant distortion-invariant Synthetic Aperture Radar (SAR) filters for detection are described. They employ new modified Minimum Noise and Correlation Energy (MINACE) filters. Test results are provided fo...
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New shift-invariant distortion-invariant Synthetic Aperture Radar (SAR) filters for detection are described. They employ new modified Minimum Noise and Correlation Energy (MINACE) filters. Test results are provided for real SAR data with 360 degrees aspect views of two different objects and for 100 real SAR clutter chips (natural and man-made) that passed the second stage of the Lincoln laboratory's SAR processor. We obtained high detection rates P-D=100% and few false alarms P-FA less than or equal to 0.82% using only three filters per object class. The shift-invariance of the filters allow their use as adjuncts for all stages (detection, discrimination, classification) of a SAR image processor. Classification results are also briefly reported. Copyright (C) 1996 Pattern Recognition Society.
A system for specification and proof of distributed programs is presented. The method is based directly on the partial order of local states (poset) and avoids the notions of time and simultaneity. Programs are specif...
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A system for specification and proof of distributed programs is presented. The method is based directly on the partial order of local states (poset) and avoids the notions of time and simultaneity. Programs are specified by documenting the relationship between local states which are adjacent to each other in the poset. Program properties are defined by stating properties of the poset. Many program properties can be expressed succinctly and elegantly using this method because poset properties inherently account for varying processor execution speeds. The system utilizes a proof technique which uses induction on the complement of the causally precedes relation and is shown to be useful in proving poset properties. We demonstrate the system on three example algorithms: vector clocks, mutual exclusion, and direct dependency clocks.
In this paper, we present a new system to segment and label CT/MRI Brain slices using feature extraction and unsupervised clustering. In this technique, each voxel is assigned a feature pattern consisting of a scaled ...
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ISBN:
(纸本)0780341236
In this paper, we present a new system to segment and label CT/MRI Brain slices using feature extraction and unsupervised clustering. In this technique, each voxel is assigned a feature pattern consisting of a scaled family of differential geometrical invariant features. The invariant feature pattern is then assigned to a specific region using a two-stage neural network system. The first stage is a self-organizing principal components analysis (SOPCA) network that is used to project the feature vector onto its leading principal axes found by using principal components analysis. This step provides an effective basis for feature extraction. The second stage consists of a self-organizing feature map (SOFM) which will automatically cluster the input vector into different regions. The optimum number of regions (clusters) is obtained by a model fitting approach. Finally, a 3D connected component labeling algorithm is applied to ensure region connectivity. Implementation and performance of this technique are presented. Compared to other approaches, the new system is more accurate in extracting 3D anatomical structures of the brain, and can be apdated to real-time imaging scenarios.
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