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A technique of object-adaptive vertex-based shape coding for MPEG-4 videos

INTERNATIONAL JOURNAL OF IMAGING SYSTEMS AND TECHNOLOGY 2000年第5期11卷 277-282页

作者： Lin, SFD Lin, CC Shie, SC Natl Dong Hwa Univ Dept Comp Sci & Informat Engn Hualien Taiwan

The MPEG-4 visual standard Is the first international standard that allows the transmission of arbitrarily shaped video objects and provides technologies to view, access, and manipulate objects rather than pixels. It addresses the encoding of video objects by shape coding, motion estimation, and texture coding for Interactivity, high compression, and scalability. Current binary shape-coding techniques can be classified into two categories: bitmap based and contour based. O'Connell (1997) proposed an object-adaptive vertex-based shape-coding method to improve the efficiency of shape coding. This method encodes the relative locations of a video object's vertices by adapting the representation to the dynamic range of the relative locations and by exploiting an octant-based representation for each relative location. We propose an extension of O'Connell's method. Two relative locations of a video object's vertices are grouped and the x pairs and y pairs of the locations are encoded, respectively. Simulation results demonstrate that our method outperforms O'Connell's method. (C) 2001 John Wiley & Sons, Inc. Int J Imaging Syst Technol, 11, 277-282, 2000.

关键词： MPEG-4 video object vertex-based shape coding

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Optimal vertex adjustment method using a Viterbi algorithm for vertex-based shape coding

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ELECTRONICS LETTERS 1999年第9期35卷 706-707页

作者： Lee, JH Chung, JW Kim, JK Korea Adv Inst Sci & Technol Dept Elect Engn Taejon 305701 South Korea Hyundai Elect Ind Co Ltd Informat & Telecommun R&D Ctr Seoul 137070 South Korea

An optimal vertex adjustment method is presented for vertex-based shape coding. The method optimally shifts the vertices, selected by a conventional vertex selection method, within the window that satisfies the allowable maximum distortion using a Viterbi algorithm. Experimental results show that the proposed method reduces the approximation distortion of the contour by similar to 30% for the same rate over a wide range of distortion, compared with the conventional method.

关键词： vertex selection method approximation distortion reduction Image and video coding Viterbi decoding vertex-based shape coding Viterbi algorithm image coding vectors Computer vision and image processing techniques optimal vertex adjustment method

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A vertex-based shape coding technique for video objects

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IEICE TRANSACTIONS ON INFORMATION AND SYSTEMS 2001年第7期E84D卷 918-922页

作者： Lin, STD Lin, CC Shie, SC Natl Dong Hwa Univ Dept Comp Sci & Informat Engn Hualien Taiwan

MPEG-4 emphasizes on coding efficiency and allows for content-based access and transmission of arbitrary shaped object. It addresses the encoding of video object using shape coding, motion estimation, and texture coding for interactivity, high compression ratio, and scalability. In this letter, an advanced object-adaptive vertex-based shape coding method is proposed for encoding the shape of video objects. This method exploits octant-based representation to represent the relation of adjacent vertices and that relation can be used to improve coding efficiency. Simulation results demonstrate that the proposed method may reduce more bits fur closely spaced vertices.

关键词： MPEG-4 video object alpha plane vertex-based shape coding

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New dynamic enhancements to the vertex-based rate-distortion optimal shape coding framework

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IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS FOR VIDEO TECHNOLOGY 2007年第10期17卷 1408-1413页

作者： Sohel, Ferdous Ahmed Dooley, Laurence S. Karmakar, Gour C. Monash Univ GSIT Churchill Vic 3842 Australia

Existing vertex-based operational rate-distortion (ORD) optimal shape coding algorithms use a vertex band around the shape boundary as the source of candidate control points (CP) usually in combination with a tolerance band (TB) and sliding window (SW) arrangement, as their distortion measuring technique. These algorithms however, employ a fixed vertex-band width irrespective of the shape and admissible distortion (AD), so the full bit-rate reduction potential is not fulfilled. Moreover, despite the causal impact of the SW-length upon both the bit-rate and computational-speed, there is no formal mechanism for determining the most suitable SW-length. This paper introduces the,concept of a variable width admissible CP band and new adaptive SW-length selection strategy to address these issues. The presented quantitative and qualitative results analysis endorses the superior performance achieved by integrating these enhancements into the existing vertex-based ORD optimal algorithms.

