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A new vertex adjustment method for polygon-based shape coding

IEICE TRANSACTIONS ON INFORMATION AND SYSTEMS 2006年第10期E89D卷 2693-2695页

作者： Yun, Byoung-Ju Cho, Jae-Soo Ko, Yun-Ho Kyungpook Natl Univ Sch Elect Engn & Comp Sci Taegu 702701 South Korea Korea Univ Technol & Educ Dept Internet Media Engn Cheonan 330708 South Korea Chungnam Natl Univ Dept Mechatron Engn Taejon 305764 South Korea

In this paper, we propose a new vertex adjustment method which is based on the size ratio of an object and that of a polygon. In the conventional polygonal approximation methods, the sizes of an object and an approximating polygon are quite different, therefore there are so many error pixels between them. The proposed method reduces the size of error regions by adjusting the size of the polygon to that of an object. Simulation results show outstanding performance of the proposed method.

关键词： shape coding contour coding object oriented coding polygonal approximation

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Adaptive vertex selection based on interregion contrast for polygon-based contour approximation

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OPTICAL ENGINEERING 2004年第1期43卷 44-50页

作者： Lee, SW Kang, HS Yun, BJ Choi, JG Hong, SH Hanbat Natl Univ Div Informat Commun & Comp Engn Taejon South Korea Chung Ang Univ Grad Sch Adv Imaging Sci Multimedia & Film Seoul 156756 South Korea Kyungpook Natl Univ Ctr Next Generat Informat Technol Taegu 702701 South Korea Dongeui Univ Div Comp Applicat Engn Pusan South Korea Chonnam Natl Univ Dept Elect Comp & Informat Engn Gwangju South Korea

We present a new vertex selection scheme for polygon-based contour coders. When contour coding is used for image coding applications, it is argued that partitioning a contour into partial segments and then approximating these segments with a variable accuracy is required to efficiently handle their relative significance. Accordingly, a decision rule for the allowable maximum distortion (d(max)) is derived based on interregion contrasts, and an adaptive vertex selection method is proposed based on the derived rule. Experimental results are presented to show the superiority of the proposed method over conventional methods. (C) 2004 Society of Photo-Optical Instrumentation Engineers.

关键词： contour coding polygonal approximation region-based image coding

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Asymmetric binary tree coding for contour images

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IMAGE AND VISION COMPUTING 2003年第9期21卷 797-807页

作者： Shamim, A Robinson, JA Mem Univ Newfoundland Fac Engn & Appl Sci St Johns NF A1B 3X5 Canada

We consider the coding of featured contours, i.e. texture, object or motion boundaries in images. The MPEG-4 and MPEG-7 video coding standards provide for a content-based representation of video information, so efficient coding of boundaries can play an important role. We propose a new coding scheme that uses an asymmetric binary tree. We show that the new scheme outperforms conventional quadtree, binary tree, contour and READ coding algorithms applied to typical boundary images and also offers competitive performance for general-purpose two-level image coding. (C) 2003 Elsevier B.V. All rights reserved.

关键词： hierarchical coding contour coding

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Sparse coding of natural contours

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NEUROCOMPUTING 2002年 44卷 459-466页

作者： Hoyer, PO Hyvärinen, A Helsinki Univ Technol Neural Networks Res Ctr FIN-02015 Helsinki Finland

An important approach in visual neuroscience considers how the function of the early visual system relates to the statistics of its natural input. Previous work has shown how the classical receptive fields and the organization (topography) of the primary visual cortex can be viewed as efficient coding of natural images. Here, we extend the framework by considering how the responses of complex cells could be efficiently coded by a higher-order neural layer. This leads to the sparse coding of contours in natural images, and can explain certain extra-classical properties of receptive fields. (C) 2002 Elsevier Science B.V. All rights reserved.

