Sharper spectrograms with Fast Local Sharpening

摘要

Spectrograms have to make compromises between time and frequency resolution because of the limitations of the short-time Fourier transform (Gabor, 1946). Wavelets have the same issue. As a result spectrograms often appear blurry, either in time, frequency, or both. A method called Reassignment was introduced in 1978 (Kodera et al.) to make spectrograms look sharper. Unfortunately it also adds visual noise, and its algorithm does not make it suitable for realtime scenarios. Fast Local Sharpening is a new method which attempt to overcome both theses drawbacks.