A recursive orthogonal wavelet device

A design for a one‐dimensional (1‐D), 2‐D recursive orthogonal wavelet consisting of a parallel connection of a delay and allpass network is presented. There have been some methods to obtain wavelet functions from perfect reconstruction filter banks following an investigation by Mallat of the relation between wavelet transform and filter banks. These methods are based mostly on an FIR filter. A method based on IIR filters has never been investigated. IIR digital filter has fewer orders than FIR digital filters to realize the same specification and satisfies the orthogonal condition of the orthogonal wavelet by using both parallel connection of some delays and an allpass filter. Furthermore, a maximum number of zeros are placed at aliasing frequencies in the lowpass filter as a way of obtaining the regularity of the wavelet. Finally, some design samples of discrete scaling and wavelet functions are presented.