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Cheak, Seck Fai. "Detecting near-UV and near-IR wavelengths with the FOVEON Image Sensor /." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2004. http://library.nps.navy.mil/uhtbin/hyperion/04Dec%5FCheak.pdf.
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Thesis (M.S. in Combat Systems Technology)--Naval Postgraduate School, Dec. 2004.Thesis Advisor(s): Gamani Karunasiri, Richard C. Olsen. Includes bibliographical references (p. 57-60). Also available online.
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Nugent, Devon Courtney. "Analysis of FOVEON multi-spectral sensor for counter-camouflage, concealment and deception applications." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2005. http://library.nps.navy.mil/uhtbin/hyperion/05Dec%5FNugent.pdf.
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Thesis (M.S. in Applied Physics)--Naval Postgraduate School, December 2005.Thesis Advisor(s): Richard C. Olsen, Gamani Karunasiri. Includes bibliographical references (p. 49). Also available online.
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Nováček, Petr. "Moderní prostředky pro digitální snímání scény." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2015. http://www.nusl.cz/ntk/nusl-221292.
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The thesis composes conventional and modern methods for digital scene capturing. The target of the thesis is a comparison of CMOS with Bayer mask and Foveon X3 Merrill sensors followed by a design of algorithms for image fusion which can combine advantages of the both sensor types. The thesis starts with an introduction and a description of methods and processes leading to scene capturing. The next part deals with capturing a gallery of test images and with a comparison of both sensors based on the gallery images. Further there are algorithms designed for image fusion which can combine advantages of the selected sensors. The last part of the thesis is devoted to an evaluation of results and of the used algorithms.
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Andreux, Mathieu. "Foveal autoregressive neural time-series modeling." Electronic Thesis or Diss., Paris Sciences et Lettres (ComUE), 2018. http://www.theses.fr/2018PSLEE073.
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Cette thèse s'intéresse à la modélisation non-supervisée de séries temporelles univariées. Nous abordons tout d'abord le problème de prédiction linéaire des valeurs futures séries temporelles gaussiennes sous hypothèse de longues dépendances, qui nécessitent de tenir compte d'un large passé. Nous introduisons une famille d'ondelettes fovéales et causales qui projettent les valeurs passées sur un sous-espace adapté au problème, réduisant ainsi la variance des estimateurs associés. Dans un deuxième temps, nous cherchons sous quelles conditions les prédicteurs non-linéaires sont plus performants que les méthodes linéaires. Les séries temporelles admettant une représentation parcimonieuse en temps-fréquence, comme celles issues de l'audio, réunissent ces conditions, et nous proposons un algorithme de prédiction utilisant une telle représentation. Le dernier problème que nous étudions est la synthèse de signaux audios. Nous proposons une nouvelle méthode de génération reposant sur un réseau de neurones convolutionnel profond, avec une architecture encodeur-décodeur, qui permet de synthétiser de nouveaux signaux réalistes. Contrairement à l'état de l'art, nous exploitons explicitement les propriétés temps-fréquence des sons pour définir un encodeur avec la transformée en scattering, tandis que le décodeur est entraîné pour résoudre un problème inverse dans une métrique adaptéeThis dissertation studies unsupervised time-series modelling. We first focus on the problem of linearly predicting future values of a time-series under the assumption of long-range dependencies, which requires to take into account a large past. We introduce a family of causal and foveal wavelets which project past values on a subspace which is adapted to the problem, thereby reducing the variance of the associated estimators. We then investigate under which conditions non-linear predictors exhibit better performances than linear ones. Time-series which admit a sparse time-frequency representation, such as audio ones, satisfy those requirements, and we propose a prediction algorithm using such a representation. The last problem we tackle is audio time-series synthesis. We propose a new generation method relying on a deep convolutional neural network, with an encoder-decoder architecture, which allows to synthesize new realistic signals. Contrary to state-of-the-art methods, we explicitly use time-frequency properties of sounds to define an encoder with the scattering transform, while the decoder is trained to solve an inverse problem in an adapted metric
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Eilerman, Amanda Louise. "Foveal Pit Curvature in a Normal Population." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1461109213.
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Pierce, Gilbert E. "Psychophysical analysis of foveal visual losses in glaucoma /." The Ohio State University, 1994. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487857546389003.
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White, Sarah Jane. "Non-foveal text processing and fixation positions in reading." Thesis, Durham University, 2003. http://etheses.dur.ac.uk/3137/.
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This thesis reports seven experiments which investigate what determines where the eyes move during reading. Specifically, the experiments examine what kinds of linguistic information can influence where words are first fixated and refixated. Experiment 1 showed that fixations landed nearer to the beginning of words in which the initial letter sequence was misspelled, compared to when the words were spelled correctly. Experiments 2 and 3 showed that the effects of misspellings on saccade programming can not be explained by lexical non-foveal preprocessing, and therefore the results of Experiment 1 must be due to preprocessing of the orthographic familiarity of word initial letter sequences. These results were confirmed in Experiment 4, which showed that first fixations landed nearer to the beginning of correctly spelled words with orthographically irregular, compared to orthographically regular, initial letter sequences. Furthermore, Experiment 5 showed that these effects held for sentences presented in upper case text. Furthermore, Experiments 6 and 7 demonstrated that the influence of orthography on saccade programming was independent of foveal processing difficulty. These results are most consistent with an attraction based explanation in which preprocessing of orthography, independent of processing load, influences the word length and launch site based saccade programme to produce a small shift in the preferred viewing position in the direction of the orthographic irregularity. The results also show that linguistic processing can influence the direction and length of refixation saccades. Furthermore, although preprocessing of orthography can influence saccade programming, the results provide no consistent evidence for an influence of orthography on prior fixation durations or probabilities. These results indicate that there is independent processing of when and where the eyes move. The absence of robust "parafoveal-on-foveal" effects provides no support for parallel processing models of reading.
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Fong, Aik Meng. "Aspects of multi-resolutional foveal images for robot vision." Thesis, Imperial College London, 1991. http://hdl.handle.net/10044/1/46773.
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Ciamacca, Marisa Lynn. "Foveal Phase Retardation Correlation with Henle Fiber Layer Thickness." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1492631647528424.
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Chui, Toco Yuen Ping. "Influence of myopia on cone packing density and foveal morphology." [Bloomington, Ind.] : Indiana University, 2009. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3386667.
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Thesis (Ph.D.)--Indiana University, School of Optometry, 2009.Title from PDF t.p. (viewed on Jul 20, 2010). Source: Dissertation Abstracts International, Volume: 70-12, Section: B, page: 7503. Adviser: Stephen A. Burns.
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Kliegl, Reinhold, Sarah Risse, and Jochen Laubrock. "Preview Benefit and Parafoveal-on-Foveal Effects from Word N+2." Universität Potsdam, 2007. http://opus.kobv.de/ubp/volltexte/2011/5718/.
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Using the gaze-contingent boundary paradigm with the boundary placed after word n, we manipulated preview of word n+2 for fixations on word n. There was no preview benefit for first-pass reading on word n+2, replicating the results of Rayner, Juhasz, and Brown (2007), but there was a preview benefit on the three-letter word n+1, that is, after the boundary, but before word n+2. Additionally, both word n+1 and word n+2 exhibited parafoveal-on-foveal effects on word n. Thus, during a fixation on word n and given a short word n+1, some information is extracted from word n+2, supporting the hypothesis of distributed processing in the perceptual span.
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Witz, Nirel. "Properties of global stereopsis in fovea and periphery." Thesis, McGill University, 2013. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=114281.
