The ability to examine the frequency content of a signal is critical in a variety of fields, and many techniques have been proposed to fill this need, including the Fourier and wavelet family of transforms. One of these, the S-transform, is a Fourier based transform that provides simultaneous time and frequency information similar to the wavelet transform but uses sinusoidal basis functions to produce true frequency and globally referenced phase measurements. It has been shown to be useful in several medical imaging applications but its use is limited due to high computational requirements of the original, continuous form. The described embodiments include a general framework for describing linear time-frequency transforms, using the Fourier, wavelet and S-transforms as examples. As an illustration of the utility of this formalism, a fast discrete S-transform algorithm is developed that has the same computational complexity as the fast Fourier transform.