Tesi sul tema "Image processin"
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Bergström, Britt, e Erica Burlin. "Bildens godkännandeprocessi katalogproduktion : The image approval processin a catalog production". Thesis, Högskolan Dalarna, Grafisk teknik, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:du-4210.
Testo completoMurphy, Brian P. "Image processing techniques for acoustic images". Thesis, Monterey, California. Naval Postgraduate School, 1991. http://hdl.handle.net/10945/26585.
Testo completoThe primary goal of this research is to test the effectiveness of various image processing techniques applied to acoustic images generated in MATLAB. The simulated acoustic images have the same characteristics as those generated by a computer model of a high resolution imaging sonar. Edge Detection and Segmentation are the two image processing techniques discussed in this study. The two methods tested are a modified version of the Kalman filtering and median filtering
Khan, Preoyati. "Cluster Based Image Processing for ImageJ". Kent State University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=kent1492164847520322.
Testo completoYallop, Marc Richard. "Image processing techniques for passive millimetre wave images". Thesis, University of Reading, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.409545.
Testo completoBaabd, A., M. Y. Tymkovich e О. Г. Аврунін. "Image Processing of Panoramic Dental X-Ray Images". Thesis, ХГУ, 2018. http://openarchive.nure.ua/handle/document/6204.
Testo completoAbouRayan, Mohamed. "Real-time Image Fusion Processing for Astronomical Images". University of Toledo / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1461449811.
Testo completoKim, Younhee. "Towards lower bounds on distortion in information hiding". Fairfax, VA : George Mason University, 2008. http://hdl.handle.net/1920/3403.
Testo completoVita: p. 133. Thesis directors: Zoran Duric, Dana Richards. Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Computer Science. Title from PDF t.p. (viewed Mar. 17, 2009). Includes bibliographical references (p. 127-132). Also issued in print.
Tummala, Sai Virali, e Veerendra Marni. "Comparison of Image Compression and Enhancement Techniques for Image Quality in Medical Images". Thesis, Blekinge Tekniska Högskola, Institutionen för tillämpad signalbehandling, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-15360.
Testo completoAcosta, Edward Kelly. "A programmable processor for the Cheops image processing system". Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/36557.
Testo completoAbdulla, Ghaleb. "An image processing tool for cropping and enhancing images". Master's thesis, This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-12232009-020207/.
Testo completoMusoke, David. "Digital image processing with the Motorola 56001 digital signal processor". Scholarly Commons, 1992. https://scholarlycommons.pacific.edu/uop_etds/2236.
Testo completoLaunay, Claire. "Discrete determinantal point processes and their application to image processing". Thesis, Université de Paris (2019-....), 2020. http://www.theses.fr/2020UNIP7034.
Testo completoDeterminantal point processes (DPPs in short) are probabilistic models that capture negative correlations or repulsion within a set of elements. They tend to generate diverse or distant subsets of elements. This notion of similarity or proximity between elements is defined and stored in the kernel associated with each DPP. This thesis studies these models in a discrete framework, defined on a discrete and finite set of elements. We are interested in their application to image processing, when the initial set of points corresponds to the pixels or the patches of an image. Chapter 1 and 2 introduce determinantal point processes in a general discrete framework, their main properties and the algorithms usually used to sample them, i.e. used to select a subset of points distributed according to the chosen DPP. In this framework, the kernel of a DPP is a matrix. The main algorithm is a spectral algorithm based on the computation of the eigenvalues and the eigenvectors of the DPP kernel. In Chapter 2, we present a sampling algorithm based on a thinning procedure and a Cholesky decomposition but which does not require the spectral decomposition of the kernel. This algorithm is exact and, under certain conditions, competitive with the spectral algorithm. Chapter 3 studies DPPs defined over all the pixels of an image, called Determinantal Pixel Processes (DPixPs). This new framework imposes periodicity and stationarity assumptions that have consequences on the kernel of the process and on properties of the repulsion generated by this kernel. We study this model applied to Gaussian textures synthesis, using shot noise models. In this chapter, we are also interested in the estimation of the DPixP kernel from one or several samples. Chapter 4 explores DPPs defined on the set of patches of an image, that is the family of small square images contained in the image. The aim is to select a proportion of these patches, diverse enough to be representative of the information contained in the image. Such a selection can speed up certain patch-based image processing algorithms, or even improve the quality of existing algorithms that require patch subsampling. We present an application of this question to a texture synthesis algorithm
Pedron, Ilario. "Digital image processing for cancer cell finding using color images". Thesis, McGill University, 1988. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=61720.
