Parallel algorithms for iris biometrics

Iris biometrics involves preprocessing, feature extraction and identification phase. In this thesis,an effort has been made to introduce parallelism in feature extraction and identification phases. Local features invariant to scale, rotation, illumination are extracted using Scale Invariant Feature Transform (SIFT). In order to achieve speedup during feature extraction, parallelism has been introduced during scale space construction using SIMD hypercube. The parallel time complexity is O(N2) whereas sequential algorithm performs with complexity of O(lsN2, where l is the number of octaves, s is the number of Gaussian scale levels within an octave and N × N is the size of iris image

SEARCHING HETEROGENEOUS DOCUMENT IMAGE COLLECTIONS

A decrease in data storage costs and widespread use of scanning devices has led to massive quantities of scanned digital documents in corporations, organizations, and governments around the world. Automatically processing these large heterogeneous collections can be difficult due to considerable variation in resolution, quality, font, layout, noise, and content. In order to make this data available to a wide audience, methods for efficient retrieval and analysis from large collections of document images remain an open and important area of research. In this proposal, we present research in three areas that augment the current state of the art in the retrieval and analysis of large heterogeneous document image collections. First, we explore an efficient approach to document image retrieval, which allows users to perform retrieval against large image collections in a query-by-example manner. Our approach is compared to text retrieval of OCR on a collection of 7 million document images collected from lawsuits against tobacco companies. Next, we present research in document verification and change detection, where one may want to quickly determine if two document images contain any differences (document verification) and if so, to determine precisely what and where changes have occurred (change detection). A motivating example is legal contracts, where scanned images are often e-mailed back and forth and small changes can have severe ramifications. Finally, approaches useful for exploiting the biometric properties of handwriting in order to perform writer identification and retrieval in document images are examined

Pattern search for the visualization of scalar, vector, and line fields

The main topic of this thesis is pattern search in data sets for the purpose of visual data analysis. By giving a reference pattern, pattern search aims to discover similar occurrences in a data set with invariance to translation, rotation and scaling. To address this problem, we developed algorithms dealing with different types of data: scalar fields, vector fields, and line fields. For scalar fields, we use the SIFT algorithm (Scale-Invariant Feature Transform) to find a sparse sampling of prominent features in the data with invariance to translation, rotation, and scaling. Then, the user can define a pattern as a set of SIFT features by e.g. brushing a region of interest. Finally, we locate and rank matching patterns in the entire data set. Due to the sparsity and accuracy of SIFT features, we achieve fast and memory-saving pattern query in large scale scalar fields. For vector fields, we propose a hashing strategy in scale space to accelerate the convolution-based