65,529 research outputs found
Medical images modality classification using multi-scale dictionary learning
In this paper, we proposed a method for classification of medical images captured by different sensors (modalities) based on multi-scale wavelet representation using dictionary learning. Wavelet features extracted from an image provide discrimination useful for classification of medical images, namely, diffusion tensor imaging (DTI), magnetic resonance imaging (MRI), magnetic resonance angiography (MRA) and functional magnetic resonance imaging (FRMI). The ability of On-line dictionary learning (ODL) to achieve sparse representation of an image is exploited to develop dictionaries for each class using multi-scale representation (wavelets) feature. An experimental analysis performed on a set of images from the ICBM medical database demonstrates efficacy of the proposed method
Reducible conformal holonomy in any metric signature and application to twistor spinors in low dimension
We prove that given a pseudo-Riemannian conformal structure whose conformal
holonomy representation fixes a totally lightlike subspace of arbitrary
dimension, there is, wrt. a local metric in the conformal class defined off a
singular set, a parallel, totally lightlike distribution on the tangent bundle
which contains the image of the Ricci-tensor. This generalizes results obtained
for invariant lightlike lines and planes and closes a gap in the understanding
of the geometric meaning of reducibly acting conformal holonomy groups. We show
how this result naturally applies to the classification of geometries admitting
twistor spinors in some low-dimensional split signatures when they are
described using conformal spin tractor calculus. Together with already known
results about generic distributions in dimensions 5 and 6 we obtain a complete
geometric description of local geometries admitting real twistor spinors in
signatures (3,2) and (3,3). In contrast to the generic case where generic
geometric distributions play an important role, the underlying geometries in
the non-generic case without zeroes turn out to admit integrable distributions.Comment: 15 page
Tensor-Based Algorithms for Image Classification
Interest in machine learning with tensor networks has been growing rapidly in recent years. We show that tensor-based methods developed for learning the governing equations of dynamical systems from data can, in the same way, be used for supervised learning problems and propose two novel approaches for image classification. One is a kernel-based reformulation of the previously introduced multidimensional approximation of nonlinear dynamics (MANDy), the other an alternating ridge regression in the tensor train format. We apply both methods to the MNIST and fashion MNIST data set and show that the approaches are competitive with state-of-the-art neural network-based classifiers
End-to-End Learning of Representations for Asynchronous Event-Based Data
Event cameras are vision sensors that record asynchronous streams of
per-pixel brightness changes, referred to as "events". They have appealing
advantages over frame-based cameras for computer vision, including high
temporal resolution, high dynamic range, and no motion blur. Due to the sparse,
non-uniform spatiotemporal layout of the event signal, pattern recognition
algorithms typically aggregate events into a grid-based representation and
subsequently process it by a standard vision pipeline, e.g., Convolutional
Neural Network (CNN). In this work, we introduce a general framework to convert
event streams into grid-based representations through a sequence of
differentiable operations. Our framework comes with two main advantages: (i)
allows learning the input event representation together with the task dedicated
network in an end to end manner, and (ii) lays out a taxonomy that unifies the
majority of extant event representations in the literature and identifies novel
ones. Empirically, we show that our approach to learning the event
representation end-to-end yields an improvement of approximately 12% on optical
flow estimation and object recognition over state-of-the-art methods.Comment: To appear at ICCV 201
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