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To better understand the properties and mechanisms underlying global stereopsis we examined the relationship between carrier luminance spatial frequency and modulator disparity spatial frequency. Thresholds for detecting global sinusoidal disparity corrugations of equi-detectable spatially band-pass noise were measured as a function of modulator disparity spatial frequency for both centrally and peripherally located stimuli using a standard 2-IFC task. We found a characteristic relationship that depended on modulator disparity spatial frequency. At high modulator disparity spatial frequencies (>1 c/d), there is an optimum ratio of around 2.6, whereas at low modulator disparity spatial frequencies, there is an optimum absolute carrier luminance spatial frequency (i.e., 3 c/d). In the periphery, vision is restricted to modulator disparity spatial frequencies below 1 c/d and, as a consequence, follows the latter rule with the optimum carrier luminance spatial frequency reducing with increasing eccentricity. This finding is consistent with there being more than one channel processing global stereo. This was confirmed using a 2x2 AFC detection/discrimination paradigm. Furthermore, because of the different carrier/modulator relationships in central and peripheral vision, peripheral global stereo cannot be simply related to central global stereo by a scaling factor and thus cannot be simply due to cortical magnification as has been suggested.Afin de mieux comprendre les propriétés et les mécanismes sous-tendant la stéréoscopie, nous avons examiné la relation entre la fréquence spatiale de luminance de la porteuse et la fréquence spatiale de disparité de l'enveloppe. Les seuils de détection d'une ondulation sinusoïdale de disparité portée par un bruit passe-bande équi-détectable ont été mesurés en fonction de la fréquence spatiale de disparité de l'enveloppe à la fois pour des stimuli centraux et périphériques en utilisant une tâche standard de choix forcé entre 2 intervalles. Nous avons trouvé une relation caractéristique qui dépend de la fréquence spatiale de disparité de l'enveloppe. À hautes-fréquences spatiales de disparité de l'enveloppe (>1 c/d), le rapport optimal est d'environ 2.6, alors qu'à basses-fréquences spatiales de disparité de l'enveloppe, la fréquence spatiale de luminance absolue de la porteuse présente un optimum (i.e., 3 c/d). En périphérie, la vision est restreinte aux fréquences spatiales de disparité de l'enveloppe inférieures à 1 c/d. En conséquence, suivant cette dernière règle, la fréquence spatiale de luminance optimale de la porteuse diminue avec l'excentricité. Cette observation est cohérente avec la présence de plusieurs canaux de traitement de la stéréoscopie globale et se confirme en utilisant un paradigme de 2x2 choix forcés détection/discrimination. De plus, en raison des différentes relations entre porteuse et enveloppe en vision centrale et périphérique, la stéréoscopie globale périphérique ne peut pas être simplement liée à la stéréoscopie globale centrale par un facteur d'échelle et ne peut ainsi pas être simplement due à la magnification corticale comme il a été suggéré.
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Sharp, Leila Vail. "Human visual hyperacuities in the fovea and parafovea." Thesis, University College London (University of London), 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.284214.
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Venkataraman, Abinaya Priya. "Vision Beyond the Fovea: Evaluation and Stimuli Properties." Doctoral thesis, KTH, Biomedicinsk fysik och röntgenfysik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-191212.
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This research is about evaluating vision in the periphery. Peripheral vision is of fundamental importance in the performance of our everyday activities. The aim of this thesis is to develop methods suitable for the evaluation of peripheral vision and to assess how different visual functions vary across the visual field. The results have application both within the field of visual rehabilitation of people with central visual field loss (CFL)and as well as in myopia research. All methods for assessing peripheral vision were implemented with adaptive psychophysical algorithms based on Bayesian statistics. A routine for time-efficient evaluation of peripheral contrast sensitivity was implemented and verified for measurements out to 30° in the visual field. Peripheral vision was evaluated for different properties of the stimuli: sharpness, motion, orientation, and extent. Optical quality was controlled using adaptive optics and/or corrective spectacles specially adapted for the peripheral viewing angle. We found that many peripheral visual functions improved with optical correction, especially in people with CFL. We also found improvements in peripheral contrast sensitivity for low spatial frequencies when stimuli drifted at 5 to 10 Hz; this applies both for people with normal vision and those with CFL. In the periphery, it is easier to see lines that are oriented parallel with respect to the visual field meridian. We have shown that this directional bias is present for both resolution and detection tasks in the periphery, even when the asymmetric optical errors are minimized. For accurate evaluation of peripheral vision, we therefore recommend using gratings that are oriented oblique to the visual field meridian. The directional bias may have implications in how peripheral image quality affects myopia progression. Another proof that peripheral vision can influence central visual function is the fact that, when the stimulus extent was increased beyond the fovea, the blur in the stimulus was less noticeable.Denna forskning handlar om att utvärdera synen i periferin. Vår perifera syn är ovärderlig i det dagliga livet. Målsättningen med denna avhandling är dels att utveckla metoder speciellt lämpade för perifer synutvärdering och dels att mäta hur olika synfunktioner varierar över synfältet. Resultaten har tillämpning både inom synrehabilitering för personer med centraltsynfältsbortfall och inom närsynthetsforskning. Adaptiv psykofysisk metodologi baserad på Bayesiansk statistik användes vid all utvärdering av det perifera seendet. Vi implementerade en rutin för tidseffektiv mätning av perifer kontrastkänslighet och verifierade den ut till 30° i synfältet. Den perifera synen utvärderades för olika egenskaper hos objektet: skärpa, rörelse, riktning och utbredning. Skärpan kontrollerades med hjälp av adaptiv optik och/eller glasögonkorrektion speciellt anpassad för den perifera synvinkeln. Vi fann att många periferasynfunktioner förbättras av optisk korrektion, särskilt för personer med centralt synfältsbortfall. Vi hittade även förbättringar i periferkontrastkänslighet för låga ortsfrekvenser när objektet modulerades med hastigheter mellan 5 och 10 Hz, vilket gäller både normalseende och personer med centralt synfältsbortfall. I periferin är det lättare att se linjer som är orienterade parallellt med synfältsmeridianen. Vi har visat att denna riktningsbias gäller både för upplösning och detektion i periferin, även när de asymmetriska optiska felen minimeras. För bästa mätnoggrannhet rekommenderar vi därför att använda randmönster som ligger snett relativt synfältsmeridianen. Denna riktningsbias skulle även kunna påverka hur den perifera bildkvalitén inverkar på utvecklingen av närsynthet. Ytterligare ett bevis för att perifer syn kan påverka den centrala synfunktionen är att, när objektets utbredning ökades, uppfattade personen det som mindre suddigt.
QC 20160826
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Xu, Xiayu. "Simultaneous automatic detection of optic disc and fovea." Thesis, University of Iowa, 2010. https://ir.uiowa.edu/etd/630.
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Automated localization of the optic disc and fovea are important in the field of analysis of fundus images. We introduce a simultaneous detection method for optic disc and fovea with an enhancement and correction step. In the first step, a set of features are extracted from the color fundus image, and the relationship between the feature set and a distance variable d is established during training phase. For a test image, the same set of features is measured and the distance to the optic disc and fovea can be estimated using k-nearest-neighbor regression. A probability image is generated during this step. In the second, a second k-nearest-neighbor regression is applied on the probability image. Detected high likelihood regions from the first step can be enhanced only if they satisfy the trained relationship. The detected regions that do not get support from the other detected structure will be suppressed. 150 color fundus images were used to train the system. 50 color fundus images were used to test the system. The distance error for the optic disc is 9.8±8.3 pixels. The distance error for the fovea is 13.7±6.6 pixels.
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Gareze, Lynn. "The role of foveal and extrafoveal vision in the processing of scene semantics." Thesis, Durham University, 2003. http://etheses.dur.ac.uk/4123/.
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This thesis investigated the ability to process semantic information from foveal and extrafoveal vision during scene viewing. Existing research suggested that object semantics could be detected from extrafoveal vision. This suggestion was investigated using three experimental paradigms. Semantic inconsistency was defined as a target semantically incompatible with scene gist. In Experiments 1 to 4, fixation position during a brief scene presentation was manipulated relative to a target object. The target's semantic inconsistency, presented foveally or extrafoveally, influenced performance on an object identification task. Extrafoveally presented semantically inconsistent targets were facilitated when simple line drawings were displayed, although this effect was unlikely to be mediated by semantic processing. No similar effect was found with complex line drawings or photographic stimuli. Experiments 5 and 6 attempted to replicate significant advantages for inconsistent targets in a change detection paradigm. However, no significant difference was found between performance for consistent and inconsistent targets in a two-exposure, forced-choice change detection task or an alternating display change detection task. There was no evidence that changing inconsistent targets were detected more reliably or earlier than changing consistent targets. Experiment 7 investigated the proposal that the extrafoveal processing of inconsistent objects could influence saccade patterns by attracting earlier fixations. Participants freely scanned both line drawings and photographs of scenes with no task. Again, no evidence was found supporting the earlier fixation of inconsistent objects in scenes. Therefore, this thesis could not confirm previous evidence of an inconsistent object advantage in either brief scene presentations, change detection or natural scene viewing. The evidence suggested that the preferential processing of inconsistent scene objects could occur under very limited circumstances, but would be unlikely to be mediated by semantic processing. When viewing complex, realistic scenes, there was no evidence of differential processing for consistent and inconsistent objects.
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Strang, Niall C. "Modulation of foveal image quality in myopia : investigation of spatiotopic and retinotopic factors." Thesis, Glasgow Caledonian University, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.261581.
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Bergdahl, Sara. "Skillnaden i central och perifer retinal tjocklek mellan olika ametropier - en OCT-studie." Thesis, Linnéuniversitetet, Institutionen för medicin och optometri (MEO), 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-26595.
