Ding, Ning. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references (leaves 215-225). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts also in Chinese.

Typescript (photocopy). / Digitized by Kansas Correctional Industries / Department: Computer Science.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1982. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Bibliography: leaf 56. / by Ricardo Eugenio Velez. / M.S.

This work is concerned with the problem of 3-D object recognition and orientation determination from single 2-D image frames in which objects may be noisy, partially occluded or both. Global descriptors of shape such as moments and Fourier descriptors rely on the whole shape being present. If part of a shape is missing then all of the descriptors will be affected. Consequently, such approaches are not suitable when objects are partially occluded, as results presented here show. Local methods of describing shape, where distortion of part of the object affects only the descriptors associated with that particular region, and nowhere else, are more likely to provide a successful solution to the problem. One such method is to locate points of maximum curvature on object boundaries. These are commonly believed to be the most perceptually significant points on digital curves. However, results presented in this thesis will show that estimators of point curvature become highly unreliable in the presence of noise. Rather than attempting to locate such high curvature points directly, an approach is presented which searches for boundary segments which exhibit significant linearity; curvature discontinuities are then assigned to the junctions between boundary segments. The resulting object descriptions are more stable in the presence of noise. Object orientation and recognition is achieved through a directed search and comparison to a database of similar 2-D model descriptions stored at various object orientations. Each comparison of sensed and model data is realised through a 2-D pose-clustering procedure, solving for the coordinate transformation which maps model features onto image features. Object features are used both to control the amount of computation and to direct the search of the database. In conditions of noise and occlusion objects can be recognised and their orientation determined to within less than 7 degrees of arc, on average.

Wang Tong. / Thesis submitted in: June 2004. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (leaves 64-69). / Abstracts in English and Chinese. / ABSTRACT --- p.I / 摘要 --- p.IV / ACKNOWLEDGMENTS --- p.VI / TABLE OF CONTENTS --- p.VIII / LIST OF FIGURES --- p.XIIV / Chapter CHAPTER 1 --- INTRODUCTION --- p.1 / Chapter 1.1 --- Hough Transform --- p.2 / Chapter 1.2 --- Template Matching --- p.3 / Chapter 1.3 --- Genetic Algorithms --- p.4 / Chapter 1.4 --- Outline of the Thesis --- p.6 / Chapter CHAPTER 2 --- HOUGH TRANSFORM AND ITS COMMON VARIANTS --- p.7 / Chapter 2.1 --- Hough Transform --- p.7 / Chapter 2.1.1 --- What is Hough Transform --- p.7 / Chapter 2.1.2 --- Parameter Space --- p.7 / Chapter 2.1.3 --- Accumulator Array --- p.9 / Chapter 2.2 --- Gradient-based Hough Transform --- p.10 / Chapter 2.2.1 --- Direction of Gradient --- p.11 / Chapter 2.2.2 --- Accumulator Array --- p.14 / Chapter 2.2.3 --- Peaks in the accumulator array --- p.16 / Chapter 2.2.4 --- Performance of Gradient-based Hough Transform --- p.18 / Chapter 2.3 --- Generalized Hough Transform (GHT) --- p.19 / Chapter 2.3.1 --- What Is GHT --- p.19 / Chapter 2.3.2 --- R-table of GHT --- p.20 / Chapter 2.3.3 --- GHT Procedure --- p.21 / Chapter 2.3.4 --- Analysis --- p.24 / Chapter 2.4 --- Edge Detection --- p.25 / Chapter 2.4.1 --- Gradient-Based Method --- p.25 / Chapter 2.4.2 --- Laplacian