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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.
21

Vodoznačení statických obrazů / Image watermarking

Štágl, Luboš January 2009 (has links)
This diploma thesis is concerned in static pictures Security problems. That means, additional informations (watermark) are embedded to the original picture in a specific way. This complex picture structure (watermark) should be unremoval by different attacks runing processes. The main goal of this diploma thesis is realize two separated methods digital data watermarking in MATLAB program. For reason of a quite large scale of different watermarking methods are chosen at this time only two of take were choosen. First of the methods is Watermark injection in the spatial domain and the second in the freuquency domain. Both methods are set up in a special way and finish goals of the process. Expected result are, that digital picture user doesn't know about the watermarking technique was aplied on this picture and the watermarking data are the most resistant as possible as can be. These attacks were simulated in Checkmark program.
22

Návrh digitálního IP bloku pro diskrétní kosinovu transformaci / Design of digital IP block for discrete cosine transform

Veškrna, Filip January 2015 (has links)
Tato diplomová práce se zabývá návrhem IP bloku pro diskrétní kosinovou transformaci. V~teoretické části jsou shrnuty algoritmy pro výpočet diskrétní kosinové transformace a diskutována jejich použitelnost v~hardwaru. Zvolený algoritmus pro hardwarovou implementaci je modelován v jazyce C. Poté je popsán na RTL úrovni, verifikován a je provedena syntéza v~technologii TSMC 65 nm. Hardwarová implementace je poté zhodnocena s ohledem na datovou propustnost, plochu, rychlost and spotřebu.
23

Contribution à la définition, à l'optimisation et à l'implantation d'IP de traitement du signal et des données en temps réel sur des cibles programmables / Contribution to the definition, optimization and implementation of signal processing IPs on programmable target

Ouerhani, Yousri 16 November 2012 (has links)
En dépit du succès que les implantations optiques des applications de traitement d'images ont connu, le traitement optique de l'information suscite aujourd'hui moins d'intérêt que dans les années 80-90. Ceci est dû à l'encombrement des réalisations optiques, la qualité des images traitées et le coût des composants optiques. De plus, les réalisations optiques ont eu du mal à s’affranchir de l’avènement des circuits numériques. C’est dans ce cadre que s’inscrivent les travaux de cette thèse dont l’objectif est de proposer une implantation numérique des méthodes optiques de traitement d’images. Pour réaliser cette implantation nous avons choisi d’utiliser les FPGA et les GPU grâce aux bonnes performances de ces circuits en termes de rapidité. En outre, pour améliorer la productivité nous nous sommes focalisés à la réutilisation des blocs préconçus ou IP « Intellectual Properties ». Malgré que les IP commerciales existantes soient optimisées, ces dernières sont souvent payantes et dépendent de la famille de la carte utilisée. La première contribution est de proposer une implantation optimisée des IP pour le calcul de la transformée de Fourier FFT et de la DCT. En effet, le choix de ces deux transformations est justifié par l'utilisation massive de ces deux transformées (FFT et DCT), dans les algorithmes de reconnaissance de formes et de compression, respectivement. La deuxième contribution est de valider le fonctionnement des IP proposées par un banc de test et de mesure. Enfin, la troisième contribution est de concevoir sur FPGA et GPU des implantations numériques des applications de reconnaissance de formes et de compression. Un des résultats probant obtenu dans cette thèse consiste à avoir une rapidité de l’IP FFT proposée 3 fois meilleure que celle de l’IP FFT Xilinx et de pouvoir réaliser 4700 corrélations par seconde. / The main objective of this thesis is to realize a numerical implementation of optical methods of image and signal processing. To achieve this end, we opted to use FPGA (Field Programmable Gate Array) and GPU (Graphical Processing Unit) devices. This choice is justified by their high performance in terms of speed. In addition, to improve productivity, we focused on the reuse of predesigned blocks or "Intellectual Properties" IP. While existing commercial IP are optimized, they are often paid and highly dependent on the card. The first contribution is to provide an optimized IP for Fourier transform (FFT) and the cosine transform (DCT) computing. Indeed, the choice of these two transformations is justified by the widespread use of these two transforms (FFT and DCT), particularly in pattern recognition and compression algorithms. The second contribution is to validate the operation of the proposed IP using a bench test. The last contribution is to implement on FPGA and GPU applications for pattern recognition and compression. One of the convincing results obtained in this thesis is to propose an IP for FFT computing three times faster than Xilinx IP and thus to achieve 4700 correlations per second.
24

Um método iterativo e escalonável para super-resolução de imagens usando a interpolação DCT e representação esparsa. / Iterative and scalable image super-resolution method with DCT interpolation and sparse representation.

