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Dissertations / Theses on the topic 'Image feature extraction'
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Ljumić, Elvis. "Image feature extraction using fuzzy morphology." Diss., Online access via UMI:, 2007.
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Thesis (Ph. D.)--State University of New York at Binghamton, Department of Systems Science and Industrial Engineering, Thomas J. Watson School of Engineering and Applied Science, 2007.Includes bibliographical references.
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Palma, Alberto de Jesus Pastrana. "Feature Extraction, Correspondence Regions and Image Retrieval using Structured Images." Thesis, University of East Anglia, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.502556.
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This thesis is about image descriptors, image retrieval and correspondence regions. The advantages of using scale-space on image descriptors are first discussed and a novel implementation of the sieve algorithm is introduced. We call this implementation 'The Structured Image'. It is shown here how such implementation decomposes the image in to a tree hierarchy collecting colour and texture descriptors throughout scale-space whilst remaining on a nearly linear order complexity. The algorithm is evaluated for correspondence repeatability rates and content based image retrieval. Results confirm the effectiveness of the implementation for both applications. We have also developed a graphic user interface to enable relevance feedback in to our image retrieval model. Our model is prepared to deal with segmentations of images rather than global att~ibutes of the image and it has been tested using two types of segmentations. Results in terms of precision rates are presented here for different iterations of relevance feedback.
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Westin, Carl-Fredrik. "Feature extraction based on a tensor image description." Licentiate thesis, Linköping University, Linköping University, Computer Vision, 1991. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-54888.
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Feature extraction from a tensor based local image representation introduced by Knutsson in [37] is discussed. The tensor representation keeps statements of structure, certainty of statement and energy separate. Further processing for obtaining new features also having these three entities separate is achieved by the use of a new concept, tensor field filtering. Tensor filters for smoothing and for extraction of circular symmetries are presented and discussed in particular. These methods are used for corner detection and extraction of more global features such as lines in images. A novel method for grouping local orientation estimates into global line parameters is introduced. The method is based on a new parameter space, the Möbius Strip parameter space, which has similarities to the Hough transform. A local centroid clustering algorithm is used for classification in this space. The procedure automatically divides curves into line segments with appropriate lengths depending on the curvature. A linked list structure is built up for storing data in an efficient way.
Ogiltigt nummer / annan version: I publ. nr 290:s ISBN: 91-7870-815-X.
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Hong, Qi He. "3D feature extraction from a single 2D image." Thesis, University of Reading, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.293175.
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Gardiner, Brian Calvin. "Compressive image feature extraction by means of folding." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/76812.
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Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2012.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (p. 61-62).
We explore the utility of a dimensionality reducing process we term folding for the purposes of image feature extraction. We seek to discover whether image features are preserved under this process and how to efficiently extract them. The application is in size weight and power constrained imaging scenarios where an efficient implementation of this dimensionality reduction can save power and computation costs. The specific features we explore are image corners, rotation, and translation. We present algorithms for recovering these features from folded representations of images followed by simulation results showing the performance of the algorithms when operating on real images.
by Brian Calvin Gardiner.
M.Eng.
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Gunn, Steve R. "Dual active contour models for image feature extraction." Thesis, University of Southampton, 1996. https://eprints.soton.ac.uk/250089/.
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Active contours are now a very popular technique for shape extraction, achieved by minimising a suitably formulated energy functional. Conventional active contour formulations suffer difficulty in appropriate choice of an initial contour and values of parameters. Recent approaches have aimed to resolve these problems, but can compromise other performance aspects. To relieve the problem in initialisation, an evolutionary dual active contour has been developed, which is combined with a local shape model to improve the parameterisation. One contour expands from inside the target feature, the other contracts from the outside. The two contours are inter-linked to provide a balanced technique with an ability to reject weak’local energy minima. Additionally a dual active contour configuration using dynamic programming has been developed to locate a global energy minimum and complements recent approaches via simulated annealing and genetic algorithms. These differ from conventional evolutionary approaches, where energy minimisation may not converge to extract the target shape, in contrast with the guaranteed convergence of a global approach. The new techniques are demonstrated to extract successfully target shapes in synthetic and real images, with superior performance to previous approaches. The new technique employing dynamic programming is deployed to extract the inner face boundary, along with a conventional normal-driven contour to extract the outer face boundary. Application to a database of 75 subjects showed that the outer contour was extracted successfully for 96% of the subjects and the inner contour was successful for 82%. This application highlights the advantages new dual active contour approaches for automatic shape extraction can confer.
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Liu, Xiuwen. "Computational investigation of feature extraction and image organization /." The Ohio State University, 1999. http://rave.ohiolink.edu/etdc/view?acc_num=osu148819296016944.
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Lorentzon, Matilda. "Feature Extraction for Image Selection Using Machine Learning." Thesis, Linköpings universitet, Datorseende, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-142095.
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During flights with manned or unmanned aircraft, continuous recording can result in avery high number of images to analyze and evaluate. To simplify image analysis and tominimize data link usage, appropriate images should be suggested for transfer and furtheranalysis. This thesis investigates features used for selection of images worthy of furtheranalysis using machine learning. The selection is done based on the criteria of havinggood quality, salient content and being unique compared to the other selected images.The investigation is approached by implementing two binary classifications, one regardingcontent and one regarding quality. The classifications are made using support vectormachines. For each of the classifications three feature extraction methods are performedand the results are compared against each other. The feature extraction methods used arehistograms of oriented gradients, features from the discrete cosine transform domain andfeatures extracted from a pre-trained convolutional neural network. The images classifiedas both good and salient are then clustered based on similarity measures retrieved usingcolor coherence vectors. One image from each cluster is retrieved and those are the resultingimages from the image selection. The performance of the selection is evaluated usingthe measures precision, recall and accuracy. The investigation showed that using featuresextracted from the discrete cosine transform provided the best results for the quality classification.For the content classification, features extracted from a convolutional neuralnetwork provided the best results. The similarity retrieval showed to be the weakest partand the entire system together provides an average accuracy of 83.99%.
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Lim, Suryani. "Feature extraction, browsing and retrieval of images." Monash University, School of Computing and Information Technology, 2005. http://arrow.monash.edu.au/hdl/1959.1/9677.
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Alfraih, Areej S. "Feature extraction and clustering techniques for digital image forensics." Thesis, University of Surrey, 2015. http://epubs.surrey.ac.uk/808306/.