of Gaussian --- p.29 / Chapter 2.4.3 --- Canny edge detection --- p.30 / Chapter CHAPTER 3 --- PROBABILISTIC MODELS --- p.33 / Chapter 3.1 --- Randomized Hough Transform (RHT) --- p.33 / Chapter 3.1.1 --- Basics of the RHT --- p.33 / Chapter 3.1.2 --- RHT algorithm --- p.34 / Chapter 3.1.3 --- Advantage of RHT --- p.37 / Chapter 3.2 --- Genetic Model --- p.37 / Chapter 3.2.1 --- Genetic algorithm mechanism --- p.38 / Chapter 3.2.2 --- A Genetic Algorithm for Primitive Extraction --- p.39 / Chapter CHAPTER 4 --- PROPOSED ARBITRARY SHAPE DETECTION --- p.42 / Chapter 4.1 --- Randomized Generalized Hough Transform --- p.42 / Chapter 4.1.1 --- R-table properties and the general notion of a shape --- p.42 / Chapter 4.1.2 --- Using pairs of edges --- p.44 / Chapter 4.1.3 --- Extend to Arbitrary shapes --- p.46 / Chapter 4.2 --- A Genetic algorithm with the Hausdorff distance --- p.47 / Chapter 4.2.1 --- Hausdorff distance --- p.47 / Chapter 4.2.2 --- Chromosome strings --- p.48 / Chapter 4.2.3 --- Discussion --- p.51 / Chapter CHAPTER 5 --- EXPERIMENTAL RESULTS AND COMPARISONS --- p.52 / Chapter 5.1 --- Primitive extraction --- p.53 / Chapter 5.2 --- Arbitrary Shape Detection --- p.54 / Chapter 5.3 --- Summary of the Experimental Results --- p.60 / Chapter CHAPTER 6 --- CONCLUSIONS --- p.62 / Chapter 6.1 --- Summary --- p.62 / Chapter 6.2 --- Future work --- p.63 / BIBLIOGRAPHY --- p.64

Li Ngai. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references. / Abstracts in English and Chinese. / Chapter Chapter 1. --- Introduction --- p.1-1 / Chapter 1.1. --- A Brief Review on Pattern Matching --- p.1-1 / Chapter 1.2. --- Objective of the Research Work --- p.1-5 / Chapter 1.3. --- Organization of the Thesis --- p.1-6 / Chapter 1.4. --- Notes on Publications --- p.1-7 / Chapter Chapter 2. --- Background Information --- p.2-1 / Chapter 2.1. --- Introduction --- p.2-1 / Chapter 2.2. --- Review of Block Based Pattern Matching --- p.2-3 / Chapter 2.2.1 --- Gradient Descent Strategy --- p.2-3 / Chapter 2.2.2 --- Simplified Matching Operations --- p.2-10 / Chapter 2.2.3 --- Fast Full-Search Methods --- p.2-14 / Chapter 2.2.4 --- Transform-domain Manipulations --- p.2-19 / Chapter Chapter 3. --- Statistical Rejection Threshold for Pattern Matching --- p.3-1 / Chapter 3.1. --- Introduction --- p.3-1 / Chapter 3.2. --- Walsh Hadamard Transform --- p.3-3 / Chapter 3.3. --- Coarse-to-fine Pattern Matching in Walsh Hadamard Domain --- p.3-4 / Chapter 3.3.1. --- Bounding Euclidean Distance in Walsh Hadamard Domain --- p.3-5 / Chapter 3.3.2. --- Fast Projection Scheme --- p.3-9 / Chapter 3.3.3. --- Using the Projection Scheme for Pattern Matching --- p.3-17 / Chapter 3.4. --- Statistical Rejection Threshold --- p.3-18 / Chapter 3.5. --- Experimental Results --- p.3-22 / Chapter 3.6. --- Conclusions --- p.3-29 / Chapter 3.7. --- Notes on Publication --- p.3-30 / Chapter Chapter 4. --- Fast Walsh Search --- p.4-1 / Chapter 4.1. --- Introduction --- p.4-1 / Chapter 4.2. --- Approximating Sum-of-absolute Difference Using PS AD --- p.4-3 / Chapter 4.3. --- Two-level Threshold Scheme --- p.4-6 / Chapter 4.4. --- Block Matching Using SADDCC --- p.4-10 / Chapter 4.5. --- Optimization of Threshold and Number of Coefficients in PSAD --- p.4-15 / Chapter 4.6. --- Candidate Elimination by the Mean of PSAD --- p.4-23 / Chapter 4.7. --- Computation Requirement --- p.4-28 / Chapter 4.8. --- Experimental Results --- p.4-32 / Chapter 4.9. --- Conclusions --- p.4-45 / Chapter 4.10. --- Notes on Publications --- p.4-46 / Chapter Chapter 5. --- Conclusions & Future Works --- p.5-1 / Chapter 5.1. --- Contributions and Conclusions --- p.5-1 / Chapter 5.1.1. --- Statistical Rejection Threshold for Pattern Matching --- p.5-2 / Chapter 5.1.2. --- Fast Walsh Search --- p.5-3 / Chapter 5.2. --- Future Works --- p.5-4 / References --- p.I

