Reassigned scalograms and their fast algorithms
Patrick Flandrin, Eric Chassande-Mottin, Patrice Abry · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 1995
Reassignment is a technique which consists in moving the computed value of a time-frequency or time-scale energy distribution to a different location in the plane, so as to increase its readability. In the case of scalograms (squared modulus of wavelet transforms), a general form is given for the reassignment operators and their properties are discussed with respect to the chosen wavelet. Characterization of local singularities after reassignment is investigated by simulation and some examples (from mathematics and physics) are presented in order to support the usefulness of the approach. Since reassigning a scalogram amounts to compute two extra wavelet transforms, it is finally shown how this can be achieved in a fast and efficient way within a multiresolution framework.