Testo completoAhtaiba, Ahmed Mohamed A. "Restoration of AFM images using digital signal and image processing". Thesis, Liverpool John Moores University, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.604322.
Testo completoWear, Steven M. "Shift-invariant image reconstruction of speckle-degraded images using bispectrum estimation /". Online version of thesis, 1990. http://hdl.handle.net/1850/11219.
Testo completoKariani, H. "Review of Modern Frameworks for Microscopy Image Processing". Thesis, Ukraine, Kharkiv, 2021. https://openarchive.nure.ua/handle/document/16613.
Testo completoSahandi, Reza. "Image Processing". Thesis, University of Bradford, 1987. http://eprints.bournemouth.ac.uk/9884/.
Testo completoSoares, Andre Borin. "Exploração do paralelismo em arquiteturas para processamento de imagens e vídeo". reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2007. http://hdl.handle.net/10183/10539.
Testo completoNowadays video and image processing is a very important research area, because of its widespread use in a broad class of applications like entertainment, surveillance, control, medicine and many others. Some of the used algorithms to perform recognition, compression, decompression, filtering, restoration and enhancement of the images, require a computational power higher than the one available in conventional processors, requiring the development of dedicated architectures. This document presents the work developed in the design space exploration in the field of video and image processing architectures by the use of parallel processing. Many characteristics of this kind of architecture are pointed out. A novel technique is presented in which customized Processing Elements work in a cooperative way over a communication structure using a network on chip.
Louridas, Efstathios. "Image processing and analysis of videofluoroscopy images in cleft palate patients". Thesis, University of Kent, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.267392.
Testo completoBandyopadhyay, Abhishek. "Matrix transform imager architecture for on-chip low-power image processing". Diss., Available online, Georgia Institute of Technology, 2004:, 2004. http://etd.gatech.edu/theses/available/etd-08192004-133909/unrestricted/bandyopadhyay%5Fabhishek%5F200412%5Fphd.pdf.
Testo completoSmith, Mark, Committee Member ; DeWeerth, Steve, Committee Member ; Jackson, Joel, Committee Member ; David Anderson, Committee Member ; Hasler, Paul, Committee Chair. Includes bibliographical references.
Hillmer, Dirk. "Computer-based analysis of Biological Images Neuronal Networks for Image Processing". Electronic Thesis or Diss., Bordeaux, 2024. https://theses.hal.science/tel-04650911.
Testo completoAI in medicine is a rapidly growing field, and its significance in dermatology is increasingly pronounced. Advancements in neural networks, accelerated by powerful GPUs, have catalyzed the development of AI systems for skin disorder analysis. This study presents a novel approach that harnesses computer graphics techniques to create AI networks tailored to skin disorders. The synergy of these techniques not only generates training data but also optimizes image manipulation for enhanced processing. Vitiligo, a common depigmenting skin disorder, serves as a poignant case study. The evolution of targeted therapies underscores the necessity for precise assessment of the affected surface area. However, traditional evaluation methods are time-intensive and prone to inter- and intra-rater variability. In response, this research endeavors to construct an artificial intelligence (AI) system capable of objectively quantifying facial vitiligo severity.The AI model's training and validation leveraged a dataset of one hundred facial vitiligo images. Subsequently, an independent dataset of sixty-nine facial vitiligo images was used for final evaluation. The scores assigned by three expert physicians were compared with both inter- and intra-rater performances, as well as the AI's assessments. Impressively, the AI model achieved a remarkable accuracy of 93%, demonstrating its efficacy in quantifying facial vitiligo severity. The outcomes highlighted substantial concordance between AI-generated scores and those provided by human raters.Expanding beyond facial vitiligo, this model's utility in analyzing full-body images and images from various angles emerged as a promising avenue for exploration. Integrating these images into a comprehensive representation could offer insights into vitiligo's progression over time, thereby enhancing clinical diagnosis and research outcomes. While the journey has been fruitful, certain aspects of the research encountered roadblocks due to insufficient image and data resources. An exploration into analysis of in vivo mouse models and analysing pigmentation of skin cells in a preclinical embryo models as well as retina image recognition was regrettably halted. Nevertheless, these challenges illuminate the dynamic nature of research and underscore the importance of adaptability in navigating unforeseen obstacles.In conclusion, this study showcases the potential of AI to revolutionize dermatological assessment. By providing an objective evaluation of facial vitiligo severity, the proposed AI model offers a valuable adjunct to human assessment in both clinical practice and research settings. The ongoing pursuit of integrating AI into the analysis of diverse image datasets holds promise for broader applications in dermatology and beyond
Munechika, Curtis K. "Merging panchromatic and multispectral images for enhanced image analysis /". Online version of thesis, 1990. http://hdl.handle.net/1850/11366.