Cao Liangliang. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (leaves 64-69). / Abstracts in English and Chinese. / Chapter 1 --- Introduction and Related Work --- p.1 / Chapter 1.1 --- Reconstruction from Single Line Drawings and the Applications --- p.1 / Chapter 1.2 --- Optimization-based Reconstruction --- p.2 / Chapter 1.3 --- Other Reconstruction Methods --- p.2 / Chapter 1.3.1 --- Line Labeling and Algebraic Methods --- p.2 / Chapter 1.3.2 --- CAD Reconstruction --- p.3 / Chapter 1.3.3 --- Modelling from Images --- p.3 / Chapter 1.4 --- Finding Faces of Line Drawings --- p.4 / Chapter 1.5 --- Generalized Cylinder --- p.4 / Chapter 1.6 --- Research Problems and Our Contribution --- p.5 / Chapter 1.6.1 --- A New Criteria --- p.5 / Chapter 1.6.2 --- Recover Objects from Line Drawings without Hidden Lines --- p.6 / Chapter 1.6.3 --- Reconstruction of Curved Objects --- p.6 / Chapter 1.6.4 --- Planar Limbs Assumption and the Derived Models --- p.6 / Chapter 2 --- A New Criteria for Reconstruction --- p.8 / Chapter 2.1 --- Introduction --- p.8 / Chapter 2.2 --- Human Visual Perception and the Symmetry Measure --- p.10 / Chapter 2.3 --- Reconstruction Based on Symmetry and Planarity --- p.11 / Chapter 2.3.1 --- Finding Faces --- p.11 / Chapter 2.3.2 --- Constraint of Planarity --- p.11 / Chapter 2.3.3 --- Objective Function --- p.12 / Chapter 2.3.4 --- Reconstruction Algorithm --- p.13 / Chapter 2.4 --- Experimental Results --- p.13 / Chapter 2.5 --- Summary --- p.18 / Chapter 3 --- Line Drawings without Hidden Lines: Inference and Reconstruction --- p.19 / Chapter 3.1 --- Introduction --- p.19 / Chapter 3.2 --- Terminology --- p.20 / Chapter 3.3 --- Theoretical Inference of the Hidden Topological Structure --- p.21 / Chapter 3.3.1 --- Assumptions --- p.21 / Chapter 3.3.2 --- Finding the Degrees and Ranks --- p.22 / Chapter 3.3.3 --- Constraints for the Inference --- p.23 / Chapter 3.4 --- An Algorithm to Recover the Hidden Topological Structure --- p.25 / Chapter 3.4.1 --- Outline of the Algorithm --- p.26 / Chapter 3.4.2 --- Constructing the Initial Hidden Structure --- p.26 / Chapter 3.4.3 --- Reducing Initial Hidden Structure --- p.27 / Chapter 3.4.4 --- Selecting the Most Plausible Structure --- p.28 / Chapter 3.5 --- Reconstruction of 3D Objects --- p.29 / Chapter 3.6 --- Experimental Results --- p.32 / Chapter 3.7 --- Summary --- p.32 / Chapter 4 --- Curved Objects Reconstruction from 2D Line Drawings --- p.35 / Chapter 4.1 --- Introduction --- p.35 / Chapter 4.2 --- Related Work --- p.36 / Chapter 4.2.1 --- Face Identification --- p.36 / Chapter 4.2.2 --- 3D Reconstruction of planar objects --- p.37 / Chapter 4.3 --- Reconstruction of Curved Objects --- p.37 / Chapter 4.3.1 --- Transformation of Line Drawings --- p.37 / Chapter 4.3.2 --- Finding 3D Bezier Curves --- p.39 / Chapter 4.3.3 --- Bezier Surface Patches and Boundaries --- p.40 / Chapter 4.3.4 --- Generating Bezier Surface Patches --- p.41 / Chapter 4.4 --- Results --- p.43 / Chapter 4.5 --- Summary --- p.45 / Chapter 5 --- Planar Limbs and Degen Generalized Cylinders --- p.47 / Chapter 5.1 --- Introduction --- p.47 / Chapter 5.2 --- Planar Limbs and View Directions --- p.49 / Chapter 5.3 --- DGCs in Homogeneous Coordinates --- p.53 / Chapter 5.3.1 --- Homogeneous Coordinates --- p.53 / Chapter 5.3.2 --- Degen Surfaces --- p.54 / Chapter 5.3.3 --- DGCs --- p.54 / Chapter 5.4 --- Properties of DGCs --- p.56 / Chapter 5.5 --- Potential Applications --- p.59 / Chapter 5.5.1 --- Recovery of DGC Descriptions --- p.59 / Chapter 5.5.2 --- Deformable DGCs --- p.60 / Chapter 5.6 --- Summary --- p.61 / Chapter 6 --- Conclusion and Future Work --- p.62 / Bibliography --- p.64

