Fast operators for arbitrary warping maps

In this work we describe a mathematical operator for the fast calculation of frequency warping. Such invertible transformation can be used to reshape the tiling of time-frequency analysis in a flexible way. In our approach the warping is computed by splitting the transformation operator in two additive terms: the first term represents its Non-uniform Fourier Transform approximation while the second term is imposed for aliasing suppression. The first transformation is known to be analytically characterized and rapidly computable by interpolation approaches. An analytical characterization of the second transformation operator is proposed for arbitrary shaped non-smooth warping maps commonly used for signal processing applications.