pattern query. We encode the local flow behavior in scale space using a sequence of hierarchical base descriptors, which are pre-computed and hashed into a number of hash tables. This ensures a fast fetching of similar occurrences in the flow and requires only a constant number of table lookups. For line fields, we present a stream line segmentation algorithm to split long stream lines into globally-consistent segments, which provides similar segmentations for similar flow structures. It gives the benefit of isolating a pattern from long and dense stream lines, so that our patterns can be defined sparsely and have a significant extent, i.e., they are integration-based and not local. This allows for a greater flexibility in defining features of interest. For user-defined patterns of curve segments, our algorithm finds similar ones that are invariant to similarity transformations. Additionally, we present a method for shape recovery from multiple views. This semi-automatic method fits a template mesh to high-resolution normal data. In contrast to existing 3D reconstruction approaches, we accelerate the data acquisition time by omitting the structured light scanning step of obtaining low frequency 3D information.Das Hauptthema dieser Arbeit ist die Mustersuche in Datensätzen zur visuellen Datenanalyse. Durch die Vorgabe eines Referenzmusters versucht die Mustersuche ähnliche Vorkommen in einem Datensatz mit Translations-, Rotations- und Skalierungsinvarianz zu entdecken. In diesem Zusammenhang haben wir Algorithmen entwickelt, die sich mit verschiedenen Arten von Daten befassen: Skalarfelder, Vektorfelder und Linienfelder. Bei Skalarfeldern benutzen wir den SIFT-Algorithmus (Scale-Invariant Feature Transform), um ein spärliches Abtasten von markanten Merkmalen in Daten mit Translations-, Rotations- und Skalierungsinvarianz zu finden. Danach kann der Benutzer ein Muster als Menge von SIFT-Merkmalspunkten definieren, zum Beispiel durch Markieren einer interessierenden Region. Schließlich lokalisieren wir passende Muster im gesamten Datensatz und stufen sie ein. Aufgrund der spärlichen Verteilung und der Genauigkeit von SIFT-Merkmalspunkten erreichen wir eine schnelle und speichersparende Musterabfrage in großen Skalarfeldern. Für Vektorfelder schlagen wir eine Hashing-Strategie zur Beschleunigung der faltungsbasierten Musterabfrage im Skalenraum vor. Wir kodieren das lokale Flussverhalten im Skalenraum durch eine Sequenz von hierarchischen Basisdeskriptoren, welche vorberechnet und als Zahlen in einer Hashtabelle gespeichert sind. Dies stellt eine schnelle Abfrage von ähnlichen Vorkommen im Fluss sicher und benötigt lediglich eine konstante Anzahl von Nachschlageoperationen in der Tabelle. Für Linienfelder präsentieren wir einen Algorithmus zur Segmentierung von Stromlinien, um lange Stromlinen in global konsistente Segmente aufzuteilen. Dies erlaubt eine größere Flexibilität bei der Definition von Mustern. Für vom Benutzer definierte Muster von Kurvensegmenten findet unser Algorithmus ähnliche Kurvensegmente, die unter Ähnlichkeitstransformationen invariant sind. Zusätzlich präsentieren wir eine Methode zur Rekonstruktion von Formen aus mehreren Ansichten. Diese halbautomatische Methode passt ein Template an hochauflösendeNormalendatenan. Im Gegensatz zu existierenden 3D-Rekonstruktionsverfahren beschleunigen wir die Datenaufnahme, indem wir auf die Streifenprojektion verzichten, um niederfrequente 3D Informationen zu gewinnen

