**3. Multiresolution**

The multiresolution concept has been introduced first by Mallat (Mallat, 1989). It defines clearly the relationships between the QMF, pyramid algorithms and orthonormal wavelet bases through basically, the definition of a set of nested subspaces and a so-called scaling function. The strength of multiresolution lies in its ability to decompose a signal in finer and finer details. Most importantly, it allows the description of a signal in terms of timefrequency or time-scale analysis.