Testo completoROS, RENATO A. "Fusão de imagens médicas para aplicação de sistemas de planejamento de tratamento em radioterapia". reponame:Repositório Institucional do IPEN, 2006. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11417.
Testo completoMade available in DSpace on 2014-10-09T14:10:00Z (GMT). No. of bitstreams: 0
Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
Karelid, Mikael. "Image Enhancement over a Sequence of Images". Thesis, Linköping University, Department of Electrical Engineering, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-12523.
Testo completoThis Master Thesis has been conducted at the National Laboratory of Forensic Science (SKL) in Linköping. When images that are to be analyzed at SKL, presenting an interesting object, are of bad quality there may be a need to enhance them. If several images with the object are available, the total amount of information can be used in order to estimate one single enhanced image. A program to do this has been developed by studying methods for image registration and high resolution image estimation. Tests of important parts of the procedure have been conducted. The final results are satisfying and the key to a good high resolution image seems to be the precision of the image registration. Improvements of this part may lead to even better results. More suggestions for further improvementshave been proposed.
Detta examensarbete har utförts på uppdrag av Statens Kriminaltekniska Laboratorium (SKL) i Linköping. Då bilder av ett intressant objekt som ska analyseras på SKL ibland är av dålig kvalitet finns det behov av att förbättra dessa. Om ett flertal bilder på objektet finns tillgängliga kan den totala informationen fråndessa användas för att skatta en enda förbättrad bild. Ett program för att göra detta har utvecklats genom studier av metoder för bildregistrering och skapande av högupplöst bild. Tester av viktiga delar i proceduren har genomförts. De slutgiltiga resultaten är goda och nyckeln till en bra högupplöst bild verkar ligga i precisionen för bildregistreringen. Genom att förbättra denna del kan troligtvis ännu bättre resultat fås. Även andra förslag till förbättringar har lagts fram.
Akremi, Mohamed. "Manifold-Based Approaches for Action and Gesture Recognition". Electronic Thesis or Diss., université Paris-Saclay, 2025. http://www.theses.fr/2025UPAST045.
