We address the problem of representing captured images in the continuous mathematical space more usually associated with certain forms of drawn ('vector') images. Such an image is resolution-independent so can...
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ISBN:
(纸本)9780769538938
We address the problem of representing captured images in the continuous mathematical space more usually associated with certain forms of drawn ('vector') images. Such an image is resolution-independent so can be used as a master for varying resolution-specific formats. We briefly describe the main features of a vectorising codec for photographic images, whose significance is that drawing programs can access images and image components as first-class vector objects. This paper focuses on the problem of rendering from the isochromic contour form of a vectorised image and demonstrates a new fill algorithm which could also be used in drawing generally. The fill method is described in terms of level set diffusion equations for clarity. Finally we show that image warping is both simplified and enhanced in this form and that we can demonstrate real histogram equalisation with genuinely rectangular histograms.
In this paper, a next generation 3-D video conferencing system is presented that provides immersive tele-presence and natural representation of all participants in a shared virtual meeting space. The system is based o...
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ISBN:
(纸本)0819450235
In this paper, a next generation 3-D video conferencing system is presented that provides immersive tele-presence and natural representation of all participants in a shared virtual meeting space. The system is based on the principle of a shared virtual table environment which guarantees correct eye contact and gesture reproduction and enhances the quality of human-centered communication. The virtual environment is modeled in MPEG-4 which also allows the seamless integration of explicit 3-D head models for a low-bandwidth connection to mobile users. In this case, facial expression and motion information is transmitted instead of video streams resulting in bit-rates of a few kbit/s per participant. Beside low bit-rates, the model-based approach enables new possibilities for image enhancements like digital make-up, digital dressing, or modification of scene lighting.
This paper describes a procedure for model-based coding of dl channels of a multiview image sequence. The 3D model is initialized by accurate adaptation of a 2D wireframe model to the foreground object of one of the v...
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ISBN:
(纸本)0819427497
This paper describes a procedure for model-based coding of dl channels of a multiview image sequence. The 3D model is initialized by accurate adaptation of a 2D wireframe model to the foreground object of one of the views. The rigid 3D motion is estimated for each triangle, and spatial homogeneity neighbourhood constraints are used to improve the reliability of the estimation efficiency and to smooth the motion field produced. A novel technique is used to estimate flexible motion of the nodes of the wireframe from the rigid 3D motion vectors of the wireframe triangles containing each node. Kalman filtering is used to track both rigid 3D motion of each triangle and flexible deformation of each node of the wireframe. The performance of the resulting 3D flexible motion estimation method is evaluated experimentally.
Previous model-based video coding studies have focused on the modelling techniques themselves and have not considered the transportation of an implementable coder over lossy networks. In this contribution a hybrid swi...
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ISBN:
(纸本)0818688211
Previous model-based video coding studies have focused on the modelling techniques themselves and have not considered the transportation of an implementable coder over lossy networks. In this contribution a hybrid switched 3D model-based/H.261 video coder designed for one-to-many distance learning applications over the Internet multicast backbone (MBONE) is employed to study the susceptibility to data loss of modelbased packet video. Data is considered as;texture, motion and shape, with further sub-division to periodic and aperiodic types. Absence of the various data streams in isolation is investigated to reveal the types of degradation possible and then statistical loss is applied to all streams simultaneously to observe the combined effects using a simple loss model. The ability of the various streams to recover from these errors is investigated and an order of priority for the data types then identified.
This paper presents a two-stage Multiple-model Compression (MMC) approach for sampled electrical waveforms. To limit latency, the processing is window-based, with a window length commensurate to the electrical period....
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ISBN:
(纸本)9798350385885;9798350385878
This paper presents a two-stage Multiple-model Compression (MMC) approach for sampled electrical waveforms. To limit latency, the processing is window-based, with a window length commensurate to the electrical period. For each window, the first stage compares several parametric models to get a coarse representation of the samples. The second stage then compares different residual compression techniques to minimize the norm of the reconstruction error. The allocation of the rate budget among the two stages is optimized. The proposed MMC approach provides better signal-to-noise ratios than state-of-the-art solutions on periodic and transient waveforms.
Recently, studies aiming at the next generation of visual communication services which support better human communication have been carried out intensively in Japan. The principal motive of these studies is to develop...
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Recently, studies aiming at the next generation of visual communication services which support better human communication have been carried out intensively in Japan. The principal motive of these studies is to develop new services which are not restricted to a conventional communication framework based on the transmission of waveform signals. This paper focuses on three important key words in these studies;''intelligent,'' ''real,'' and ''distributed and collaborative,'' and describes recent research activities. The first key word ''intelligent'' relates to intelligent image coding. As a particular example, model-based coding of moving facial images is discussed in detail. In this method, shape change and motion of the human face is described by a small number of parameters. This feature leads to the development of new applications such as very low bit-rate transmission of moving facial images, analysis and synthesis of facial expression, human interfaces, and so on. The second key word ''real'' relates to communication with realistic sensations and virtual space teleconferencing. Among various component technologies, real-time reproduction of 3-D human images and a cooperative work environment with virtual space are discussed in detail. The last key word ''distributed and collaborative'' relates to collaborative work in a distributed work environment. The importance of visual media in collaborative work, a concept of CSCW, and requirements for realizing a distributed collaborative environment are discussed. Then, four examples of CSCW systems are briefly outlined.
We present a system for finding and tracking a face and extract global and local animation parameters from a video sequence. The system uses an initial colour processing step for finding a rough estimate of the positi...
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We present a system for finding and tracking a face and extract global and local animation parameters from a video sequence. The system uses an initial colour processing step for finding a rough estimate of the position, size, and inplane rotation of the face, followed by a refinement step drived by an active model. The latter step refines the previous estimate, and also extracts local animation parameters. The system is able to track the face and some facial features in near real-time, and can compress the result to a bitstream compliant to MPEG-4 face and body animation.
In this paper, we propose the use of modified Hough transforms to efficiently extract object feature parameters, which are usually contaminated by heavily noisy corrugation and discontinuity. The modified HT (MHT) is ...
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In this paper, we propose the use of modified Hough transforms to efficiently extract object feature parameters, which are usually contaminated by heavily noisy corrugation and discontinuity. The modified HT (MHT) is developed by introducing spatial and parameter weighting functions to improve the detection performance for the traditional Hough transform (HT), which generally fails to robustly detect natural object parameters. Using designed test patterns and real images, simulations show that the proposed weighting functions are helpful in detecting noise-corrupted object features. Due to its robustness, the MHT can be easily figured with a coarse-re-fine adaptive search mechanism to reduce the huge amount of computation for feature parameters extraction.
This paper deals with video coding of static scenes viewed by a moving camera. We propose an automatic way to encode such video sequences using several 3D models. Contrary to prior art in model-based coding where 3D m...
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This paper deals with video coding of static scenes viewed by a moving camera. We propose an automatic way to encode such video sequences using several 3D models. Contrary to prior art in model-based coding where 3D models have to be known, the 3D models are automatically computed from the original video sequence. We show that several independent 3D models provide the same functionalities as one single 3D model, and avoid some drawbacks of the previous approaches. To achieve this goal we propose a novel algorithm of sliding adjustment, which ensures consistency of successive 3D models. The paper presents a method to automatically extract the set of 3D models and associate camera positions. The obtained representation can be used for reconstructing the original sequence, or virtual ones. It also enables 3D functionalities such as synthetic object insertion, lightning modification, or stereoscopic visualization. Results on real video sequences are presented.
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