Reis, Saulo Roberto Sodré dos 23 April 2014 (has links)
Num cenário em que dispositivos de aquisição de imagens e vídeo possuem recursos limitados ou as imagens disponíveis não possuem boa qualidade, as técnicas de super-resolução (SR) apresentam uma excelente alternativa para melhorar a qualidade das imagens. Nesta tese é apresentada uma proposta para super-resolução de imagem única que combina os benefícios da interpolação no domínio da transformada DCT e a eficiência dos métodos de reconstrução baseados no conceito de representação esparsa de sinais. A proposta busca aproveitar as melhorias já alcançadas na qualidade e eficiência computacional dos principais algoritmos de super-resolução existentes. O método de super-resolução proposto implementa algumas melhorias nas etapas de treinamento e reconstrução da imagem final. Na etapa de treinamento foi incluída uma nova etapa de extração de características utilizando técnicas de aguçamento por máscara de nitidez e construção de um novo dicionário. Esta estratégia busca extrair mais informações estruturais dos fragmentos de baixa e alta resolução do conjunto de treinamento e ao mesmo tempo reduzir o tamanho dos dicionários. Outra importante contribuição foi a inclusão de um processo iterativo e escalonável no algoritmo, reinserindo no conjunto de treinamento e na etapa de reconstrução, uma imagem de alta resolução obtida numa primeira iteração. Esta solução possibilitou uma melhora na qualidade da imagem de alta resolução final utilizando poucas imagens no conjunto de treinamento. As simulações computacionais demonstraram a capacidade do método proposto em produzir imagens com qualidade e com tempo computacional reduzido. / In a scenario in which the acquisition systems have limited resources or available images do not have good quality, the super-resolution (SR) techniques have become an excellent alternative for improving the image quality. In this thesis, we propose a single-image super-resolution (SR) method that combines the benefits of the DCT interpolation and efficiency of sparse representation method for image reconstruction. Also, the proposed method seeks to take advantage of the improvements already achieved in quality and computational efficiency of the existing SR algorithms. The proposed method implements some improvements in the dictionary training and the reconstruction process. A new dictionary was built by using an unsharp mask technique to characteristics extraction. Simultaneously, this strategy aim to extract more structural information of the low resolution and high resolution patches and reduce the dictionaries size. Another important contribution was the inclusion of an iterative and scalable process by reinserting the HR image obtained of first iteration. This solution aim to improve the quality of the final HR image using a few images in the training set. The results have demonstrated the ability of the proposed method to produce high quality images with reduced computational time.
25

Um método iterativo e escalonável para super-resolução de imagens usando a interpolação DCT e representação esparsa. / Iterative and scalable image super-resolution method with DCT interpolation and sparse representation.

Saulo Roberto Sodré dos Reis 23 April 2014 (has links)
Num cenário em que dispositivos de aquisição de imagens e vídeo possuem recursos limitados ou as imagens disponíveis não possuem boa qualidade, as técnicas de super-resolução (SR) apresentam uma excelente alternativa para melhorar a qualidade das imagens. Nesta tese é apresentada uma proposta para super-resolução de imagem única que combina os benefícios da interpolação no domínio da transformada DCT e a eficiência dos métodos de reconstrução baseados no conceito de representação esparsa de sinais. A proposta busca aproveitar as melhorias já alcançadas na qualidade e eficiência computacional dos principais algoritmos de super-resolução existentes. O método de super-resolução proposto implementa algumas melhorias nas etapas de treinamento e reconstrução da imagem final. Na etapa de treinamento foi incluída uma nova etapa de extração de características utilizando técnicas de aguçamento por máscara de nitidez e construção de um novo dicionário. Esta estratégia busca extrair mais informações estruturais dos fragmentos de baixa e alta resolução do conjunto de treinamento e ao mesmo tempo reduzir o tamanho dos dicionários. Outra importante contribuição foi a inclusão de um processo iterativo e escalonável no algoritmo, reinserindo no conjunto de treinamento e na etapa de reconstrução, uma imagem de alta resolução obtida numa primeira iteração. Esta solução possibilitou uma melhora na qualidade da imagem de alta resolução final utilizando poucas imagens no conjunto de treinamento. As simulações computacionais demonstraram a capacidade do método proposto em produzir imagens com qualidade e com tempo computacional reduzido. / In a scenario in which the acquisition systems have limited resources or available images do not have good quality, the super-resolution (SR) techniques have become an excellent alternative for improving the image quality. In this thesis, we propose a single-image super-resolution (SR) method that combines the benefits of the DCT interpolation and efficiency of sparse representation method for image reconstruction. Also, the proposed method seeks to take advantage of the improvements already achieved in quality and computational efficiency of the existing SR algorithms. The proposed method implements some improvements in the dictionary training and the reconstruction process. A new dictionary was built by using an unsharp mask technique to characteristics extraction. Simultaneously, this strategy aim to extract more structural information of the low resolution and high resolution patches and reduce the dictionaries size. Another important contribution was the inclusion of an iterative and scalable process by reinserting the HR image obtained of first iteration. This solution aim to improve the quality of the final HR image using a few images in the training set. The results have demonstrated the ability of the proposed method to produce high quality images with reduced computational time.
26