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Syfte: Syftet med studien var att, med hjälp av Optical Coherence Tomography (OCT), undersöka om det finns någon skillnad i central och perifer retinal tjocklek mellan olika ametropier. Metod: Studien omfattade 36 försökspersoner, som grupperades beroende på ametropi i en myop, emmetrop och hyperop grupp. Av de 36 försökspersonerna var det 15 myoper, 15 emmetroper och 6 hyperoper. En inledande mätning gjordes där försökspersonernas objektiva refraktion uppmättes med autorefraktor och därefter gjordes en avstämning i provbåge för att säkerställa refraktionen. Med OPKO Spectral OCT/SLO mättes retinas tjocklek både centralt och perifert på höger öga. För att analysera resultatet delades retina in i 15 olika zoner som jämfördes mellan de olika ametropierna. Resultat: Resultatet av studien visade en signifikant skillnad i foveal tjocklek mellan de olika ametropierna (p=0,03). Det var en siginifikant skillnad i retinal tjocklek mellan retinas zoner i alla tre ametropier (p<0,01), dock var det ingen signifikant skillnad i perifer retinal tjocklek mellan de tre olika ametropierna (p=0.07). Slutsats: Ingen skillnad i central och perifer retinal tjocklek kunde redovisas mellan de olika ametropierna. Då en tidigare studie har visat att den retinala tjockleken skiljer sig mellan olika ametropier kan resultatet av vår studie diskuteras då det i vår studie fanns brister som få antal personer, olika antal personer inom grupperna och en låg utbredning av synfel.
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St, John Murphy K. "Effects of an artificial foveal scotoma on the visual detection lobe and search performance." Thesis, University of Reading, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.374701.
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Jesus, Bacelo Machado Sousa Joao Antonio. "Sensory processing in the Electrosensory Lobe of the weakly electric fish Gnathonemus petersii." Paris 6, 2007. http://www.theses.fr/2007PA066341.
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Young, Rupert. "Visual control in natural and artificial systems." Thesis, University of Surrey, 2000. http://epubs.surrey.ac.uk/843083/.
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The desire to produce artificial vision systems which behave in an intelligent, humanlike way or which can autonomously and automatically perform tasks currently only performed by humans has been a goal of Artificial Intelligence research for many decades. Until recently much of the research concentrated on extracting visual representations of objects from single, static scenes. The last decade has seen an increase in interest concerning mobile robotics for navigation, planning and autonomous control as well as for the interpretation of events in real, dynamic scenes. Presented in this thesis is research on artificial vision systems from two different, but both necessary, standpoints. One concerns low-level vision-based behaviour of object tracking based upon a naturalistic theory of perception and behaviour within living systems. The other takes a more application and engineering based approach and its goal is to address high-level scene interpretation and control of processing resources. Numerous experiments are presented to demonstrate the various issues. The two main experiments, corresponding to the two research streams, are a system which is able to fixate complex multi-coloured objects and a fully integrated vision system for predicting and following, with a mobile sensor, events in a dynamic scene.
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Bek, Rim. "The Perceptual and Psychological Effects of Artificial Lighting on Peripheral Vision in Humans." Thesis, KTH, Ljusdesign, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-233630.
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Information processing differences between foveal and peripheral vision allow for different perceptual experiences and emotional responses. A lighting set-up was used to test the spatial perception and emotional state of 14 participants with the use of foveal and peripheral vision in a photograph and immersive environment respectively. The space was associated with high levels of tension, inspiration, and alertness and was regarded as being more spacious, with higher light intensity, and more uniform lighting distribution when perceived with peripheral vision.
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Al-Araimi, Musallam Said Mohammad. "Genetic analysis of two forms of inherited childhood blindness : foveal hypoplasia and Leber congenital amaurosis." Thesis, University of Leeds, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.598017.
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Childhood blindness is a global public health problem with a worldwide prevalence of 0.75/1000 children. More than 1.5 million children are registered blind in the world. The work described in this thesis aims to identify the genetic basis, and so provide new insights into the clinical phenotype, of two recessively inherited disorders; Leber Hereditary Amaurosis (LCA) and FHONDA (Foveal Hypoplasia and Optic Nerve Decussation Abnormalities) syndrome. LCA is a severe inherited retinal dystrophy that presents at birth or within the first year of life. LCA is a genetically heterogeneous condition with over 20 genes identified to date. This thesis details the genetic analysis of ten "large LCA pedigrees leading to the identification of novel mutations in known LCA genes in six of the families. For each family, whole genome single nucleotide polymorphism genotyping was performed on pooled DNA from the affected members. Regions of homozygosity shared between the affected individuals within each family were identified and confirmed by microsatellite genotyping. Six of the families showed convincing regions of homozygosity over known LCA genes and sequencing of these led to the identification of six novel mutations, three in LCAS, two in GUCY20 and one in CEP290. FHONDA syndrome is a rare disorder that describes an underdeveloped fovea and optic nerve decussation defect without albinism. Occasionally mild anterior segment dysgenesis is also associated with this disorder. This thesis details the identification of the gene mutated in FHONDA syndrome. FHONDA syndrome had previously only been described in one consanguineous family of Pakistani origin and linkage analysis in this family allowed the causative gene to be mapped to a 6.S-Mb region on chromosome 16q22-24. In this thesis, a second consanguineous family from Afghanistan, with the same clinical phenotype, was identified and the mutated gene mapped to the same locus at chromosome 16q. High-resolution genotyping in both families refined the disease gene interval to 3-Mb containing 32 genes. Sequential screening of all the genes within this interval identified different homozygous mutations in SLC38AB in both families. Subsequent sequencing of this gene in additional patients identified another three different homozygous mutations. The identification of the disease causing genes in both LCA and FHONDA is important as it facilitates the genetic counselling of families, contributes to phenotype/genotype studies, extends the mutation spectrum for each gene which aids protein characterisation and ultimately identifies a cohort of patients for future therapeutic and early prevention strategies.
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Ctori, I. "Ethnic differences in the spatial distribution of macular pigment and its association with foveal anatomy." Thesis, City University London, 2016. http://openaccess.city.ac.uk/14612/.
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Macular pigment (MP) at the centre of the retina is thought to serve a protective function shielding the photoreceptors from damaging effects of blue light. The amount of MP and its spatial density distribution across the macula i.e. its spatial profile varies among individuals. Lower levels of MP and certain MP spatial profile phenotypes are believed to be associated with increased risk of age-related macular degeneration (AMD). There is suggestion that MP spatial profiles differ between ethnicities, with non-exponential profiles occurring more frequently in non-whites. This may explain some of the ethnic variations seen in AMD prevalence. However, previous investigations have used several methodologies to measure MP. In addition, inconsistent MP spatial profile definitions have been used; thus comparing data between studies is difficult. Nevertheless, it has been hypothesised that variations in MP spatial distribution could be due to differences in foveal architecture, in particular at the foveal centre where MP levels peak. A study was designed to investigate the effect of ethnicity on MP spatial density distribution and its relation to foveal architecture. The influence of known risk factors for AMD was also considered. Young (18 to 39 years), healthy volunteers of white (n = 76), South Asian (n = 80) and black (n = 70) ethnic origin were recruited to take part. MP measurements were obtained using a method based on heterochromatic flicker photometry (HFP) and foveal morphology measurements were taken from optical coherence tomography (OCT) scans. The coefficients of repeatability of each of these were confirmed in a sub-study. A systematic objective MP spatial profile classification technique was implemented throughout. The feasibility of applying this to MP measurements obtained with different techniques such as HFP and fundus autofluorescence (FAF) was also explored in a sub-study. The results showed that measures of MP optical density (MPOD) over the central retinal area were statistically significantly increased in South Asian and black compared to white subjects, whereby ethnicity explained around 10% of the variation (P < 0.0005). Non-exponential MP spatial profiles (ring-like and central dip respectively) were significantly more prevalent in South Asian and black compared with white subjects (χ2 (4, n = 226) = 13.4, P = 0.009). Integrated MPOD up to 1.8º was significantly increased in ring-like and central dip compared to exponential profiles (P < 0.0005) irrespective of ethnicity. South Asian and black individuals presented thinner central retinas and wider foveas compared to white individuals (P < 0.0005). However, while accounting for these ethnic variations, foveal architecture provided no predictive values for the MP spatial profile phenotype.
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Hesse, Rüdiger [Verfasser]. "Psychophysische Untersuchungen zur Rolle der Fovea centralis bei der Bewegungswahrnehmung / Rüdiger Hesse." Mainz : Universitätsbibliothek der Johannes Gutenberg-Universität Mainz, 2005. http://d-nb.info/1225685443/34.
