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Image Understanding Using Sparse Representations [Pehme köide]

Teised raamatud teemal:
Teised raamatud teemal:
Image understanding has been playing an increasingly crucial role in several inverse problems and computer vision. Sparse models form an important component in image understanding, since they emulate the activity of neural receptors in the primary visual cortex of the human brain. Sparse methods have been utilized in several learning problems because of their ability to provide parsimonious, interpretable, and efficient models. Exploiting the sparsity of natural signals has led to advances in several application areas including image compression, denoising, inpainting, compressed sensing, blind source separation, super-resolution, and classification.

The primary goal of this book is to present the theory and algorithmic considerations in using sparse models for image understanding and computer vision applications. To this end, algorithms for obtaining sparse representations and their performance guarantees are discussed in the initial chapters. Furthermore, approaches for designing overcomplete, data-adapted dictionaries to model natural images are described. The development of theory behind dictionary learning involves exploring its connection to unsupervised clustering and analyzing its generalization characteristics using principles from statistical learning theory. An exciting application area that has benefited extensively from the theory of sparse representations is compressed sensing of image and video data. Theory and algorithms pertinent to measurement design, recovery, and model-based compressed sensing are presented. The paradigm of sparse models, when suitably integrated with powerful machine learning frameworks, can lead to advances in computer vision applications such as object recognition, clustering, segmentation, and activity recognition. Frameworks that enhance the performance of sparse models in such applications by imposing constraints based on the prior discriminatory information and the underlying geometrical structure, and kernelizing the sparse coding and dictionary learning methods are presented. In addition to presenting theoretical fundamentals in sparse learning, this book provides a platform for interested readers to explore the vastly growing application domains of sparse representations.
1 Introduction
1(12)
1.1 Modeling Natural Images
1(1)
1.2 Natural Image Statistics
1(2)
1.3 Sparseness in Biological Vision
3(2)
1.4 The Generative Model for Sparse Coding
5(1)
1.5 Sparse Models for Image Reconstruction
6(3)
1.5.1 Dictionary Design
6(1)
1.5.2 Example Applications
7(2)
1.6 Sparse Models for Recognition
9(4)
1.6.1 Discriminative Dictionaries
10(1)
1.6.2 Bag of Words and its Generalizations
11(1)
1.6.3 Dictionary Design with Graph Embedding Constraints
12(1)
1.6.4 Kernel Sparse Methods
12(1)
2 Sparse Representations
13(16)
2.1 The Sparsity Regularization
13(4)
2.1.1 Other Sparsity Regularizations
14(2)
2.1.2 Non-Negative Sparse Representations
16(1)
2.2 Geometrical Interpretation
17(1)
2.3 Uniqueness of l0 and its Equivalence to the l1 Solution
17(3)
2.3.1 Phase Transitions
20(1)
2.4 Numerical Methods for Sparse Coding
20(9)
2.4.1 Optimality conditions
21(1)
2.4.2 Basis Pursuit
22(1)
2.4.3 Greedy Pursuit Methods
23(3)
2.4.4 Feature-Sign Search
26(2)
2.4.5 Iterated Shrinkage Methods
28(1)
3 Dictionary Learning: Theory and Algorithms
29(26)
3.1 Dictionary Learning and Clustering
31(2)
3.1.1 Clustering Procedures
31(1)
3.1.2 Probabilistic Formulation
32(1)
3.2 Learning Algorithms
33(17)
3.2.1 Method of Optimal Directions
33(1)
3.2.2 K-SVD
34(2)
3.2.3 Multilevel Dictionaries
36(5)
3.2.4 Online Dictionary Learning
41(1)
3.2.5 Learning Structured Sparse Models
42(4)
3.2.6 Sparse Coding Using Examples
46(4)
3.3 Stability and Generalizability of Learned Dictionaries
50(5)
3.3.1 Empirical Risk Minimization
51(1)
3.3.2 An Example Case: Multilevel Dictionary Learning
52(3)
4 Compressed Sensing
55(12)
4.1 Measurement Matrix Design
56(3)
4.1.1 The Restricted Isometry Property
56(2)
4.1.2 Geometric Interpretation
58(1)
4.1.3 Optimized Measurements
58(1)
4.2 Compressive Sensing of Natural Images
59(1)
4.3 Video Compressive Sensing
60(7)
4.3.1 Frame-by-Frame Compressive Recovery
61(1)
4.3.2 Model-Based Video Compressive Sensing
62(1)
4.3.3 Direct Feature Extraction from Compressed Videos
63(4)
5 Sparse Models in Recognition
67(24)
5.1 A Simple Classification Setup
67(4)
5.2 Discriminative Dictionary Learning
71(1)
5.3 Sparse-Coding-Based Subspace Identification
72(1)
5.4 Using Unlabeled Data in Supervised Learning
73(1)
5.5 Generalizing Spatial Pyramids
74(4)
5.5.1 Supervised Dictionary Optimization
77(1)
5.6 Locality in Sparse Models
78(2)
5.6.1 Local Sparse Coding
78(1)
5.6.2 Dictionary Design
79(1)
5.7 Incorporating Graph Embedding Constraints
80(3)
5.7.1 Laplacian Sparse Coding
81(1)
5.7.2 Local Discriminant Sparse Coding
81(2)
5.8 Kernel Methods in Sparse Coding
83(8)
5.8.1 Kernel Sparse Representations
84(1)
5.8.2 Kernel Dictionaries in Representation and Discrimination
85(2)
5.8.3 Combining Diverse Features
87(2)
5.8.4 Application: Tumor Identification
89(2)
Bibliography 91(14)
Authors' Biographies 105