視覺質量評估在各種多媒體應用中起到了關鍵性的作用。因為人類的視覺系統是視覺信號的最終接收髓，王觀視覺質量評估被認為是最可靠的視覺質量評估方法。然而，王觀視覺質量評估耗時、昂貴，並且不適合線上應用。因此，自動的、客觀的視覺質量評估方法已經被開發並被應用於很多實用埸合當中。最廣泛使用的客觀視覺質量度量方法，如均方差(MSE) 、峰值信噪比(PSNR) 等與人IN對視覺信號質量的判斷相距甚遠。因此，開發更準確的客觀質量度量算法將會成為未來視覺信號處理和傳輸應用成功與否的重要因素。 / 該論文主要研究全參考客觀視覺質量度量算法。主要內容分為三部分。 / 第一部分討論圖像質量評估。首先研究了一個經典的圖像質量度量算法--SSIM。提出了個新的加權方法並整合至IjSSIM 當中，提升了SSIM自可預測精度。之後，受到前面這個工作的故發，設計7 個全新的圖像質量度量算法，將噪聲分類為加性噪聲和細節失兩大類。這個算法在很多主觀質量圓像資料庫上都有很優秀的預測表現。 / 第二部分研究視頻質量評估。首先，將上面提到的全新的圓像質量度量算法通過挖掘視頻運動信息和時域相關的人眼視覺特性擴展為視頻質量度量算法。方法包括:使用基於人自民運動的時空域對比敏感度方程，使用基於運動崗量的時域視覺掩蓋，使用基於認知層面的空域整合等等。這個算法被證明對處理標清和高清序列同樣有效。其次，提出了一個測量視頻順間不一致程度的算法。該算法被整合到MSE 中，提高了MSE的預測表現。 / 上面提到的算法只考慮到了亮度噪聲。論文的最後部分通過個具體應用色差立體圓像生成究了色度噪聲。色差立體圖像是三維立體顯示技衛的其中種方法。它使在普通電視、電腦顯示器、甚至印刷品上顯示三維立體效果成為可能。我們提出了一個新的色差立體圖像生成方法。該方法工作在CIELAB彩色空間，並力圖匹配原始圖像與觀測立體圖像的色彩屬性值。 / Visual quality assessment (VQA) plays a fundamental role in multimedia applications. Since the human visual system (HVS) is the ultimate viewer of the visual information, subjective VQA is considered to be the most reliable way to evaluate visual quality. However, subjective VQA is time-consuming, expensive, and not feasible for on-line manipulation. Therefore, automatic objective VQA algorithms, or namely visual quality metrics, have been developed and widely used in practical applications. However, it is well known that the popular visual quality metrics, such as Mean Square Error (MSE), Peak Signal to Noise Ratio (PSNR), etc., correlate poorly with the human perception of visual quality. The development of more accurate objective VQA algorithms becomes of paramount importance to the future visual information processing and communication applications. / In this thesis, full-reference objective VQA algorithms are investigated. Three parts of the work are discussed as briefly summarized below. / The first part concerns image quality assessment. It starts with the investigation of a popular image quality metric, i.e., Structural Similarity Index (SSIM). A novel weighting function is proposed and incorporated into SSIM, which leads to a substantial performance improvement in terms of matching subjective ratings. Inspired by this work, a novel image quality metric is developed by separately evaluating two distinct types of spatial distortions: detail losses and additive impairments. The pro- posed method demonstrates the state-of-the-art predictive performance on most of the publicly-available subjective quality image databases. / The second part investigates video quality assessment. We extend the proposed image quality metric to assess video quality by exploiting motion information and temporal HVS characteristics, e.g., eye movement spatio-velocity contrast sensitivity function, temporal masking using motion vectors, temporal pooling considering human cognitive behaviors, etc. It has been experimentally verified that the proposed video quality metric can achieve good performance on both standard-definition and high-definition video databases. We also propose a novel method to measure temporal inconsistency, an essential type of video temporal distortions. It is incorporated into the MSE for video quality assessment, and experiments show that it can significantly enhance MSE's predictive performance. / The aforementioned algorithms only analyze luminance distortions. In the last part, we investigate chrominance distortions for a specific application: anaglyph image generation. Anaglyph image is one of the 3D displaying techniques, which enables stereoscopic perception on traditional TVs, PC monitors, projectors, and even papers. Three perceptual color attributes are taken into account for the color distortion measure, i.e., lightness, saturation, and hue, based on which a novel anaglyph image generation algorithm is developed via approximation in the CIELAB color space. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Li, Songnan. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2012. / Includes bibliographical references (leaves 122-130). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese. / Dedication --- p.ii / Acknowledgments --- p.iii / Abstract --- p.vi / Publications --- p.viii / Nomenclature --- p.xii / Contents --- p.xvii / List of Figures --- p.xx / List of Tables --- p.xxii / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Motivation and Objectives --- p.1 / Chapter 1.2 --- Overview of Subjective Visual Quality Assessment --- p.3 / Chapter 1.2.1 --- Viewing condition --- p.4 / Chapter 1.2.2 --- Candidate observer selection --- p.4 / Chapter 1.2.3 --- Test sequence selection --- p.4 / Chapter 1.2.4 --- Structure of test session --- p.5 / Chapter 1.2.5 --- Assessment procedure --- p.6 / Chapter 1.2.6 --- Post-processing of scores --- p.7 / Chapter 1.3 --- Overview of Objective Visual Quality Assessment --- p.8 / Chapter 1.3.1 --- Classification --- p.8 / Chapter 1.3.2 --- HVS-model-based metrics --- p.9 / Chapter 1.3.3 --- Engineering-based metrics --- p.21 / Chapter 1.3.4 --- Performance evaluation method --- p.28 / Chapter 1.4 --- Thesis Outline --- p.29 / Chapter I --- Image Quality Assessment --- p.32 / Chapter 2 --- Weighted Structural Similarity Index based on Local Smoothness --- p.33 / Chapter 2.1 --- Introduction --- p.33 / Chapter 2.2 --- The Structural Similarity Index --- p.33 / Chapter 2.3 --- Influence of the Smooth Region on SSIM --- p.35 / Chapter 2.3.1 --- Overall performance analysis --- p.35 / Chapter 2.3.2 --- Performance analysis for individual distortion types --- p.37 / Chapter 2.4 --- The Proposed Weighted-SSIM --- p.40 / Chapter 2.5 --- Experiments --- p.41 / Chapter 2.6 --- Summary --- p.43 / Chapter 3 --- Image Quality Assessment by Decoupling Detail Losses and Additive Impairments --- p.44 / Chapter 3.1 --- Introduction --- p.44 / Chapter 3.2 --- Motivation --- p.45 / Chapter 3.3 --- Related Works --- p.47 / Chapter 3.4 --- The Proposed Method --- p.48 / Chapter 3.4.1 --- Decoupling additive impairments and useful image contents --- p.48 / Chapter 3.4.2 --- Simulating the HVS processing --- p.56 / Chapter 3.4.3 --- Two quality measures and their combination --- p.58 / Chapter 3.5 --- Experiments --- p.59 / Chapter 3.5.1 --- Subjective quality image databases --- p.59 / Chapter 3.5.2 --- Parameterization --- p.60 / Chapter 3.5.3 --- Overall performance --- p.61 / Chapter 3.5.4 --- Statistical significance --- p.62 / Chapter 3.5.5 --- Performance on individual distortion types --- p.64 / Chapter 3.5.6 --- Hypotheses validation --- p.66 / Chapter 3.5.7 --- Complexity analysis --- p.69 / Chapter 3.6 --- Summary --- p.70 / Chapter II --- Video Quality Assessment --- p.71 / Chapter 4 --- Video Quality Assessment by Decoupling Detail Losses and Additive Impairments --- p.72 / Chapter 4.1 --- Introduction --- p.72 / Chapter 4.2 --- Related Works --- p.73 / Chapter 4.3 --- The Proposed Method --- p.74 / Chapter 4.3.1 --- Framework --- p.74 / Chapter 4.3.2 --- Decoupling additive impairments and useful image contents --- p.75 / Chapter 4.3.3 --- Motion estimation --- p.76 / Chapter 4.3.4 --- Spatio-velocity contrast sensitivity function --- p.77 / Chapter 4.3.5 --- Spatial and temporal masking --- p.79 / Chapter 4.3.6 --- Two quality measures and their combination --- p.80 / Chapter 4.3.7 --- Temporal pooling --- p.81 / Chapter 4.4 --- Experiments --- p.82 / Chapter 4.4.1 --- Subjective quality video databases --- p.82 / Chapter 4.4.2 --- Parameterization --- p.83 / Chapter 4.4.3 --- With/without decoupling --- p.84 / Chapter 4.4.4 --- Overall predictive performance --- p.85 / Chapter 4.4.5 --- Performance on individual distortion types --- p.88 / Chapter 4.4.6 --- Cross-distortion performance evaluation --- p.89 / Chapter 4.5 --- Summary --- p.91 / Chapter 5 --- Temporal Inconsistency Measure --- p.92 / Chapter 5.1 --- Introduction --- p.92 / Chapter 5.2 --- The Proposed Method --- p.93 / Chapter 5.2.1 --- Implementation --- p.93 / Chapter 5.2.2 --- MSE TIM --- p.94 / Chapter 5.3 --- Experiments --- p.96 / Chapter 5.4 --- Summary --- p.97 / Chapter III --- Application related to Color and 3D Perception --- p.98 / Chapter 6 --- Anaglyph Image Generation --- p.99 / Chapter 6.1 --- Introduction --- p.99 / Chapter 6.2 --- Anaglyph Image Artifacts --- p.99 / Chapter 6.3 --- Related Works --- p.101 / Chapter 6.3.1 --- Simple anaglyphs --- p.101 / Chapter 6.3.2 --- XYZ and LAB anaglyphs --- p.102 / Chapter 6.3.3 --- Ghosting reduction methods --- p.103 / Chapter 6.4 --- The Proposed Method --- p.104 / Chapter 6.4.1 --- Gamma transfer --- p.104 / Chapter 6.4.2 --- Converting RGB to CIELAB --- p.105 / Chapter 6.4.3 --- Matching color appearance attributes in CIELAB color space --- p.106 / Chapter 6.4.4 --- Converting CIELAB to RGB --- p.110 / Chapter 6.4.5 --- Parameterization --- p.111 / Chapter 6.5 --- Experiments --- p.112 / Chapter 6.5.1 --- Subjective tests --- p.112 / Chapter 6.5.2 --- Results and analysis --- p.113 / Chapter 6.5.3 --- Complexity --- p.115 / Chapter 6.6 --- Summary --- p.115 / Chapter 7 --- Conclusions --- p.117 / Chapter 7.1 --- Contributions of the Thesis --- p.117 / Chapter 7.2 --- Future Research Directions --- p.120 / Bibliography --- p.122

Based on the fixed block size FWS algorithm, we further proposed a fast full-pel variable block size motion estimation algorithm called Fast Walsh Search in Variable Block Size (FWS-VBS). As in FWS, FWS-VBS employs the PSAD as the error measure to identify likely mismatches. Mismatches are rejected by thresholding method and the thresholds are determined adaptively to cater for different activity levels in each block. Early termination techniques are employed to further reduce the number of candidates and modes to be searched of each block. FWS-VBS performs equally well to the exhaustive full search algorithm in the reference H.264/AVC encoder and requires only about 10% of the computation time. / Furthermore, we modified our proposed segmentation algorithm to handle video sequences that are already encoded in the H.264 format. Since the video is compressed, no spatial information is available. Instead, quantized transform coefficients of the residual frame are used to approximate spatial information and improve segmentation result. The computation time of the segmentation process is merely about 16ms per frame for CIF frame size video, allowing the algorithm to be applied in real-time applications such as video surveillance and conferencing. / In the first part of our research, we proposed a block matching algorithm called Fast Walsh Search (FWS) for video motion estimation. FWS employs two new error measures defined in Walsh Hadamard domain, which are partial sum-of-absolute difference (PSAD) and sum-of-absolute difference of DC coefficients (SADDCC). The algorithm first rejects most mismatched candidates using PSAD which is a coarse measure requiring little computation. Because of the energy packing ability of Walsh Hadamard transform (WHT) and the utilization of fast WHT computation algorithm, mismatched candidates are identified and rejected efficiently. Then the proposed algorithm identifies the matched candidate from the remaining candidates using SADDCC which is a more accurate measure and can reuse computation performed for PSAD. Experimental results show that FWS can give good visual quality to most of video scene with a reasonable amount of computation. / In the second part of our research, we