检索结果-内蒙古大学图书馆

53rd International ELMAR Symposium (ELMAR)

作者： Polec, Jaroslav Ondrusova, Sandra Krulikovska, Lenka Slovak Univ Technol Bratislava Dept Telecommun Bratislava Slovakia

ISBN: (纸本)9789537044121

Static and dynamic image coding is necessary for transfer via communication network. Digital image representation requires large numbers of bits. In this paper low bit-rate human face image coding using triangulation is presented. Human faces modeling algorithm uses an available database of average faces for face synthesis. An average face is created by image registration on 2D model of human face. Mentioned method is called a model-based coding. Strong correlation between original face and synthesis face allows minimizing of bit-rate. We have implemented the proposed approach into the images coding in collaboration with standard H.264.

关键词： Triangulation H.264 model-based coding Average face

来源：评论

学校读者我要写书评

暂无评论

Video coding of model-based at very low bit rates

Video coding of model-based at very low bit rates

引用

Conference on Visual Communications and Image Processing 2003

作者： Fu, XP Wang, Z Dalian Maritime Univ Dept Comp Sci & Technol Dalian 116026 Peoples R China

ISBN: (纸本)0819450235

Very low bit rate coding is an important part of the MPEG-4 standard. To obtain maximum compression in videoconference sequences a technique called model-based coding can be used. With this technique, the face of the speaker is represented by a model, and its movement between frames is coded with a small set of parameters. As with all MPEG standards, the encoder algorithm is not described and this leaves the door open to many possible implementations. In this paper, a summary of model-based coding is presented. Many fields have been studied, including 3D wire-frame models, face detection, facial feature extraction, motion parameter estimation, and face model parameter coding. Several problems need to be solved before model-based video communication will become practical. Some of them are discussed in this paper, such as how to detect and locate a face in an image, how to extract parameters from an image to adapt a face model, and how to compress the animation parameters.

关键词： videoconference model-based coding 3D wire-frame model face detection facial feature extraction motion parameter estimation face model parameter coding

来源：评论

学校读者我要写书评

暂无评论

Overview of intelligent video coding: from model-based to learning-based approaches

引用

Visual Intelligence 2023年第1期1卷 1-19页

作者： Ma, Siwei Gao, Junlong Wang, Ruofan Chang, Jianhui Mao, Qi Huang, Zhimeng Jia, Chuanmin National Engineering Research Center of Visual Technology School of Computer Science Peking University Beijing 100871 China State Key Laboratory of Media Convergence and Communication Communication University of China Beijing 100024 China Wangxuan Institue of Computer Technology Peking University Beijing 100871 China

Intelligent video coding (IVC), which dates back to the late 1980s with the concept of encoding videos with knowledge and semantics, includes visual content compact representation models and methods enabling structural, detailed descriptions of visual information at different granularity levels (i.e., block, mesh, region, and object) and in different areas. It aims to support and facilitate a wide range of applications, such as visual media coding, content broadcasting, and ubiquitous multimedia computing. We present a high-level overview of the IVC technology from model-based coding (MBC) to learning-based coding (LBC). MBC mainly adopts a manually designed coding scheme to explicitly decompose videos to be coded into blocks or semantic components. Thanks to emerging deep learning technologies such as neural networks and generative models, LBC has become a rising topic in the coding area. In this paper, we first review the classical MBC approaches, followed by the LBC approaches for image and video data. We also discuss and overview our recent attempts at neural coding approaches, which are inspiring for both academic research and industrial implementation. Some critical yet less studied issues are discussed at the end of this paper. © The Author(s) 2023.

关键词： Multimedia communication Video compression Artificial intelligence model-based coding Generative coding Learning-based coding

来源：评论

学校读者我要写书评

暂无评论

Advances in very low bit rate video coding in North America

引用

IEICE TRANSACTIONS ON COMMUNICATIONS 1996年第10期E79B卷 1425-1433页

作者： Huang, TS Stroming, JW Kang, Y Lopez, R Beckman Institute University of Illinois Champaign United States

Research in very low-bit rate coding has made significant advancements in the past few years. Most recently, the introduction of the MPEG-4 proposal has motivated a wide variety of approaches aimed al achieving a new level of video compression. In this paper we review progress in VLBV categorized into 3 main areas: (1) Waveform coding, (2) 2D Content-based coding, and (3) model-based coding. Where appropriate we also described proposals to the MPEG-4 committee in each of these areas.

关键词： content-based coding object-based coding MPEG-4 affine transform model-based coding very-low bit rate coding motion compensation DCT wavelets

来源：评论

学校读者我要写书评

暂无评论

Flexible 3D motion estimation and tracking for multiview image sequence coding

引用

SIGNAL PROCESSING-IMAGE COMMUNICATION 1998年第1-2期14卷 95-110页

作者： Kompatsiaris, I Tzovaras, D Strintzis, MG Aristotle Univ Thessaloniki Informat Proc Lab Dept Elect & Comp Engn Thessaloniki 54006 Greece

This paper describes a procedure for model-based coding of all channels of a multiview image sequence. The 3D model is initialised 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 held 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. (C) 1998 Elsevier Science B.V. All rights reserved.