Testo completoHuman action recognition (HAR) has emerged as a critical research area due to its wide range of real-world applications, including human-computer interaction, intelligent healthcare, virtual reality, surveillance, UAV control, and autonomous systems. Over the past few decades, numerous approaches have been developed to recognize human actions from monocular RGB video sequences. More recently, the advent of depth sensors has fueled the growth of 3D activity analysis and 3D gesture recognition, leading to significant advancements in the field. Among the various techniques proposed, manifold-based approaches have gained prominence due to their ability to effectively model the temporal evolution of 3D skeletal data through manifold-invariant representations. These methods have demonstrated remarkable performance in addressing the challenging task of action recognition.In this work, we explore the properties of the Symmetric Positive Definite (SPD) manifold, one of the most widely used manifolds in action and gesture recognition. We propose a novel recognition framework that integrates both a detector and a classifier, leveraging an SPD-based neural network known as the SPD Siamese Neural Network. We validate its performance through extensive experiments on both segmented and continuous action sequences across multiple datasets. Our results demonstrate that this approach outperforms state-of-the-art methods in various scenarios.Despite these advancements, significant challenges persist, particularly in complex environments such as UAV-based human action recognition. To overcome these limitations, we introduce an improved model, SPDAGG-TransNet, which enhances the baseline SPD Siamese network by refining its temporal-spatial feature extraction and integrating a Transformer module. This enhancement strengthens the model's ability to capture long-range dependencies, enrich feature representations, and maintain the intrinsic geometric properties of SPD representations. By incorporating Transformer encoders, our approach further improves recognition accuracy by effectively modeling both local and global motion dynamics. Extensive evaluations on benchmark datasets, including DHG-14, UAV-Human, and UAV-Gesture, demonstrate that SPDAGG-TransNet achieves state-of-the-art performance.Beyond SPD-based approaches, we also explore hyperbolic space as an alternative geometric framework for motion recognition. Hyperbolic neural networks (HNNs) offer a promising direction for modeling hierarchical and structured relationships in motion data. Unlike conventional Euclidean-based deep learning models, hyperbolic architectures leverage Lorentz transformations and novel optimization techniques, such as the Riemannian Adam optimizer, to stabilize embeddings and enhance scalability. These advancements enable more effective hierarchical motion modeling, making hyperbolic learning particularly suitable for action recognition tasks.Extensive experiments conducted across multiple benchmarks—ranging from hand gesture recognition to full-body action recognition and UAV-based datasets demonstrate the effectiveness of both SPD-based and hyperbolic-based approaches in challenging scenarios. Our findings highlight the superiority of geometric learning frameworks in accurately modeling human motion, ensuring real-time adaptability, and overcoming the limitations of traditional Euclidean methods
Roudot, Philippe. "Image processing methods for dynamical intracellular processes analysis in quantitative fluorescence microscopy". Thesis, Rennes 1, 2014. http://www.theses.fr/2014REN1S025/document.
Testo completoWe propose in this manuscript a study of the instrumentation required for the quantification in frequency domain fluorescence lifetime imaging microscopy (FD FLIM). A FD FLIM measurement is defined as a series of images with sinusoidal intensity variations. The fluorescence lifetime is defined as the nanosecond-scale delay between excitation and emission of fluorescence. We propose two main contributions in the area: a modeling of the image process and noise introduced by the acquisition system (ICCD sensor); a robust statistical method for lifetime estimation on moving structures and intracellular vesicles. The second part presents a contribution to the tracking of multiple particles presenting heterogeneous transports in dense conditions. We focus here on the switching between confined diffusion in the cytosol and motor-mediated active transport in random directions. We show that current multiple model filtering and gating strategies fail at estimating unpredictable transitions between Brownian and directed displacements. We propose a new algorithm, based on the u-track algorithm [Jaqaman et al., 2008], based on a set of Kalman filters adapted to several motion types, for each tracked object. The algorithm has been evaluated on simulated and real data (vimentin, virus) data. We show that our method outperforms competing methods in the targeted scenario, but also on more homogeneous types of dynamics challenged by density
Guarino, de Vasconcelos Luiz Eduardo, André Yoshimi Kusomoto e Nelson Paiva Oliveira Leite. "Using Image Processing and Pattern Recognition in Images from Head-Up Display". International Foundation for Telemetering, 2013. http://hdl.handle.net/10150/579665.
Testo completoImages frames have always been used as information source for the Flight Test Campaigns (FTC). During the flight tests, the images displayed on the Head-Up Display (HUD) could be stored for later analysis. HUD images presents aircraft data provided by its avionics system. For a simplified Flight Test Instrumentation (FTI), where data accuracy is not a big issue, HUD images could become the primary information source. However in this case data analysis is executed manually, frame by frame for information extraction (e.g. Aircraft position parameters: Latitude; Longitude and Altitude). In approximately one hour of flight test about 36,000 frames are generated using standard-definition television format, therefore data extraction becomes complex, time consuming and prone to failures. To improve efficiency and effectiveness for this FTC, the Instituto de Pesquisas e Ensaios em Voo (IPEV - Flight Test and Research Institute) with Instituto Tecnológico de Aeronáutica (ITA - Aeronautical Technology Institute) developed an image processing application with pattern recognition using the correlation process to extract information from different positions on the images of the HUD. Preliminary test and evaluation carried out by 2012 using HUD images of the jet fighter EMBRAER A1. The test results demonstrate satisfactory performance for this tool.
