检索结果-内蒙古大学图书馆

A robust model generation technique for model-based video coding

IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS FOR VIDEO TECHNOLOGY 2001年第11期11卷 1188-1192页

作者： Siu, M Chan, YH Siu, WC Hong Kong Polytech Univ Dept Elect & Informat Engn Ctr Multimedia Signal Proc Hong Kong Hong Kong Peoples R China

In conventional model-based coding schemes, predefined static models are generally used. These models cannot adapt to new situations, and hence, they have to be very specific and cannot be generated from a single generic model even though they are very similar. In this letter, we present a model-generation technique that can gradually build a model and dynamically modify it according to new video frames scanned. The proposed technique is robust to the object's orientation in the view and can be efficiently implemented with a parallel processing technique. As a result, the proposed technique is more attractive to the practical use of model-based coding techniques in real applications.

关键词： model-based coding model synthesis

来源：评论

学校读者我要写书评

暂无评论

modeling of 2D+1 texture movies for video coding

引用

IMAGE AND VISION COMPUTING 2003年第1期21卷 49-59页

作者： Valaeys, S Menegaz, G Ziliani, F Reichel, J Swiss Fed Inst Technol Audio Visual Commun Lab CH-1015 Lausanne Switzerland VisioWave SA CH-1024 Ecublens Switzerland

We propose a novel model-based coding system for video. model-based coding aims at improving compression gain by replacing the non-informative image elements with some perceptually equivalent models. Images enclosing large textured regions are ideal candidates. Texture movies are obtained by filming a static texture with a moving camera. The integration of the motion information within the generative texture process allows to replace the 'real' texture with a 'visually equivalent' synthetic one, while preserving the correct motion perception. Global motion estimation is used to determine the movement of the camera and to identify the overlapping region between two successive frames. Such an information is then exploited for the generation of the texture movies. The proposed method for synthesizing 2D + 1 texture movies is able to emulate any piece-wise linear trajectory. The compression performance is very encouraging. On this kind of video sequences, the proposed method improves the compression rate of an MPEG4 state-of-the-art video coder of an order of magnitude while providing a sensibly better perceptual quality. Importantly, the current implementation is real-time on Intel PIII processors. (C) 2002 Elsevier Science B.V. All rights reserved.

关键词： model-based coding dynamic textures dynamic coding

来源：评论

学校读者我要写书评

暂无评论

Multi-view coding for Image-based Rendering using 3-D scene geometry

引用

IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS FOR VIDEO TECHNOLOGY 2003年第11期13卷 1092-1106页

作者： Magnor, M Ramanathan, P Girod, B Max Planck Inst Informat D-66123 Saarbrucken Germany Stanford Univ Stanford CA 94305 USA

To store and transmit the large, amount of image data necessary for Image-based Rendering (IBR), efficient coding schemes are required. This paper presents two different approaches which exploit three-dimensional scene geometry for multi-view compression. In texture-based coding, images are converted to view-dependent texture maps for compression. In model-aided predictive coding, scene geometry is used for disparity compensation and occlusion detection between images. While both coding strategies are able to attain compression ratios exceeding 2000:1, individual coding performance is found to depend on the accuracy of the available geometry model. Experiments with real-world as well as synthetic image sets show that texture-based coding is more sensitive to geometry inaccuracies than predictive coding. A rate-distortion theoretical analysis of both schemes supports these findings. For reconstructed approximate geometry models, model-aided predictive coding performs best, while texture-based coding yields superior coding results if scene geometry is exactly known.

关键词： geometry coding image-based rendering (IBR) light field compression model-based coding multi-view coding analysis multi-view compression

来源：评论

学校读者我要写书评

暂无评论

Hierarchical motion estimation with content-based meshes

引用

IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS FOR VIDEO TECHNOLOGY 2003年第10期13卷 1000-1005页

作者： Al-Regib, G Altunbasak, Y Mersereau, RM Georgia Inst Technol Ctr Signal & Image Proc Atlanta GA 30332 USA

Two-dimensional mesh-based models provide a good alternative to motion estimation and compensation. The estimation of the best node-point motion vectors is a challenging task. To this effect, Nakaya and Harashima proposed a hexagonal matching procedure. Toklu et al improved the hexagonal search algorithm in terms of both motion-estimation accuracy and computational complexity by employing a hierarchy of regular meshes. Recognizing the limitations of regular meshes, Van Beek et al. extended Toklu et al.'s work by utilizing content-based meshes. Here, we provide an alternative hierarchical motion-estimation method with content-based meshes where hierarchical representations are employed for both the images and the irregular meshes in order to provide further improvements in computational complexity as well as motion accuracy. The comparison results are provided with real video sequences.

关键词： hierarchical motion estimation model-based coding two-dimensional mesh two-dimensional mesh-based motion representation video compression

来源：评论

学校读者我要写书评

暂无评论

MPEG-4 facial animation in video analysis and synthesis

引用

INTERNATIONAL JOURNAL OF IMAGING SYSTEMS AND TECHNOLOGY 2003年第5期13卷 245-256页

作者： Eisert, P Heinrich Hertz Inst Nachrichtentech Berlin GmbH Fraunhofer Inst Telecommun Image Proc Dept D-10587 Berlin Germany

MPEG-4 supports the definition, encoding, transmission, and animation of 3-D head and body models. These features can be used for a variety of different applications ranging from low bit-rate video coding to character and avatar animation. In this article, an entire system for the analysis of facial expressions from image sequences and their synthesis is presented. New methods for the estimation of MPEG-4 facial animation parameters as well as scene illumination are proposed. Experiments for different applications demonstrate the potential of using facial animation techniques in video analysis and synthesis. A model-based codec is presented that is able to encode head-and-shoulder video sequences at bit-rates of about 1 kbit/s. Besides the low bit-rate, many enhancements and scene modifications can be easily applied, like scene lighting changes or cloning of expressions for character animation. But also for the encoding of arbitrary sequences, 3-D knowledge can help to increase the coding efficiency. With our model-aided codec, bit-rate reductions of up to 45% at the same quality can be achieved in comparison to standard hybrid video codecs. (C) 2004 Wiley Periodicals, Inc.

