Title from PDF of title page. / Document formatted into pages; contains 76 pages. / Thesis (M.S.E.E.)--University of South Florida, 2003. / Includes bibliographical references. / Text (Electronic thesis) in PDF format. / ABSTRACT: The use of digitized information is rapidly gaining acceptance in bio-medical applications. Video compression plays an important role in the archiving and transmission of different digital diagnostic modalities. The present scheme of video compression for low bit-rate networks is not suitable for medical video sequences. The instability is the result of block artifacts resulting from the block based DCT coefficient quantization. The possibility of applying deformable motion estimation techniques to make the video compression standard (H.263) more adaptable for bio-medial applications was studied in detail. The study on the network characteristics and the behavior of various congestion control mechanisms was used to analyze the complete characteristics of existing low bit rate video compression algorithms. The study was conducted in three phases. The first phase involved the implementation and study of the present H.263 compression standard and its limitations. / ABSTRACT: The second phase dealt with the analysis of an external force for active contours which was used to obtain estimates for deformable objects. The external force, which is termed Gradient Vector Flow (GVF), was computed as a diffusion of the gradient vectors associated with a gray-level or binary edge map derived from the image. The mathematical aspect of a multi-scale framework based on a medial representation for the segmentation and shape characterization of anatomical objects in medical imagery was derived in detail. The medial representations were based on a hierarchical representation of linked figural models such as protrusions, indentations, neighboring figures and included figures--which represented solid regions and their boundaries. The third phase dealt with the vital parameters for effective video streaming over the internet in the bottleneck bandwidth, which gives the upper limit for the speed of data delivery from one end point to the other in a network. / ABSTRACT: If a codec attempts to send data beyond this limit, all packets above the limit will be lost. On the other hand, sending under this limit will clearly result in suboptimal video quality. During this phase the packet-drop-rate (PDR) performance of TCP(1/2) was investigated in conjunction with a few representative TCP-friendly congestion control protocols (CCP). The CCPs were TCP(1/256), SQRT(1/256) and TFRC (256), with and without self clocking. The CCPs were studied when subjected to an abrupt reduction in the available bandwidth. Additionally, the investigation studied the effect on the drop rates of TCP-Compatible algorithms by changing the queuing scheme from Random Early Detection (RED) to DropTail. / System requirements: World Wide Web browser and PDF reader. / Mode of access: World Wide Web.

Devido à variação na qualidade e ao ruído nas imagens médicas, a aplicação de técnicas tradicionais de segmentação é geralmente ineficiente. Nesse sentido, apresenta-se um novo algoritmo a partir de duas técnicas: o modelo de contornos deformáveis por fluxo do vetor gradiente (GVF deformable contours) e a técnica de espaço de escalas utilizando o processo de difusão. Assim, foi realizada uma revisão bibliográfica dos modelos que trabalham com os contornos deformáveis, os quais foram classificados em modelos paramétricos e geométricos. Entre os modelos paramétricos foi escolhido o modelo de contornos deformáveis por fluxo do vetor gradiente (GVF). Esta aproximação oferece precisão na representação de estruturas biológicas não observada em outros modelos. Desta forma, o algoritmo apresentado mapeia as bordas (edge map) e aperfeiçoa a condução da deformação utilizando uma técnica baseada em operações recursivas. Com este cálculo apoiado no comportamento de espaço de escalas, obtem-se a localização e correção de sub-regiões do edge map que perturbam a deformação. Por outro lado, é incorporada uma nova característica que permite ao algoritmo realizar atividades de classificação. O algoritmo consegue determinar a presença ou ausência de um objeto de interesse utilizando um valor mínimo de deformação. O algoritmo é validado através do tratamento de imagens sintéticas e médicas comparando os resultados com os obtidos no modelo tradicional de contornos deformáveis GVF. / Due to the variation of the quality and noise in medical images, the classic image segmentation techniques are usually ineffective. In this work, we present a new algorithm that is composed of two techniques: the gradient vector flow deformable contours (GVF) and the scale-space technique using a diffusion process. A bibliographical revision of the models that work with deformable contours was accomplished, they were classified in parametric and geometric models. Among the parametric models the gradient vector flow deformable contours (GVF) was chosen. This approach offers precision in the representation of biological structures where other models does not. Thus, the algorithm improves the edge map to guide the deformation using recursive operations. With this estimation based on the behavior of the scale-space techniques it is realized, the localization and correction of sub-areas of the edge map that disturb the deformation. On the other hand, it was incorporated a new characteristic that allows the algorithm to accomplish classification activities. That is, the algorithm determines the presence or absence of a target object using a minimal deformation area. Our method was validated on both, simulated images and medical images making a comparison with the traditional GVF deformable contours.

