Image Registration plays a very important role in the field of remote sensing. In order to have a better registration quality and make the automatization possible, choos ing and matching the control points from conjugate images become very important. In fact, the control points required for image registration should have following three key factors, that is, the amount, validity and distribution of control points. ¡@¡@In the study, we take QuickBird Satellite Images as the main ones; on the other hand, it conducts two groups of image registrations resulted from aerial images at various times. After detecting feature points using different algorithms, the study makes use of feature matching methods to get conjugate points between two overlapped images. The algorithms used above are SIFT, ASIFT and MESR. SIFT is an algorithm which invariant to scales, rotation, affine stretch and change in brightness. ASIFT undertakes simulations based on the theory of SIFT and thus carries out fully affine invariant. The feature points obtained from MSER have physical meaning in its location. By using feature matching algorithms like K-d tree and BBF, the matched feature points from two overlapped images would be turned into the conjugate points which can be control points for image registration. ¡@¡@During the process of image preprocessing, it is learned that the feature points detected by SIFT and MSER through feature matching are very few. Hence, this study attempts to employ histogram specification¡Bcontrast stretching and scale change methods to see if it is helpful to the feature detections and matching through change of image quality and image size. The experiment found that scale change will improve both the amount and accuracy of conjugate points detected by different algorithms. When considering distribution of the feature points, the study takes advantage of image cropping approach to conduct feature detections and matching individually. It is found that more conjugate points with uniform distribution can be obtained via image cropping technique.

The animal-vehicle collision has been a topic of concern for years, especially in North America. To mitigate the problem, this thesis focuses on animal detection based on the onboard camera for intelligent vehicles. In the domain of image classification and object detection, the methods of shape matching and local feature crafting have reached the technical plateau for decades. The development of Convolutional Neural Network (CNN) brings a new breakthrough. The evolution of CNN architectures has dramatically improved the performance of image classification. Effective frameworks on object detection through CNN structures are thus boosted. Notably, the family of Region-based Convolutional Neural Networks (R-CNN) perform well by combining region proposal with CNN. In this thesis, we propose to apply a new region proposal method|Maximally Stable Extremal Regions (MSER) in Fast R-CNN to construct the animal detection framework. MSER algorithm detects stable regions which are invariant to scale, rotation and viewpoint changes. We generate regions of interest by dealing with the result of MSER algorithm in two ways: by enclosing all the pixels from the resulted pixel-list with a minimum enclosing rectangle (the PL MSER) and by fitting the resulted elliptical region to an approximate box (the EL MSER). We then preprocess the bounding boxes of PL MSER and EL MSER to improve the recall of detection. The preprocessing steps consist of filtering out undesirable regions by aspect ratio model, clustering bounding boxes to merge the overlapping regions, modifying and then enlarging the regions to cover the entire animal. We evaluate the two region proposal methods by the measurement of recall over IOU-threshold curve. The proposed MSER method can cover the expected regions better than Edge Boxes and Region Proposal Network (RPN) in Faster R-CNN. We apply the MSER region proposal method to the framework of R-CNN and Fast R-CNN. The experiments on the animal database with moose, deer, elk, and horses show that Fast R-CNN with MSER achieves better accuracy and faster speed than R-CNN with MSER. Concerning the two ways of MSER, the experimental results show that PL MSER is faster than EL MSER and EL MSER gains higher precision than PL MSER. Also, by altering the structure of network used in Fast R-CNN, we verify that network stacking more layers achieves higher accuracy and recall. In addition, we compare the Fast R-CNN framework using MSER region proposal with the state-of-the-art Faster R-CNN by evaluating the experimental results of on our animal database. Using the same CNN structure, the proposed Fast R-CNN with MSER gains a higher average accuracy of the animal detection 0.73, compared to 0.42 of Faster R-CNN. In terms of detection quality, the proposed Fast R-CNN with MSER achieves better IoU histogram than that of Faster R-CNN.

Road traffic signs provide instructions, warning information, to regulate driver behavior. In addition, these signs provide a reliable guarantee for safe and convenient driving. The Traffic Sign Detection and Recognition (TSDR) system is one of the primary applications for Advanced Driver Assistance Systems (ADAS). TSDR has obtained a great deal of attention over the recent years. But, it is still a challenging field of image processing. In this thesis, we first created our own dataset for North American Traffic Signs, which is still being updated. We then decided to choose Histogram Orientation Gradients (HOG) and Support Vector Machines (SVMs) to build our system after comparing them with some other techniques. For better results, we tested different HOG parameters to find the best combination. After this, we developed a TSDR system using HOG, SVM and our new color information extraction algorithm. To reduce time-consumption, we used the Maximally Stable Extremal Region (MSER) to replace the HOG and SVM detection stage. In addition, we developed a new approach based on Global Positioning System (GPS) information other than image processing. At last, we tested these three systems; the results show that all of them can recognize traffic signs with a good accuracy rate. The MSER based system is faster than the one using only HOG and SVM; and, the GPS based system is even faster than the MSER based system.