关键词： MPEG-4 facial animation video compression model-based coding model-aided coding

来源：评论

学校读者我要写书评

暂无评论

Immersive 3-D video conferencing: Challenges, concepts, and implementations

Immersive 3-D video conferencing: Challenges, concepts, and ...

引用

Conference on Visual Communications and Image Processing 2003

作者： Eisert, P Fraunhofer Inst Telecommun Heinrich Hertz Inst Image Proc Dept D-10587 Berlin Germany

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.

关键词： immersive video conferencing tele-collaboration shared virtual table environment model-based coding view synthesis

来源：评论

学校读者我要写书评

暂无评论

Automatic facial feature extraction in model-based coding

引用

JOURNAL OF INFORMATION SCIENCE AND ENGINEERING 2000年第3期16卷 447-458页

作者： Chuang, MM Chang, RF Huang, YL Natl Chung Cheng Univ Dept Comp Sci & Informat Engn Adv Syst Integrat Lab Chiayi 621 Taiwan

model-based coding is a new image sequence compression technique for very low bit rate coding. Most researchers have paid more attention to facial image analysis and synthesis because facial images are very important in multimedia communication applications, such as video phone, video conferencing, remote learning etc. This coding method represents the image content in a structural way. This is the reason why model-based coding can get a higher compression ratio (1-10 kb/s) than can the conventional coding methods. In order to encode image signals efficiently, it is necessary to create a suitable generic model and adapt it to the actual object accurately. In this paper, we propose a scheme, based on the integral-projection algorithm, which adapts a face model to an actual face automatically. First, the image is preprocessed by means of edge detection. From the edge mapped image, we use the feature of the increasing sudden edge density to indicate the rough vertical positions of eyes and mouth. According to the local threshold value in each feature area, all of the control points about the eyes and mouth are found. Finally, we use these control points to adapt the model to an actual face.

关键词： facial model facial features integral-projection algorithm model-based coding very low bit rate coding

来源：评论

学校读者我要写书评

暂无评论

FAP extraction using three-dimensional motion estimation

引用

IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS FOR VIDEO TECHNOLOGY 2002年第10期12卷 865-876页

作者： Sarris, N Grammalidis, N Strintzis, MG Aristotle Univ Thessaloniki GR-54006 Thessaloniki Greece

An integral part of the MPEG-4 standard is the definition of face animation parameters (FAPs). This paper presents a method for the determination of FAPs by using three dimensional (3-D) rigid and nonrigid motion of human facial features found from two-dimensional (2-D) image sequences. The proposed method assumes that a 3-D model has been fitted to the first frame of the sequence, tracks the motion of characteristic facial features, calculates the 3-D rigid and nonrigid motion of facial features, and through this, estimates the FAPs as defined by the MPEG-4 coding standard. The 2-D tracking process is based on a novel enhanced version of the algorithm proposed by Kanade, Lucas, and Tomasi. The nonrigid motion estimation is achieved using the same tracking mechanism guided by the facial motion model implied by the MPEG-4 FAPs.

关键词： 3-D motion estimation FAP extraction head tracking model-based coding

来源：评论

学校读者我要写书评

暂无评论

Facial model adaptation from a monocular image sequence using a textured polygonal model

引用

SIGNAL PROCESSING-IMAGE COMMUNICATION 2002年第5期17卷 373-392页

作者： Chang, YJ Chen, YC Natl Tsing Hua Univ Dept Elect Engn Hsinchu 30013 Taiwan

Although several algorithms have been proposed for facial model adaptation from image sequences, the insufficient feature set to adapt a full facial model, imperfect matching of feature points, and imprecise head motion estimation may degrade the accuracy of model adaptation. In this paper, we propose to resolve these difficulties by integrating facial model adaptation, texture mapping, and head pose estimation as cooperative and complementary processes. By using an analysis-by-synthesis approach, salient facial feature points and head profiles are reliably tracked and extracted to form a growing and more complete feature set for model adaptation. A more robust head motion estimation is achieved with the assistance of the textured facial model. The proposed scheme is performed with image sequences acquired with single uncalibrated camera and requires only little manual adjustment in the initialization setup, which proves to be a feasible approach for facial model adaptation. (C) 2002 Elsevier Science B.V. All rights reserved.

关键词： facial model adaptation model-based coding MPEG-4 SNHC talking head

来源：评论

学校读者我要写书评

暂无评论

An active model for facial feature tracking

引用

EURASIP JOURNAL ON APPLIED SIGNAL PROCESSING 2002年第6期2002卷 566-571页

作者： Ahlberg, J Linkoping Univ Dept Elect Engn Image Coding Grp SE-58131 Linkoping Sweden

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.

关键词： active appearance models free tracking facial feature tracking model-based coding MPEG-4 face and body animation

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：