Another objective of this work is to study the perceptual optimized video object coding. Since MPEG-4 treats a scene as a composition of video objects that are separately encoded and decoded, such a flexible video coding framework makes it possible to code different video objects with different priorities. It is necessary to analyze the priorities of video objects according to their intrinsic properties and psycho-visual characteristics such that the bit budget can be distributed properly to video objects to improve the perceptual quality of the compressed video. An object-level visual attention model is developed to automatically obtain the visual attention information of video objects. The visual attention values of video objects are calculated and incorporated in the newly developed dynamic bit allocation mechanism to improve the objective quality of the high priority objects such that the perceptual quality of the overall picture can be maximized. / As strict rate control algorithms used in video coding sacrifice the quality consistency, the rate distortion tradeoff is important to achieve a balance between the bit rate and quality. A novel separable rate distortion modeling method is proposed to analyze the rate distortion characteristics of the color video signal. This method provides higher estimation accuracy when compared to the non-separable modeling method. To achieve rate distortion tradeoff in H.264/AVC, a new control strategy is presented. The feedback from the encoder buffer is analyzed by a control-theoretic adaptation approach to avoid buffer overflow and underflow. A novel rate distortion tradeoff controller is designed by considering both the quality variation and buffer fluctuation. Smooth video quality is achieved and the relevant constraints are satisfied. / Due to the unique features of the video object coding such as both texture and shape introducing distortions and video objects being of arbitrarily shapes, the rate distortion analysis and optimization strategies are different from the traditional rectangular frame-based techniques. Two new rate distortion modeling methods are proposed for the shape coding. The first one is a linear rate distortion modeling method. The computational complexity is low and the estimation is accurate. To further improve the modeling performance, a novel statistical learning based method is proposed by incorporating shape features to provide rate distortion analysis for the shape coding. Therefore, a joint texture-shape rate distortion modeling approach is derived by integrating the texture and shape rate distortion models. The new joint texture-shape distortion models provide the basis for optimal bit allocation for the video object coding to minimize the coding distortion with the bit rate constraint and stabilize the buffer fullness. The major contribution of this optimal bit allocation scheme is to provide a unified solution for the following two problems: how to allocate bits between the texture and shape and how to distribute the hit budget for multiple video objects, simultaneously. / This thesis addresses rate distortion analysis, optimization, and control problems in video coding. These rate distortion issues not only provide the theoretical background but also are concerned with the practical design for video coding systems. The main objective of this thesis is to consider the problems associated with analyzing the rate distortion characteristics of the video source and providing optimal solutions or tradeoffs for the rate and distortion in video coding systems. More specifically this thesis focuses on both the object-based video coding system, MPEG-4, and the rectangular frame-based video coding system, H.264/AVC. / Chen, Zhenzhong. / "July 2007." / Adviser: King Ngi Ngan. / Source: Dissertation Abstracts International, Volume: 69-02, Section: B, page: 1194. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (p. 225-247). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract in English and Chinese. / School code: 1307.
| Identifer | oai:union.ndltd.org:cuhk.edu.hk/oai:cuhk-dr:cuhk_344037 |
| Date | January 2007 |
| Contributors | Chen, Zhenzhong, Chinese University of Hong Kong Graduate School. Division of Electronic Engineering. |
| Source Sets | The Chinese University of Hong Kong |
| Language | English, Chinese |
| Detected Language | English |
| Type | Text, theses |
| Format | electronic resource, microform, microfiche, 1 online resource (xxii, 247 p. : ill.) |
| Rights | Use of this resource is governed by the terms and conditions of the Creative Commons “Attribution-NonCommercial-NoDerivatives 4.0 International” License (http://creativecommons.org/licenses/by-nc-nd/4.0/) |
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