关键词： vertex-based shape coding video coding

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Dynamic Bezier curves for variable rate-distortion

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PATTERN RECOGNITION 2008年第10期41卷 3153-3165页

作者： Sohel, Ferdous A. Karmakar, Gour C. Dooley, Laurence S. Univ Western Australia Sch Comp Sci & Software Engn Crawley WA 6009 Australia Monash Univ Gippsland Sch Informat Technol Gippsland Australia Open Univ Fac Maths Comp & Technol Milton Keynes MK7 6AA Bucks England

Bezier curves (BC) are important tools in a wide range of diverse and challenging applications, from computer-aided design to generic object shape descriptors. A major constraint of the classical BC is that only global information concerning control points (CP) is considered, consequently there may be a sizeable gap between the BC and its control polygon on (CtrlPoly), leading to a large distortion in shape representation. While BC variants like degree elevation, composite BC and refinement and subdivision narrow this gap, they increase the number of CP and thereby both the required bit-rate and computational complexity. In addition, while quasi-Bezier curves (QBC) close the gap without increasing the number of CP, they reduce the underlying distortion by only a fixed amount. This paper presents a novel contribution to BC theory, with the introduction of a dynamic Bezier curve (DBC) model, which embeds variable localised CP information into the inherently global Bezier framework, by strategically moving BC points towards the CtrlPoly. A shifting parameter (SP) is defined that enables curves lying within the region between the BC and CtrlPoly to be generated, with no commensurate increase in CP. DBC provides a flexible rate-distortion (RD) criterion for shape coding applications, with a theoretical model for determining the optimal SP value for any admissible distortion being formulated. Crucially DBC retains core properties of the classical BC, including the convex hull and affine invariance, and can be seamlessly integrated into both the vertex-based shape coding and shape descriptor frameworks to improve their RD performance. DBC has been empirically tested upon a number of natural and synthetically shaped objects, with qualitative and quantitative results confirming its consistently superior shape approximation performance, compared with the classical BC, QBC and other established BC-based shape descriptor techniques. (C) 2008 Elsevier Ltd. All rights reserved.

关键词： vertex-based shape coding image processing video processing Bezier curves

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B-spline-based shape coding with accurate distortion measurement using analytical model

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NEUROCOMPUTING 2015年第PartC期149卷 1631-1646页

作者： Lai, Zhongyuan Wang, Zhe Zuo, Zhen Yao, Zhijun Liu, Wenyu Huazhong Univ Sci & Technol Dept Elect & Informat Engn Wuhan 430074 Peoples R China Jianghan Univ Inst Interdisciplinary Res Wuhan 430056 Peoples R China

In this paper, we present a new model to measure the contour point distortion for the vertex-based shape coding with B-splines, called accurate distortion measurement using analytical model (ADMAM). Different from existing distortion measurements containing approximation, quantization or parameterization process, our distortion is defined on the original B-spline. It is modeled as the shortest distance of associated contour point from the original B-spline, which is in line with the subjective-based objective quality metric. The geometric relationships are introduced to simplify the model computation, followed by a hybrid admissible distortion checking algorithm to reduce the execution time. Our theoretical analysis and experimental results demonstrate that the ADMAM can lead to the smallest bit-rate among all the distortion measurements that guarantee the admissible distortion, when the operational rate-distortion optimal shape coding framework is applied. Moreover, if the original contour has N-C points, it takes only O(N-C) time for both peak and mean-squared segment distortion measuring paradigms, which is the lowest computational complexity among all the existing distortion measurements. (C) 2014 Elsevier B.V. All rights reserved.

关键词： B-spline Distortion measurement vertex-based shape coding Video coding

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Quasi-Bezier curves integrating localised information

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PATTERN RECOGNITION 2008年第2期41卷 531-542页

作者： Sohel, FerdoUs A. Karmakara, Gour C. Dooley, Laurence S. Arkinstall, John R. Monash Univ Gippsland Sch Informat Technol Churchill Vic 3842 Australia Monash Univ Sch Engn & Appl Sci Churchill Vic 3842 Australia

Bezier curves (BC) have become fundamental tools in many challenging and varied applications, ranging from computer-aided geometric design to generic object shape descriptors. A major limitation of the classical Bezier curve, however, is that only global information about its control points (CP) is considered, so there can often be a large gap between the curve and its control polygon, leading to large distortion in shape representation. While strategies such as degree elevation, composite BC, refinement and subdivision reduce this gap, they also increase the number of CP and hence bit-rate, and computational complexity. This paper presents novel contributions to BC theory, with the introduction of quasi-Bezier curves (QBC), which seamlessly integrate localised CP information into the inherent global Bezier framework, with no increase in either the number of CP or order of computational complexity. QBC crucially retains the core properties of the classical BC, such as geometric continuity and affine invariance, and can be embedded into the vertex-based shape coding and shape descriptor framework to enhance ratedistortion performance. The performance of QBC has been empirically tested upon a number of natural and synthetically shaped objects, with both qualitative and quantitative results confirming its consistently superior approximation performance in comparison with both the classical BC and other established BC-based shape descriptor methods. (c) 2007 Pattern Recognition Society. Published by Elsevier Ltd. All rights reserved.

关键词： vertex-based shape coding image processing video processing bezier curve

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