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This thesis proposes an adaptive algorithm which applies feature extraction and clustering techniques for cloning detection and localization in digital images. Multiple contributions have been made to test the performance of different feature detectors for forensic use. The �first contribution is to improve a previously published algorithm by Wang et al. by localizing tampered regions using the grey-level co-occurrence matrix (GLCM) for extracting texture features from the chromatic component of an image (Cb or Cr component). The main trade-off� is a diminishing detection accuracy as the region size decreases. The second contribution is based on extracting Maximally Stable Extremal Regions (MSER) features for cloning detection, followed by k-means clustering for cloning localization. Then, for comparison purposes, we implement the same approach using Speeded Up Robust Features (SURF) and Scale-Invariant Feature Transform (SIFT). Experimental results show that we can detect and localize cloning in tampered images with an accuracy reaching 97% using MSER features. The usability and effi�cacy of our approach is verified by comparing with recent state-of-the-art approaches. For the third contribution we propose a flexible methodology for detecting cloning in images, based on the use of feature detectors. We determine whether a particular match is the result of a cloning event by clustering the matches using k-means clustering and using a Support Vector Machine (SVM) to classify the clusters. This descriptor-agnostic approach allows us to combine the results of multiple feature descriptors, increasing the potential number of keypoints in the cloned region. Results using MSER, SURF and SIFT outperform state of the art where the highest true positive rate is achieved at approximately 99.60% and the false positive rate is achieved at 1.6%, when different descriptors are combined. A statistical �filtering step, based on computing the median value of the dissimilarity matrix, is also proposed. Moreover, our algorithm uses an adaptive technique for selecting the optimal k value for each image independently, allowing our method to detect multiple cloned regions. Finally, we propose an adaptive technique that chooses feature detectors based on the type of image being tested. Some detectors are robust in detecting features in textured images while other detectors are robust in detecting features in smooth images. Combining the detectors makes them complementary to each other and can generate optimal results. The highest value for the area under ROC curve is achieved at approximately 98.87%. We also test the performance of agglomerative hierarchical clustering for cloning localization. Hierarchical and k-means clustering techniques have a similar performance for cloning localization. The True Positive Rate (TPR) for match level localization is achieved at approximately 97.59% and 96.43% for k-means and hierarchical clustering techniques, respectively. The robustness of our technique is analyzed against additive white Gaussian noise and JPEG compression. Our technique is still reliable even when using a low signal-to-noise (SNR = 20 dB) or a low JPEG compression quality factor (QF = 50).
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Shen, Yuan. "Feature Extraction and Feasibility Study on CT Image Guided Colonoscopy." Thesis, Virginia Tech, 2010. http://hdl.handle.net/10919/32275.
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Computed tomographic colonography(CTC), also called virtual colonoscopy, uses CT scanning and computer post-processing to create two dimensional images and three dimensional virtual views inside of the colon. Computer-aided polyp detection(CAPD) automatically detects colonic polyps and presents them to the user in either a first or second reader paradigm, with a goal reducing examination time while increasing the detection sensitivity. During colonoscopy, the endoscopists use the colonoscope inside of a patient's colon to target potential polyps and validate CAPD found ones. However, there is no direct information linking between CT images and the real-time optical colonoscopy(OC) video provided during the operation, thus endoscopists need to rely largely on their past experience to locate and remove polyps. The goal of this research project is to study the feasibility of developing an image guided colonoscopy(IGC) system that combines CTC images, real-time colonoscope position measurements, and video stream to validate and guide the removal of polyps found in CAPD. System would ease polyp level validation of CTC and improve the accuracy and efficiency of guiding the endoscopist to the target polyps. In this research project, a centerline based matching algorithm has been designed to estimate, in real time, the relative location of the colonoscope in the virtual colonoscopy environment. Furthermore, the feasibility of applying online simultaneous localization and mapping(SLAM) into CT image guided colonoscopy has been evaluated to further improve the performance of localizing and removing the pre-defined target polyps. A colon phantom is used to provide a testing setup to assess the performance of the proposed algorithms.Master of Science
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Li, Jiang. "Linear unmixing of hyperspectral signals via wavelet feature extraction." Diss., Mississippi State : Mississippi State University, 2002. http://library.msstate.edu/etd/show.asp?etd=etd-11082002-213652.
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Van, Wyk BJ, Wyk MA Van, and den Bergh F. Van. "A note on difference spectra for fast extraction of global image information." SAIEE Africa Research Journal, 2007. http://encore.tut.ac.za/iii/cpro/DigitalItemViewPage.external?sp=1001081.
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The concept of an Image Difference Spectrum, a novel tool for the extraction of global
image information, is introduced. It is shown that Image Difference Spectra are fast alternatives to
granulometric curves, also referred to as pattern spectra. Image Difference Spectra are
computationally easy to implement and are suitable for real-time applications.
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Pal, Chris. "A Probabilistic Approach to Image Feature Extraction, Segmentation and Interpretation." Thesis, University of Waterloo, 2000. http://hdl.handle.net/10012/1049.
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This thesis describes a probabilistic approach to imagesegmentation and interpretation. The focus of the investigation is the development of a systematic way of combining color, brightness, texture and geometric features extracted from an image to arrive at a consistent interpretation for each pixel in the image. The contribution of this thesis is thus the presentation of a novel framework for the fusion of extracted image features producing a segmentation of an image into relevant regions. Further, a solution to the sub-pixel mixing problem is presented based on solving a probabilistic linear program. This work is specifically aimed at interpreting and digitizing multi-spectral aerial imagery of the Earth's surface. The features of interest for extraction are those of relevance to environmental management, monitoring and protection. The presented algorithms are suitable for use within a larger interpretive system. Some results are presented and contrasted with other techniques. The integration of these algorithms into a larger system is based firmly on a probabilistic methodology and the use of statistical decision theory to accomplish uncertain inference within the visual formalism of a graphical probability model.
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Lee, Kai-wah. "Mesh denoising and feature extraction from point cloud data." Click to view the E-thesis via HKUTO, 2009. http://sunzi.lib.hku.hk/hkuto/record/B42664330.
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Pal, Christopher Joseph. "A probabilistic approach to image feature extraction, segmentation and interpretation." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape3/PQDD_0017/MQ56682.pdf.
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Nilsson, Mikael. "On feature extraction and classification in speech and image processing /." Karlskrona : Department of Signal Processing, School of Engineering, Blekinge Institute of Technology, 2007. http://www.bth.se/fou/forskinfo.nsf/allfirst2/fcbe16e84a9ba028c12573920048bce9?OpenDocument.
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Callaghan, Martina. "PadeÌ methods for image reconstruction and feature extraction in MRI." Thesis, Imperial College London, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.416865.
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Lo, Tsz-Wai Rachel. "Feature extraction for range image interpretation using local topology statistics." Thesis, University of Glasgow, 2009. http://theses.gla.ac.uk/557/.
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This thesis presents an approach for interpreting range images of known subject matter, such as the human face, based on the extraction and matching of local features from the images. In recent years, approaches to interpret two-dimensional (2D) images based on local feature extraction have advanced greatly, for example, systems such as Scale Invariant Feature Transform (SIFT) can detect and describe the local features in the 2D images effectively. With the aid of rapidly advancing three-dimensional (3D) imaging technology, in particular, the advent of commercially available surface scanning systems based on photogrammetry, image representation has been able to extend into the third dimension. Moreover, range images confer a number of advantages over conventional 2D images, for instance, the properties of being invariant to lighting, pose and viewpoint changes. As a result, an attempt has been made in this work to establish how best to represent the local range surface with a feature descriptor, thereby developing a matching system that takes advantages of the third dimension present in the range images and casting this in the framework of an existing scale and rotational invariance recognition technology: SIFT. By exploring the statistical representations of the local variation, it is possible to represent and match range images of human faces. This can be achieved by extracting unique mathematical keys known as feature descriptors, from the various automatically generated stable keypoint locations of the range images, thereby capturing the local information of the distributions of the mixes of surface types and their orientations simultaneously. Keypoints are generated through scale-space approach, where the (x,y) location and the appropriate scale (sigma) are detected. In order to achieve invariance to in-plane viewpoint rotational changes, a consistent canonical orientation is assigned to each keypoint and the sampling patch is rotated to this canonical orientation. The mixes of surface types, derived using the shape index, and the image gradient orientations are extracted from each sampling patch by placing nine overlapping Gaussian sub-regions over the measurement aperture. Each of the nine regions is overlapped by one standard deviation in order to minimise the occurrence of spatial aliasing during the sampling stages and to provide a better continuity within the descriptor. Moreover, surface normals can be computed from each of the keypoint location, allowing the local 3D pose to be estimated and corrected within the feature descriptors since the orientations in which the images were captured are unknown a priori. As a result, the formulated feature descriptors have strong discriminative power and are stable to rotational changes.