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Rai, kurlethimar Yashas. "Visual attention for quality prediction at fine spatio-temporal scales : from perceptual weighting towards visual disruption modeling." Thesis, Nantes, 2017. http://www.theses.fr/2017NANT4027/document.
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Cette thèse revisite les relations entre les processus attentionnels visuels et la perception de qualité. Nous nous intéressons à la perception de dégradation dans des séquences d’images et leur impact sur la perception de qualité. Plutôt qu’un approcha globale, nous travaillons à une échelle spatio temporelle fine, plus adaptée aux décisions des encodeurs vidéo. Deux approches liant attention visuelle et qualité perçue sont explorées. La première, suit une approche classique, de type pondération des distorsions. Ceci est mis en relation avec des scénarios d’usage comme le streaming interactif ou la visualisation de contenus omnidirectionnels. Une seconde approche nous amène à introduire le concept de disruption visuelle (DV) et sa relation avec la perception de qualité. Nous proposons d’abord des techniques permettant d’étudier les saccades résultantes de la DV à partir par de données expérimentales oculométriques. Nous proposons ensuite un modèle computationnel de prédiction de la DV. Une nouvelle mesure objective de qualité est ainsi introduite nommée "Disruption Metric" permettant l’évaluation de la qualité locale de vidéos. Les résultats obtenus trouvent leurs applications dans de nombreux domaines tels que l’évaluation de qualité, la compression, la transmission perpétuellement optimisée de contenus visuel ou le rendu/visualisation foévalThis thesis revisits the relationship between visual attentional processes and the perception of quality. We mainly focus on the perception of degradation in video sequences and their overall impact on our perception of quality. Rather than a global approach, we work in a very localized spatio-temporal scale, more adapted to the decision-process in video encoders. Two approaches linking visual attention and perceived quality are explored in the thesis. The first follows a classical approach, of the distortion weighting type. This is very useful in certain scenarios such as interactive streaming or visualization of omni-directional content. The second approach leads us to the introduction of the concept of visual disruption(DV), and explore its relation to perceived quality. We first propose techniques for studying the saccades related to DV from experimental oculometric data. Then, a computational model for the prediction of DV is proposed. A new objective measurement of quality is therefore born, which we call the "Disruption Metric" : that allows the evaluation of the local quality of videos. The results obtained, find their applications in many fields such as quality evaluation, compression, perpetually optimized transmission of visual content or foveated rendering / transmission
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Ota, Masafumi. "Foveal Photoreceptor Layer in Eyes with Persistent Cystoid Macular Edema Associated with Branch Retinal Vein Occlusion." Kyoto University, 2010. http://hdl.handle.net/2433/120556.
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Hancock, Jennifer Ann. "The Mechanics of Terrestrial Locomotion and the Function and Evolutionary History of Head-bobbing in Birds." Ohio University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1282333191.
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Schulze, Céline [Verfasser], and Rüdiger [Akademischer Betreuer] Korbel. "Zur Morphologie der physiologischen Foveae am Augenhintergrund von Greifvögeln und Eulen mittels Optischer Kohärenztomografie (OCT) / Céline Schulze. Betreuer: Rüdiger Korbel." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2016. http://d-nb.info/1105374041/34.
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Porracin, Eleonora [Verfasser], and Stefan [Gutachter] Pollmann. "Role of foveal and peripheral vision in contextual cueing and its retrieval in real-world scenes / Eleonora Porracin ; Gutachter: Stefan Pollmann." Magdeburg : Universitätsbibliothek Otto-von-Guericke-Universität, 2019. http://d-nb.info/1219965189/34.
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Albuquerque, Ana Sílvia. ""Lucere et Fovere" - Congregação das Irmãs Hospitaleiras (CONFHIC): Um estudo sobre o ideário educativo da Co-Fundadora Beata Maria Clara do Menino Jesus." Doctoral thesis, Universidade Portucalense, 2015. http://repositorio.uportu.pt/11328/1376.
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Tese de Doutoramento em Educação.A ideia de tentar compreender de que forma um ideário educativo católico duma congregação específica, neste caso, a CONFHIC, se enraíza na sua cofundadora - Libânia do Carmo Galvão Mexia de Moura Telles e Albuquerque, mulher que nasceu e viveu no século XIX (nome em religião – Maria Clara do Menino Jesus) - que mereceu o reconhecimento universal da sua obra, e da sua pessoa, que conduziu à sua beatificação, e indagar sobre a viabilidade desse ideário na sociedade atual, marcada por uma forte secularização, lançou as bases para a presente investigação. Percorridos múltiplos documentos eclesiásticos para compreender o sentido da educação católica nas mensagens diretas dos mais altos dignitários da Igreja; inferindo sobre o carisma fundacional da Congregação das Irmãs Franciscanas Hospitaleiras da Imaculada Conceição que passou pela análise das polissemias de conceitos de projeto, cultura e ideário; revisitada a história portuguesa oitocentista, numa vertente que privilegia a relação entre a Igreja, Estado e Sociedade, para melhor avaliar e dar a conhecer o contexto histórico que conduziu a Igreja a reconhecer o mérito da obra da Beata Maria Clara do Menino Jesus; reconstruída a história de vida da cofundadora numa vertente que visou aferir a sua identificação com o cariz franciscano; evidenciados os aspetos da sua obra pedagógica e assistencial; por fim, procedeu-se à análise de conteúdo das reflexões retrospetivas e prospetivas - constituintes do corpus de estudo empírico – do conjunto de participantes (n=11) que vivenciaram a ação educativa e educacional da CONFHIC. No presente estudo, enquadrado numa metodologia de natureza qualitativa de cariz interpretativo, adequada ao estudo de caso, como estratégia de investigação optada, que utilizou como instrumento de recolha de dados, o «inquérito por entrevista estruturada», e como técnica de análise, a «análise de conteúdo», foram concebidos três patamares para aferir as correspondentes dimensões de vivência dos participantes do estudo: (i) Uma dimensão experiencial, na qual se pretendeu conhecer a experiência dos participantes enquanto alunos e, ou professores na Escola da CONFHIC, nomeadamente quanto aos métodos de ensino, nas relações interpessoais - colegas, docentes, educadores – em conformidade com a situação individual e ainda, se em tal vivência ocorreu alguma marca pessoal e social; (ii) Uma dimensão social, a qual visou compreender o impacto do projeto educativo no caminho existencial dos participantes, nomeadamente enquanto cidadãos, profissionais e na esfera familiar, ou seja, aferir se a experiência de aluno e, ou professor em Escolas da CONFHIC, se repercutiu na sua vida social e profissional, inclusivamente se lhe atribui utilidade; (iii) Uma dimensão crítica que almejou avaliar a pertinência do ideário e do projeto educativo da CONFHIC na atualidade, ou seja, sob um prisma crítico, aferir o sentido desse ideário e projeto educativo no mundo atual e qual a sua viabilidade, na perspetiva dos participantes. As conclusões apontam no sentido de uma viabilidade do ideário e projetos católicos em estudo, na sociedade atual, desde que sejam implementadas diversas estratégias que tenham em vista a cooptação de sinergias internas e externas à CONFHIC, no sentido de continuar a obra da cofundadora Beata Maria Clara do Menino Jesus.
It is our aim in this work to understand how a Catholic educational ideology of a specific Congregation, namely-CONFHIC- so rooted in the cofoundress, Libânia do Carmo Galvão Mexia de Moura Telles e Albuquerque, a women that was born and lived in the 19th century (religious name - Maria Clara do Menino Jesus) whose work and herself were universally recognized resulting in her beatification and to investigate the viability of that ideology in the actual society marked by such a profound secularization. It covered multiple ecclesiastical documents to understand the meaning of Catholic education in the direct messages of the highest dignitaries of the Church; inferring about the foundational charism of the Congregação das Irmãs Franciscanas Hospitaleiras da Imaculada Conceição, what went through analysis of polysemy of project, culture and ideology concepts; revisited the nineteenth century portuguese history, in a trend that favors the relationship between Church, State and Society, to better assess and make known the historical context that led the Church to recognize the merit of Beata Maria Clara do Menino Jesus´s work; reconstructed the life story of the cofoundress in a shed which aimed to measure their identification with the franciscan nature ; highlighted aspects of their pedagogical work and welfare; finally , we proceeded to the content analysis of the retrospective and forward-looking reflections - constituents of empirical corpus study – of the group of participants (n=11) who experienced CONFHIC´s educational action. In this study, framed in a qualitative methodology of interpretive nature, appropriate to the case study, as defaulted research strategy, which used as a data collection instrument, the 'investigation by structured interview" and as an analytical technique, "content analysis" are designed three levels to measure the relevant dimensions of experience of study participants: (i) An experiential dimension in which it was intended to know the participants experience as learners and, or teachers in CONFHIC Schools, such as teaching methods, interpersonal relationships - colleagues, teachers, educators - in accordance with the individual situation and yet, if in such experience occurred some personal and social brand; ( ii ) A social dimension , which aimed to understand the impact of the educational project in the existential path of participants, including as citizens, professionals and family sphere, i.e., assess whether the student experience and, or teacher in CONFHIC Schools, was reflected in his social and professional life, including if utility is attributed to it ; ( iii ) A critical dimension that craved assess the relevance of the CONFHIC´s ideology and educational project at the present time, that is, from a critical perspective, assess the meaning of this ideology and educational project in today´s world and what is its feasibility from the perspective of the participants. The research findings point towards a feasibility of catholic ideology and projects under study, in today's society, since several strategies are implemented to coopt CONFHIC´s internal and external synergies in order to continue the work of the cofoundress Beata Maria Clara do Menino Jesus.