Existe uma busca crescente por métodos de extração de texto em imagens de documentos. O uso de imagens digitais tem se tornado cada vez mais frequente em diversas áreas. O mundo moderno está cheio de texto, que os seres humanos usam para identificar objetos, navegar e tomar decisões. Embora o problema do reconhecimento de texto tenha sido amplamente estudado dentro de determinados domínios, detectar e ler texto em documentos de identificação, continua sendo um desafio aberto. Apresenta-se uma arquitetura que integra os diferentes algoritmos de localização, extração e reconhecimento aplicados à extração de texto em documentos de identificação genéricos. O método de localização proposto usa o algoritmo MSER junto com uma melhoria do contraste e a informação das bordas dos objetos da imagem, para localizar os possíveis caracteres. A etapa de seleção desenvolveu-se mediante a busca de heurísticas, capazes de classificar as regiões localizadas como textuais e não-textuais. Na etapa de reconhecimento é proposto um método iterativo para melhorar o desempenho do OCR. O processo foi avaliado usando as métricas precisão e revocação e foi realizada uma prova de conceito do sistema em um ambiente real. A abordagem proposta é robusta na detecção de textos oriundos de imagens complexas com diferentes orientações, dimensões e cores. O sistema de reconhecimento de texto proposto apresenta resultados competitivos, tanto em precisão e taxa de reconhecimento, quando comparados com outros sistemas. Mostrando excelente desempenho e viabilidade de sua implementação em sistemas reais. / The use of digital images has become more and more frequent in several areas. The modern world is full of text, which humans use to identify objects, navigate and make decisions. Although the problem of text recognition has been extensively studied within certain domains, detecting and recognizing text in identification documents remains an open challenge. We present an architecture that integrates the different localization, extraction and recognition algorithms applied to extracting text in generic identification documents. The proposed localization method uses the MSER algorithm together to contrast enhance and edge detection to find the possible characters. The selection stage was developed through the search for heuristics, capable of classifying the located regions in textual and non-textual. In the recognition step, an iterative method is proposed to improve OCR performance. The process was evaluated using the metrics precision and recall and a proof of concept of the system was performed in a real environment. The proposed approach is robust in detecting texts from complex images with different orientations, dimensions and colors. The text recognition system presents competitive results, both in accuracy and recognition rate, when compared with other systems in the current technical literature. Showing excellent performance and feasibility of its implementation in real systems.

Existe uma busca crescente por métodos de extração de texto em imagens de documentos. O uso de imagens digitais tem se tornado cada vez mais frequente em diversas áreas. O mundo moderno está cheio de texto, que os seres humanos usam para identificar objetos, navegar e tomar decisões. Embora o problema do reconhecimento de texto tenha sido amplamente estudado dentro de determinados domínios, detectar e ler texto em documentos de identificação, continua sendo um desafio aberto. Apresenta-se uma arquitetura que integra os diferentes algoritmos de localização, extração e reconhecimento aplicados à extração de texto em documentos de identificação genéricos. O método de localização proposto usa o algoritmo MSER junto com uma melhoria do contraste e a informação das bordas dos objetos da imagem, para localizar os possíveis caracteres. A etapa de seleção desenvolveu-se mediante a busca de heurísticas, capazes de classificar as regiões localizadas como textuais e não-textuais. Na etapa de reconhecimento é proposto um método iterativo para melhorar o desempenho do OCR. O processo foi avaliado usando as métricas precisão e revocação e foi realizada uma prova de conceito do sistema em um ambiente real. A abordagem proposta é robusta na detecção de textos oriundos de imagens complexas com diferentes orientações, dimensões e cores. O sistema de reconhecimento de texto proposto apresenta resultados competitivos, tanto em precisão e taxa de reconhecimento, quando comparados com outros sistemas. Mostrando excelente desempenho e viabilidade de sua implementação em sistemas reais. / The use of digital images has become more and more frequent in several areas. The modern world is full of text, which humans use to identify objects, navigate and make decisions. Although the problem of text recognition has been extensively studied within certain domains, detecting and recognizing text in identification documents remains an open challenge. We present an architecture that integrates the different localization, extraction and recognition algorithms applied to extracting text in generic identification documents. The proposed localization method uses the MSER algorithm together to contrast enhance and edge detection to find the possible characters. The selection stage was developed through the search for heuristics, capable of classifying the located regions in textual and non-textual. In the recognition step, an iterative method is proposed to improve OCR performance. The process was evaluated using the metrics precision and recall and a proof of concept of the system was performed in a real environment. The proposed approach is robust in detecting texts from complex images with different orientations, dimensions and colors. The text recognition system presents competitive results, both in accuracy and recognition rate, when compared with other systems in the current technical literature. Showing excellent performance and feasibility of its implementation in real systems.