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Ukpai, Charles Onyebuchi. "Biometric iris image segmentation and feature extraction for iris recognition." Thesis, University of Newcastle upon Tyne, 2016. http://hdl.handle.net/10443/3487.
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The continued threat to security in our interconnected world today begs for urgent solution. Iris biometric like many other biometric systems provides an alternative solution to this lingering problem. Although, iris recognition have been extensively studied, it is nevertheless, not a fully solved problem which is the factor inhibiting its implementation in real world situations today. There exists three main problems facing the existing iris recognition systems: 1) lack of robustness of the algorithm to handle non-ideal iris images, 2) slow speed of the algorithm and 3) the applicability to the existing systems in real world situation. In this thesis, six novel approaches were derived and implemented to address these current limitation of existing iris recognition systems. A novel fast and accurate segmentation approach based on the combination of graph-cut optimization and active contour model is proposed to define the irregular boundaries of the iris in a hierarchical 2-level approach. In the first hierarchy, the approximate boundary of the pupil/iris is estimated using a method based on Hough’s transform for the pupil and adapted starburst algorithm for the iris. Subsequently, in the second hierarchy, the final irregular boundary of the pupil/iris is refined and segmented using graph-cut based active contour (GCBAC) model proposed in this work. The segmentation is performed in two levels, whereby the pupil is segmented first before the iris. In order to detect and eliminate noise and reflection artefacts which might introduce errors to the algorithm, a preprocessing technique based on adaptive weighted edge detection and high-pass filtering is used to detect reflections on the high intensity areas of the image while exemplar based image inpainting is used to eliminate the reflections. After the segmentation of the iris boundaries, a post-processing operation based on combination of block classification method and statistical prediction approach is used to detect any super-imposed occluding eyelashes/eyeshadows. The normalization of the iris image is achieved though the rubber sheet model. In the second stage, an approach based on construction of complex wavelet filters and rotation of the filters to the direction of the principal texture direction is used for the extraction of important iris information while a modified particle swam optimization (PSO) is used to select the most prominent iris features for iris encoding. Classification of the iriscode is performed using adaptive support vector machines (ASVM). Experimental results demonstrate that the proposed approach achieves accuracy of 98.99% and is computationally about 2 times faster than the best existing approach.
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Lee, Kai-wah, and 李啟華. "Mesh denoising and feature extraction from point cloud data." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2009. http://hub.hku.hk/bib/B42664330.
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Rees, Stephen John. "Feature extraction and object recognition using conditional morphological operators." Thesis, University of South Wales, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.265731.
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Kaufman, Jason R. "Spatial-Spectral Feature Extraction on Pansharpened Hyperspectral Imagery." Ohio University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1408706595.
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Serce, Hakan. "Facial Feature Extraction Using Deformable Templates." Master's thesis, METU, 2003. http://etd.lib.metu.edu.tr/upload/1224674/index.pdf.
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The purpose of this study is to develop an automatic facial feature extraction system, which is able to identify the detailed shape of eyes, eyebrows and mouth from facial images. The developed system not only extracts the location information of the features, but also estimates the parameters pertaining the contours and parts of the features using parametric deformable templates approach. In order to extract facial features, deformable models for each of eye, eyebrow, and mouth are developed. The development steps of the geometry, imaging model and matching algorithms, and energy functions for each of these templates are presented in detail, along with the important implementation issues.
In addition, an eigenfaces based multi-scale face detection algorithm which incorporates standard facial proportions is implemented, so that when a face is detected the rough search regions for the facial features are readily available.
The developed system is tested on JAFFE (Japanese Females Facial Expression Database), Yale Faces, and ORL (Olivetti Research Laboratory) face image databases. The performance of each deformable templates, and the face detection algorithm are discussed separately.
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Calitz, Michaelangelo Franco. "Image understanding and feature extraction for applications in industry and mapping." Doctoral thesis, University of Cape Town, 1995. http://hdl.handle.net/11427/15942.
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Bibliography: p. 212-220.The aim of digital photogrammetry is the automated extraction and classification of the three dimensional information of a scene from a number of images. Existing photogrammetric systems are semi-automatic requiring manual editing and control, and have very limited domains of application so that image understanding capabilities are left to the user. Among the most important steps in a fully integrated system are the extraction of features suitable for matching, the establishment of the correspondence between matching points and object classification. The following study attempts to explore the applicability of pattern recognition concepts in conjunction with existing area-based methods, feature-based techniques and other approaches used in computer vision in order to increase the level of automation and as a general alternative and addition to existing methods. As an illustration of the pattern recognition approach examples of industrial applications are given. The underlying method is then extended to the identification of objects in aerial images of urban scenes and to the location of targets in close-range photogrammetric applications. Various moment-based techniques are considered as pattern classifiers including geometric invariant moments, Legendre moments, Zernike moments and pseudo-Zernike moments. Two-dimensional Fourier transforms are also considered as pattern classifiers. The suitability of these techniques is assessed. These are then applied as object locators and as feature extractors or interest operators. Additionally the use of fractal dimension to segment natural scenes for regional classification in order to limit the search space for particular objects is considered. The pattern recognition techniques require considerable preprocessing of images. The various image processing techniques required are explained where needed. Extracted feature points are matched using relaxation based techniques in conjunction with area-based methods to 'obtain subpixel accuracy. A subpixel pattern recognition based method is also proposed and an investigation into improved area-based subpixel matching methods is undertaken. An algorithm for determining relative orientation parameters incorporating the epipolar line constraint is investigated and compared with a standard relative orientation algorithm. In conclusion a basic system that can be automated based on some novel techniques in conjunction with existing methods is described and implemented in a mapping application. This system could be largely automated with suitably powerful computers.
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Shi, Qiquan. "Low rank tensor decomposition for feature extraction and tensor recovery." HKBU Institutional Repository, 2018. https://repository.hkbu.edu.hk/etd_oa/549.
