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A New shape-coding Algorithm by Using Wavelet Transform

Chinese Journal of Systems Engineering and Electronics 2003年第2期000卷

In this paper, we propose a new shape-coding algorithm called wavelet-based shape coding (WBSC). Performing wavelet transform on the orientation of original planar curve gives the corners called corner-1 points and end of arcs that belong to the original curve. Each arc is represented by a broken line and the corners called corner-2 points of the broken line are extracted. A polygonal approximation of a contour is an ordered list of corner-1 points, ends of arcs and corner-2 points which are extracted by using the above algorithm. All of the points are called polygonal vertices which will be compressed by our adaptive arithmetic encoding. Experimental results show that our method reduces code bits by about 26% compared with the context-based arithmetic encoding (CAE) of MPEG-4, and the subjective quality of the reconstructed shape is better than that of CAE at the same Dn.

关键词： Wavelet transform shape coding WBSC MPEG-4 CAE

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Efficient coding of shape and transparency for video objects

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IEEE TRANSACTIONS ON IMAGE PROCESSING 2007年第9期16卷 2234-2244页

作者： Aghito, Shankar Manuel Forchhammer, Soren Tech Univ Denmark COM DTU Dept Commun Opt & Mat Lyngby 2800 Denmark

A novel scheme for coding gray-level alpha planes in object-based video is presented. Gray-level alpha planes convey the shape and the transparency information, which are required for smooth composition of video objects. The algorithm proposed is based on the segmentation of the alpha plane in three layers: binary shape layer, opaque layer, and intermediate layer. Thus, the latter two layers replace the single transparency layer of MPEG-4 Part 2. Different encoding schemes are specifically designed for each layer, utilizing cross-layer correlations to reduce the bit rate. First, the binary shape layer is processed by a novel video shape coder. In intra mode, the DSLSC binary image coder presented in [3] is used. This is extended here with an intermode utilizing temporal redundancies in shape image sequences. Then the opaque layer is compressed by a newly designed scheme which models the strong correlation with the binary shape layer by morphological erosion operations. Finally, three solutions are proposed for coding the intermediate layer. The knowledge of the two previously encoded layers is utilized in order to increase compression efficiency. Experimental results are reported demonstrating that the proposed techniques provide substantial bit rate savings coding shape and transparency when compared to the tools adopted in MPEG-4 Part 2.

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

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Error concealment for shape in MPEG-4 object-based video coding

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IEEE TRANSACTIONS ON IMAGE PROCESSING 2005年第4期14卷 389-396页

作者： Huang, C Salama, P NTIUS Inc Irvine CA 92618 USA Indiana Univ Purdue Univ Dept Elect & Comp Engn Indianapolis IN 46202 USA

In asynchronus transfer mode networks, cell loss or channel errors can cause data to be dropped in the channel. When digital images/videos are transmitted over these networks, one must be able to reconstruct the missing data so that the impact of the errors is minimized. In this paper, we present an error-concealment technique for shape in MPEG-4 object-based video coding. This method, which is based on using global motion estimation and compensation techniques for boundary recovery, consists of three steps: 1) boundary extraction from shape;2) boundary patching using global motion compensation;and 3) boundary filling to reconstruct the shape of the damaged video object planes. Global motion parameters are inserted as part of the USER_DATA field in the compressed stream and are utilized in reconstructing the damaged boundaries of compressed video object planes.

关键词： boundary reconstruction error concealment MPEG-4 object based shape coding video coding

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Motion compensated two-link chain coding for binary shape sequence

Motion compensated two-link chain coding for binary shape se...

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Conference on Visual Communications and Image Processing 2002

作者： Lu, ZT Pearlman, WA Rensselaer Polytech Inst Dept Elect Comp & Syst Engn Troy NY 12180 USA

ISBN: (纸本)0819444111

In this paper, we present a motion compensated two-link chain coding technique to effectively encode 2-D binary shape sequences for, object-based video coding. This technique consists of a contour motion estimation and compensation algorithm and a two-link chain coding algorithm. The object contour is defined on a 6-connected contour lattice for a smoother contour representation. The contour in the current frame is first predicted by global motion and local motion based on the decoded contour in the previous frame;then, it is segmented into motion success segments, which can be predicted by the global motion or the local motion, and motion failure segments, which can not be predicted by the global and local motion. For each motion failure segment, a two-link chain code, which uses one chain code to represent two consecutive contour links, followed by an arithmetic coder is proposed for efficient coding. Each motion success segment can be represented by the motion vector and its length. For contour motion estimation and compensation, besides the translational motion model, an affine global motion model is proposed, and investigated for complex global motion. We test the performance of the proposed technique by several MPEG-4 shape test sequences. The experimental results show that our proposed scheme is better than the CAE technique which is applied in the MPEG-4 verification model.

关键词： shape coding video coding chain coding MPEG-4 motion estimation motion compensation

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Arbitrarily shape Object-based Video coding Technology by Wavelet-based Contourlet Transform

Arbitrarily Shape Object-based Video Coding Technology by Wa...

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IEEE International Conference on Information and Automation 2015

作者： Shu, Zhenghua Luo, Yihang Liu, Guodong Xie, Zhihua Jiangxi Sci & Technol Normal Univ Key Lab Opt Elect & Commun Nanchang Peoples R China

ISBN: (纸本)9781467391047

Video object coding is one of the most important functionalities proposed by MPEG4. In this paper, a new Wavelet-based Contourlet Transform method to encode the texture of an arbitrarily shaped object is presented, which both for the still and for video object. The method uses the shape adaptive Wavelet-based Contourlet Transform (SA-WBCT) in MPEG4 still object coding, but with a computationally more efficient lifting implementation. The transformed object coefficients are then quantized and entropy encoded with a partial bitplane embedded coder, which greatly improves the coding efficiency. We denote the coding algorithm as video object Wavelet-based Contourlet Transform (VOWBCT) coder. The results show that the quality of the VOWBCT algorithm is significantly higher than the results of the VOW algorithm in the same bit rate in terms of PSNR. Moreover, This VOWBCT coding method is more convenient in realization.