Gopalan, Sowmya. "Estimating Columnar Grain Size in Steel-Weld Images using Image Processing Techniques". The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1250621610.
Testo completoBen, Rabha Jamal Salh. "An image processing decisional system for the Achilles tendon using ultrasound images". Thesis, University of Salford, 2018. http://usir.salford.ac.uk/46561/.
Testo completoOuellet, Michel. "Image processing architectures". Thesis, University of Ottawa (Canada), 1986. http://hdl.handle.net/10393/5068.
Testo completoGardiner, Bryan. "Hexagonal image processing". Thesis, University of Ulster, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.535794.
Testo completoHu, Nan. "SECURE IMAGE PROCESSING". UKnowledge, 2007. http://uknowledge.uky.edu/gradschool_theses/448.
Testo completoZhang, Yi. "Blur Image Processing". University of Dayton / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1448384360.
Testo completoDas, Mohammed. "Image analysis techniques for vertebra anomaly detection in X-ray images". Diss., Rolla, Mo. : University of Missouri--Rolla i.e. [Missouri University of Science and Technology], 2008. http://scholarsmine.mst.edu/thesis/MohammedDas_Thesis_09007dcc804c3cf6.pdf.
Testo completoDegree granted by Missouri University of Science and Technology, formerly known as University of Missouri--Rolla. Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed March 24, 2008) Includes bibliographical references (p. 87-88).
Yau, Chin-ko, e 游展高. "Super-resolution image restoration from multiple decimated, blurred and noisy images". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2004. http://hub.hku.hk/bib/B30292529.
Testo completoZhang, Jun. "Rendering and Image Processing for Micro Lithography on Xeon Phi Knights Landing Processor". Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-241088.
Testo completoSegmentprogrammet i Mycronics laserskrivare omvandlar vektorgrafik till rasterbild med hög beräkningsintensitet. IntelR Xeon PhiTM Knights Landing (KNL) är en process med många kärnor som levererar omfattande tråd och dataparallellitet. Detta projekt undersöker om KNL kan vara en bra kandidat som databehandlingsplattform i mikrolitografiska applikationer. Genomförbarheten studeras genom att profilera programmet på KNL tillsammans med att jämföra prestanda på KNL med andra arkitekturer, inklusive den nuvarande plattformen. Flera optimeringsmetoder implementeras med inriktning på KNL, vilket resulterar i effektivitetshöjningar upp till 5 %. Kostnaden för systemen beaktas. Den högt parallelliserade applikationen kan dra fördel av det stora antalet kärnor, vilket leder till hög prestanda per kostnad tillsammans med det relativt låga priset på KNL. Därför kan KNL vara en bra ersättare för den nuvarande plattformen som en högpresteran-de mönstergenerator.
Liu, Chia-Chin. "Image quality as a function of unsharp masking band center /". Online version of thesis, 1988. http://hdl.handle.net/1850/10420.
Testo completoLi, Shyi-Shyang. "Comparing the ability of subjective quality factor and information theory to predict image quality /". Online version of thesis, 1994. http://hdl.handle.net/1850/11880.
Testo completoGlotfelty, Joseph Edmund. "Automatic selection of optimal window size and shape for texture analysis". Morgantown, W. Va. : [West Virginia University Libraries], 1999. http://etd.wvu.edu/templates/showETD.cfm?recnum=898.
Testo completoTitle from document title page. Document formatted into pages; contains vii, 59 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 55-59).
Kim, Kyu-Heon. "Segmentation of natural texture images using a robust stochastic image model". Thesis, University of Newcastle Upon Tyne, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.307927.
Testo completoNeupane, Aashish. "Visual Saliency Analysis on Fashion Images Using Image Processing and Deep Learning Approaches". OpenSIUC, 2020. https://opensiuc.lib.siu.edu/theses/2784.