Die vorliegende Arbeit befasst sich mit Algorithmen aus dem Bereich der Bildsegmentierung sowie der Datensynthese für das so genannte Hologrammdruck-Prinzip. Angelehnt an ein anatomisch motiviertes Forschungsprojekt werden aktive Konturen zur halbautomatischen Segmentierung digitalisierter histologischer Schnitte herangezogen. Die besondere Herausforderung liegt dabei in der Entwicklung von verschiedenen Ansätzen, die der Anpassung des Verfahrens für sehr große Bilder dienen, welche in diesem Kontext eine Größe von einigen hundert Megapixel erreichen können. Unter dem Aspekt der größtmöglichen Effizienz, jedoch mit der Beschränkung auf die Verwendung von Consumer-Hardware, werden Ideen vorgestellt, welche eine auf aktiven Konturen basierende Segmentierung bei derartigen Bildgrößen erstmals ermöglichen sowie zur Beschleunigung und Reduktion des Speicheraufwandes beitragen. Darüber hinaus wurde das Verfahren um ein intuitives Werkzeug erweitert, das eine interaktive lokale Korrektur der finalen Kontur gestattet und damit die Praxistauglichkeit der Methode maßgeblich erhöht. Der zweite Teil der Arbeit beschäftigt sich mit einem Druckprinzip für die Herstellung von Hologrammen, basierend auf virtuellen Abbildungsgegenständen. Der Hologrammdruck, der namentlich an die Arbeitsweise eines Tintenstrahldruckers erinnern soll, benötigt dazu spezielle diskrete Bilddaten, die als Elementarhologramme bezeichnet werden. Diese tragen die visuelle Information verschiedener Blickrichtungen durch einen festen geometrischen Ort auf der Hologrammebene. Ein vollständiges, aus vielen Elementarhologrammen zusammengesetztes Hologramm erzeugt dabei ein erhebliches Datenvolumen, das parameterabhängig schnell im Terabyte-Bereich liegen kann. Zwei unabhängige Algorithmen zur Erzeugung geeignet aufbereiteter Daten unter intensiver Ausnutzung von Standard-Graphikhardware werden präsentiert, hinsichtlich ihrer Berechnungs- sowie Speicherkomplexität verglichen und unter Berücksichtigung von Qualitätsaspekten bewertet.

