Search results for " Images."
showing 10 items of 193 documents
Turbidity analysis in Sicilian coastal zones by means of remote sensing images and spectroradiometric measurements
2009
Water turbidity has a wide range of variability both spatially and temporally. Rivers transport sediments to the river mouth following a seasonal behaviour and occasionally during flood events (Doxaran et al., 2006; Pribble et al., 2001). Once in the sea, sediments are spatially driven by currents, and re-suspended by waves from the bottom, changing water turbidity in the tidal and sub-tidal zones (Cloern et al., 1989; Uncles et al., 2002; Wolanski & Spagnol, 2003). Moreover human activities such as transport and dredging occasionally and locally influence turbidity magnitude and distribution (Schoellhamer, 1996). In recent years the pollution of the maritime environment suggests that only …
Graph-based minimal path tracking in the skeleton of the retinal vascular network
2012
This paper presents a semi-automatic framework for minimal path tracking in the skeleton of the retinal vascular network. The method is based on the graph structure of the vessel network. The vascular network is represented based on the skeleton of the available segmented vessels and using an undirected graph. Significant points on the skeleton are considered nodes of the graph, while the edge of the graph is represented by the vessel segment linking two neighboring nodes. The graph is represented then in the form of a connectivity matrix, using a novel method for defining vertex connectivity. Dijkstra and Floyd-Warshall algorithms are applied for detection of minimal paths within the graph…
Multi-modal Medical Image Registration by Local Affine Transformations
2018
Image registration is the process of finding the geometric transformation that, applied to the floating image, gives the registered image with the highest similarity to the reference image. Registering a pair of images involves the definition of a similarity function in terms of the parameters of the geometric transformation that allows the registration. This paper proposes to register a pair of images by iteratively maximizing the empirical mutual information through coordinate gradient descent. Hence, the registered image is obtained by applying a sequence of local affine transformations. Rather than adopting a uniformly spaced grid to select image blocks to locally register, as done by s…
Noise Filtering Using Edge-Driven Adaptive Anisotropic Diffusion
2008
This paper presents a method aimed to noise removal in MRI (Magnetic Resonance Imaging). We propose an improvement of Perona and Malik's anisotropic diffusion filter. In our schema, the diffusion equation of the filter has been modified to take into account the edges direction, This allows the filter to blur uniform areas, while it better preserves the edges. Both quantitative and qualitative evaluation is presented and the results are compared with other methods.
PHOTOGRAMMETRY NOW AND THEN - FROM HAND-CRAFTED TO DEEP-LEARNING TIE POINTS
2022
Abstract. Historical images provide a valuable source of information exploited by several kinds of applications, such as the monitoring of cities and territories, the reconstruction of destroyed buildings, and are increasingly being shared for cultural promotion projects through virtual reality or augmented reality applications. Finding reliable and accurate matches between historical and present images is a fundamental step for such tasks since they require to co-register the present 3D scene with the past one. Classical image matching solutions are sensitive to strong radiometric variations within the images, which are particularly relevant in these multi-temporal contexts due to differen…
Methods and Techniques for Multi-source Data Analysis and Fusion
This work has been inspired by the recent trend in remote sensing and environmental data acquisition. Remote sensing techniques allow us to measure information about an object without touching it. In the last decades remote sensing via satellites has been used in various applications such as Earth observation, weather and storm predictive analysis, atmospheric monitoring, climate change, human-environment interactions. Sensors on airborne and satellite platforms have been recording signals from space for many years, giving rise to a huge amount of data. Some data are processed on-board but others are treated and post-processed in ground stations. Signal and image processing are widely appli…
Exponential Entropy Driven HUM on Knee MR Images
2007
A very important artifact corrupting Magnetic Resonance Images is the RF inhomogeneity. This kind of artifact generates variations of illumination which trouble both direct examination by the doctor and segmentation algorithms. Even if homomorphic filtering approaches have been presented in literature, none of them has developed a measure to determine the cut-off frequency. In this work we present a measure based on information theory with a large experimental setup aimed to demonstrate the validity of our approach.
La Sicilia negli Orsi di Dino Buzzati e Lorenzo Mattotti
2022
Nella fiaba illustrata di Dino Buzzati La famosa invasione degli orsi in Sicilia (1945) e nella sua trasposizione filmica ad opera di Lorenzo Mattotti (2019) l’ambientazione siciliana è determinante. In entrambi i casi la Sicilia è un’isola con un grande vulcano – trasfigurata in un ambiente fantastico o riscritta secondo alcuni stereotipi – che i due autori utilizzano con accezioni diverse nella costituzione dell’ecosistema delle loro narrazioni. Soltanto attraverso una comparazione tra le due opere sarà possibile distinguere la rappresentazione delle due Sicilie che vengono raccontate con un intervallo di circa settanta anni. Se non si considera la storia degli Orsi soltanto una fiaba per…
Premessa a: Cultura visuale in Italia : immagini, sguardi, dispositivi
2022
Questo volume raccoglie le riflessioni maturate durante il convegno internazionale “Cultura visuale in Italia. Prospettive della ricerca” svoltosi a Palermo tra il 19 e il 21 marzo 2018. Si è trattato di un incontro che ha visto la partecipazio- ne di molti dei protagonisti della ricerca italiana in quell’ambito “indisciplinato” – per usare una felice espressione di W.J.T. Mitchell – che è la cultura visuale, accademica e non, un campo di studi che ha ormai solide tradizioni internazionali e anche notevoli ricadute accademiche, come dimostra la presenza a Palermo di docenti che, pur provenendo da “altre” discipline, la comparatistica letteraria, l’estetica, la storia dell’arte, la mediologi…
De l’espace à l’étendue. L’évolution de l’imaginaire spatial dans l’œuvre de Saint-Exupéry
2010
L’espace chez Saint-Exupéry refuse la définition de « décor » et plus encore celle de « paysage », tout en gardant un lien fort avec les lieux concrets qui sont des repères pour l’homme. L’espace parcouru, connu dans sa matière, se révèle surtout à travers le dynamisme de l’imaginaire de l’auteur. D’après Bachelard, l’intérêt pour Saint-Exupéry « résidait dans la poétique des matières et des dynamismes ». L’espace devient le leitmotiv de son œuvre entière, ce qui nous a guidés dans la tentative d’illustrer l’évolution que celui-ci subit. Il s’agit d’un parcours pour ainsi dire « en spirale », soutenu par un tissu d’images qui s’alimente du contact avec les éléments du réel et au même temps …