关键词： sparse coding natural image statistics contour coding collators

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Adaptive context-based arithmetic coding of arbitrary contour maps

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IEEE SIGNAL PROCESSING LETTERS 2001年第1期8卷 4-6页

作者： Pinho, AJ Univ Aveiro Dept Elect & Telecomunicacoes P-3800 Aveiro Portugal Univ Aveiro Inst Engn Elect & Telemat Aveiro P-3800 Aveiro Portugal

An efficient technique for encoding arbitrary contours is presented. It is based on the concept of transition point of a contour map and relies on a new four-symbol adaptive context-based arithmetic encoder (CAE) that calculates contexts in the (binary) domain of the contour map. The results obtained with this new technique applied to the compression of image partitions are substantially better than those previously attained, showing a clear superiority over adaptive CAE-based differential chain coding and also over the MPEG-4 shape coder.

关键词： chain coding contour coding partition coding region-based image coding shape coding transition points

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Minimum description length criterion and segmentation map coding for region-based video compression

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IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS FOR VIDEO TECHNOLOGY 2001年第2期11卷 184-198页

作者： Nicolas, H Pateux, S Le Guen, D Inst Natl Rech Informat & Automat IRISA F-35042 Rennes France

This paper presents a new technique for region-oriented video compression based on the minimization of a minimum description length (MDL) criterion. The proposed scheme is based on a region-based motion compensation approach, in which the displaced frame difference (DFD) is coded together with the segmentation map and the motion parameters. The region-based segmentation is approximated by a polygonal representation which permits us to significantly reduce the segmentation coding cost. The polygonal approximation, which minimizes the MDL criterion, is considered the optimal approximation in terms of compression performance, In this context, the MDL criterion has been developed and tested for the three following DFD coding techniques: 1) entropy coding of the quantized DFD image;2) entropy coding of the quantized DFD values obtained after morphological filtering of the DFD image;and 3) DCT-based coding of the DFD image. The experimental results, presented on real video sequences, validate the proposed approach.

关键词： contour coding curves approximation DFD coding MDL region-based video coding

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A contour-based approach to binary shape coding using a multiple grid chain code

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SIGNAL PROCESSING-IMAGE COMMUNICATION 2000年第7-8期15卷 585-599页

作者： Nunes, P Marqués, F Pereira, F Gasull, A Inst Super Tecn Inst Telecomun P-1049001 Lisbon Portugal Univ Politecn Catalunya ES-08034 Barcelona Spain

This paper presents a contour-based approach to efficiently code binary shape information in the context of object-based video coding. This approach meets some of the most important requirements identified for the MPEG-4 standard, notably efficient coding and low delay. The proposed methods support both object-based lossless and quasi-lossless coding modes. For the cases where low delay is a primary requirement, a macroblock-based coding mode is proposed which can take advantage of inter-frame coding to improve the coding efficiency. The approach presented here relies on a grid different from that used for the pixels to represent the shape - the hexagonal grid - which simplifies the task of contour coding. Using this grid, an approach based on a differential chain code (DCC) is proposed for the lossless mode while, for the quasi-lossless case, an approach based on the multiple grid chain code (MGCC) principle is proposed. The MGCC combines both contour simplification and contour prediction to reduce the number of bits needed to code the shapes. Results for alpha plane coding of MPEG-4 video test sequences are presented in order to illustrate the performance of the several modes of operation, and a comparison is made with the shape-coding tool chosen by MPEG-4. (C) 2000 Elsevier Science B.V. All rights reserved.

关键词： shape coding contour coding hexagonal grid multiple grid chain code motion estimation/compensation object-based video coding

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Generalized predictive binary shape coding using polygon approximation

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SIGNAL PROCESSING-IMAGE COMMUNICATION 2000年第7-8期15卷 643-663页

作者： Kim, JI Bovik, AC Evans, BL Univ Texas Dept Elect & Comp Engn Lab Image & Video Engn Austin TX 78712 USA Daewoo Elect Seoul South Korea