Aplicação do elemento finito DKT à análise de cascas / DKT finite element application in shells analysis

Elias Calixto Carrijo 12 December 1995 (has links)
Neste trabalho apresenta-se um elemento finito de casca plano que é obtido pela composição de um elemento de placa com um de membrana. O elemento de placa usado, o DKT (Discrete Kirchhoff Theory), pertence à classe dos elementos triangulares com nove graus de liberdade (uma translação e duas rotações por nó), e é obtido pela imposição da hipótese de Kirchhoff nos seus pontos nodais. Para o elemento de membrana, usou-se o elemento CST (Constant Strain Triangle), com seis graus de liberdade (duas translações por nó). O elemento finito resultante DCT, possui dezoito graus de liberdade (três translações e três rotações, sendo uma das rotações fictícia- no plano do elemento). Simples exemplos de placa e chapa no espaço foram analisados para se testar o elemento, e finalmente uma casca cilíndrica uniformemente carregada foi analisada e o resultado obtido comparado com o fornecido por outros autores. Neste estudo, o elemento DKT mostrou-se eficiente na análise de cascas. / This work presents a flat shell finite element composed of plates in bending and in tension finite elements. The bending element used, the DKT (Discrete Kirchhoff Theory) belongs to the class of triangular elements with nine degrees of freedom (the transverse displacement and its derivatives at each node) and it is obtained from the theory of plates with shear force influence with Kirchhoff hypothesis imposed in the nodes of the element. The tension finite element is the well known CST (Constant Strain Triangle) with six degrees of freedom (the displacement u and v at each node). The resulting finite element, called DCT, has 18 degrees of freedom, including an extra and fictitious rotation in the normal direction to the surface of elements. Single plates in bending and in tension described in a tridimensional system of coordinates were analyzed to test the adopted finite elements and finally cylindrical shell uniformly loaded were analyzed and the results compared with those of authors. In the work the DKT element shown to be a reliable finite element to be used in shell analysis.
27

Aplicação do elemento finito DKT à análise de cascas / DKT finite element application in shells analysis

Carrijo, Elias Calixto 12 December 1995 (has links)
Neste trabalho apresenta-se um elemento finito de casca plano que é obtido pela composição de um elemento de placa com um de membrana. O elemento de placa usado, o DKT (Discrete Kirchhoff Theory), pertence à classe dos elementos triangulares com nove graus de liberdade (uma translação e duas rotações por nó), e é obtido pela imposição da hipótese de Kirchhoff nos seus pontos nodais. Para o elemento de membrana, usou-se o elemento CST (Constant Strain Triangle), com seis graus de liberdade (duas translações por nó). O elemento finito resultante DCT, possui dezoito graus de liberdade (três translações e três rotações, sendo uma das rotações fictícia- no plano do elemento). Simples exemplos de placa e chapa no espaço foram analisados para se testar o elemento, e finalmente uma casca cilíndrica uniformemente carregada foi analisada e o resultado obtido comparado com o fornecido por outros autores. Neste estudo, o elemento DKT mostrou-se eficiente na análise de cascas. / This work presents a flat shell finite element composed of plates in bending and in tension finite elements. The bending element used, the DKT (Discrete Kirchhoff Theory) belongs to the class of triangular elements with nine degrees of freedom (the transverse displacement and its derivatives at each node) and it is obtained from the theory of plates with shear force influence with Kirchhoff hypothesis imposed in the nodes of the element. The tension finite element is the well known CST (Constant Strain Triangle) with six degrees of freedom (the displacement u and v at each node). The resulting finite element, called DCT, has 18 degrees of freedom, including an extra and fictitious rotation in the normal direction to the surface of elements. Single plates in bending and in tension described in a tridimensional system of coordinates were analyzed to test the adopted finite elements and finally cylindrical shell uniformly loaded were analyzed and the results compared with those of authors. In the work the DKT element shown to be a reliable finite element to be used in shell analysis.
28