Testo completoMadaris, Aaron T. "Characterization of Peripheral Lung Lesions by Statistical Image Processing of Endobronchial Ultrasound Images". Wright State University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=wright1485517151147533.
Testo completoShajahan, Sunoj. "Agricultural Field Applications of Digital Image Processing Using an Open Source ImageJ Platform". Diss., North Dakota State University, 2019. https://hdl.handle.net/10365/29711.
Testo completoUnited States. Agricultural Research Service
National Institute of Food and Agriculture (U.S.)
Elmowafy, Osama Mohammed Elsayed. "Image processing systems for TV image tracking". Thesis, University of Kent, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.310164.
Testo completoKarlsson, Simon, e Per Welander. "Generative Adversarial Networks for Image-to-Image Translation on Street View and MR Images". Thesis, Linköpings universitet, Institutionen för medicinsk teknik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-148475.
Testo completoSchultz, Leah Hastings Samantha K. "Image manipulation and user-supplied index terms". [Denton, Tex.] : University of North Texas, 2009. http://digital.library.unt.edu/permalink/meta-dc-9828.
Testo completoWang, Bin. "Pixel-parallel image processing techniques and algorithms". Thesis, University of Manchester, 2014. https://www.research.manchester.ac.uk/portal/en/theses/pixelparallel-image-processing-techniques-and-algorithms(848f077c-4594-40f0-8dbe-8ac39fc69d0f).html.
Testo completoMohd, Padzil Fatihah. "Linear and nonlinear filter for image processing using MATLAB's image processing toolbox". Thesis, Mohd Padzil, Fatihah (2016) Linear and nonlinear filter for image processing using MATLAB's image processing toolbox. Honours thesis, Murdoch University, 2016. https://researchrepository.murdoch.edu.au/id/eprint/30815/.
Testo completoPérez, Benito Cristina. "Color Image Processing based on Graph Theory". Doctoral thesis, Universitat Politècnica de València, 2019. http://hdl.handle.net/10251/123955.
Testo completo[CAT] La visió artificial és un dels camps en major creixement en l'actualitat que, junt amb altres tecnlogies com la Biometria o el Big Data, s'ha convertit en el focus d'interés de nombroses investigacions i és considerada com una de les tecnologies del futur. Aquest ampli camp comprén diversos m`etodes entre els quals es troba el processament digital d'imatges i anàlisis d'imatges digitals. L'èxit de l'anàlisis d'imatges i altres tasques de processament d'alt nivell, com poden ser el reconeixement de patrons o la visió 3D, dependrà en gran manera de la bona qualitat de les imatges de partida. Avui dia existeixen multitud de factors que danyen les imatges dificultant l'obtenció d'imatges de qualitat òptima, açò ha convertit el (pre-) processament digital d'imatges en un pas fonamental previa la l'aplicació de qualsevol altra tasca de processament. Els factors més comuns són el soroll i les males condicions d'adquisició: els artefactes provocats pel soroll dificulten la inter- pretació adequada de la imatge i l'adquisició en condicions d'il·luminació o exposició deficients, com a escenes dinàmiques, causen pèrdua d'informació de la imatge que pot ser clau per a certes tasques de processament. Els passos de (pre-) processament d'imatges coneguts com suavitzat i realç s'apliquen comunament per a resoldre aquests problemes: El suavitzat té com a objecte reduir el soroll mentres que el real se centra a millorar o recuperar la informació imprecisa o danyada. Amb aquests mètodes aconseguim reparar informació dels detalls i bords de la imatge amb una nitidesa insuficient o un contingut borrós que impedeix el (post-)processament òptim de la imatge. Existeixen nombrosos mètodes que suavitzen el soroll d'una imatge, no obstant això, en molts casos el procés de filtrat provoca emborronamiento en els bords i detalls de la imatge. De la mateixa manera podem trobar una enorme quantitat de tècniques de realç que intenten combatre les pèrdues d'informació, no obstant això, aquestes tècniques no contemplen l'existència de soroll en la imatge que processen: davant d'una image sorollosa, qualsevol tècnica de realç provocarà també un augment del soroll. Encara que la idea intuïtiva per a solucionar aquest últim cas seria el previ filtrat i posterior realç, aquest enfocament ha demostrat no ser òptim: el filtrat podria eliminar informació que, al seu torn, podria no ser recuperable en el seguënt pas de realç. En la present Tesi doctoral es proposa un model basat en teoria de grafs per al processament d'imatges en color. En aquest model, es construïx un graf per a cada píxel de tal manera que les seues propietats permeten caracteritzar i classificar el píxel en quëstió. Com veurem, el model proposat és robust i capaç d'adaptar-se