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Feature extraction and tensor recovery problems are important yet challenging, particularly for multi-dimensional data with missing values and/or noise. Low-rank tensor decomposition approaches are widely used for solving these problems. This thesis focuses on three common tensor decompositions (CP, Tucker and t-SVD) and develops a set of decomposition-based approaches. The proposed methods aim to extract low-dimensional features from complete/incomplete data and recover tensors given partial and/or grossly corrupted observations.;Based on CP decomposition, semi-orthogonal multilinear principal component analysis (SO-MPCA) seeks a tensor-to-vector projection that maximizes the captured variance with the orthogonality constraint imposed in only one mode, and it further integrates the relaxed start strategy (SO-MPCA-RS) to achieve better feature extraction performance. To directly obtain the features from incomplete data, low-rank CP and Tucker decomposition with feature variance maximization (TDVM-CP and TDVM-Tucker) are proposed. TDVM methods explore the relationship among tensor samples via feature variance maximization, while estimating the missing entries via low-rank CP and Tucker approximation, leading to informative features extracted directly from partial observations. TDVM-CP extracts low-dimensional vector features viewing the weight vectors as features and TDVM-Tucker learns low-dimensional tensor features viewing the core tensors as features. TDVM methods can be generalized to other variants based on other tensor decompositions. On the other hand, this thesis solves the missing data problem by introducing low-rank matrix/tensor completion methods, and also contributes to automatic rank estimation. Rank-one matrix decomposition coupled with L1-norm regularization (L1MC) addresses the matrix rank estimation problem. With the correct estimated rank, L1MC refines its model without L1-norm regularization (L1MC-RF) and achieve optimal recovery results given enough observations. In addition, CP-based nuclear norm regularized orthogonal CP decomposition (TREL1) solves the challenging CP- and Tucker-rank estimation problems. The estimated rank can improve the tensor completion accuracy of existing decomposition-based methods. Furthermore, tensor singular value decomposition (t-SVD) combined with tensor nuclear norm (TNN) regularization (ARE_TNN) provides automatic tubal-rank estimation. With the accurate tubal-rank determination, ARE_TNN relaxes its model without the TNN constraint (TC-ARE) and results in optimal tensor completion under mild conditions. In addition, ARE_TNN refines its model by explicitly utilizing its determined tubal-rank a priori and then successfully recovers low-rank tensors based on incomplete and/or grossly corrupted observations (RTC-ARE: robust tensor completion/RTPCA-ARE: robust tensor principal component analysis).;Experiments and evaluations are presented and analyzed using synthetic data and real-world images/videos in machine learning, computer vision, and data mining applications. For feature extraction, the experimental results of face and gait recognition show that SO-MPCA-RS achieves the best overall performance compared with competing algorithms, and its relaxed start strategy is also effective for other CP-based PCA methods. In the applications of face recognition, object/action classification, and face/gait clustering, TDVM methods not only stably yield similar good results under various multi-block missing settings and different parameters in general, but also outperform the competing methods with significant improvements. For matrix/tensor rank estimation and recovery, L1MC-RF efficiently estimates the true rank and exactly recovers the incomplete images/videos under mild conditions, and outperforms the state-of-the-art algorithms on the whole. Furthermore, the empirical evaluations show that TREL1 correctly determines the CP-/Tucker- ranks well, given sufficient observed entries, which consistently improves the recovery performance of existing decomposition-based tensor completion. The t-SVD recovery methods TC-ARE, RTPCA-ARE, and RTC-ARE not only inherit the ability of ARE_TNN to achieve accurate rank estimation, but also achieve good performance in the tasks of (robust) image/video completion, video denoising, and background modeling. This outperforms the state-of-the-art methods in all cases we have tried so far with significant improvements.
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Brennan, Michael. "Comparison of automated feature extraction methods for image based screening of cancer cells." Thesis, Uppsala universitet, Institutionen för informationsteknologi, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-167602.
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Image based screening is an important tool used in research for development of drugs to fight cancer. Phase contrast video microscopy - a cheap and fast image screening technology - enables a rapid generation of large amounts of data, which requires a fast method for analysis of this data. As videos contain a lot of redundant information, the difficulty is to extract usable information in form of features from the videos, by compressing available information, or filter out redundant data. In this thesis, the problem is approached in an experimental fashion where three different methods have been devised and tested, to evaluate different ways to automatically extract features from phase contrast microscopy videos containing cultured cancer cells. The three methods considered are, in order: an adaptive linear filter, an on-line clustering algorithm, and an artificial neural network. The ambition is that outputs from these methods can create time-varying histograms of features that can be used in further mathematical modeling of cell dynamics. It is concluded that, while the results of the first method is not impressive and can be dismissed, the remaining two are more promising and are able to successfully extract features automatically and aggregate them into time-varying histograms.
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Marrugo, Hernández Andrés G. (Andrés Guillermo). "Comprehensive retinal image analysis: image processing and feature extraction techniques oriented to the clinical task." Doctoral thesis, Universitat Politècnica de Catalunya, 2013. http://hdl.handle.net/10803/134698.
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Medical digital imaging has become a key element of modern health care procedures. It provides a visual documentation, a permanent record for the patients, and most importantly the ability to extract information about many diseases. Ophthalmology is a field that is heavily dependent on the analysis of digital images because they can aid in establishing an early diagnosis even before the first symptoms appear. This dissertation contributes to the digital analysis of such images and the problems that arise along the imaging pipeline, a field that is commonly referred to as retinal image analysis. We have dealt with and proposed solutions to problems that arise in retinal image acquisition and longitudinal monitoring of retinal disease evolution. Specifically, non-uniform illumination, poor image quality, automated focusing, and multichannel analysis. However, there are many unavoidable situations in which images of poor quality, like blurred retinal images because of aberrations in the eye, are acquired. To address this problem we have proposed two approaches for blind deconvolution of blurred retinal images. In the first approach, we consider the blur to be space-invariant and later in the second approach we extend the work and propose a more general space-variant scheme.
For the development of the algorithms we have built preprocessing solutions that have enabled the extraction of retinal features of medical relevancy, like the segmentation of the optic disc and the detection and visualization of longitudinal structural changes in the retina. Encouraging experimental results carried out on real retinal images coming from the clinical setting demonstrate the applicability of our proposed solutions.
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Plahl, Christian [Verfasser]. "Neural network based feature extraction for speech and image recognition / Christian Plahl." Aachen : Hochschulbibliothek der Rheinisch-Westfälischen Technischen Hochschule Aachen, 2014. http://d-nb.info/1058851160/34.
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Baboulaz, Loic. "Feature extraction for image super-resolution using finite rate of innovation principles." Thesis, Imperial College London, 2008. http://hdl.handle.net/10044/1/1351.
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To understand a real-world scene from several multiview pictures, it is necessary to find the disparities existing between each pair of images so that they are correctly related to one another. This process, called image registration, requires the extraction of some specific information about the scene. This is achieved by taking features out of the acquired images. Thus, the quality of the registration depends largely on the accuracy of the extracted features. Feature extraction can be formulated as a sampling problem for which perfect re- construction of the desired features is wanted. The recent sampling theory for signals with finite rate of innovation (FRI) and the B-spline theory offer an appropriate new frame- work for the extraction of features in real images. This thesis first focuses on extending the sampling theory for FRI signals to a multichannel case and then presents exact sampling results for two different types of image features used for registration: moments and edges. In the first part, it is shown that the geometric moments of an observed scene can be retrieved exactly from sampled images and used as global features for registration. The second part describes how edges can also be retrieved perfectly from sampled images for registration purposes. The proposed feature extraction schemes therefore allow in theory the exact registration of images. Indeed, various simulations show that the proposed extraction/registration methods overcome traditional ones, especially at low-resolution. These characteristics make such feature extraction techniques very appropriate for applications like image super-resolution for which a very precise registration is needed. The quality of the super-resolved images obtained using the proposed feature extraction meth- ods is improved by comparison with other approaches. Finally, the notion of polyphase components is used to adapt the image acquisition model to the characteristics of real digital cameras in order to run super-resolution experiments on real images.
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Albukhanajer, Wissam A. "Multi-objective feature extraction and ensembles of classifiers for invariant image identification." Thesis, University of Surrey, 2015. http://epubs.surrey.ac.uk/807832/.