Analyse de l'apport des technologies d'intégration tri-dimensionnelles pour les imageurs CMOS : application aux imageurs à grande dynamique / Benefits of tri-dimensional integration for CMOS image sensors : case study of high dynamic range imagers

Guezzi Messaoud, Fadoua 26 May 2014 (has links)
La poursuite de l'intégration de fonctions toujours plus complexes au sein d'un même circuit constitue un des principaux enjeux de la microélectronique. L'intégration tridimensionnelle par empilement de circuits (3D stacking) constitue une voie prometteuse pour y parvenir. Elle permet notamment de dépasser certaines limitations atteintes par les circuits actuels, plus particulièrement dans les circuits pour lesquelles les données sont distribuées et qui nécessitent des bandes passantes importantes. Néanmoins, à ce jour, très peu de travaux ont montré les avantages de l'intégration 3D, en particulier ceux s'appuyant sur des résultats expérimentaux et de circuits concrets notamment dans le domaine des imageurs. Le présent travail de thèse a eu pour objectif d'exploiter la technologie 3D dans le cadre des capteurs d'images et dépasser la preuve de concept présentée dans l'état de l'art afin d'apporter une analyse concrète des apports de cette technologie dans le domaine des imageurs visibles. Nous avons identifié, d'une part l'extension de dynamique qui requiert un traitement proche pixel, d'autre part la compression locale, destinée à adresser les problèmes d'intégrité du signal, bande passante et consommation qui deviennent critiques avec l'augmentation des formats des imageurs. Ce choix permet d'apporter une réponse à la limitation de la dynamique des capteurs d'images 2D actuels, tout en gardant une architecture classique des pixels et en adressant le problème de la réduction de la quantité de données à transmettre. Une nouvelle méthode de codage flottant par groupe de pixels a été proposée et implémentée. Le principe s'appuie sur l'adaptation du temps d'intégration par groupe de pixels via l'application d'un exposant commun au groupe. Le temps d'intégration est ajusté à l'image suivante. Un premier niveau de compression est ainsi réalisé par le codage mantisse-exposant proposé. L'implémentation de cette technique a été validée sur un démonstrateur 2D au détriment de pixels sacrifiés aveugles de chaque groupe de pixels, comportant l'électronique de génération des signaux de commande de la HDR. La technique d'extension de dynamique proposée est suivie d'une compression à base de DCT (Discrete Cosine Transform} permettant de réduire le flux de données en sortie de la puce imageur. Les deux niveaux de compression permettent d'atteindre des taux de compression élevés allant jusqu'à 93% en maintenant un PSNR de 30dB et une qualité d'image acceptable pour des post-traitements. Une étude théorique de l'apport de l'intégration 3D en termes de consommation a été élaborée. Enfin, un démonstrateur 2D a été réalisé en technologie CMOS 180 nm en vue de valider l'architecture grande dynamique proposée. L'utilisation de la technologie 3D, dans la suite des travaux, permet l'implémentation d'une boucle courte, devenue possible grâce aux interconnexions verticales sans sacrifier des pixels morts. Le traitement local proche du pixel et la réduction de la latence, du flux de données et de la consommation sont les apports majeurs de l'intégration 3D étudiés dans ce travail / With the increase of systems complexity, integrating different technologies together has become a major challenge. Another challenge has traditionally been the limitation on the throughout between different part of the system coming from the interconnections. If traditional two dimensional integration solutions like System In a Package (SIP) bring heterogonous technologies together there is still limitations coming from the restricted number and lengths of interconnections between the different system components. Three Dimensional stacking (3D), by exploiting short vertical interconnections between different circuits of mixed technologies, has the potential to overcome these limitations. Still, despite strong interests for the 3D concepts, there is no advanced analysis of 3D integration benefits, especially in the field of imagers and smart image sensors. This thesis study the potential benefits of 3D integration, with local processing and short feedback loops, for the realisation of a High Dynamic Range (HDR) image sensor. The dense vertical interconnections are used to locally adapt the integration time by group of pixels, called macro-pixels, while keeping a classic pixel architecture and hence a high fill factor. Stacking the pixel section and circuit section enables a compact pixel and the integration of flexible and versatile functions. High Dynamic Range values producing an important quantity of data, the choice has been made to implement data compression to reduce the circuit throughout. A first level of compression is produced by coding the pixel value using a floating format with a common exponent shared among the macro-pixel. A second level of compression is proposed based on a simplified version of the Discrete Cosine Transform (DCT). Using this two level scheme, a compression of 93% can be obtained with a typical PSNR of 30 dB. A validation of the architecture was carried out by the development; fabrication and test of a prototype on a 2D, 180 nm, CMOS technology. A few pixels of each macro-pixel had to be sacrificed to implement the high dynamic range control signals and emulate the 3D integration. The test results are very promising proving the benefits that will bring the 3D integration in term of power consumption and image quality compared to a classic 2D integration. Future realisations of this architecture, done using a real 3D technology, separating sensing and processing on different circuits communicating by vertical interconnection will not need the sacrifice of any pixel to adjust the integration time, improving power consumption, image quality and latency
29

