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The efficient realization of linear space-variant (non-convolution) filters is a challenging computational problem in image processing. In this paper, we demonstrate that it is possible to filter an image with a Gaussian-like elliptic…

Computer Vision and Pattern Recognition · Computer Science 2016-11-17 Kunal Narayan Chaudhury , Arrate Munoz-Barrutia , Michael Unser

It is well-known that box filters can be efficiently computed using pre-integrations and local finite-differences [Crow1984,Heckbert1986,Viola2001]. By generalizing this idea and by combining it with a non-standard variant of the Central…

Computer Vision and Pattern Recognition · Computer Science 2015-05-30 Kunal N. Chaudhury , Sebanti Sanyal

Detecting elliptical objects from an image is a central task in robot navigation and industrial diagnosis where the detection time is always a critical issue. Existing methods are hardly applicable to these real-time scenarios of limited…

Computer Vision and Pattern Recognition · Computer Science 2017-08-02 Qi Jia , Xin Fan , Zhongxuan Luo , Lianbo Song , Tie Qiu

The bilateral filter is a non-linear filter that uses a range filter along with a spatial filter to perform edge-preserving smoothing of images. A direct computation of the bilateral filter requires $O(S)$ operations per pixel, where $S$ is…

Computer Vision and Pattern Recognition · Computer Science 2016-05-04 Kunal N. Chaudhury , Swapnil D. Dabhade

Fast methods for convolution and correlation underlie a variety of applications in computer vision and graphics, including efficient filtering, analysis, and simulation. However, standard convolution and correlation are inherently limited…

Computer Vision and Pattern Recognition · Computer Science 2020-07-29 Thomas W. Mitchel , Benedict Brown , David Koller , Tim Weyrich , Szymon Rusinkiewicz , Michael Kazhdan

In the classical bilateral filter, a fixed Gaussian range kernel is used along with a spatial kernel for edge-preserving smoothing. We consider a generalization of this filter, the so-called adaptive bilateral filter, where the center and…

Computer Vision and Pattern Recognition · Computer Science 2018-11-07 Ruturaj G. Gavaskar , Kunal N. Chaudhury

We define a new framework that unifies the filtration and mapper approaches from TDA, and present efficient algorithms to compute it. Termed the box filtration of a PCD, we grow boxes (hyperrectangles) that are not necessarily centered at…

Computational Geometry · Computer Science 2025-10-10 Enrique Alvarado , Prashant Gupta , Bala Krishnamoorthy

Existing fast algorithms for bilateral and nonlocal means filtering mostly work with grayscale images. They cannot easily be extended to high-dimensional data such as color and hyperspectral images, patch-based data, flow-fields, etc. In…

Computer Vision and Pattern Recognition · Computer Science 2018-11-07 Pravin Nair , Kunal. N. Chaudhury

We propose an efficient method for spatial filtering of light beams by propagating them through 2D (also 3D) longitudinally chirped photonic crystals, i.e. through the photonic structures with fixed transverse lattice period and with the…

Optics · Physics 2015-05-13 Kestutis Staliunas , Victor J. Sanchez-Morcillo

The problem of finding elliptical shapes in an image will be considered. We discuss the solution which uses cross-entropy clustering. The proposed method allows the search for ellipses with predefined sizes and position in the space.…

Computer Vision and Pattern Recognition · Computer Science 2015-12-09 Jacek Tabor , Krzysztof Misztal

Expanding the receptive field to capture large-scale context is key to obtaining good performance in dense prediction tasks, such as human pose estimation. While many state-of-the-art fully-convolutional architectures enlarge the receptive…

Machine Learning · Computer Science 2019-06-28 Linguang Zhang , Maciej Halber , Szymon Rusinkiewicz

This paper addresses the search for a fast and meaningful image segmentation in the context of $k$-means clustering. The proposed method builds on a widely-used local version of Lloyd's algorithm, called Simple Linear Iterative Clustering…

Computer Vision and Pattern Recognition · Computer Science 2018-05-30 Georg Maierhofer , Daniel Heydecker , Angelica I. Aviles-Rivero , Samar M. Alsaleh , Carola-Bibiane Schönlieb

In this paper we describe an adaptive refinement strategy for LR B-splines. The presented strategy ensures, at each iteration, local linear independence of the obtained set of LR B-splines. This property is then exploited in two…

Numerical Analysis · Mathematics 2020-07-15 Francesco Patrizi , Carla Manni , Francesca Pelosi , Hendrik Speleers

We investigate methods to calibrate the non-common path aberrations at an adaptive optics system having a wavefront-correcting device working at an extremely high resolution (larger than 150x150). We use focal-plane images collected…

Instrumentation and Methods for Astrophysics · Physics 2015-06-22 Visa Korkiakoski , Christoph U. Keller , Niek Doelman , Matthew Kenworthy , Gilles Otten , Michel Verhaegen

We present and discuss different algorithms for converting rectangular imagery into elliptical regions. We mainly focus on methods that use mathematical mappings with explicit and invertible equations. The key idea is to start with…

Image and Video Processing · Electrical Eng. & Systems 2019-11-13 Chamberlain Fong

We introduce generalised finite difference methods for solving fully nonlinear elliptic partial differential equations. Methods are based on piecewise Cartesian meshes augmented by additional points along the boundary. This allows for…

Numerical Analysis · Mathematics 2017-06-26 Brittany D. Froese , Tiago Salvador

We present an efficient algorithm designed for and capable of detecting elongated, thin features such as lines and curves in astronomical images, and its application to the automatic detection of gravitational arcs. The algorithm is…

Astrophysics · Physics 2009-11-11 Gregor Seidel , Matthias Bartelmann

We present a new pixelized method for the inversion of gravitationally lensed extended source images which we term adaptive semi-linear inversion (SLI). At the heart of the method is an h-means clustering algorithm which is used to derive a…

Instrumentation and Methods for Astrophysics · Physics 2015-08-06 James Nightingale , Simon Dye

Detecting and visualizing what are the most relevant changes in an evolving network is an open challenge in several domains. We present a fast algorithm that filters subsets of the strongest nodes and edges representing an evolving weighted…

Social and Information Networks · Computer Science 2014-11-05 Przemyslaw A. Grabowicz , Luca Maria Aiello , Filippo Menczer

This paper focused on the design of an optimized object tracking technique which would minimize the processing time required in the object detection process while maintaining accuracy in detecting the desired moving object in a cluttered…

Computer Vision and Pattern Recognition · Computer Science 2021-03-10 Liana Ellen Taylor , Midriem Mirdanies , Roni Permana Saputra
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