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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
321

Learning person-specific face representations = Aprendendo representações específicas para a face de cada pessoa / Aprendendo representações específicas para a face de cada pessoa

Chiachia, Giovani, 1981- 23 August 2018 (has links)
Orientadores: Alexandre Xavier Falcão, Anderson de Rezende Rocha / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Computação / Made available in DSpace on 2018-08-23T15:41:33Z (GMT). No. of bitstreams: 1 Chiachia_Giovani_D.pdf: 4376963 bytes, checksum: 8f7d18d591f2a5d943313d89416f96d4 (MD5) Previous issue date: 2013 / Resumo: Os seres humanos são especialistas natos em reconhecimento de faces, com habilidades que excedem em muito as dos métodos automatizados vigentes, especialmente em cenários não controlados, onde não há a necessidade de colaboração por parte do indivíduo sendo reconhecido. No entanto, uma característica marcante do reconhecimento de face humano é que nós somos substancialmente melhores no reconhecimento de faces familiares, provavelmente porque somos capazes de consolidar uma grande quantidade de experiência prévia com a aparência de certo indivíduo e de fazer uso efetivo dessa experiência para nos ajudar no reconhecimento futuro. De fato, pesquisadores em psicologia têm até mesmo sugeridos que a representação interna que fazemos das faces pode ser parcialmente adaptada ou otimizada para rostos familiares. Enquanto isso, a situação análoga no reconhecimento facial automatizado | onde um grande número de exemplos de treinamento de um indivíduo está disponível | tem sido muito pouco explorada, apesar da crescente relevância dessa abordagem na era das mídias sociais. Inspirados nessas observações, nesta tese propomos uma abordagem em que a representação da face de cada pessoa é explicitamente adaptada e realçada com o intuito de reconhecê-la melhor. Apresentamos uma coleção de métodos de aprendizado que endereça e progressivamente justifica tal abordagem. Ao aprender e operar com representações específicas para face de cada pessoa, nós somos capazes de consistentemente melhorar o poder de reconhecimento dos nossos algoritmos. Em particular, nós obtemos resultados no estado da arte na base de dados PubFig83, uma desafiadora coleção de imagens instituída e tornada pública com o objetivo de promover o estudo do reconhecimento de faces familiares. Nós sugerimos que o aprendizado de representações específicas para face de cada pessoa introduz uma forma intermediária de regularização ao problema de aprendizado, permitindo que os classificadores generalizem melhor através do uso de menos |, porém mais relevantes | características faciais / Abstract: Humans are natural face recognition experts, far outperforming current automated face recognition algorithms, especially in naturalistic, \in-the-wild" settings. However, a striking feature of human face recognition is that we are dramatically better at recognizing highly familiar faces, presumably because we can leverage large amounts of past experience with the appearance of an individual to aid future recognition. Researchers in psychology have even suggested that face representations might be partially tailored or optimized for familiar faces. Meanwhile, the analogous situation in automated face recognition, where a large number of training examples of an individual are available, has been largely underexplored, in spite of the increasing relevance of this setting in the age of social media. Inspired by these observations, we propose to explicitly learn enhanced face representations on a per-individual basis, and we present a collection of methods enabling this approach and progressively justifying our claim. By learning and operating within person-specific representations of faces, we are able to consistently improve performance on both the constrained and the unconstrained face recognition scenarios. In particular, we achieve state-of-the-art performance on the challenging PubFig83 familiar face recognition benchmark. We suggest that such person-specific representations introduce an intermediate form of regularization to the problem, allowing the classifiers to generalize better through the use of fewer | but more relevant | face features / Doutorado / Ciência da Computação / Doutor em Ciência da Computação
322

Evaluation of biometric security systems against artificial fingers

Blommé, Johan January 2003 (has links)
Verification of users’ identities are normally carried out via PIN-codes or ID- cards. Biometric identification, identification of unique body features, offers an alternative solution to these methods. Fingerprint scanning is the most common biometric identification method used today. It uses a simple and quick method of identification and has therefore been favored instead of other biometric identification methods such as retina scan or signature verification. In this report biometric security systems have been evaluated based on fingerprint scanners. The evaluation method focuses on copies of real fingers, artificial fingers, as intrusion method but it also mentions currently used algorithms for identification and strengths and weaknesses in hardware solutions used. The artificial fingers used in the evaluation were made of gelatin, as it resembles the surface of human skin in ways of moisture, electric resistance and texture. Artificial fingers were based on ten subjects whose real fingers and artificial counterpart were tested on three different fingerprint scanners. All scanners tested accepted artificial fingers as substitutes for real fingers. Results varied between users and scanners but the artificial fingers were accepted between about one forth and half of the times. Techniques used in image enhancement, minutiae analysis and pattern matching are analyzed. Normalization, binarization, quality markup and low pass filtering are described within image enhancement. In minutiae analysis connectivity numbers, point identification and skeletonization (thinning algorithms) are analyzed. Within pattern matching, direction field analysis and principal component analysis are described. Finally combinations of both minutiae analysis and pattern matching, hybrid models, are mentioned. Based on experiments made and analysis of used techniques a recommendation for future use and development of fingerprint scanners is made.
323