developed a real-time video object segmentation algorithm. The motion information is obtained by FWS-VBS to minimize the computation time while maintaining an adequate accuracy. The algorithm makes use of the motion information to identify background motion model and moving objects. In order to preserve spatial and temporal continuity of objects, Markov random field (MRF) is used to model the foreground field. The block-based foreground object mask is obtained by minimizing the energy function of the MRF. The resulting object mask is then post-processed to generate a smooth object mask. Experimental results show that the proposed algorithm can effectively extract moving objects from different kind of sequences, at a speed of less than 100ms per frame for CIF frame size video. / Motion estimation is an important part in many video processing applications, such as video compression, object segmentation, and scene analysis. In all video compression applications, motion information is used to reduce temporal redundancy between frames, thus significantly reduce the required bitrate for transmission and storage of compressed video. In addition, in object-based video coding, video object can be automatically identified by its motion against the background. / Mak, Chun Man. / "June 2008." / Adviser: Wai-Kuen Cham. / Source: Dissertation Abstracts International, Volume: 70-03, Section: B, page: 1849. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references. / 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. / Abstracts in English and Chinese. / School code: 1307.

In the first part, some efficient algorithms are proposed to reduce the complexity of H.264 encoder, which is the latest state-of-the-art video coding standard. Intra and Inter mode decision play a vital role in H.264 encoder and can reduce the spatial and temporal redundancy significantly, but the computational cost is also high. Here, a fast Intra mode decision algorithm and a fast Inter mode decision algorithm are proposed. Experimental results show that the proposed algorithms not only save a lot of computational cost, but also maintain coding performance quite well. Moreover, a real time H.264 baseline codec is implemented on mobile device. Based on our real time H.264 codec, an H.264 based mobile video conferencing system is achieved. / The objective of this thesis is to develop some efficient and perceptual image and video coding techniques. Two parts of the work are investigated in this thesis. / The second part of this thesis investigates two kinds of perceptual picture coding techniques. One is the just noticeable distortion (JND) based picture coding. Firstly, a DCT based spatio-temporal JND model is proposed, which is an efficient model to represent the perceptual redundancies existing in images and is consistent with the human visual system (HVS) characteristic. Secondly, the proposed JND model is incorporated into image and video coding to improve the perceptual quality. Based on the JND model, a transparent image coder and a perceptually optimized H.264 video coder are implemented. Another technique is the image compression scheme based on the recent advances in texture synthesis. In this part, an image compression scheme is proposed with the perceptual visual quality as the performance criterion instead of the pixel-wise fidelity. As demonstrated in extensive experiments, the proposed techniques can improve the perceptual quality of picture coding significantly. / Wei Zhenyu. / Adviser: Ngan Ngi. / Source: Dissertation Abstracts International, Volume: 73-01, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references (leaves 148-154). / 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, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.