关键词： Wavelet-Based Contourlet Transform(WBCT) Image coding Video object coding shape coding VOWBCT

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Arbitrarily shape Object-based Video coding Technology by Wavelet-based Contourlet Transform

Arbitrarily Shape Object-based Video Coding Technology by Wa...

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IEEE International Conference on Information and Automation

作者： Zhenghua Shu Yihang Luo Guodong Liu Zhihua Xie Key Lab of Optic-Electronic and Communication Jiangxi Science and Technology Normal University

ISBN: (纸本)9781467391054

关键词： Wavelet-Based Contourlet Transform (WBCT) Image coding Video object coding shape coding VOWBCT

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On Growth and Formlets: Sparse Multi-Scale coding of Planar shape

On Growth and Formlets: Sparse Multi-Scale Coding of Planar ...

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IEEE Conference on Computer Vision and Pattern Recognition

作者： Timothy D. Oleskiw James H. Elder Gabriel Peyre York University Universite Paris-Dauphine

ISBN: (纸本)9781424469840;9781424469857

This paper presents a sparse representation of 2D planar shape through the composition of warping functions, termed formlets, localized in scale and space. Each formlet subjects the 2D space in which the shape is embedded to a localized isotropic radial deformation. By constraining these localized warping transformations to be diffeomor-phisms, the topology of shape is preserved, and the set of simple closed curves is closed under any sequence of these warpings. A generative model based on a composition of formlets applied to an embryonic shape, e.g., an ellipse, has the advantage of synthesizing only those shapes that could correspond to the boundaries of physical objects. To compute the set of formlets that represent a given boundary, we demonstrate a greedy coarse-to-fine formlet pursuit algorithm that serves as a non-commutative generalization of matching pursuit for sparse approximations. We evaluate our method by pursuing partially occluded shapes, comparing performance against a contour-based sparse shape coding framework.

关键词： sparse representation Warping Pursuit algorithms shape Planar matching pursuits multi-scale Ellipse addendum modification shape coding

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Rate-distortion optimal bit allocation for object-based video coding

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IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS FOR VIDEO TECHNOLOGY 2005年第9期15卷 1113-1123页

作者： Wang, HH Schuster, GM Katsaggelos, AK Qualcomm Inc Qualcomm CDMA Technol San Diego CA 92121 USA Hsch Tech Abt Elektrotech CH-8640 Rapperswil Switzerland Northeastern Univ Dept Elect & Comp Engn Evanston IL 60208 USA

In object-based video encoding, the encoding of the video data is decoupled into the encoding of shape, motion, and texture information, which enables certain functionalities, like content-based interactivity and content-based scalability. The fundamental problem, however, of how to jointly encode this separate information to reach the best coding efficiency has not been studied thoroughly. In this paper, we present an operational rate-distortion optimal scheme for the allocation of bits among shape, motion, and texture in object-based video encoding. Our approach is based on Lagrangian relaxation and dynamic programming. We implement our algorithm on the MPEG-4 video verification model, although it is applicable to any object-based video encoding scheme. The performance is accessed utilizing a proposed metric that jointly captures the distortion due to the encoding of the shape and texture. Experimental results demonstrate that the gains of lossy shape encoding depend on the percentage the shape bits occupy out of the total bit budget. This gain may be small or may be realized at very low bit rates for certain typical scenes.

关键词： MPEG-4 object-based video rate-distortion shape coding video coding

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Redundancy reducing coding of moving object shapes

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SIGNAL PROCESSING-IMAGE COMMUNICATION 1997年第2期9卷 91-98页

作者： Heckner, G Department of Communication and Measurement Technical University of Ilmenau P. O. Box 0565 D-98684 Ilmenau Germany

A redundancy reducing technique for coding of object shapes in image sequences is presented. Polygon-spline approximation as known from object-based analysis-synthesis coding is used as a basis. A parametric hexagonal coordinate system is introduced in place of the cartesian one. The range of relative coordinates is limited. By these two methods the data rate required for coding the shapes is decreased by about 13%. When additionally using temporal prediction, by exploiting the fact that the slope of an object shape does not differ so much in time, a total decrease of about 28% is achieved.

关键词： shape coding silhouette coding contour coding outline coding hexagonal coordinate system parametrization limitation of grid point set shape prediction OBASC

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coding of subregions for content-based scalable video

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IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS FOR VIDEO TECHNOLOGY 1997年第1期7卷 256-260页

作者： Chen, TH Swain, CT Haskell, BG AT and T Research Laboratories Holmdel NJ USA

We propose a scheme for coding subregions in video scenes to provide content-based scalable video. For each region, a special color is used to represent the nonobject area, and the resulting frames are coded using conventional video coding algorithms. At the decoder, the region shape is recovered based on chroma keying, and hence, content-based manipulations are made possible. A number of techniques that eliminate boundary artifacts common to region-based coding are presented. In this scheme, no explicit shape coding is needed, and advantages of existing coding algorithms are retained. This scheme was submitted to ISO MPEG-4 and performed very well in the subjective tests.

关键词： chroma keying MPEG object scalability region-based coding shape coding

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