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Robustness to geometrical transformations such as rotation, scaling and translation (RST) as well as noise are major concerns in computer vision and image analysis. This thesis proposes an effective feature extraction approach using Trace transform and ensembles of classifiers for invariant image identification. The key question in Trace transform is to select the best combinations of the Trace functionals to produce and apply the optimal Triple features with minimum computational cost, which is a challenging task because robustness and computational speed conflict with each other. This challenge poses a series of experimental and analytical discussions outlined into two phases. In the first phase, we propose Evolutionary Trace Transform (ETT) that adopts evolutionary algorithms and Pareto optimality principles to select the best functionals used in Trace transform. To tackle noise, we deliberately inject noisy samples in the example images in the evolutionary training of Trace transform, which is termed Evolutionary Trace Transform with Noise (ETTN). Single-objective and multi-objective optimisation were developed and compared. A one-shot approach is considered, which uses a very small number of examples in the evolutionary training process and applies the extracted features to test the entire dataset. The second phase deals with building classifiers. To complete the identification task, a variant of classifiers were constructed and compared. To further enhance the performance and to increase the reliability of the system, we propose ensembles of classifiers that use multiple Pareto optimal image features. The proposed ensembles take advantage of the diversity inherent in the Pareto optimal features extracted using the ETTN algorithm and empirical results show that on average, ensembles using Pareto optimal features perform much better than traditional classifier ensembles using the same features and data randomisation. Diversity analysis using a number of measures is also considered, indicating that the proposed ensembles consistently produce a higher degree of diversity than traditional ensembles. Furthermore, a tuning process of the Trace transform parameters is conducted to obtain a trade-off between complexity and robustness using two evolutionary multi-objective approaches. In the first approach, two-objective evolutionary algorithms are adopted using the within-class variance and between-class variance as objectives. The second approach adopts three-objective evolutionary algorithms, which consider the computational complexity as a third objective. Two different coding schemes are considered for each approach, which are integer-coding and real-coding schemes. The proposed schemes were compared by conducting experiments on sample images and results showed that the integer-coding scheme presents a better performance compared to the real-coding scheme. Moreover, while the three-objective approach enforces a balance between robustness and computational complexity, without enforcing a minimum acceptable accuracy, features extracted tend to have a lower computational complexity at the expense of the accuracy, compared with the two-objective approach.
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Chaofan, Hao, and Yu Haisheng. "Feature Extraction of Gesture Recognition Based on Image Analysis by Using Matlab." Thesis, Högskolan i Gävle, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-17367.
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This thesis mainly focuses on the research of gesture extraction and finger segmentation in the gesture recognition. In this paper, we used image analysis technologies to create an application by encoding in Matlab program. We used this application to segment and extract the finger from one specific gesture (the gesture "one") and ran successfully. We explored the success rate of extracting the characteristic of the specific gesture "one" in different natural environments. We divided the natural environment into three different conditions which are glare and dark condition, similar object condition and different distances condition, then collected the results to calculate the successful extraction rate. We also evaluated and analyzed the inadequacies and future works of this application.Technology
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He, Xiaochen. "Feature extraction from two consecutive traffic images for 3D wire frame reconstruction of vehicle." Click to view the E-thesis via HKUTO, 2006. http://sunzi.lib.hku.hk/hkuto/record/B3786791X.
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Xu, Dongjiang. "HYBRID AND HIERARCHICAL IMAGE REGISTRATION TECHNIQUES." Doctoral diss., University of Central Florida, 2004. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3232.
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A large number of image registration techniques have been developed for various types of sensors and applications, with the aim to improve the accuracy, computational complexity, generality, and robustness. They can be broadly classified into two categories: intensity-based and feature-based methods. The primary drawback of the intensity-based approaches is that it may fail unless the two images are misaligned by a moderate difference in scale, rotation, and translation. In addition, intensity-based methods lack the robustness in the presence of non-spatial distortions due to different imaging conditions between images. In this dissertation, the image registration is formulated as a two-stage hybrid approach combining both an initial matching and a final matching in a coarse-to-fine manner. In the proposed hybrid framework, the initial matching algorithm is applied at the coarsest scale of images, where the approximate transformation parameters could be first estimated. Subsequently, the robust gradient-based estimation algorithm is incorporated into the proposed hybrid approach using a multi-resolution scheme. Several novel and effective initial matching algorithms have been proposed for the first stage. The variations of the intensity characteristics between images may be large and non-uniform because of non-spatial distortions. Therefore, in order to effectively incorporate the gradient-based robust estimation into our proposed framework, one of the fundamental questions should be addressed: what is a good image representation to work with using gradient-based robust estimation under non-spatial distortions. With the initial matching algorithms applied at the highest level of decomposition, the proposed hybrid approach exhibits superior range of convergence. The gradient-based algorithms in the second stage yield a robust solution that precisely registers images with sub-pixel accuracy. A hierarchical iterative searching further enhances the convergence range and rate. The simulation results demonstrated that the proposed techniques provide significant benefits to the performance of image registration.Ph.D.
Department of Electrical and Computer Engineering
Engineering and Computer Science
Electrical Engineering
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Brown, Dane. "Investigating combinations of feature extraction and classification for improved image-based multimodal biometric systems at the feature level." Thesis, Rhodes University, 2018. http://hdl.handle.net/10962/63470.
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Multimodal biometrics has become a popular means of overcoming the limitations of unimodal biometric systems. However, the rich information particular to the feature level is of a complex nature and leveraging its potential without overfitting a classifier is not well studied. This research investigates feature-classifier combinations on the fingerprint, face, palmprint, and iris modalities to effectively fuse their feature vectors for a complementary result. The effects of different feature-classifier combinations are thus isolated to identify novel or improved algorithms. A new face segmentation algorithm is shown to increase consistency in nominal and extreme scenarios. Moreover, two novel feature extraction techniques demonstrate better adaptation to dynamic lighting conditions, while reducing feature dimensionality to the benefit of classifiers. A comprehensive set of unimodal experiments are carried out to evaluate both verification and identification performance on a variety of datasets using four classifiers, namely Eigen, Fisher, Local Binary Pattern Histogram and linear Support Vector Machine on various feature extraction methods. The recognition performance of the proposed algorithms are shown to outperform the vast majority of related studies, when using the same dataset under the same test conditions. In the unimodal comparisons presented, the proposed approaches outperform existing systems even when given a handicap such as fewer training samples or data with a greater number of classes. A separate comprehensive set of experiments on feature fusion show that combining modality data provides a substantial increase in accuracy, with only a few exceptions that occur when differences in the image data quality of two modalities are substantial. However, when two poor quality datasets are fused, noticeable gains in recognition performance are realized when using the novel feature extraction approach. Finally, feature-fusion guidelines are proposed to provide the necessary insight to leverage the rich information effectively when fusing multiple biometric modalities at the feature level. These guidelines serve as the foundation to better understand and construct biometric systems that are effective in a variety of applications.
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He, Xiaochen, and 何小晨. "Feature extraction from two consecutive traffic images for 3D wire frame reconstruction of vehicle." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2006. http://hub.hku.hk/bib/B3786791X.
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Gonulsen, Aysegul. "Feature Extraction Of Honeybee Forewings And Hindlegs Using Image Processing And Active Contours." Master's thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/12604738/index.pdf.
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Honeybees have a rich genetic diversity in Anatolia. This is reflected in the presence of numerous subspecies of honeybee in Turkey. In METU, Department of Biology, honeybee populations of different regions in Turkey are investigated in order to characterize population variation in these regions. A total of 23 length and angle features belonging to the honeybee hindlegs and forewings are measured in these studies using a microscope and a monitor. These measurements are carried out by placing rulers on the monitor that shows the honeybee image and getting the length and angle features. However, performing measurements in this way is a time consuming process and is open to human-dependent errors.
In this thesis, a &ldquosemi-automated honeybee feature extraction system&rdquo
is presented. The aim is to increase the efficiency by decreasing the time spent on handling these measurements and by increasing the accuracy of measured hindleg and forewing features. The problem is studied from the acquisition of the microscope images, to the feature extraction of the honeybee features. In this scope, suitable methods are developed for segmentation of honeybee hindleg and forewing images. Within intermediate steps, blob analysis is utilized, and edges of the forewing and hindlegs are thinned using skeletonization. Templates that represent the forewing and hindleg edges are formed by either Bezier Curves or Polynomial Interpolation. In the feature extraction phase, Active Contour (Snake) algorithm is applied to the images in order to find the critical points using these templates.