This paper introduces a new binary shape coding technique called generalized predictive shape coding (GPSC) to encode the boundary of a visual object compactly by using a vertex-based approach. GPSC consists of a contour pixel matching algorithm and a motion-compliant contour coding algorithm. The contour pixel matching algorithm utilizes the knowledge of previously decoded contours by using a uniform translational model for silhouette motion, and generalizes polygon approximation for lossless and lossy motion estimation by adjusting a tolerance parameter d(max). To represent motion-compliant regions with minimum information in the transmitted bitstream, we develop a reference index-based coding scheme to represent the 2D positions of the matched segments using 1D reference contour indices. Finally, we encode the mismatched segments by sending residual polygons until the distortion is less than d(max). While GPSC realizes polygon approximation exactly at every encoding stage, we can guarantee quality of service because the peak distortion is no greater than d(max), and we improve coding efficiency as long as a silhouette complies with the model. The tolerance parameter d(max) can be assigned to each contour to smooth the transmitted data rate, which is especially useful for constant bandwidth channels. Compared with non-predictive approaches, simulation using MPEG-4 sequences demonstrates that GPSC not only improves objective gain but also enhances visual quality based on MPEG-4 subjective tests. The significance of GPSC is that it provides a generic framework for seamlessly extending conventional vertex coding schemes into the temporal domain yet it retains the advantages of existing polygon-based algorithms for visual content description while furnishing better geometric compression. (C) 2000 Elsevier Science B.V, All rights reserved.

关键词： video coding chain coding contour coding contour motion estimation contour pixel matching contour representation predictive shape coding vertex coding

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Hybrid compression of video with graphics in DTV communication systems

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IEEE TRANSACTIONS ON CONSUMER ELECTRONICS 2000年第4期46卷 1007-1017页

作者： Schaar-Mitrea, MVD de With, PHN Philips Res Labs Briarcliff Manor NY USA Univ Mannheim Fac Comp Engn Mannheim Germany

Advanced broadcast manipulation of TV sequences and enhanced user interfaces for TV systems have resulted in an increased amount of pre- and post-editing of video sequences, where graphical information is inserted. However, in the current broadcasting chain, there are no provisions for enabling an efficient transmission/storage of these mixed video and graphics signals and, at this emerging stage of DTV systems, introducing new standards is not desired. Nevertheless, in the professional video communication chain between content provider and broadcaster and locally, in the DTV receiver, proprietary video-graphics compression schemes can be used to enable more efficient transmission/storage of mixed video and graphics signals. For example, in the DTV receiver case, this will lead to a significant memory-cost reduction. To preserve a high overall image quality, the video and graphics data require independent coding systems, matched with their specific visual and statistical properties. In this paper, we introduce various efficient algorithms that support both the lossless (contour, runlength and arithmetic coding) and the lossy (block predictive coding) compression of graphics data. If the graphics data are apriori mixed with video and the graphics position is unknown at compression time, an accurate detection mechanism is applied to distinguish the two signals, such that independent coding algorithms can be employed for each data-type. In the DTV memory-reduction scenario, an overall bit-rate control completes the system, ensuring a fixed compression factor of 2-3 per frame without sacrificing the quality of the graphics.

关键词： TV communication systems lossless image compression graphics contour coding arithmetic coding runlength coding embedded compression architecture

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Morphological reversible contour representation

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IEEE TRANSACTIONS ON PATTERN ANALYSIS AND MACHINE INTELLIGENCE 2000年第3期22卷 227-240页

作者： Hasan, YMY Karam, LJ Arizona State Univ Dept Elect Engn Ctr Telecommun Res Tempe AZ 85287 USA

In this paper, a novel morphological reversible contour representation of discrete binary images is proposed. A binary image is represented by a set of nonoverlapping multilevel contours and a residual image. In this proposed representation, the total number of pixels representing an image is far less than the total number of pixels obtained by the seed-based morphological contour-skeleton lossless representation. The proposed contour representation is simple, unique. and general without restrictions on the binary image to be represented. Moreover, it requires fewer number of operations to compute the proposed representation compared with other lossless morphological representation methods. The resulting multicontour image component is also robust to noise. An efficient differential chain contour coding scheme is employed to further compress the represented image. The proposed method yields very low bit rates compared to the existing morphological techniques. To exactly reconstruct an original image, an automatic filling procedure, which properly fills a proper multicontour image according to its topological structure without need of seed points, is proposed. The morphological unique contour representation and its lossless reconstruction techniques have been tested on images with varying size and complexity. Examples are presented to illustrate the performance of the proposed method.

关键词： shape analysis binary images mathematical morphology shape representation homotopy topology contour coding contour filling

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