Orientação: Prof. Doutor Eusébio André da Costa Machado.
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Hsiao, Janet Hui-wen. "Hemispheric processing in reading Chinese characters : statistical, experimental, and cognitive modeling." Thesis, University of Edinburgh, 2006. http://hdl.handle.net/1842/2562.
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In Chinese orthography, phonetic compounds comprise about 80% of the most frequent characters. They contain separate phonological and semantic elements, referred to as phonetic and semantic radicals respectively. A dominant type exists in which the se-mantic radical appears on the left and the phonetic radical on the right (SP characters); an opposite, minority structure also exists in which the semantic radical appears on the right and the phonetic radical on the left (PS characters). Through statistical analyses, connectionist modelling, behavioural experiments, and neuroimaging studies, this dis-sertation demonstrates that the distinct structures of these two types of characters allow us crucial insights into the relationship between brain structure and reading processes. The statistical analyses of a Chinese lexical database show that, because of the different information profiles of SP and PS characters and the imbalanced distribution between them in the lexicon, the overall information is skewed to the right. This information skew provides important opportunities to examine the interaction between foveal split-ting and the information structure of the characters. The foveal splitting hypothesis as-sumes a vertical meridian split in the foveal representation and the consequent contra-lateral projection to the two cerebral hemispheres; it has been shown to have important implications for visual word recognition. The square shape and the condensed structure of Chinese characters make them a severe test case for the split fovea claim. Through a lateralized cueing examination and a TMS study of the semantic radical combinability effect with foveally presented characters in character semantic judgements, a flexible division of labour between the hemispheres in character recognition is demonstrated, with each hemisphere responding optimally to the information in the contralateral visual hemifield. The interaction between stimulation site and radical combinability in the TMS study also provides further support for the split fovea claim, suggesting functional foveal splitting as a universal processing constraint in reading. Even if foveal splitting is true, it is still unclear about how far the effects of foveal split-ting can extend from the retina into the process of character recognition. We show that, in naming isolated, foveally presented SP and PS characters, adult male and female readers process them differently, with opposite patterns of ease and difficulty: males responded significantly faster to SP than PS characters; females showed a non-significant tendency in the opposite direction. This result is also supported by a corre-sponding ERP study showing larger N350 amplitude elicited by PS character than SP characters in the male brain, and an opposite pattern in the female brain. The split fovea claim suggests that the two halves of a centrally fixated character are initially processed in different hemispheres. The male brain typically relies more on the left hemisphere for phonological processing compared with the female brain, causing this gender difference to emerge. This interaction is also predicted by an implemented computational model, contrasting a split cognitive architecture, in which the mapping between orthography to phonology is mediated by two partially encapsulated, interconnected processing do-mains, and a non-split cognitive architecture, in which the mapping is mediated by a single, undifferentiated processing domain. Thus, the effects of foveal splitting in read-ing extend far enough to interact with the gender of the reader in a naturalistic reading task. In short, this dissertation demonstrates that foveal splitting is a universal language proc-essing phenomenon, precise enough to project the two radicals of a centrally-fixated Chinese character to different hemispheres to allow a flexible division of labour be-tween the two hemispheres to emerge, and its effects in reading extend far enough into word recognition to interact with the gender of the reader in a naturalistic reading task. The results can also be extrapolated to Chinese word and sentence processing as well as to other languages. This dissertation thus has contributed to a better understanding of the relationship between brain structure and language processes.
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Bruce, Alison. "Structural Integrity of Eyes Diagnosed with Amblyopia. The measurement of retinal structure in amblyopia using Optical Coherence Tomography." Thesis, University of Bradford, 2010. http://hdl.handle.net/10454/4894.
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Amblyopia is the leading cause of monocular visual impairment in children. Therapy for amblyopia is extremely beneficial in some children but ineffective in others. It is critical that the reasons for this discrepancy are understood. Emerging evidence indicates that current clinical protocols for the diagnosis of amblyopia may not be sufficiently sensitive in identifying individuals who, on more detailed examination, exhibit subtle structural defects of the eye. Presently, the magnitude of this problem is unknown. The aim of this study was to establish the prevalence of subtle retinal/optic nerve head defects in eyes diagnosed with amblyopia, to distinguish between possible explanations for the origin of such defects and to investigate the relationship between quantitative measures of retinal structure, retinal nerve fibre layer thickness and optic nerve head dimensions. Using the imaging technique of Optical Coherence Tomography (OCT) retinal structure has been investigated in detail, following the visual pathway across the retina from the fovea, via the paramacular bundle to the optic disc, where peripapillary retinal nerve fibre thickness has been imaged and subjected to detailed measures along with optic disc size and shape. The study formed two phases, the first imaging the eyes of visually normal adults and children, comparing them to amblyopes, both adults and children who had completed their treatment. The second phase, a longitudinal study, investigated retinal structure of amblyopic children undertaking occlusion therapy for the first time. By relating pre-therapy quantitative measures to the visual outcome the second phase of the study aimed to examine whether OCT imaging could identify children achieving a poor final outcome. The results show a clear picture of inter-ocular symmetry structure in all individuals, visually normal and amblyopic. Optic disc characteristics revealed no structural abnormalities in amblyopes, in any of the measured parameters, nor was there any association between the level of visual acuity and the measured structure. At the fovea differences were shown to occur in the presence of amblyopia, with thickening of the fovea and reduction of the foveal pit depth. The structural changes were found to be both bilateral and symmetrical with the fellow eye also affected. In the longitudinal phase of the study these changes were demonstrated to a greater extent in children who 'failed' to respond to treatment. This bilateral, symmetrical structural change found at the fovea, which has not been previously reported, cannot therefore be the primary cause of the visual loss which has been diagnosed as amblyopia.
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Wakeford, Laura Jane. "The link between fixation location and attention during reading : its extent and nature." Thesis, University of Dundee, 2015. https://discovery.dundee.ac.uk/en/studentTheses/de0849c1-123c-41a2-9b7b-15a1d490d179.
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This thesis explores the relationship between fixation location and the locus of attention during reading. Early theories of eye movement control during reading suggested that a very tight coupling exists between the two (Just & Carpenter, 1980); however, it has since been shown that dissociations do exist. Whether these dissociations necessarily implicate parallel lexical processing, or whether they can be accommodated for within a serial-sequential framework is explored in a series of experiments. Experiment 1 tested whether parallel lexical processing is, at the very least, psychologically plausible. Two horizontally aligned letter strings were presented simultaneously on a screen, the task being to decide whether they were physically identical or not. Even when presentation duration should have been short enough to prohibit the strictly serial processing of each word in turn, the results show clear lexical effects: high frequency words were responded to faster and with fewer errors than low frequency words. Effects of lexicality and orthography were also found. These results suggest that the two words had been processed at a lexical level in an overlapping fashion. Experiments 2 and 3 investigated the nature and range of word n+2 preview effects. In Experiment 2, word n+1 was either a determiner or 3-letter alternative higher frequency word; in Experiment 3, word n+1 was either a 4- or a 6-letter high frequency word. A gaze contingent display change technique was employed, where prior to passing an invisible boundary located immediately after word n, one, the other, neither or both of words n+1 and n+2 received a nonword preview. In addition to showing orthographic parafoveal-on-foveal effects stemming from word n+1, there was also evidence that word n+2 preview influenced targeting decisions on words n and n+1. Word n+2 preview effects are also found on word n+2 and in the spillover region. These effects were most wide ranging when word n+1 length was an average of 5- compared to 3-letters. Higher-level plausibility preview effects were explored in Experiments 4-6, again using a gaze contingent display change technique. In Experiment 4 word n+1 received either an identical preview, a different but plausible one, or an anomalous, or nonword preview. Critically, an effect of plausibility arose on word n+1, with anomalous previews receiving longer inspection times than alternative plausible previews. Experiments 5 and 6 investigated the range over which these effects might occur, testing for a plausibility preview effect on word n+2. Results showed numerical, but not statistical evidence for a plausibility-related preview effect on word n+2. There were, however, clear orthographic word n+2 preview effects. Finally, Experiment 7 experimentally tested the immediate oculomotor response to a mislocated fixation, using a text shift paradigm to simulate saccadic error and measuring the effect on lexical processing. Critically, this experiment showed that a quick error correction strategy appears to be engaged following a simulated saccadic undershoot, rather than a stay and process response. This suggests that a mislocated fixation account coupled with a stay and process response is unlikely to provide a viable explanation for lexical parafoveal-on-foveal effects. Overall, it is suggested that current instantiations of both serial (e.g., Reichle, Warren & McConnell, 2009) and parallel (e.g., Schad & Engbert, 2012) models of eye movement control during reading appear to fail to capture major aspects of these patterns of results. The results do, however, appear to fit most parsimoniously with a perspective on eye movement control that allows for multiple words to be processed in an overlapping fashion.