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Halling, Leonard. "Feature Extraction for ContentBased Image Retrieval Using a PreTrained Deep Convolutional Neural Network." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-274340.
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This thesis examines the performance of features, extracted from a pre-trained deep convolutional neural network, for content-based image retrieval in images of news articles. The industry constantly awaits improved methods for image retrieval, including the company hosting this research project, who are looking to improve their existing image description-based method for image retrieval. It has been shown that in a neural network, the invoked activations from an image can be used as a high-level representation (feature) of the image. This study explores the efficiency of these features in an image similarity setting. An experiment is performed, evaluating the performance through a comparison of the answers in an image similarity survey, containing solutions made by humans. The new model scores 72.5% on the survey, and outperforms the existing image description-based method which only achieved a score of 37.5%. Discussions about the results, design choices, and suggestions for further improvements of the implementation are presented in the later parts of the thesis.Detta examensarbete utforskar huruvida representationer som extraherats ur en förtränad djup CNN kan användas i innehållsbaserad bildhämtning för bilder i nyhetsartiklar. Branschen letar ständigt efter förbättrade metoder för bildhämtning, inte minst företaget som detta forskningsprojekt har utförts på, som vill förbättra sin befintliga bildbeskrivningsbaserade metod för bildhämtning. Det har visats att aktiveringarna från en bild i ett neuralt nätverk kan användas som en beskrivning av bildens visuella innehåll (features). Denna studie undersöker användbarheten av dessa features i ett bildlikhetssammanhang. Ett experiment med syfte att utvärdera den nya modellens prestanda utförs genom en jämförelse av svaren i en bildlikhetsundersökning, innehållande lösningar gjorda av människor. Den nya modellen får 72,5% på undersökningen, vilket överträffar den existerande bildbeskrivningsbaserade metoden som bara uppnådde ett resultat på 37,5%. Diskussioner om resultat, designval samt förslag till ytterligare förbättringar av utförandet presenteras i de senare delarna av rapporten.
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Wang, Yuanxun. "Radar signature prediction and feature extraction using advanced signal processing techniques /." Digital version accessible at:, 1999. http://wwwlib.umi.com/cr/utexas/main.
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Li, Qi. "An integration framework of feature selection and extraction for appearance-based recognition." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file 8.38 Mb., 141 p, 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:3220745.
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Kiang, Kai-Ming Mechanical & Manufacturing Engineering Faculty of Engineering UNSW. "Natural feature extraction as a front end for simultaneous localization and mapping." Awarded by:University of New South Wales. School of Mechanical and Manufacturing Engineering, 2006. http://handle.unsw.edu.au/1959.4/26960.
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This thesis is concerned with algorithms for finding natural features that are then used for simultaneous localisation and mapping, commonly known as SLAM in navigation theory. The task involves capturing raw sensory inputs, extracting features from these inputs and using the features for mapping and localising during navigation. The ability to extract natural features allows automatons such as robots to be sent to environments where no human beings have previously explored working in a way that is similar to how human beings understand and remember where they have been. In extracting natural features using images, the way that features are represented and matched is a critical issue in that the computation involved could be wasted if the wrong method is chosen. While there are many techniques capable of matching pre-defined objects correctly, few of them can be used for real-time navigation in an unexplored environment, intelligently deciding on what is a relevant feature in the images. Normally, feature analysis that extracts relevant features from an image is a 2-step process, the steps being firstly to select interest points and then to represent these points based on the local region properties. A novel technique is presented in this thesis for extracting a small enough set of natural features robust enough for navigation purposes. The technique involves a 3-step approach. The first step involves an interest point selection method based on extrema of difference of Gaussians (DOG). The second step applies Textural Feature Analysis (TFA) on the local regions of the interest points. The third step selects the distinctive features using Distinctness Analysis (DA) based mainly on the probability of occurrence of the features extracted. The additional step of DA has shown that a significant improvement on the processing speed is attained over previous methods. Moreover, TFA / DA has been applied in a SLAM configuration that is looking at an underwater environment where texture can be rich in natural features. The results demonstrated that an improvement in loop closure ability is attained compared to traditional SLAM methods. This suggests that real-time navigation in unexplored environments using natural features could now be a more plausible option.
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Tao, Chuang. "Automated approaches to object measurement and feature extraction from georeferenced mobile mapping image sequences." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0011/NQ31076.pdf.
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Mühlfellner, Peter. "Selection, Analysis and Implementationof Image-based Feature Extraction Approaches for a Heterogenous, Modular and FPGA-based Architecture for Camera-based Driver Assistance Systems." Thesis, Högskolan i Halmstad, Intelligenta system (IS-lab), 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-16377.
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We propose a scalable and fexible hardware architecture for the extraction of image features, used in conjunction with an attentional cascade classifier for appearance-based object detection. Individual feature processors calculate feature-values in parallel, using parameter-sets and image data that is distributed via BRAM buffers. This approach can provide high utilization- and throughput-rates for a cascade classifier. Unlike previous hardware implementations, we are able to flexibly assign feature processors to either work on a single- or multiple image windows in parallel, depending on the complexity of the current cascade stage. The core of the architecture was implemented in the form of a streaming based FPGA design, and validated in simulation, synthesis, as well as via the use of a Logic Analyser for the verification of the on-chip functionality. For the given implementation, we focused on the design of Haar-like feature processors, but feature processors for a variety of heterogenous feature types, such as Gabor-like features, can also be accomodated by the proposed hardware architecture.
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Lozano, Vega Gildardo. "Image-based detection and classification of allergenic pollen." Thesis, Dijon, 2015. http://www.theses.fr/2015DIJOS031/document.
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Le traitement médical des allergies nécessite la caractérisation des pollens en suspension dans l’air. Toutefois, cette tâche requiert des temps d’analyse très longs lorsqu’elle est réalisée de manière manuelle. Une approche automatique améliorerait ainsi considérablement les applications potentielles du comptage de pollens. Les dernières techniques d’analyse d’images permettent la détection de caractéristiques discriminantes. C’est pourquoi nous proposons dans cette thèse un ensemble de caractéristiques pertinentes issues d’images pour la reconnaissance des principales classes de pollen allergènes. Le cœur de notre étude est l’évaluation de groupes de caractéristiques capables de décrire correctement les pollens en termes de forme, texture, taille et ouverture. Les caractéristiques sont extraites d’images acquises classiquement sous microscope, permettant la reproductibilité de la méthode. Une étape de sélection des caractéristiques est appliquée à chaque groupe pour évaluer sa pertinence.Concernant les apertures présentes sur certains pollens, une méthode adaptative de détection, localisation et comptage pour différentes classes de pollens avec des apparences variées est proposée. La description des apertures se base sur une stratégie de type Sac-de-Mots appliquée à des primitives issues des images. Une carte de confiance est construite à partir de la confiance donnée à la classification des régions de l’image échantillonnée. De cette carte sont extraites des caractéristiques propres aux apertures, permettant leur comptage. La méthode est conçue pour être étendue de façon modulable à de nouveaux types d’apertures en utilisant le même algorithme mais avec un classifieur spécifique.Les groupes de caractéristiques ont été testés individuellement et conjointement sur les classes de pollens les plus répandues en Allemagne. Nous avons montré leur efficacité lors d’une classification de type SVM, notamment en surpassant la variance intra-classe et la similarité inter-classe. Les résultats obtenus en utilisant conjointement tous les groupes de caractéristiques ont abouti à une précision de 98,2 %, comparable à l’état de l’artThe correct classification of airborne pollen is relevant for medical treatment of allergies, and the regular manual process is costly and time consuming. An automatic processing would increase considerably the potential of pollen counting. Modern computer vision techniques enable the detection of discriminant pollen characteristics. In this thesis, a set of relevant image-based features for the recognition of top allergenic pollen taxa is proposed and analyzed. The foundation of our proposal is the evaluation of groups of features that can properly describe pollen in terms of shape, texture, size and apertures. The features are extracted on typical brightfield microscope images that enable the easy reproducibility of the method. A process of feature selection is applied to each group for the determination of relevance.Regarding apertures, a flexible method for detection, localization and counting of apertures of different pollen taxa with varying appearances is proposed. Aperture description is based on primitive images following the Bag-of-Words strategy. A confidence map is built from the classification confidence of sampled regions. From this map, aperture features are extracted, which include the count of apertures. The method is designed to be extended modularly to new aperture types employing the same algorithm to build individual classifiers.The feature groups are tested individually and jointly on of the most allergenic pollen taxa in Germany. They demonstrated to overcome the intra-class variance and inter-class similarity in a SVM classification scheme. The global joint test led to accuracy of 98.2%, comparable to the state-of-the-art procedures
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Zhang, Jing. "Extraction of Text Objects in Image and Video Documents." Scholar Commons, 2012. http://scholarcommons.usf.edu/etd/4266.