Design, implementation, and evaluation of scalable content-based image retrieval techniques.

Wong, Yuk Man.Thesis (M.Phil.)--Chinese University of Hong Kong, 2007.Includes bibliographical references (leaves 95-100).Abstracts in English and Chinese.Abstract --- p.iiAcknowledgement --- p.vChapter 1 --- Introduction --- p.1Chapter 1.1 --- Overview --- p.1Chapter 1.2 --- Contribution --- p.3Chapter 1.3 --- Organization of This Work --- p.5Chapter 2 --- Literature Review --- p.6Chapter 2.1 --- Content-based Image Retrieval --- p.6Chapter 2.1.1 --- Query Technique --- p.6Chapter 2.1.2 --- Relevance Feedback --- p.7Chapter 2.1.3 --- Previously Proposed CBIR systems --- p.7Chapter 2.2 --- Invariant Local Feature --- p.8Chapter 2.3 --- Invariant Local Feature Detector --- p.9Chapter 2.3.1 --- Harris Corner Detector --- p.9Chapter 2.3.2 --- DOG Extrema Detector --- p.10Chapter 2.3.3 --- Harris-Laplacian Corner Detector --- p.13Chapter 2.3.4 --- Harris-Affine Covariant Detector --- p.14Chapter 2.4 --- Invariant Local Feature Descriptor --- p.15Chapter 2.4.1 --- Scale Invariant Feature Transform (SIFT) --- p.15Chapter 2.4.2 --- Shape Context --- p.17Chapter 2.4.3 --- PCA-SIFT --- p.18Chapter 2.4.4 --- Gradient Location and Orientation Histogram (GLOH) --- p.19Chapter 2.4.5 --- Geodesic-Intensity Histogram (GIH) --- p.19Chapter 2.4.6 --- Experiment --- p.21Chapter 2.5 --- Feature Matching --- p.27Chapter 2.5.1 --- Matching Criteria --- p.27Chapter 2.5.2 --- Distance Measures --- p.28Chapter 2.5.3 --- Searching Techniques --- p.29Chapter 3 --- A Distributed Scheme for Large-Scale CBIR --- p.31Chapter 3.1 --- Overview --- p.31Chapter 3.2 --- Related Work --- p.33Chapter 3.3 --- Scalable Content-Based Image Retrieval Scheme --- p.34Chapter 3.3.1 --- Overview of Our Solution --- p.34Chapter 3.3.2 --- Locality-Sensitive Hashing --- p.34Chapter 3.3.3 --- Scalable Indexing Solutions --- p.35Chapter 3.3.4 --- Disk-Based Multi-Partition Indexing --- p.36Chapter 3.3.5 --- Parallel Multi-Partition Indexing --- p.37Chapter 3.4 --- Feature Representation --- p.43Chapter 3.5 --- Empirical Evaluation --- p.44Chapter 3.5.1 --- Experimental Testbed --- p.44Chapter 3.5.2 --- Performance Evaluation Metrics --- p.44Chapter 3.5.3 --- Experimental Setup --- p.45Chapter 3.5.4 --- Experiment I: Disk-Based Multi-Partition Indexing Approach --- p.45Chapter 3.5.5 --- Experiment II: Parallel-Based Multi-Partition Indexing Approach --- p.48Chapter 3.6 --- Application to WWW Image Retrieval --- p.55Chapter 3.7 --- Summary --- p.55Chapter 4 --- Image Retrieval System for IND Detection --- p.60Chapter 4.1 --- Overview --- p.60Chapter 4.1.1 --- Motivation --- p.60Chapter 4.1.2 --- Related Work --- p.61Chapter 4.1.3 --- Objective --- p.62Chapter 4.1.4 --- Contribution --- p.63Chapter 4.2 --- Database Construction --- p.63Chapter 4.2.1 --- Image Representations --- p.63Chapter 4.2.2 --- Index Construction --- p.64Chapter 4.2.3 --- Keypoint and Image Lookup Tables --- p.67Chapter 4.3 --- Database Query --- p.67Chapter 4.3.1 --- Matching Strategies --- p.68Chapter 4.3.2 --- Verification Processes --- p.71Chapter 4.3.3 --- Image Voting --- p.75Chapter 4.4 --- Performance Evaluation --- p.76Chapter 4.4.1 --- Evaluation Metrics --- p.76Chapter 4.4.2 --- Results --- p.77Chapter 4.4.3 --- Summary --- p.81Chapter 5 --- Shape-SIFT Feature Descriptor --- p.82Chapter 5.1 --- Overview --- p.82Chapter 5.2 --- Related Work --- p.83Chapter 5.3 --- SHAPE-SIFT Descriptors --- p.84Chapter 5.3.1 --- Orientation assignment --- p.84Chapter 5.3.2 --- Canonical orientation determination --- p.84Chapter 5.3.3 --- Keypoint descriptor --- p.87Chapter 5.4 --- Performance Evaluation --- p.88Chapter 5.5 --- Summary --- p.90Chapter 6 --- Conclusions and Future Work --- p.92Chapter 6.1 --- Conclusions --- p.92Chapter 6.2 --- Future Work --- p.93Chapter A --- Publication --- p.94Bibliography --- p.9