关键词： multiview image sequence compression model-based coding non-rigid 3D motion estimation

来源：评论

学校读者我要写书评

暂无评论

AUTOMATIC FACE LOCATION DETECTION FOR model-ASSISTED RATE CONTROL IN H.261-COMPATIBLE coding OF VIDEO

引用

SIGNAL PROCESSING-IMAGE COMMUNICATION 1995年第4-6期7卷 435-455页

作者： ELEFTHERIADIS, A JACQUIN, A COLUMBIA UNIV DEPT ELECT ENGNNEW YORKNY 10027

We present a novel and practical way to integrate techniques from computer vision to low bit-rate coding systems for video teleconferencing applications. Our focus is to locate and track the faces and selected facial features of persons in typical head-and-shoulders video sequences, and to exploit the location information in a 'classical' video coding/decoding system. The motivation is to enable the system to encode selectively various image areas and to produce perceptually pleasing coded images where faces are sharper. We refer to this approach-a mix of classical waveform coding and model-based coding-as model-assisted coding. We propose two totally automatic algorithms which, respectively, perform the detection of a head outline, and identify an 'eyes-nose-mouth' region, both from downsampled binary thresholded edge images. The algorithms operate accurately and robustly, even in cases of significant head rotation or partial occlusion by moving objects. We show how the information about face and facial feature location can be advantageously exploited by low bit-rate waveform-based video coders. In particular, we describe a method of object-selective quantizer control in a standard coding system based on motion-compensated discrete cosine transform-CCITT's recommendation H.261. The approach is based on two novel algorithms, namely buffer rate modulation and buffer size modulation. By forcing the rate control algorithm to transfer a fraction of the total available bit-rate from the coding of the non-facial to that of the facial area, the coder produces images with better-rendered facial features, i.e. coding artefacts in the facial area are less pronounced and eye contact is preserved. The improvement was found to be perceptually significant on video sequences coded at the ISDN rate of 64 kbps, with 48 kbps for the input (color) video signal in QCIF format.

关键词： VERY LOW BIT-RATE coding FACIAL FEATURE DETECTION model-based coding H.261 VIDEO COMPRESSION

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

model-aided coding: A new approach to incorporate facial animation into motion-compensated video coding

引用

IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS FOR VIDEO TECHNOLOGY 2000年第3期10卷 344-358页

作者： Eisert, P Wiegand, T Girod, B Univ Erlangen Nurnberg Telecommun Lab D-91058 Erlangen Germany

We show that traditional waveform coding and 3-D model-based coding are not competing alternatives, but should be combined to support and complement each other. Both approaches are combined such that the generality of waveform coding and the efficiency of 3-D model-based coding are available where needed. The combination is achieved by providing the block-based video coder with a second reference frame for prediction, which is synthesized by the model-based coder. The model-based coder uses a parameterized 3-D head model, specifying shape and color of a person. We therefore restrict our investigations to typical videotelephony scenarios that show head-and-shoulder scenes. Motion and deformation of the 3-D head model constitute facial expressions which are represented by facial animation parameters (FAP's) based on the MPEG-4 standard. An intensity gradient based approach that exploits the 3-D model information is used to estimate the FAP's, as well as illumination parameters, that describe changes of the brightness in the scene. model failures and objects that are not known at the decoder are handled by standard block-based motion-compensated prediction, which is not restricted to a special scene content, but results in lower coding efficiency. A Lagrangian approach is employed to determine the most efficient prediction for each block from either the synthesized model frame or the previous decoded frame. Experiments on five video sequences show that bit-rate savings of about 35% are achieved at equal average peak signal-to-noise ratio (PSNR) when comparing the model-aided codec to TMN-10, the state-of-the-art test model of the H.263 standard. This corresponds to a gain of 2-3 dB in PSNR when encoding at the same average bit rate.

关键词： facial animation model-aided coding model-based coding multiframe prediction

来源：评论

学校读者我要写书评

暂无评论

AUTOMATIC FACE LOCATION DETECTION AND TRACKING FOR model-ASSISTED coding OF VIDEO TELECONFERENCING SEQUENCES AT LOW BIT-RATES

引用

SIGNAL PROCESSING-IMAGE COMMUNICATION 1995年第3期7卷 231-248页

作者： ELEFTHERIADIS, A JACQUIN, A COLUMBIA UNIV DEPT ELECT ENGNNEW YORKNY 10027

We present a novel and practical way to integrate techniques from computer vision to low bit-rate coding systems for video teleconferencing applications. Our focus is to locate and track the faces of persons in typical head-and-shoulders video sequences, and to exploit the face location information in a 'classical' video coding/decoding system, The motivation is to enable the system to selectively encode various image areas and to produce psychologically pleasing coded images where faces are sharper, We refer to this approach as model-assisted coding. We propose a totally automatic, low-complexity algorithm, which robustly performs face detection and tracking. A priori assumptions regarding sequence content are minimal and the algorithm operates accurately even in cases of partial occlusion by moving objects. Face location information is exploited by a low bit-rate 3D subband-based video coder which uses both a novel model-assisted pixel-based motion compensation scheme, as well as model-assisted dynamic bit allocation with object-selective quantization. By transferring a small fraction of the total available bit-rate from the non-facial to the facial area, the coder produces images with better-rendered facial features. The improvement was found to be perceptually significant on video sequences coded at 96 kbps for an input luminance signal in CIF format, The technique is applicable to any video coding scheme that allows for fine-grain quantizer selection (e.g. MPEG, H.261), and can maintain full decoder compatibility.

关键词： FACE TRACKING model-based coding TELECONFERENCING VIDEO 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

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：