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Rima, Ghashut. "EVALUATION OF MACULAR ISCHEMIA IN EYES WITH CENTRAL RETINAL VEIN OCCLUSION: An Optical Coherence Tomography Angiography Study." Kyoto University, 2018. http://hdl.handle.net/2433/232114.
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Risse, Sarah, and Reinhold Kliegl. "Adult age differences in the perceptual span during reading." Universität Potsdam, 2011. http://opus.kobv.de/ubp/volltexte/2011/5693/.
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Following up on research suggesting an age-related reduction in the rightward extent of the perceptual span during reading (Rayner, Castelhano, & Yang, 2009), we compared old and young adults in an N+2-boundary paradigm in which a nonword preview of word N+2 or word N+2 itself is replaced by the target word once the eyes cross an invisible boundary located after word N. The intermediate word N+1 was always three letters long. Gaze durations on word N+2 were significantly shorter for identical than nonword N+2 preview both for young and for old adults with no significant difference in this preview benefit. Young adults, however, did modulate their gaze duration on word N more strongly than old adults in response to the difficulty of the parafoveal word N+1. Taken together, the results suggest a dissociation of preview benefit and parafoveal-on-foveal effect. Results are discussed in terms of age-related decline in resilience towards distributed processing while simultaneously
preserving the ability to integrate parafoveal information into foveal processing. As such, the present results relate to proposals of regulatory compensation strategies older adults use to secure an overall reading speed very similar to that of young adults.
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Takiyama, Felipe Iwao. "Algoritmos de inferência exata para modelos de primeira ordem." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/3/3152/tde-23122014-145932/.
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Este trabalho descreve a implementação de algoritmos de inferência para modelos de primeira ordem. Três algoritmos foram implementados: ve, c-fove e ac-fove. Este último e o estado da arte no calculo de probabilidades em Redes Bayesianas Relacionais e não possua nenhuma implementação disponível. O desenvolvimento foi feito segundo uma metodologia ágil que resultou em um pacote de software que pode ser utilizado em outras implementações. Mostra-se que o software criado possui o desempenho esperado em teoria, embora apresente algumas limitações. Esta dissertação contribui também com novos tópicos teóricos que complementam o algoritmo.In this work, we describe the implementation of inference algorithms for first order models. Three algorithms were implemented: ve, c-fove and ac-fove. The latter is the state of the art in probability calculations for Relational Bayesian Networks and had no implementation available. The development was done according to an agile methodology, which resulted in a software that can be used in other packages. We show that the resulting software has the expected performance from the theory, although with some limitations. This work also contributes with new theoretical topics that complement the algorithm.
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Veras, Rodrigo de Melo Souza. "DetecÃÃo e SegmentaÃÃo de Estruturas em Imagens MÃdicas de Retina." Universidade Federal do CearÃ, 2014. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=12224.
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nÃo hÃImagens de fundo de olho constituem um valioso recurso para o diagnÃstico mÃdico, pois muitas vezes apresentam indicaÃÃes de doenÃas oftÃlmicas como as da retina e atà mesmo doenÃas sistÃmicas como diabetes, hipertensÃo e arteriosclerose. Esta tese trata de algoritmos de detecÃÃo de estruturas como a fÃvea, mÃcula, exsudatos e disco Ãptico (DO) em imagens de retina. Em se tratando de algoritmos de detecÃÃo da fÃvea em imagens coloridas de retina, propomos um algoritmo assim como conjunto de regras para avaliaÃÃo dos mesmos. A detecÃÃo automÃtica desta estrutura anatÃmica à um prÃ-requisito para o diagnÃstico auxiliado por computador de vÃrias doenÃas da retina, como a degeneraÃÃo macular. Entretanto, as pequenas dimensÃes e baixo contraste da fÃvea dificultam a execuÃÃo desta tarefa de detecÃÃo. O algoritmo proposto determina a regiÃo de interesse levando em consideraÃÃo as coordenadas do DO e o fato da fÃvea ser uma Ãrea escura, homogÃnea e sem presenÃa de vasos sanguÃneos. Em seguida, o mÃtodo realiza a etapa de segmentaÃÃo dos vasos e pesquisa pela janela com menor mÃdia de intensidade de cor na imagem resultante da fusÃo entre os canais vermelho e verde. Os testes do algoritmo de detecÃÃo da fÃvea foram realizados em trÃs bases de imagens pÃblicas de referÃncia ARIA, DRIVE e MESSIDOR. Neste trabalho, propomos ainda um algoritmo de detecÃÃo de exsudatos em imagens de retina. A metodologia proposta combina agrupamento nebuloso e tÃcnicas de morfologia matemÃtica. Os resultados confirmam a melhoria no desempenho do mÃtodo de detecÃÃo quando comparado aos mÃtodos disponÃveis na literatura. Portanto, comparamos os resultados de seis algoritmos automÃticos de detecÃÃo do DO disponÃveis na literatura, utilizando dados de referÃncia das bases pÃblicas ARIA, STARE, DRIVE e MESSIDOR. O objetivo era determinar a robustez dos mesmos em detectar o DO em imagens de retina saudÃveis e com a presenÃa de patologias. Observamos que em geral os mÃtodos de detecÃÃo de DO que apresentam melhor desempenho o fazem em bases menos desafiadoras como as duas Ãltimas, ou seja, eles alcanÃam as maiores taxas de acerto.
Fundus images are valuable resource in diagnosis because they often present indications about retinal, ophthalmic, and even systemic diseases such as diabetes, hypertension, and arteriosclerosis. This thesis focuses on algorithms to detect fovea, exudates and optic disk (OD) in retina images. Regarding fovea detection algorithms in colored retina images, we propose an algorithm and furthermore a set of rules to assess them. Automatic detection of this anatomical structure is a prerequisite for computer-aided diagnosis of several retinal diseases, such as macular degeneration. However, the small dimension and weak contrast of the fovea area on retina images make difficult this task detection, directly. The proposed algorithm determines a region of interest taking into account OD coordinates and the fact that the fovea is a homogeneous dark area without blood vessels. Then, the method performs the vessel segmentation step and searches for the lowest mean color intensity window in the image that results from the fusion between the red and green channels. Tests were carried out on three public benchmark databases. In addition, this thesis proposes an algorithm for exudate detection in retina images. The proposed methodology combines fuzzy clustering and mathematical morphology techniques. The results confirm the performance improvement provided by the proposed methodology, when comparing it to other methods available in the literature. In this work, we compare the results of six different automatic algorithms for OD detection, using the public benchmark image database named ARIA, STARE, DRIVE and MESSIDOR. We aimed to test the robustness of the algorithms in detecting the OD in healthy and pathological retina images. In general, we observed that these methods performed better in less challenging databases as the two last ones, i.e. they achieved the highest success rates in DRIVE and MESSIDOR.
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Gomes, Rafael Beserra. "Multi-resolu??o com f?vea m?vel para redu??o e abstra??o de dados em tempo real." Universidade Federal do Rio Grande do Norte, 2009. http://repositorio.ufrn.br:8080/jspui/handle/123456789/15302.