Learning Pose Invariant and Covariant Classifiers from Image Sequences

Object tracking and detection over a wide range of viewpoints is a long-standing problem in Computer Vision. Despite significant advance in wide-baseline sparse interest point matching and development of robust dense feature models, it remains a largely open problem. Moreover, abundance of low cost mobile platforms and novel application areas, such as real-time Augmented Reality, constantly push the performance limits of existing methods. There is a need to modify and adapt these to meet more stringent speed and capacity requirements. In this thesis, we aim to overcome the difficulties due to the multi-view nature of the object detection task. We significantly improve upon existing statistical keypoint matching algorithms to perform fast and robust recognition of image patches independently of object pose. We demonstrate this on various 2D and 3D datasets. The statistical keypoint matching approaches require massive amounts of training data covering a wide range of viewpoints. We have developed a weakly supervised algorithm to greatly simplify their training for 3D objects. We also integrate this algorithm in a 3D tracking-by-detection system to perform real-time Augmented Reality. Finally, we extend the use of a large training set with smooth viewpoint variation to category-level object detection. We introduce a new dataset with continuous pose annotations which we use to train pose estimators for objects of a single category. By using these estimators' output to select pose specific classifiers, our framework can simultaneously localize objects in an image and recover their pose. These decoupled pose estimation and classification steps yield improved detection rates. Overall, we rely on image and video sequences to train classifiers that can either operate independently of the object pose or recover the pose parameters explicitly. We show that in both cases our approaches mitigate the effects of viewpoint changes and improve the recognition performance

Human-document interaction systems: a new frontier for document image analysis

© 2016 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.All indications show that paper documents will not cede in favour of their digital counterparts, but will instead be used increasingly in conjunction with digital information. An open challenge is how to seamlessly link the physical with the digital – how to continue taking advantage of the important affordances of paper, without missing out on digital functionality. This paper presents the authors’ experience with developing systems for Human-Document Interaction based on augmented document interfaces and examines new challenges and opportunities arising for the document image analysis field in this area. The system presented combines state of the art camera-based document image analysis techniques with a range of complementary technologies to offer fluid Human-Document Interaction. Both fixed and nomadic setups are discussed that have gone through user testing in real-life environments, and use cases are presented that span the spectrum from business to educational applications.Peer ReviewedPostprint (author's final draft

Long-term Information Preservation and Access

An unprecedented amount of information encompassing almost every facet of human activities across the world is generated daily in the form of zeros and ones, and that is often the only form in which such information is recorded. A good fraction of this information needs to be preserved for periods of time ranging from a few years to centuries. Consequently, the problem of preserving digital information over a long-term has attracted the attention of many organizations, including libraries, government agencies, scientific communities, and individual researchers. In this dissertation, we address three issues that are critical to ensure long-term information preservation and access. The first concerns the core requirement of how to guarantee the integrity of preserved contents. Digital information is in general very fragile because of the many ways errors can be introduced, such as errors introduced because of hardware and media degradation, hardware and software malfunction, operational errors, security breaches, and malicious alterations. To address this problem, we develop a new approach based on efficient and rigorous cryptographic techniques, which will guarantee the integrity of preserved contents with extremely high probability even in the presence of malicious attacks. Our prototype implementation of this approach has been deployed and actively used in the past years in several organizations, including the San Diego Super Computer Center, the Chronopolis Consortium, North Carolina State University, and more recently the Government Printing Office. Second, we consider another crucial component in any preservation system - searching and locating information. The ever-growing size of a long-term archive and the temporality of each preserved item introduce a new set of challenges to providing a fast retrieval of content based on a temporal query. The widely-used cataloguing scheme has serious scalability problems. The standard full-text search approach has serious limitations since it does not deal appropriately with the temporal dimension, and, in particular, is incapable of performing relevancy scoring according to the temporal context. To address these problems, we introduce two types of indexing schemes - a location indexing scheme, and a full-text search indexing scheme. Our location indexing scheme provides optimal operations for inserting and locating a specific version of a preserved item given an item ID and a time point, and our full-text search indexing scheme efficiently handles the scalability problem, supporting relevancy scoring within the temporal context at the same time. Finally, we address the problem of organizing inter-related data, so that future accesses and data exploration can be quickly performed. We, in particular, consider web contents, where we combine a link-analysis scheme with a graph partitioning scheme to put together more closely related contents in the same standard web archive container. We conduct experiments that simulate random browsing of preserved contents, and show that our data organization scheme greatly minimizes the number of containers needed to be accessed for a random browsing session. Our schemes have been tested against real-world data of significant scale, and validated through extensive empirical evaluations