a una gran varietat d'aplicacions. En particular, apliquem el model per a crear noves solucions als dos problemes fonamentals del processament d'imatges: suavitzat i realç. S'ha estudiat el model en profunditat en funció del llindar, paràmetre clau que assegura la correcta classificació dels píxels de la imatge. A més, també s'han estudiat les possibles característiques i possibilitats del model que ens han permés traure-li el màxim partit en cadascuna de les possibles aplicacions. Basat en aquest model s'ha dissenyat un filtre adaptatiu capaç d'eliminar soroll gaussià d'una imatge sense difuminar els bords ni perdre informació dels detalls. A més, també ha permés desenvolupar un mètode capaç de realçar els bords i detalls d'una imatge al mateix temps que se suavitza el soroll present en la mateixa. Aquesta aplicació simultània aconseguix combinar dues operacions oposades per definició i superar així els inconvenients presentats per l'enfocament en dues etapes.
[EN] Computer vision is one of the fastest growing fields at present which, along with other technologies such as Biometrics or Big Data, has become the focus of interest of many research projects and it is considered one of the technologies of the future. This broad field includes a plethora of digital image processing and analysis tasks. To guarantee the success of image analysis and other high-level processing tasks as 3D imaging or pattern recognition, it is critical to improve the quality of the raw images acquired. Nowadays all images are affected by different factors that hinder the achievement of optimal image quality, making digital image processing a fundamental step prior to the application of any other practical application. The most common of these factors are noise and poor acquisition conditions: noise artefacts hamper proper image interpretation of the image; and acquisition in poor lighting or exposure conditions, such as dynamic scenes, causes loss of image information that can be key for certain processing tasks. Image (pre-) processing steps known as smoothing and sharpening are commonly applied to overcome these inconveniences: Smoothing is aimed at reducing noise and sharpening at improving or recovering imprecise or damaged information of image details and edges with insufficient sharpness or blurred content that prevents optimal image (post-)processing. There are many methods for smoothing the noise in an image, however in many cases the filtering process causes blurring at the edges and details of the image. Besides, there are also many sharpening techniques, which try to combat the loss of information due to blurring of image texture and need to contemplate the existence of noise in the image they process. When dealing with a noisy image, any sharpening technique may amplify the noise. Although the intuitive idea to solve this last case would be the previous filtering and later sharpening, this approach has proved not to be optimal: the filtering could remove information that, in turn, may not be recoverable in the later sharpening step. In the present PhD dissertation we propose a model based on graph theory for color image processing from a vector approach. In this model, a graph is built for each pixel in such a way that its features allow to characterize and classify the pixel. As we will show, the model we proposed is robust and versatile: potentially able to adapt to a variety of applications. In particular, we apply the model to create new solutions for the two fundamentals problems in image processing: smoothing and sharpening. To approach high performance image smoothing we use the proposed model to determine if a pixel belongs to a at region or not, taking into account the need to achieve a high-precision classification even in the presence of noise. Thus, we build an adaptive soft-switching filter by employing the pixel classification to combine the outputs from a filter with high smoothing capability and a softer one to smooth edge/detail regions. Further, another application of our model allows to use pixels characterization to successfully perform a simultaneous smoothing and sharpening of color images. In this way, we address one of the classical challenges within the image processing field. We compare all the image processing techniques proposed with other state-of-the-art methods to show that they are competitive both from an objective (numerical) and visual evaluation point of view.
Pérez Benito, C. (2019). Color Image Processing based on Graph Theory [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/123955
TESIS
Bibby, Geoffrey Thomas. "Digital image processing using parallel processing techniques". Thesis, Liverpool John Moores University, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.304539.
Testo completo