Σε αυτή την εργασία παρουσιάζεται μια πλήρως αυτοματοποιημένη μεθοδολογία κατάτμησης για την ανίχνευση των ορίων του αρτηριακού τοιχώματος σε διαμήκεις εικόνες καρωτίδας β-σάρωσης. Συγκεκριμένα υλοποιείται ένας συνδυασμός της μεθοδολογίας του μετασχηματισμού Hough για την ανίχνευση ευθειών με μια μεθοδολογία ενεργών καμπυλών. Η μεθοδολογία του μετασχηματισμού Hough χρησιμοποιείται για τον ορισμό της αρχικής καμπύλης, η οποία στη συνέχεια παραμορφώνεται σύμφωνα με ένα μοντέλο ενεργών καμπυλών βασισμένων σε πεδίο ροής του διανύσματος κλίσης (Gradient Vector Flow - GVF). Το GVF μοντέλο ενεργών καμπυλών βασίζεται στον υπολογισμό του χάρτη ακμών της εικόνας και τον μετέπειτα υπολογισμό του διανυσματικού πεδίου ροής κλίσης, το οποίο με τη σειρά του προκαλεί την παραμόρφωση της αρχικής καμπύλης με σκοπό την εκτίμηση των πραγματικών ορίων του αρτηριακού τοιχώματος. Η προτεινόμενη μεθοδολογία εφαρμόστηκε σε είκοσι (20) εικόνες υγιών περιπτώσεων και δεκαοχτώ (18) εικόνες περιπτώσεων με αθηρωμάτωση για τον υπολογισμό της διαμέτρου του αυλού και την αξιολόγηση της μεθόδου από ποσοτικούς δείκτες ανάλυσης κατά ROC (Receiver Operating Characteristic – ROC). Σύμφωνα με τα αποτελέσματα, δεν παρατηρήθηκαν στατιστικά σημαντικές διαφορές ανάμεσα στις μετρήσεις της διαμέτρου που πραγματοποιήθηκαν από τη διαδικασία της αυτόματης ανίχνευσης και τις αντίστοιχες μετρήσεις που προέκυψαν από την χειροκίνητη ανίχνευση. Οι τιμές της ευαισθησίας, της ειδικότητας και της ακρίβειας στις υγιείς περιπτώσεις ήταν αντίστοιχα 0.97, 0.99 και 0.98 για τις διαστολικές και τις συστολικές εικόνες. Στις παθολογικές περιπτώσεις οι αντίστοιχες τιμές ήταν μεγαλύτερες από 0.89, 0.96 και 0.93. Συμπερασματικά, η προτεινόμενη μεθοδολογία αποτελεί μια ακριβή και αξιόπιστη μέθοδο κατάτμησης εικόνων καρωτίδας και μπορεί να χρησιμοποιηθεί στην κλινική πράξη. / In this thesis, a fully automatic segmentation method based on a combination of a combination of the Hough Transform for the detection of straight lines with active contours is presented, for detecting the carotid artery wall in longitudinal B-mode ultrasound images. A Hough-transform-based methodology is used for the definition of the initial snake, followed by a gradient vector flow (GVF) snake deformation. The GVF snake is based on the calculation of the image edge map and the calculation of the gradient vector flow field which guides its deformation for the estimation of the real arterial wall boundaries. The proposed methodology was applied in twenty and eighteen cases of healthy and atherosclerotic carotid respectively, in order to calculate the lumen diameter and evaluate the method by means of ROC analysis (Receiver Operating Characteristic – ROC). According to the results, there was no significant difference between the automated segmentation and the manual diameter measurements. In healthy cases the sensitivity, specificity and accuracy were 0.97, 0.99 and 0.98, respectively, for both diastolic and systolic phase. In atherosclerotic cases the calculated values of the indices were larger than 0.89, 0.96 and 0.93, respectively. In conclusion, the proposed methodology provides an accurate and reliable way to segment ultrasound images of the carotid wall and can be used in clinical practice.

This master’s thesis is focused on automating the process of differential leukocyte count in peripherial blood using image processing. It deals with the design of the processing of digital images - from scanning and image preprocessing, segmentation nucleus and cytoplasm, feature selection and classifier, including testing on a set of images that were scanned in the context of this work. This work introduces used segmentation methods and classification procedures which separate nucleus and the cytoplasm of leukocytes. A statistical analysis is performed on the basis of these structures. Following adequate statistical parameters, a set of features has been chosen. This data then go through a classification process realized by three artificial neural networks. Overall were classified 5 types of leukocytes: neutropfiles, lymphocytes, monocytes, eosinophiles and basophiles. The sensitivity and specificity of the classification made for 4 out of 5 leukocyte types (neutropfiles, lymphocytes, monocytes, eosinophiles) is higher than 90 %. Sensitivity of classiffication basophiles was evaluated at 75 % and specificity at 67 %. The total ability of classification has been tested on 111 leukocytes and was approximately 91% successful. All algorithms were created in the MATLAB program.

This master´s thesis deals with depiction aplication of camera like sensitive element for assisting system of car. It was proposed, how find a road, a lane and a obstacle on roadways. Only one camera was aplication for it. Solution is realized by methods, that are based on color and gradient of image. It applies simple methods and methods with mathematical model. Result is sum of method and its test and comparing. Realization of my program is present at resume of this thesis.

In computer graphics we can handle unstructured triangular 3D meshes which are not too usable for processing through their irregularity. In these situations it occurs need of conversion that 3D mesh to more suitable representation. Some kind of 3D spline surface can be proper alternative because it institutes regularity in the form of control points grid and that's why it is more suitable for next processing. During conversion, which is described in this thesis, quadrilateral 3D mesh is constructed at first. This mesh has regular structure but mainly the structure corresponds to structure of control points grid of resulting 3D spline surface. Created quadrilateral 3D mesh can be saved and consequently used in specific modeling applications for T-spline surface creation.