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Previous issue date: 2009-08-07Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico
We propose a new approach to reduction and abstraction of visual information for robotics vision applications. Basically, we propose to use a multi-resolution representation in combination with a moving fovea for reducing the amount of information from an image. We introduce the mathematical formalization of the moving fovea approach and mapping functions that help to use this model. Two indexes (resolution and cost) are proposed that can be useful to choose the proposed model variables. With this new theoretical approach, it is possible to apply several filters, to calculate disparity and to obtain motion analysis in real time (less than 33ms to process an image pair at a notebook AMD Turion Dual Core 2GHz). As the main result, most of time, the moving fovea allows the robot not to perform physical motion of its robotics devices to keep a possible region of interest visible in both images. We validate the proposed model with experimental results
N?s propomos uma nova abordagem para reduzir e abstrair informa??es visuais para aplica??es de vis?o rob?tica. Basicamente, usamos uma representa??o emmulti-resolu??o em combina??o com uma f?vea m?vel para reduzir a quantidade de informa??es de uma imagem. Apresentamos a formaliza??o matem?tica do modelo em conjunto com fun??es de mapeamento que auxiliam na utiliza??o do modelo. Propomos dois ?ndices (resolu??o e custo) que visam auxiliar na escolha das vari?veis do modelo proposto. Com essa nova abordagem te?rica, ? poss?vel aplicar diversos filtros, calcular disparidade est?reo e obter an?lise de movimento em tempo real (menos de 33ms para processar um par de imagens em um notebook AMD Turion Dual Core 2GHz). Como principal resultado, na maior parte do tempo, a f?vea m?vel permite ao rob? n?o realizar movimenta??o f?sica de seus dispositivos rob?ticos para manter uma poss?vel regi?o de interesse vis?vel nas duas imagens. Validamos o modelo proposto com resultados experimentais
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Biarnés, Pérez Marc 1973. "Increased fundus autofluorescence, a biomarker of lipofuscin content, as a risk factor for the progression of geographic atrophy secondary to age-related macular degeneration." Doctoral thesis, Universitat Pompeu Fabra, 2014. http://hdl.handle.net/10803/318157.
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L’atròfia geogràfica (AG) és la variant avançada de la degeneració macular associada a l’edat seca i es caracteritza per la presència d’àrees d’atròfia de l’epiteli pigmentari de la retina (EPR) que creixen progressivament, amb pèrdua secundària dels fotorreceptors i la coriocapilar adjacents. Actualment és una condició sense tractament.
L’acumulació de lipofuscina a l’EPR, visualitzable clínicament mitjançant l’autofluorescència del fons d’ull (AFU) com a zones d’elevada autofluorescència, ha estat vinculada a la progressió de l’AG en alguns estudis. De fet, s’han descrit certs patrons (“fenotips”) en l’AFU basats en la distribució d’hiperautofluorescència que s’han associat amb taxes específiques de progressió de la malaltia.
En aquesta Tesi hem fet un estudi clínic prospectiu per simplificar la complexa classificació dels patrons d’AFU i avaluar el paper de la hiperautofluorescència, un biomarcador de la lipofuscina, en la progressió de l’AG.Geographic atrophy (GA) is the advanced form of dry age-related macular degeneration. It is characterized by large areas of retinal pigment epithelium (RPE) atrophy that grow progressively, with concomitant loss of photoreceptors and choriocapillaris. Currently, there is no treatment for this disorder. Lipofuscin build-up within the RPE, which is identifiable by fundus autofluorescence (FAF) as areas of increased autofluorescence, has been linked to GA progression in some studies. Actually, the distribution of hyperautofluorescence on FAF identified some patterns (“phenotypes”), which have been associated with specific rates of disease growth. We conducted a prospective clinical study to simplify the complex classification of FAF patterns and to determine the role of increased FAF, a biomarker of lipofuscin, in the progression of GA.
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Gehrke, Ralf. "RGBI-Bilddaten mit RPAS und FOVEON Sensoren." Doctoral thesis, 2015. https://repositorium.ub.uni-osnabrueck.de/handle/urn:nbn:de:gbv:700-2015081013517.
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In den letzten Jahren hat sich der Einsatz von Remotely Piloted Aerial Systems (RPAS)
zur Geodatenerfassung immer mehr verbreitet. Dabei liegt das Hauptaugenmerk auf dem Einsatz von herkömmlichen Kameras mit drei Kanälen (Rot, Grün, Blau (RGB)). Mit dieser Kombination werden 3D-Daten und Orthophotomosaike erzeugt. Ein weiteres, jedoch kleineres Augenmerk liegt auf der Entwicklung von Sensoren mit mehr als drei Kanälen für Fragestellungen der Fernerkundung. Auffallend ist dabei, dass die Hersteller viel Arbeit in die radiometrische Qualität und die spektrale Auflösung der Sensoren stecken, deren geometrische Qualität ganz im Gegensatz zur herkömmlichen RGB-Kamera aber vernachlässigen. Die vorliegende Arbeit verfolgt einen anderen Ansatz: Ein bestehendes System wird unter der Berücksichtigung eines begrenzten Budgets (low-cost) und dem Erhalt der hohen geometrischen Abbildungsqualität um einen vierten Kanal im nahen Infrarot ergänzt. Anwendungsmöglichkeiten ergeben sich überall dort, wo gleichzeitig das Vorhandensein oder der Zustand von Vegetation und die Geometrie mit RPAS erfasst werden soll.
Sigma Kameras mit Foveon® Sensoren sind bereits für ihre hohe Abbildungsqualität bekannt. Durch den Ausbau des Infrarot-Sperrfilters kann diese Kamera, ebenso wie fast alle Sensoren auf Silizium-Basis, für die Erfassung des Near Infrared (NIR) modifiziert werden. Mit der Kombination einer RGB- und einer NIR-Kamera zu einem Sensorkopf und einer selbst entwickelten Datenverarbeitung können Vierkanalbilddaten erzeugt werden, die die hohe Abbildungsqualität der Sigma Kamera und gleichzeitig die Zusatzinformation im NIR besitzen. Die Weiterverarbeitung in einer modernen Photogrammetriesoftware mit einem Structure from Motion (SFM)-Ansatz verspricht ein effizientes und praxisgerechtes Arbeiten.
Der entwickelte Sensorkopf wird in zwei Einsatzszenarien zur Anwendung gebracht. In der Luftbildarchäologie kann der Zeitraum der Erfassung von Bodendenkmälern mit RPAS durch diesen Sensorkopf erheblich erweitert werden. Das Bodendenkmal ist sowohl im hochaufgelösten Oberflächenmodell als auch im NIR deutlicher zu erkennen als in einer herkömmlichen RGB-Aufnahme. Bei der Filterung eines Oberflächenmodells zu einem Geländemodell konnte gezeigt werden, dass die Verwendung des NIR den herkömmlichen Einsatz von neigungsbasierten Filtern sinnvoll ergänzt und zu besseren Ergebnissen führt. Durch den Rückgriff auf gebrauchte Sigma Kompaktkameras und weit verbreitete Software mit SFM-Algorithmen konnte der low-cost Ansatz voll erfüllt werden. Die radiometrische Qualität wurde untersucht und es wurde festgestellt, dass diese nicht an den Stand der Technik von speziellen und teuren Algorithmen und Sensoren heranreicht. Für die gezeigten Anwendungen ist sie jedoch als ausreichend zu bewerten.
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Hollmann, Michael [Verfasser]. "Die elektrorezeptiven Foveae von Gnathonemus petersii : die elektrorezeptiven Foveae von Rezeptorverteilung, Rezeptormorphologie und Futtersuchverhalten / vorgelegt von Michael Hollmann." 2008. http://d-nb.info/989802434/34.
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Bruce, A., I. E. Pacey, J. A. Bradbury, A. J. Scally, and B. T. Barrett. "Bilateral changes in foveal structure in individuals with amblyopia." 2013. http://hdl.handle.net/10454/5894.
