Search results for " Transformation"

A New Class of Searchable and Provably Highly Compressible String Transformations

2019

The Burrows-Wheeler Transform is a string transformation that plays a fundamental role for the design of self-indexing compressed data structures. Over the years, researchers have successfully extended this transformation outside the domains of strings. However, efforts to find non-trivial alternatives of the original, now 25 years old, Burrows-Wheeler string transformation have met limited success. In this paper we bring new lymph to this area by introducing a whole new family of transformations that have all the "myriad virtues" of the BWT: they can be computed and inverted in linear time, they produce provably highly compressible strings, and they support linear time pattern search direc…

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…

Effective and Efficient Interpolation for Mutual Information based Multimodality Elastic Image Registration

2009

Mutual information (MI) is a popular similarity metric for multimodality image registration purpose. However, it is negatively influenced by artifacts due to interpolation effects. As a result, registration algorithms performance could be affected. In this paper a novel interpolation scheme is presented. It is both effective and efficient. Effective because it limits the presence of local maxima in the mutual information curve, efficient because it is simple to compute being based on simple and optimized distance measures. The method is validated and compared against other techniques both from performance and time complexity persepectives. Differently from other reference works, which perfo…

An Evolution of the Non-Parameter Harris Affine Corner Detector: A Distributed Approach

2009

A parallel version of a new automatic Harris-based corner detector is presented. A scheduler to dynamically and homogeneously distribute high computational workload on heterogeneous parallel architectures such as Grid systems has been implemented to speedup the whole procedure. Experimental results show the robustness of the underlying scheduler, which can be easily exploited in various automatic image analysis systems.

Fuzzy Smoothed Composition of Local Mapping Transformations for Non-rigid Image Registration

2009

This paper presents a novel method for medical image regis- tration. The global transformation is obtained by composing affine trans- formations, which are recovered locally from given landmarks. Transfor- mations of adjacent regions are smoothed to avoid blocking artifacts, so that a unique continuous and differentiable global function is obtained. Such composition is operated using a technique derived from fuzzy C- means clustering. The method was successfully tested on several datasets; results, both qualitative and quantitative, are shown. Comparisons with other methods are reported. Final considerations on the efficiency of the technique are explained.

Introduction: Shakespearean Subversions.

2014

Dialettica e trasformazione in Th. W. Adorno

2020

La dialettica può svolgere un’effettiva funzione critico-conoscitiva in quanto, pur irretita nelle maglie del pensare identico, di esso è capace di ridisegnare la struttura concettuale, rendendola permeabile a quel che le sue rigide procedure classificatorie tendono inevitabilmente ad opprimere e occultare. Se la dialettica non è logica manifestativa del vero, se anzi rivela una compromissione inevitabile con il sapere illusorio prodotto dal pensiero identificante, del pensiero identificante rappresenta però l’unica chance di trasformazione Dialectics can play an effective critical-cognitive function in that, although caught in the mesh of «identity thinking», it is capable of redesigning t…

I vincoli della trasformazione: riflessioni sulla metamorfosi tra letteratura, filosofia e biologia

2019

Per sopravvivere gli esseri viventi sono costretto a modificarsi di continuo, adattandosi all’ambiente e al variare delle circostanze. In questa costante alterazione formale come si conciliano identità e mutamento? Come può l’individuo preservarsi dal totale dissolvimento in qualcos’altro? Questi sono solo alcuni dei quesiti che nei secoli hanno spinto studiosi di Morfologia, Estetica e Biologia a indagare le trasformazioni organiche. Nella presente trattazione cercheremo di chiarire le somiglianze e le differenze fra alcuni concetti chiave del vocabolario della metamorfosi (trasformazione, permutazione, vincolo, libertà di cambiamento, modularità organica) adottando un approccio multidisci…

Deformation

2020

In the continuous model of a solid object, which is ideally considered composed of such material points that each one of them is surrounded by a dense neighbourhood fully occupied by other points, the deformation is a variation carried out by a transformation, which does not preserve isometry. Deformations differ from displacements caused by rigid motions. For a closed boundary curve in the three-dimensional space, Plateau wondered what surfaces would minimize the potential surface energy. Deformation was held to underlie the evolution of biological forms, described by the “Cartesian transformations”, or the interpolation function of landmarks covariation over a thin-plate spline, the perce…

Shape

2020

In geometry, shape is the object of theorems associated to a class of transformations. It corresponds to the invariant properties of regions, figures, solids, which are not altered by transformations. The concept of shape implies the concepts of space, upon which transformations are acted, and metric, if distance is preserved, or a measurement function. The invariant properties of shape are fundamental to perception too. However, the classes of transformations build a hierarchy along which shape is more and more abstract from the Euclidean to the topological group, and accordingly, a greater number of perceptual properties are being lost. The science of perception addresses also the questio…