Biometrics : Attitudes and factors influencing a breakthrough in Sweden / Biometri : Attityder och faktorer som påverkar ett genombrott i Sverige

Brobeck, Stefan, Folkman, Tobias January 2005 (has links)
Biometrics is a collection of methods for identifying and authorizing individuals with something they are, or do. It is considered to be one of the most secure technologies for security, both physical and logical. Security is something very important for organizations today, but yet there has been a low interest in investing in biometrics for security in Sweden. The purpose of this thesis has been to establish factors to why biometrics has not been implementedto any large extent, even though the technology has been around for long. We have evaluated the attitudes and views of individuals, as well as company leaders. Problem and questions with biometrics that often are discussed are privacy concerns, costs and ROI (return on investment) and user acceptance. Foremost there is a concern about the costs of implementing such a solution, although some claim that money can be saved by avoiding the costs in more traditional security methods, such as password administration and in security cards. There is a range of different technologies to use, such as facial-scan, voice-scan and the most mature and well known technique, finger-scan which has been around for a long time, especially for identifying criminals. All these techniques have there positive and negative sides, often measured in different levels of universality, uniqueness, permanence and collectability, e.g. eye-scan has a high uniqueness, facial-scan has a high universability and signature-scan has a low permanence level. We have collected our data through interviews with companies and suppliers of biometric systems as well as a questionnaire given to private persons. By interpreting the data in a qualitative way we have made our analysis and reached a conclusion. Our result shows that a cost related to biometric solutions is the largest reason why investments have been absent. This verifies the results of other authors, that the cost is the largest obstacle. Another important factor is that companies believe that biometrics is for organizations with a very high security need. Further our result show that individuals are positive towards biometrics. / Biometri är ett samlingsnamn för tekniker som identifierar och auktoriserar individer, antingen något de är eller gör. Biometri anses vara en av de säkraste teknologierna för säkerhet, både fysisk och logisk. Säkerhet är något som är mycket viktigt för organisationer i dagens läge, men än så länge så har investeringar i biometriska säkerhetslösningar i Sverige uteblivit. Syftet med denna magisteruppsats har varit att fastställa faktorer som bidrar till att biometriska lösningar inte har blivit implementerade i någon större utsträckning, trots att teknologin har funnits länge. Vi har utvärderat individers samt företagsledares attityder och synsätt angående biometri. Frågor och problem som ofta relateras till biometri är personligintegritet, kostnader och avkastning på investering samt användaracceptans. Framförallt är det osäkerheten kring kostnaderna av en implementering av en biometrisklösning. Det finns även de som hävdar att biometriska lösningar kan spara pengar jämfört med traditionella system därför att man undviker till exempel lösenordsadministration och passerkort. Det finns en rad olika tekniker att använda, exempelvis ansiktsavläsning, röstigenkänning och den mest mogna och kända tekniken, fingeravtrycksläsning som har existerat en längre tid, framförallt för att identifiera kriminella. Det finns positiva och negativa sidor med alla dessa tekniker, de mäts oftast i olika nivåer av hur många som kan använda det, hur unikt biometrin är, beständighet och hur biometrin samlas in. Genom intervjuer med företag och leverantörer av biometriska lösningar samt en utdelad enkät till privat personer har vi samlat in data. Vi har sedan tolkat data kvalitativt och utfört vår analys och slutligen kommit fram till ett resultat. Vårt resultat har visat att kostnader relaterade till biometriska system är det största skälet till varför investeringar har uteblivit. Detta bekräftar vad många andra författare tidigare har funnit, att kostnaderna är det största hindret. En annan viktig faktor är att företag anser att biometri är något för verksamheter som kräver den allra högsta säkerheten. Vidare har individer en positiv inställning till biometri.
324

Zpracování osobních údajů v rámci EU se zřetelem na policejní a justiční spolupráci / Processing of personal data in the EU within police and judicial cooperation

Jašková, Jitka January 2009 (has links)
The thesis deals with the approach level, meaning, purpose and benefit of personal data protection in their processing within police and judicial cooperation in the EU. In the introduction the fundamental issues of personal data protection in the context of the EU and the Czech republic are defined, focusing on terminology and explanations of current issues, particularly the area of biometric data and data retention. Extra attention is also given to the conflict of the right to privacy, and the related right to personal data protection and protection of public interests and safety. After that the thesis deals with a performing of police and judicial cooperation in the EU through specific subjects, in particular Europol and Eurojust. The final part of the thesis focuses on the practical implementation of personal data protection in police and judicial cooperation in the EU, and secondly the importance of personal data protection in police and judicial cooperation, as a deduced basic human right, and the difficulties with which the personal data protection in police and judicial cooperation in the EU are joined. The final part of this thesis consider the main sections in which we can find area for adjustment towards more effective police and judicial cooperation in the EU, with full respect for the right to personal data protection.
325

Implementace dynamického biometrického podpisu v podniku po nabytí účinnosti nařízení eIDAS / Implementation of Dynamic Biometric Signature in the Company after the Entry into Force of the Regulation eIDAS

