1,720,969 research outputs found
Dynamic shape detection and analysis of deformable structures in biomedical imaging
Full text linkThe goal of this work is to discuss a three-step-approach to detect, analyze and synthesize a shape given an image, or a sequence of images. Chapter 1 discusses what is a shape. The concept of shape is fuzzy: before delving with more complex topics we need at least to agree on what we call “shape”. Chapter 2 briefly present the biological case studies we used along the work.
Chapter 3 deals with the single shape detection problem, the easiest problem one could face: given a single image with a single shape of interest, how do we design an algorithm to detect it? Chapter 4 extends the single shape detection approach to reticular shapes, a kind of shapes common in biological images. Chapter 5 extends the single shape detection approach (and its reticular analogous) to a sequence of images, exploiting the temporal coherence.
Chapter 6 analyzes the shape, developing new metrics and measures, while chapter 7 closes the work dealing with the synthesis step.
A special section is chapter 8, which covers the Toolbox we developed to detect shapes. The Toolbox is meant to provide functions reusable on a plethora of problems.
Conclusions and future works are discussed in chapter 9.The goal of this work is to discuss a three-step-approach to detect, analyze and synthesize a shape given an image, or a sequence of images. Chapter 1 discusses what is a shape. The concept of shape is fuzzy: before delving with more complex topics we need at least to agree on what we call “shape”. Chapter 2 briefly present the biological case studies we used along the work.
Chapter 3 deals with the single shape detection problem, the easiest problem one could face: given a single image with a single shape of interest, how do we design an algorithm to detect it? Chapter 4 extends the single shape detection approach to reticular shapes, a kind of shapes common in biological images. Chapter 5 extends the single shape detection approach (and its reticular analogous) to a sequence of images, exploiting the temporal coherence.
Chapter 6 analyzes the shape, developing new metrics and measures, while chapter 7 closes the work dealing with the synthesis step.
A special section is chapter 8, which covers the Toolbox we developed to detect shapes. The Toolbox is meant to provide functions reusable on a plethora of problems.
Conclusions and future works are discussed in chapter 9
A ROBUST ACTIVE CONTOUR APPROACH FOR STUDYING CELL DEFORMATION FROM NOISY IMAGES
No full textThis work presents a generalized formulation of the Snake model defining new terms for the internal and the external energy functionals. These modifications conjugate features of the object contour as well as the inside of the shape. The obtained model is significantly more accurate spatially on the image plane and temporally on the frame sequence. In particular, the application to single cell analysis is in focus: In this context, we show how to cast the specific problem into the extended framework we propose. Shape descriptors and suitable metrics are then derived from the curve representation. The boundary identification produced through the classic formulation shows a poor and imprecise segmentation and leads to misleading metrics. The new model instead represents the boundary and the derived shape parameters in a way more consistent with the visual perception of shape evolution and deformation
VirtualShave: automated hair removal from digital dermatoscopic images
No full textVirtualShave is a novel tool to remove hair from digital dermatoscopic images. First, individual hairs are identified using a top-hat filter followed by morphological postprocessing. Then, they are replaced through PDE-based inpainting with an estimate of the underlying occluded skin. VirtualShave's performance is comparable to that of a human operator removing hair manually, and the resulting images are almost indistinguishable from those of hair-free skin
Is (N)PRI suitable for evaluating automated segmentation of cutaneous lesions?
No full textAn example of anomalous behaviour of the (Normalised) Probabilistic Rand Index – due to its non-monotonicity with the fraction of misclassified pixels – raises doubts on its suitability as a metric for cutaneous lesion segmentation
THE EMERGENT STRUCTURE OF THE DROSOPHILA WING A Dynamic Model Generator
No full textDrosophila melanogaster is a model organism in genetics thanks to the compactness of its genome and its relative simplicity. Recently, certain developmental patterns in Drosophila have been studied by mathematical models, with the aim of gaining deeper and quantitative insight into the morphogenesis of this insect. There is a need for accurate dynamical of the epithelial cell structure and organization within the fly wing, to further the understanding of a phenomenon known as planar cell polarity. The present study tackles the problem of retrieving such a salient structure using classical tools of dynamical system theory embedded with network and graph concepts. On the one hand the goal is to provide a visual detection and representation of the cell packaging that is accurate and fine. Particular care is also put in obtaining a model of this structure, whose main features are the compactness and simplicity
Where's the naevus? Inter-operator variability in the localization of melanocytic lesion border.
No full textBACKGROUND:
The first step in the analysis of a dermatoscopically imaged melanocytic lesion is segmentation - informally, isolating those points in the image belonging to the lesion from those belonging to the surrounding non-lesional skin. Although typically studied in the context of automated analysis, segmentation is a necessary step even for human operators who plan to evaluate quantitative features of a lesion (such as diameter or asymmetry).
METHODS:
In a double blind evaluation of the segmentation of 77 digital dermatoscopic images by 12 dermatologists of different experience, for each image and each pair of dermatologists, we compared the area of the lesion (according to the first dermatologist of the pair) and the area of the disagreement region (that classified as lesion by one of the two dermatologists but not by the other).
RESULTS:
The area of the disagreement region was on average 15.28% of the area of the lesion itself, and in 10% of the cases it was more than 28%. More experienced dermatologists showed greater agreement among themselves than with less experienced dermatologists, and a slight tendency toward 'tighter' segmentations.
CONCLUSION:
The evaluation methodology addresses a number of crucial difficulties encountered in previous studies and may be of independent interest. Our results underscore the necessity of taking into account inter-operator variability in large epidemiological studies, in particular those involving less experienced dermatologists, and of striving toward techniques allowing greater standardization and replicability in the evaluation of the fundamental visual parameters of lesions
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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