Fast Gabor-Like Windowed Fourier and Continuous Wavelet Transforms
M. Unser
IEEE Signal Processing Letters, vol. 1, no. 5, pp. 76-79, May 1994.
Fast algorithms for the evaluation of running windowed Fourier and continuous wavelet transforms are presented. The analysis functions approximate complex-modulated Gaussians as closely as desired and may be optimally localized in time and frequency. The Gabor filtering is performed indirectly by convolving a premodulated signal with a Gaussian-like window and demodulating the output. The window functions are either B-splines dilated by an integer factor m or quasi-Gaussians of arbitrary size generated from the n-fold convolution of a symmetrical exponential. Both approaches result in a recursive implementation with a complexity independent of the window size (O(N)).
Erratum
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p. 77, the right-hand side of Equation (14) should read (2 α) ⁄ (1 - α)2 instead of α2 ⁄ (1 - α)2.
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