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Many areas of science and engineering encounter data defined on spherical manifolds. Modelling and analysis of spherical data often necessitates spherical harmonic transforms, at high degrees, and increasingly requires efficient computation…

Computational Physics · Physics 2025-06-19 Matthew A. Price , Jason D. McEwen

We review scale-discretized wavelets on the sphere, which are directional and allow one to probe oriented structure in data defined on the sphere. Furthermore, scale-discretized wavelets allow in practice the exact synthesis of a signal…

Information Theory · Computer Science 2013-12-10 J. D. McEwen , P. Vandergheynst , Y. Wiaux

We describe S2LET, a fast and robust implementation of the scale-discretised wavelet transform on the sphere. Wavelets are constructed through a tiling of the harmonic line and can be used to probe spatially localised, scale-depended…

Information Theory · Computer Science 2013-10-29 B. Leistedt , J. D. McEwen , P. Vandergheynst , Y. Wiaux

We construct a directional spin wavelet framework on the sphere by generalising the scalar scale-discretised wavelet transform to signals of arbitrary spin. The resulting framework is the only wavelet framework defined natively on the…

Information Theory · Computer Science 2017-06-06 Jason D. McEwen , Boris Leistedt , Martin Büttner , Hiranya V. Peiris , Yves Wiaux

Curvelets are efficient to represent highly anisotropic signal content, such as a local linear and curvilinear structure. First-generation curvelets on the sphere, however, suffered from blocking artefacts. We present a new…

Information Theory · Computer Science 2016-11-29 Jennifer Y. H. Chan , Boris Leistedt , Thomas D. Kitching , Jason D. McEwen

A new construction of a directional continuous wavelet analysis on the sphere is derived herein. We adopt the harmonic scaling idea for the spherical dilation operator recently proposed by Sanz et al. but extend the analysis to a more…

Astrophysics · Physics 2011-10-28 J. D. McEwen , M. P. Hobson , A. N. Lasenby

We propose the use of automatic differentiation through the programming framework jax for accelerating a variety of analysis tasks throughout gravitational wave (GW) science. Firstly, we demonstrate that complete waveforms which cover the…

Instrumentation and Methods for Astrophysics · Physics 2023-02-13 Thomas D. P. Edwards , Kaze W. K. Wong , Kelvin K. H. Lam , Adam Coogan , Daniel Foreman-Mackey , Maximiliano Isi , Aaron Zimmerman

In this paper, we propose a new two-dimensional directional discrete wavelet transform that can decompose an image into 12 multiscale directional edge components. The proposed transform is designed in a fully discrete setting and thus is…

Signal Processing · Electrical Eng. & Systems 2021-12-03 Kensuke Fujinoki , Keita Ashizawa

Scale-discretised wavelets yield a directional wavelet framework on the sphere where a signal can be probed not only in scale and position but also in orientation. Furthermore, a signal can be synthesised from its wavelet coefficients…

Information Theory · Computer Science 2017-08-17 Jason D. McEwen , Claudio Durastanti , Yves Wiaux

We develop an exact wavelet transform on the three-dimensional ball (i.e. on the solid sphere), which we name the flaglet transform. For this purpose we first construct an exact transform on the radial half-line using damped Laguerre…

Information Theory · Computer Science 2013-08-15 B. Leistedt , J. D. McEwen

In this article, we construct discrete tight frames for $L^2(\mathbb{S}^{d-1})$, $d\geq3$, which consist of localized polynomial wavelets with adjustable degrees of directionality. In contrast to the well studied isotropic case, these…

Classical Analysis and ODEs · Mathematics 2025-12-09 Frederic Schoppert

Segmentation, a useful/powerful technique in pattern recognition, is the process of identifying object outlines within images. There are a number of efficient algorithms for segmentation in Euclidean space that depend on the variational…

Computer Vision and Pattern Recognition · Computer Science 2019-11-12 Xiaohao Cai , Christopher G. R. Wallis , Jennifer Y. H. Chan , Jason D. McEwen

We propose a transform for signals defined on the sphere that reveals their localized directional content in the spatio-spectral domain when used in conjunction with an asymmetric window function. We call this transform the directional…

Information Theory · Computer Science 2013-04-23 Z. Khalid , R. A. Kennedy , S. Durrani , P. Sadeghi , Y. Wiaux , J. D. McEwen

We summarise the construction of exact axisymmetric scale-discretised wavelets on the sphere and on the ball. The wavelet transform on the ball relies on a novel 3D harmonic transform called the Fourier-Laguerre transform which combines the…

Information Theory · Computer Science 2013-01-28 Boris Leistedt , Jason D. McEwen

A new formalism is derived for the analysis and exact reconstruction of band-limited signals on the sphere with directional wavelets. It represents an evolution of the wavelet formalism developed by Antoine & Vandergheynst (1999) and Wiaux…

Astrophysics · Physics 2008-12-09 Y. Wiaux , J. D. McEwen , P. Vandergheynst , O. Blanc

We present in this paper new multiscale transforms on the sphere, namely the isotropic undecimated wavelet transform, the pyramidal wavelet transform, the ridgelet transform and the curvelet transform. All of these transforms can be…

Astrophysics · Physics 2016-08-30 Jean-Luc Starck , Yassir Moudden , Pierrick Abrial , Mai Nguyen

We construct spherical wavelets based on approximate identities that are directional, i.e. not rotation-invariant, and have an adaptive angular selectivity. The problem of how to find a proper representation of distinct kinds of details of…

Classical Analysis and ODEs · Mathematics 2018-04-10 Ilona Iglewska-Nowak

We describe the construction of a spherical wavelet analysis through the inverse stereographic projection of the Euclidean planar wavelet framework, introduced originally by Antoine and Vandergheynst and developed further by Wiaux et al.…

Astrophysics · Physics 2011-10-28 J. D. McEwen , M. P. Hobson , D. J. Mortlock , A. N. Lasenby

Recent work introduced a unified framework for steerable and directional wavelets in two and three dimensions that ensures many desirable properties, such as a multi-scale structure, fast transforms, and a flexible angular localization. We…

Numerical Analysis · Computer Science 2018-05-08 Christian Lessig

The paper presents a versatile library of analytic and quasi-analytic complex-valued wavelet packets (WPs) which originate from discrete splines of arbitrary orders. The real parts of the quasi-analytic WPs are the regular spline-based…

Numerical Analysis · Mathematics 2019-07-04 Amir Averbuch , Pekka Neittaanmaki , Valery Zheludev
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