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The popularity of digital image and video is increasing rapidly. To help users navigate libraries of image and video, Content Based Information Retrieval (CBIR) system that can automatically index image and video documents are needed. However, due to the semantic gap between low-level machine descriptors and high-level semantic descriptors, the existing CBIR systems are still far from perfect. Text embedded in multi-media data, as a well-defined model of concepts for humans' communication, contains much semantic information related to the content. This text information can provide a much truer form of content-based access to the image and video documents if it can be extracted and harnessed efficiently.
This dissertation solves the problem involved in detecting text object in image and video and tracking text event in video. For text detection problem, we propose a new unsupervised text detection algorithm. A new text model is constructed to describe text object using pictorial structure. Each character is a part in the model and every two neighboring characters are connected by a spring-like link. Two characters and the link connecting them are defined as a text unit. We localize candidate parts by extracting closed boundaries and initialize the links by connecting two neighboring candidate parts based on the spatial relationship of characters. For every candidate part, we compute character energy using three new character features, averaged angle difference of corresponding pairs, fraction of non-noise pairs, and vector of stroke width. They are extracted based on our observation that the edge of a character can be divided into two sets with high similarities in length, curvature, and orientation. For every candidate link, we compute link energy based on our observation that the characters of a text typically align along certain direction with similar color, size, and stroke width. For every candidate text unit, we combine character and link energies to compute text unit energy which indicates the probability that the candidate text model is a real text object. The final text detection results are generated using a text unit energy based thresholding. For text tracking problem, we construct a text event model by using pictorial structure as well. In this model, the detected text object in each video frame is a part and two neighboring text objects of a text event are connected by a spring-like link. Inter-frame link energy is computed for each link based on the character energy, similarity of neighboring text objects, and motion information. After refining the model using inter-frame link energy, the remaining text event models are marked as text events.
At character level, because the proposed method is based on the assumption that the strokes of a character have uniform thickness, it can detect and localize characters from different languages in different styles, such as typewritten text or handwriting text, if the characters have approximately uniform stroke thickness. At text level, however, because the spatial relationship between two neighboring characters is used to localize text objects, the proposed method may fail to detect and localize the characters with multiple separate strokes or connected characters. For example, some East Asian language characters, such as Chinese, Japanese, and Korean, have many strokes of a single character. We need to group the strokes first to form single characters and then group characters to form text objects. While, the characters of some languages, such Arabic and Hindi, are connected together, we cannot extract spatial information between neighboring characters since they are detected as a single character. Therefore, in current stage the proposed method can detect and localize the text objects that are composed of separate characters with connected strokes with approximately uniform thickness.
We evaluated our method comprehensively using three English language-based image and video datasets: ICDAR 2003/2005 text locating dataset (258 training images and 251 test images), Microsoft Street View text detection dataset (307 street view images), and VACE video dataset (50 broadcast news videos from CNN and ABC). The experimental results demonstrate that the proposed text detection method can capture the inherent properties of text and discriminate text from other objects efficiently.
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Cremer, Sandra. "Adapting iris feature extraction and matching to the local and global quality of iris image." Thesis, Evry, Institut national des télécommunications, 2012. http://www.theses.fr/2012TELE0026.
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La reconnaissance d'iris est un des systèmes biométriques les plus fiables et les plus précis. Cependant sa robustesse aux dégradations des images d'entrées est limitée. Généralement les systèmes basés sur l'iris peuvent être décomposés en quatre étapes : segmentation, normalisation, extraction de caractéristiques et comparaison. Des dégradations de la qualité des images d'entrées peuvent avoir des répercussions sur chacune de ses étapes. Elles compliquent notamment la segmentation, ce qui peut engendrer des images normalisées contenant des distorsions ou des artefacts non détectés. De plus, la quantité d'information disponible pour la comparaison peut être réduite. Dans cette thèse, nous proposons des solutions pour améliorer la robustesse des étapes d'extraction de caractéristiques et de comparaison à la dégradation des images d'entrées. Nous travaillons avec deux algorithmes pour ces deux étapes, basés sur les convolutions avec des filtres de Gabor 2D, mais des processus de comparaison différents. L'objectif de la première partie de notre travail est de contrôler la qualité et la quantité d'information sélectionnée pour la comparaison dans les images d'iris normalisées. Dans ce but nous avons défini des mesures de qualité locale et globale qui mesurent la quantité d'occlusions et la richesse de la texture dans les images d'iris. Nous utilisons ces mesures pour déterminer la position et le nombre de régions à exploiter pour l'extraction. Dans une seconde partie de ce travail, nous étudions le lien entre la qualité des images et les performances de reconnaissance des deux algorithmes de reconnaissance décrits ci-dessus. Nous montrons que le second est plus robuste aux images dégradées contenant des artefacts, des distorsions ou une texture pauvre. Enfin, nous proposons un système complet pour la reconnaissance d'iris, qui combine l'utilisation de nos mesures de qualités locale et globale pour optimiser les performances des algorithmes d'extraction de caractéristiques et de comparaisonIris recognition has become one of the most reliable and accurate biometric systems available. However its robustness to degradations of the input images is limited. Generally iris based systems can be cut into four steps : segmentation, normalization, feature extraction and matching. Degradations of the input image quality can have repercussions on all of these steps. For instance, they make the segmentation more difficult which can result in normalized iris images that contain distortion or undetected artefacts. Moreover the amount of information available for matching can be reduced. In this thesis we propose methods to improve the robustness of the feature extraction and matching steps to degraded input images. We work with two algorithms for these two steps. They are both based on convolution with 2D Gabor filters but use different techniques for matching. The first part of our work is aimed at controlling the quality and quantity of information selected in the normalized iris images for matching. To this end we defined local and global quality metrics that measure the amount of occlusion and the richness of texture in iris images. We use these measures to determine the position and the number of regions to exploit for feature extraction and matching. In the second part, we study the link between image quality and the performance of the two recognition algoritms just described. We show that the second one is more robust to degraded images that contain artefacts, distortion or a poor iris texture. Finally, we propose a complete system for iris recognition that combines the use of our local and global quality metrics to optimize recognition performance
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Wong, Kok Cheong. "Representation, feature extraction and geometric constraints for recognising 3D objects from a single perspective view." Thesis, University of Surrey, 1992. http://epubs.surrey.ac.uk/843449/.
