Wavelet transform on the torus: a group theoretical approach

Abstract

We construct a Continuous Wavelet Transform (CWT) on the torus ${\mathbb{T}}^2$ following a group-theoretical approach based on the conformal group $SO(2,2)$. The Euclidean limit reproduces wavelets on the plane ${\mathbb{R}}^2$ with two dilations, which can be defined through the natural tensor product representation of usual wavelets on $\mathbb{R}$. Restricting ourselves to a single dilation imposes severe conditions for the mother wavelet that can be overcome by adding extra modular group $SL(2,\mathbb{Z})$ transformations, thus leading to the concept of \emph{modular wavelets}. We define modular-admissible functions and prove frame conditions.

21 pages, 10 figures