Comparação da transformada wavelet discreta e da transformada do cosseno, para compressão de imagens de impressão digital / Comparison of the discrete transform cosine and the discrete wavelet transform for image of compression of fingerprint

Reigota, Nilvana dos Santos 27 February 2007 (has links)
Este trabalho tem por objetivo comparar os seguintes métodos de compressão de imagens de impressão digital: transformada discreta do cosseno (DCT), transformada de wavelets de Haar, transformada de wavelets de Daubechies e transformada de wavelets de quantização escalar (WSQ). O propósito da comparação é identificar o método que resulta numa menor perda de dados, para a maior taxa de compressão possível. São utilizadas as seguintes métricas para avaliação da qualidade da imagem para os métodos: erro quadrático médio (ERMS), a relação sinal e ruído (SNR) e a relação sinal ruído de pico (PSNR). Para as métricas utilizadas a DCT apresentou os melhores resultados, seguida pela WSQ. No entanto, o melhor tempo de compressão e a melhor qualidade das imagens recuperadas avaliadas pelo software GrFinger 4.2, foram obtidos com a técnica WSQ. / This research aims to compare the following fingerprint image compression methods: the discrete cosseno transform (DCT), Haar wavelet transform, Daubechies wavelets transform and wavelet scalar quantization (WSQ). The main interest is to find out the technique with the smallest distortion and higher compression ratio. Image quality is measured using peak signal-to-noise ratio (PSNR), signal-to-noise ratio (SNR) and root mean square (ERMS). Image quality using these metrics showed best results for the DCT followed by WSQ, although the WSQ had the best compression time and presented the best quality when evaluated by the GrFinger 4.2 software.
30

Comparação da transformada wavelet discreta e da transformada do cosseno, para compressão de imagens de impressão digital / Comparison of the discrete transform cosine and the discrete wavelet transform for image of compression of fingerprint

Nilvana dos Santos Reigota 27 February 2007 (has links)
Este trabalho tem por objetivo comparar os seguintes métodos de compressão de imagens de impressão digital: transformada discreta do cosseno (DCT), transformada de wavelets de Haar, transformada de wavelets de Daubechies e transformada de wavelets de quantização escalar (WSQ). O propósito da comparação é identificar o método que resulta numa menor perda de dados, para a maior taxa de compressão possível. São utilizadas as seguintes métricas para avaliação da qualidade da imagem para os métodos: erro quadrático médio (ERMS), a relação sinal e ruído (SNR) e a relação sinal ruído de pico (PSNR). Para as métricas utilizadas a DCT apresentou os melhores resultados, seguida pela WSQ. No entanto, o melhor tempo de compressão e a melhor qualidade das imagens recuperadas avaliadas pelo software GrFinger 4.2, foram obtidos com a técnica WSQ. / This research aims to compare the following fingerprint image compression methods: the discrete cosseno transform (DCT), Haar wavelet transform, Daubechies wavelets transform and wavelet scalar quantization (WSQ). The main interest is to find out the technique with the smallest distortion and higher compression ratio. Image quality is measured using peak signal-to-noise ratio (PSNR), signal-to-noise ratio (SNR) and root mean square (ERMS). Image quality using these metrics showed best results for the DCT followed by WSQ, although the WSQ had the best compression time and presented the best quality when evaluated by the GrFinger 4.2 software.

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