1,720,963 research outputs found
Wavelet transform for texture analysis with application to document analysis
No full textTexture analysis is an important problem in machine vision, with applications in many fields including medical imaging, remote sensing (SAR), automated flaw detection in various products, and document analysis to name but a few. Over the last four decades many techniques for the analysis of textured images have been proposed in the literature for the purposes of classification, segmentation, synthesis and compression. Such approaches include analysis the properties of individual texture elements, using statistical features obtained from the grey-level values of the image itself, random field models, and multichannel filtering. The wavelet transform, a unified framework for the multiresolution decomposition of signals, falls into this final category, and allows a texture to be examined in a number of resolutions whilst maintaining spatial resolution.\ud
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This thesis explores the use of the wavelet transform to the specific task of texture classification and proposes a number of improvements to existing techniques, both in the area of feature extraction and classifier design. By applying a nonlinear transform to the wavelet coefficients, a better characterisation can be obtained for many natural textures, leading to increased classification performance when using first and second order statistics of these coefficients as features. In the area of classifier design, a combination of an optimal discriminate function and a non-parametric Gaussian mixture model classifier is shown to experimentally outperform other classifier configurations.\ud
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By modelling the relationships between neighbouring bands of the wavelet trans- form, more information regarding a texture can be obtained. Using such a representation, an efficient algorithm for the searching and retrieval of textured images from a database is proposed, as well as a novel set of features for texture classification. These features are experimentally shown to outperform features proposed in the literature, as well as provide increased robustness to small changes in scale. Determining the script and language of a printed document is an important task in the field of document processing. In the final part of this thesis, the use of texture analysis techniques to accomplish these tasks is investigated. Using maximum a posterior (MAP) adaptation, prior information regarding the nature of script images can be used to increase the accuracy of these methods. Novel techniques for estimating the skew of such documents, normalising text block prior to extraction of texture features and accurately classifying multiple fonts are also presented
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Delineation Methodology Advancements of Retinal Vessels
No full textRetinal vessel trees play an essential role in clinical decision and quantitative analysis of ophthalmopathy. The changes in the morphological properties of retinal vessels provide accessible information used for diagnosing, screening, and monitoring many eye-related and systemic diseases. Due to the complexity of vessel structures, the manual annotation of vessel network by human experts is a labour-intensive, time-consuming, and error-prone process. Therefore, the automated and accurate delineation of retinal vessels is highly desirable. However, this is a difficult task because of multiple challenges such as the inadequate contrast between vessels and background, variability of vessel widths, uneven background illumination, crossing and bifurcation regions, tiny vessels, and the presence of noise and pathological regions. In this thesis, we aim at introducing novel theoretical concepts that advance the delineation technology of retinal blood vessels to address the shortcomings in existing methods. [...]Thesis (PhD Doctorate)Doctor of Philosophy (PhD)School of Eng & Built EnvScience, Environment, Engineering and TechnologyFull Tex
Machine vision approach to identifying and grading Strawberries
No full textMachine vision systems for quality inspection of processing and production lines are associated with increases in productivity, cost savings, and quality control consistency, having become common place in many industries including agriculture. However, automated strawberry quality control has historically been a challenge due to the delicate nature of the fruit’s flesh, making it more prone to damage, bruising, discolouration, and softening than other fruits and vegetables. Previous efforts have been made to grade strawberries using conveyor systems and cameras, generating good or excellent results. However, these methods do not consider the speed at which berries are packed, or the amount of damage-inducing handling required in order to place the fruit on a process line (automated or not), making these systems unsuitable for real-time production.
This thesis outlines the research, design, experimentation, and development of an Strawberry Quality Assurance (SQA) vision system which is capable of grading full punnets of strawberries after they have been packed. Fruit is picked from the field, and packaged into containers, before the additional step of being loaded into the quality control vision system and finally, a heat-seal machine which seals the punnets with tamper-proof plastic film. Using this method, the packing workers do not need to slow down, or perform any new tasks, rather the flow of filled punnets is simply diverted to the additional production line. The cameras acquire four images at a rate of up to two per second in order to capture each punnet from above and below (through the transparent plastic) in visible and infrared wavelengths. Visible (RGB) images are used to assess the berry’s colour (ripeness), and visible foreign object likelihood, whilst the infrared images are used for bruise detection. Once the images have been analysed, the system uses an orthogonally directed pneumatic burst of air to eject the defected punnets from the line so that they can be repackaged and reassessed.
The initial version of the system used algorithms involving image processing and colour analysis in order to perform under and over ripe detection with good results of 94.7% and 90.6%, respectively, for the multiple instance category. After redesign and upgrade to strobing LEDs and open-source software, machine learning experiments showed that the SVM and unique neural networks underperformed with the best training accuracy results of 84.11% and 76.30%, respectively. Improved performance was found using Resnet-50 pre-trained network in order to extract a feature vector for each image, which is then evaluated by each of the binary classification models. Area Under ROC (AUROC) curves are greater than 80% for both under ripe and foreign object models, whilst the over ripe class score is lower at 58%.
The system has entered it’s fifth season as production-ready having already imaged and assessed 290,888 punnets of which 50,270 were rejected, resulting in 17.28% failure rate in total, helping to ensure the consistent quality assurance of production. The successful implementation of the SQA project provides a platform for continuing work including improving performance of the current classifiers, and investigating the potential of improved region-based bounding box method in order to improve visibility for both operator and developer. Data collection and labelling/annotation are performed regularly in order to re-train networks generating improved results, and to reduce inter-seasonal or inter-cultivar concept shift in the models.Thesis (PhD Doctorate)Doctor of Philosophy (PhD)School of Eng & Built EnvScience, Environment, Engineering and TechnologyFull Tex
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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