In digital signal processing, a quadrature mirror filter is a filter most commonly used to implement a filter bank that splits an input signal into two bands. The resulting high-pass and low-pass signals are often reduced by a factor of 2, giving a critically sampled two-channel representation of the original signal.
The analysis filters are related by the following formulae:
where is the frequency, and the sampling rate is normalized to .
In other words, the power sum of the high-pass and low-pass filters is equal to 1. The filter responses are symmetric about
Orthogonal wavelets -- the Haar wavelets and related Daubechies wavelets, Coiflets, and some developed by Mallat, are generated by scaling functions which, with the wavelet, satisfy a quadrature mirror filter relationship.
Read more about Quadrature Mirror Filter: Further Description, Further Reading
Famous quotes containing the word mirror:
“When Walser first put on his make-up, he looked in the mirror and did not recognise himself ... he experienced the freedom that lies behind the mask, within dissimulation.”
—Angela Carter (1940–1992)