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This dissertation considers the problem of modelling, feature extraction and recognizing 3D objects from a single perspective view. A solid modelling system based on generalized cylinder is presented. A new algorithm is proposed for grouping 2D line segments into intermediate token features to be used as geometric cues for indexing into the model database and for generating hypotheses for polyhedral objects. A polyhedral object recognition system using a hypothesis and verification paradigm has been proposed and developed. In the modelling system, generalized cylinders are used as geometric primitives for representing objects. The analysis of generalized cylinders is presented. A number of useful expressions and properties of the contour generators of straight homogeneous generalized cylinders are derived under perspective projection. Right and oblique straight homogeneous generalized cylinders with circular and abitrary cross-section are discussed. A novel algorithm for extracting geometric features such as triples of connected edges, triangle- pairings, image trihedral vertices and closed polygons is implemented. Both heuristic and physical rules are utilised to control the combinatorial explosion of the feature grouping process. Physical rules are used to reject closed polygons which are incompatible with a single planar surface hypothesis. Experiments are demonstrated on real data and many features which could reasonably be due to spatial physical properties of the objects are idenified. Only a few spurious features are accidently detected. These irrelevant features are then pruned away in the hypothesis generation and verification process modules of the proposed recognition system. A polyhedral object recognition system based on a single perspective image is developed. A hypothesis and verification paradigm based on the use of local geometric features of objects is presented. In the framework, two high-level geometric primitives, namely triangle-pair and quadrilateral are employed as key features for model invocation and hypothesis generation. Two geometric constraints, namely distance and angle constraints are proposed and integrated into the recognition system. Many model and scene correspondences are pruned away in the early stage of the matching process using the two geometric constraints. As a by-product of the hypothesis generation the relative pose of the 3D objects expressed in camera frame is recovered. A verification process for performing a detailed check on the model-to-scene correspondences is developed. Detailed experimental results are performed to confirm the feasibility and robustness of the recognition system. An intuitive mathematical formulation is proposed for the interpretation of the geometric relationships of a triple of spatial edges and their perspective projection forming image lines. No restriction is imposed on the configuration of the triple of spatial edges. An eighth-degree polynomial equation explicitly defined by the space angles between the corresponding three spatial edges measured with respect to an object centered coordinate system is derived. The crux of this representation is that the angular attributes of pairs of spatial edges are object-independent. An effective hypothesis generation scheme is proposed which can take advantage of the commonality of this novel representation. It avoids replicating the same recognition module for every occurrence of the same triple feature in the same generic triple group. The groups are distinguished by the angles between the constituent model edges and do not involve any length metric property. Generally, a relatively small number of defined generic triple groups are employed to describe a wide range of polyhedral object models. Particular closed form solutions are derived for specific but common configurations of edges such as rectangular bar end and orthogonal triple. The practical significance and generality of our result are multifold. Extensive experiments are performed to verify the plausibility of employing connected triple edges and trihedral vertices as key features in the paradigm of hypothesis-generation and Hough-clustering approaches to object recognition. It is demonstrated that the accuracy of the estimated pose of objects is adequate. Finally, outstanding problems identified and possible solutions to these problems are discussed. Future research directions are proposed.
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Choi, Hyunjong. "Medical Image Registration Using Artificial Neural Network." DigitalCommons@CalPoly, 2015. https://digitalcommons.calpoly.edu/theses/1523.
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Image registration is the transformation of different sets of images into one coordinate system in order to align and overlay multiple images. Image registration is used in many fields such as medical imaging, remote sensing, and computer vision. It is very important in medical research, where multiple images are acquired from different sensors at various points in time. This allows doctors to monitor the effects of treatments on patients in a certain region of interest over time. In this thesis, artificial neural networks with curvelet keypoints are used to estimate the parameters of registration. Simulations show that the curvelet keypoints provide more accurate results than using the Discrete Cosine Transform (DCT) coefficients and Scale Invariant Feature Transform (SIFT) keypoints on rotation and scale parameter estimation.
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Ahonen, T. (Timo). "Face and texture image analysis with quantized filter response statistics." Doctoral thesis, University of Oulu, 2009. http://urn.fi/urn:isbn:9789514291821.
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Abstract
Image appearance descriptors are needed for different computer vision applications dealing with, for example, detection, recognition and classification of objects, textures, humans, etc. Typically, such descriptors should be discriminative to allow for making the distinction between different classes, yet still robust to intra-class variations due to imaging conditions, natural changes in appearance, noise, and other factors.
The purpose of this thesis is the development and analysis of photometric descriptors for the appearance of real life images. The two application areas included in this thesis are face recognition and texture classification.
To facilitate the development and analysis of descriptors, a general framework for image description using statistics of quantized filter bank responses modeling their joint distribution is introduced. Several texture and other image appearance descriptors, including the local binary pattern operator, can be presented using this model. This framework, within which the thesis is presented, enables experimental evaluation of the significance of each of the components of this three-part chain forming a descriptor from an input image.
The main contribution of this thesis is a face representation method using distributions of local binary patterns computed in local rectangular regions. An important factor of this contribution is to view feature extraction from a face image as a texture description problem. This representation is further developed into a more precise model by estimating local distributions based on kernel density estimation. Furthermore, a face recognition method tolerant to image blur using local phase quantization is presented.
The thesis presents three new approaches and extensions to texture analysis using quantized filter bank responses. The first two aim at increasing the robustness of the quantization process. The soft local binary pattern operator accomplishes this by making a soft quantization to several labels, whereas Bayesian local binary patterns make use of a prior distribution of labelings, and aim for the one maximizing the a posteriori probability. Third, a novel method for computing rotation invariant statistics from histograms of local binary pattern labels using the discrete Fourier transform is introduced.
All the presented methods have been experimentally validated using publicly available image datasets and the results of experiments are presented in the thesis. The face description approach proposed in this thesis has been validated in several external studies, and it has been utilized and further developed by several research groups working on face analysis.
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Yilmaz, Turgay. "Object Extraction From Images/videos Using A Genetic Algorithm Based Approach." Master's thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/12609263/index.pdf.
Full textAbstract:
The increase in the use of digital video/image has showed the need for modeling and querying the semantic content in them. Using manual annotation techniques for defining the semantic content is both costly in time and have limitations on querying capabilities. So, the need for content based information retrieval in multimedia domain is to extract the semantic content in an automatic way. The semantic content is usually defined with the objects in images/videos. In this thesis, a Genetic Algorithm based object extraction and classification mechanism is proposed for extracting the content of the videos and images. The object extraction is defined as a classification problem and a Genetic Algorithm based classifier is proposed for classification. Candidate objects are extracted from videos/images by using Normalized-cut segmentation and sent to the classifier for classification. Objects are defined with the Best Representative and Discriminative Feature (BRDF) model, where features are MPEG-7 descriptors. The decisions of the classifier are calculated by using these features and BRDF model. The classifier improves itself in time, with the genetic operations of GA. In addition to these, the system supports fuzziness by making multiple categorization and giving fuzzy decisions on the objects. Externally from the base model, a statistical feature importance determination method is proposed to generate BRDF model of the categories automatically. In the thesis, a platform independent application for the proposed system is also implemented.