The wavelet transform modulus maxima (WTMM) is a method for detecting the fractal dimension of a signal.
More than this, the WTMM is capable of partitioning the time and scale domain of a signal into fractal dimension regions, and the method is sometimes referred to as a "mathematical microscope" due to its ability to inspect the multi-scale dimensional characteristics of a signal and possibly inform about the sources of these characteristics.
The WTMM method uses continuous wavelet transform rather than Fourier transforms to detect singularities – that is discontinuities, areas in the signal that are not continuous at a particular derivative.
In particular, this method is useful when analyzing multifractal signals, that is, signals having multiple fractal dimensions.