Augmented Reality (AR) involves adding virtual content into real scenes. Scenes are viewed using a Head-Mounted Display or other display type. In order to place content into the user's view of a scene, the user's position and orientation relative to the scene, commonly referred to as their pose, must be determined accurately. This allows the objects to be placed in the correct positions and to remain there when the user moves or the scene changes. It is achieved by tracking the user in relation to their environment using a variety of technology. One technology which has proven to provide accurate results is computer vision. Computer vision involves a computer analysing images and achieving an understanding of them. This may be locating objects such as faces in the images, or in the case of AR, determining the pose of the user. One of the ultimate goals of AR systems is to be capable of operating under any condition. For example, a computer vision system must be robust under a range of different scene types, and under unpredictable environmental conditions due to variable illumination and weather. The majority of existing literature tests algorithms under the assumption of ideal or 'normal' imaging conditions. To ensure robustness under as many circumstances as possible it is also important to evaluate the systems under adverse conditions. This thesis seeks to analyse the effects that variable illumination has on computer vision algorithms. To enable this analysis, test data is required to isolate weather and illumination effects, without other factors such as changes in viewpoint that would bias the results. A new dataset is presented which also allows controlled viewpoint differences in the presence of weather and illumination changes. This is achieved by capturing video from a camera undergoing a repeatable motion sequence. Ground truth data is stored per frame allowing images from the same position under differing environmental conditions, to be easily extracted from the videos. An in depth analysis of six detection algorithms and five matching techniques demonstrates the impact that non-uniform illumination changes can have on vision algorithms. Specifically, shadows can degrade performance and reduce confidence in the system, decrease reliability, or even completely prevent successful operation. An investigation into approaches to improve performance yields techniques that can help reduce the impact of shadows. A novel algorithm is presented that merges reference data captured at different times, resulting in reference data with minimal shadow effects. This can significantly improve performance and reliability when operating on images containing shadow effects. These advances improve the robustness of computer vision systems and extend the range of conditions in which they can operate. This can increase the usefulness of the algorithms and the AR systems that employ them.

This thesis treats topics within the area of object recognition. A real-time view matching method has been developed to compute the transformation between two different images of the same scene. This method uses a color based region detector called MSCR and affine transformations of these regions to create affine-invariant patches that are used as input to the SIFT algorithm. A parallel method to compute the SIFT descriptor has been created with relaxed constraints so that the descriptor size and the number of histogram bins can be adjusted. Additionally, a matching step to deduce correspondences and a parallel RANSAC method have been created to estimate the undergone transformation between these descriptors. To achieve real-time performance, the implementation has been targeted to use the parallel nature of the GPU with CUDA as the programming language. Focus has been put on the architecture of the GPU to find the best way to parallelize the different processing steps. CUDA has also been combined with OpenGL to be able to use the hardware accelerated anisotropic sampling method for affine transformations of regions. Parts of the implementation can also be used individually from either Matlab or by using the provided C++ library directly. The method was also evaluated in terms of accuracy and speed. It was shown that our algorithm has similar or better accuracy at finding correspondences than SIFT when the 3D geometry changes are large but we get a slightly worse result on images with flat surfaces.

Document describes selected techniques and approaches to problem of text detection, extraction and recognition on modern mobile devices. It also describes their proper presentation to the user interface and their conversion to hyperlinks as a source of information about surrounding world. The paper outlines text detection and recognition technique based on MSER detection and also describes the use of image features tracking method for text motion estimation.

This thesis presents a novel method to solve the problem of estimating the carrier frequency set in an Orthogonal Frequency Division Multiplexing (OFDM) system. The approach is based on the minimization of the probability of symbol error. Hence, this approach is called the Minimum Symbol Error Rate (MSER) approach. An existing approach based on Maximum Likelihood (ML) is chosen to benchmark the performance of the MSER-based algorithm. The MSER approach is computationally intensive. The thesis evaluates the approximations that can be made to the MSER-based objective function to make the computation tractable. A modified gradient function based on the MSER objective is developed which provides better performance characteristics than the ML-based estimator. The estimates produced by the MSER approach exhibit lower Mean Squared Error compared to the ML benchmark. The performance of MSER-based estimator is simulated with Quaternary Phase Shift Keying (QPSK) symbols, but the algorithm presented is applicable to all complex symbol constellations.

This study reports on the quantitative evaluation of a set of state-of-the-art feature detectors and descriptors in the context of repeat photography. Unlike most related work, the proposed study assesses the performance of feature detectors when intra-pair variations are uncontrolled and due to a variety of factors (landscape change, weather conditions, different acquisition sensors). There is no systematic way to model the factors inducing image change. The proposed evaluation is performed in the context of image matching, i.e. in conjunction with a descriptor and matching strategy. Thus, beyond just comparing the performance of these detectors and descriptors, we also examine the feasibility of feature-based matching on repeat photography. Our dataset consists of a set of repeat and historic images pairs that are representative for the database created by the Mountain Legacy Project www.mountainlegacy.ca. / Graduate