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PURPOSE: To examine foveal structure in amblyopia using spectral-domain optical coherence tomography (SD-OCT). DESIGN: Prospective, cross-sectional study. PARTICIPANTS AND CONTROLS: Two subject groups were recruited to the study: 85 amblyopes (34 adults, 51 children) and 110 visually normal controls (44 adults, 66 children). METHODS: A detailed eye examination, including an SD-OCT scan, was performed in all participants. A total of 390 eyes of 195 subjects were imaged using a 3-dimensional (3D) macula scan covering a nominal 6 x 6-mm area with a resolution of 256 x 256 (65,536 axial scans). Data from the B-scans bisecting the fovea both horizontally and vertically were fitted with a mathematical model of the fovea to determine a range of foveal parameters. MAIN OUTCOME MEASURES: Foveal thickness, foveal pit depth, and foveal pit slope. RESULTS: Bilateral differences between the eyes of amblyopes compared with visually normal controls were found. The difference between foveal structure in amblyopic participants relative to structure in subjects with normal vision persisted even when variables such as age, ethnicity, axial length, and sex were taken into account. Amblyopes showed increased foveal thickness (+8.31 mum; P = 0.006) and a reduction in pit depth in the horizontal meridian (-10.06 mum; P = 0.005) but not in the vertical meridian (P = 0.082) when compared with subjects with normal vision. Foveal pit slopes were found to be approximately 1 degree flatter in the nasal (P = 0.033) and temporal (P = 0.014) meridians in amblyopes, but differences between amblyopes and controls in the superior (P = 0.061) and inferior (P = 0.087) meridians did not reach statistical significance. No statistically significant interocular differences were found in the foveal structure between amblyopic and fellow eyes. CONCLUSIONS: Differences were found in the foveal structure in both eyes of amblyopes compared with subjects with normal vision. These differences consisted of increased foveal thickness, reduced pit depth when measured along the horizontal meridian, and flattening of the nasal and temporal sides of the foveal pit.
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Wei, Chian-Chen, and 魏千琛. "A method of breast calcifications detection : GS-foveal algorithm." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/da83gy.
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碩士中山醫學大學
醫學資訊學系碩士班
103
Breast cancer is one of the most common malignant tumors for the women, the main way to decrease mortality caused by breast cancer is the inchoate diagnosis and treatment. It has been shown to be very effective in the reduction of breast cancer mortality rates. The appearance of microcalcifications in mammograms is one of the early signs of breast cancer. So, early detection of microcalcification clusters in mammograms can be helpful for cancer diagnosis and better treatment of breast cancer. Therefore, we presents a method (golden search foveal algorithm) to detect breast calcifications, to assist physicians for the diagnosis of breast calcifications. The results also proved that the proposed method of this paper is effective and desirable.
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Kambe, Gretchen. "Parafoveal versus foveal processing of morphologically complex (prefixed) words." 2001. https://scholarworks.umass.edu/dissertations/AAI3027217.
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Three experiments investigated whether morphological constituents influence word processing during reading. Individuals read sentences containing free stem, bound stem, and pseudo-prefixed words. In Experiments 1 and 2, a parafoveal display change manipulation indicated that the morphological constituents of a prefixed word are not available for preprocessing in the parafovea as reading times on the target word did not differ for prefixed versus pseudo-prefixed words. Interestingly, parafoveal preview of word initial and word final letters resulted in an equivalent amount orthographic facilitation for all word types. In Experiment 3, a fast priming manipulation indicated that morphological priming effects for prefixed words are obscured during sentence processing. However, the form of the prime did facilitate subsequent word processing for all three word types. The results suggest that English prefixed words are accessed via their whole word form, as there was no evidence of morphological decomposition for prefixed words during sentence processing.
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Wu, Chia-Yu, and 吳珈瑜. "Microcalcification detection method based on greedy foveal algorithm for mammography." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/22qh4v.
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碩士國立中興大學
資訊科學與工程學系所
101
Mortality rates of breast cancer are always high in all countries. Because detecting warning signs from human body in early stages of breast cancer is very difficult, it always leads to the delayed diagnosis of cancer for the patients. In fact, in early stages of breast cancer, microcalcification may be found in the breast region. Thus, we may detect microcalcification in mammography to diagnose whether the patient gets cancer. In this paper, we propose a method to detect microcalcification in mammography to assist the physician in diagnosing breast cancer in an early stage. There are several procedures to be carried out: first, we enhance the contrast of an image to make the microcalcification be distinguished from the background more easily. Next, the enhanced image is divided into some overlapping square areas which are marked as preliminary ROIs. Some of these preliminary ROIs may not contain microcalcification; therefore, we propose an algorithm to remove those unsuitable ROIs. Finally, in order to get the best parameters for detecting microcalcification, we use some of ROIs contain microcalcification to train our greedy foveal algorithm. Experiments showed that 92.38% accuracy rate can be achieved, and computation time is significantly reduced by using a well-trained greedy foveal algorithm.
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Phillips, Rick L. "The role of fixational eye movements in foveal spatio-temporal vision." 1985. http://catalog.hathitrust.org/api/volumes/oclc/12686018.html.
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Thesis (Ph. D.)--University of Wisconsin--Madison, 1985.Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 81-89).
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Scheibe, Patrick. "A Parametric Model for the Analysis and Quantification of Foveal Shapes." 2019. https://ul.qucosa.de/id/qucosa%3A34313.
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Recently, the advance of OCT enables a detailed examination of the human retina in-vivo for clinical routine and experimental eye research. One of the structures inside the retina of immense scientific interest is the fovea, a small retinal pit located in the central region with extraordinary visual resolution. Today, only a few investigations captured foveal morphology based on a large subject group by a detailed analysis employing mathematical models.
In this work, we develop a parametric model function to describe the shape of the human fovea. Starting with a detailed discussion on the history and present of fovea research, we define the requirements for a suitable model and derive a function which can represent a broad range of foveal shapes. The model is one-dimensional in its basic form and can only account for the shape of one particular section through a fovea. Therefore, we apply a radial fitting scheme in different directions which can capture a fovea in its full three-dimensional appearance.
Highly relevant foveal characteristics, derived from the model, provide valuable descriptions to quantify the fovea and allow for a detailed analysis of different foveal shapes.
To put the theoretical model into practice, we develop a numerical scheme to compute model parameters from retinal \ac{oct} scans and to reconstruct the shape of an entire fovea. For the sake of scientific reproducibility, this section includes implementation details, examples and a discussion of performance considerations.
Finally, we present several studies which employed the fovea model successfully.
A first feasibility study verifies that the parametric model is suitable for foveal shapes occurring in a large set of healthy human eyes.
In a follow-up investigation, we analyse foveal characteristics occurring in healthy humans in detail. This analysis will concern with different aspects including, e.g. an investigation of the fovea's asymmetry, a gender comparison, a left versus right eye correlation and the computation of subjects with extreme foveal shapes. Furthermore, we will show how the model was used to support investigations unrelated to the direct quantification of the fovea itself. In these investigations we employed the model to compute anatomically correct regions of interest in an analysis of the OCB and the calculation of an average fovea for an optical simulation of light rays.
We will conclude with currently unpublished data that shows the fovea modelling of hunting birds which have unusual, funnel-like foveal shapes.
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Li, Dong-yi, and 李東逸. "Stability Evaluation of Different Repair Approaches on Triangular Fibrocartilage Complex Foveal Tear." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/rrycun.
Full textAbstract:
碩士義守大學
生物醫學工程學系
105
The pain of ulnar side of wrist is a challenging issue in orthopedics. This is often caused by the damage of triangular fibrocartilage complex (TFCC). The function of TFCC is to maintain the stability of the wrist joint when rotation and distribute the mechanical stress from the hand. It is still controversial in the surgical approach of TFCC repair. Due to the development of minimal invasive surgery, arthroscopic transosseus suture repair was recommended. However, some surgeons still believed that open repair had better prognosis. Hence, the objective of this study was to evaluate the biomechanical stability of arthroscopic and open approaches for triangular fibrocartilage complex foveal repair Six matched pairs of fresh-frozen forearm cadaver specimens were prepared for testing. Open repair with suture anchor and arthroscopic transosseous suture with a new aiming device were evaluated. Before and after disruption of the TFCC fovea and after its repair, dorsal and palmar translation of the ulna was measured in both groups in response to a load (3 kg) applied in the palmar and then in the dorsal direction. The total translation of the ulna was calculated as the sum of the mean dorsal and palmar translations. The athroscopic transosseous suture technique demonstrated superior repair efficacy to the open repair technique in terms of biomechanical strength. This cadaveric study also demonstrated the feasibility of a new aiming device
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Nortje, Benjamin. "A system for eye-directed control in an split-foveal-peripheral-display." Diss., 1999. http://hdl.handle.net/2263/23000.
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In this thesis an eye-directed controller is developed that slaves the narrow field display within a split-foveal-peripheral-display system to the operator's gaze position. A neural network controller is proposed that directly maps the gaze position to the narrow field projection co-ordinates without the need for any axis or co-ordinate transformations. A novel image feature-extraction algorithm, for extraction of the pupil-purkinje difference measure, has been developed that exhibits robust and reproducible real-time performance. By providing foveal and peripheral vision in a far-field teleoperator through the eye-directed split-foveal-peripheral-display, visual information is sufficiently and naturally provided for the establishment of telepresence.Dissertation (M Eng (Electronic Engineering))--University of Pretoria, 2007.
Electrical, Electronic and Computer Engineering
unrestricted