Jelečková, Pavla January 2017 (has links)
The diploma thesis focuses on the problematics of elektronic signing in the Czech Republic after the Entry into Force of Regulation eIDAS. It specifies the key words in this area, compares the properties of cryptographic electronic signature and dynamic biometric signature. Within the main objective of the work, which is the implementation of dynamic biometric signature in the company, a solution is proposed to the process of approving business tax forms. At the end, an economic comparison of paper and electronic solutions is made.
326

Identifikace osob pomocí biometrie sítnice / Identification of persons using retinal biometry

Klimešová, Lenka January 2018 (has links)
This paper deals with identification of persons using retinal biometry. The retinal vasculature is invariant and unique to everyone, which determines it for biometric purposes. The first part of the work includes information about biometrics, biometric systems and reliability measures. The next part describes the principle of using experimental video ophthalmoscope, which was used for retinal vascular imaging and includes the literature research of use of retinal images for biometrics, feature extraction methods and similarity measures. Finally, two algorithms to use the input data are proposed and realized in programming environment MATLAB®. The methods are tested and evaluated on a data set from experimental video ophthalmoscope and on publicly available STRaDe and DRIVE databases.
327

System for Recognition of 3D Hand Geometry / System for Recognition of 3D Hand Geometry

Svoboda, Jan January 2014 (has links)
V posledním desetiletí došlo ke zvýšení zájmu o užití 3D dat k biometrické identifikaci osob. Možná vůbec největší výzkum proběhl v oblasti 3D rozpoznávání podle obličeje, přičemž je v současné době dostupných vícero komerčních zařízení. V oblastni rozpoznávání podle 3D geometrie ruky byl v minulých letech proveden určitý výzkum jehož výsledkem však nebylo žádné komerční zařízení. Nezávisle na tomto výzkumu se v posledních letech velmi rozšířil trh s cenově dostupnými 3D sensory, což potenciálně umožňuje jejich nasazení v mnoha typech biometrických systémů. Hlavním cílem této práce je vytvořit funkční vzorek bezdotykového systému pro rozpoznávání osob podle 3D geometrie ruky, který bude používat novou levnou kameru RealSense 3D vyvíjenou v současné době firmou Intel. Jedním z problémů při použití RealSense kamery je její velmi malý form factor, který je příčinou nižší kvality výsledných snímků v porovnání s velmi drahými alternativami, které byly použity v již dříve zmíněném výzkumu 3D biometrických systémů. Práce se snaží analyzovat robustnost různých 2D a 3D příznaků a vyzkoušet několik různých přístupů k jejich fúzi. Rovněž je vyhodnocena výkonnost výsledného systému, kde je ukázáno, že navržené řešení dosahuje výsledků porovnatelných se state-of-the-art.
328

Podpora výuky biometrických přístupových systémů / Support for education of biometric access systems

Navrátil, Petr January 2008 (has links)
This thesis describes general function of biometric access systems and summarizes problems of their practical use. It also shows security risks of these systems. It defines basic terms, which are used in this area, describes kinds of errors and their representation. One part of this thesis deals with biometric method of fingerprints recognition. It explains fingerprints’ atomic basics, basic principles and processing of digital fingerprint image. Next part describes concrete biometric access system V-Station by Bioscrypt Inc. Besides basic description it focuses on technology of biometric sensor and algorithm, essential parts of biometric system. The thesis continues with security analysis of this concrete system. In this part I target on weak points of the system and I design possible attack on the system. In the last part of my thesis I designed laboratory exercise, which is supposed to be realized by student. It is composed it by several tasks to let students understand working with the system and attached software. At the same time, they have opportunity to think about system by themselves a make their own opinion about possibilities of the system. There are many pictures in this thesis to make term clear and to better understanding of problems of biometric security systems.
329

Jádro multimodálního biometrického systému / Core of the Multimodal Biometric System

Pokorný, Karel January 2012 (has links)
The aim of this thesis is a design and realization of the core of multimodal biometric system. First part of the thesis sumarizes contemporary knowledge about biometric systems and about combination of their outputs. Second part introduces concept and implementation of multimodal biometric system, which uses weighted score combination and user-specific weights.
330

Fingerprint Image Quality Assessment / Fingerprint Image Quality Assessment

Šmida, Vladimír January 2011 (has links)
Kritickým prvkem biometrického systému pro rozpoznávání otisků prstů je proces snímání. Kvalita snímku totiž ovlivňuje všechny další části systému počínaje zpracováním obrazu, přes extrakci rysů až po samotné rozhodnutí. Přestože bylo navrženo několik metod určování kvality snímku, chybějící formální specifikace kvality otisku nedovoluje ověřit jejich přesnost. Tato diplomová práce se zabývá hodnocením metod určujících kvalitu biometrického signálu otisku prstu. Popisuje jednotlivé faktory ovlivňující kvalitu spolu se současnými přístupy používanými pro její odhad. V práci je rovněž vysvětlena evaluační technika navržená za účelem porovnání schopnosti jednotlivých metod předpovědět výkon biometrického systému. Několik metod pro odhad kvality bylo implementováno a ohodnoceno touto technikou.

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