WFBTINIT - Initialize Filterbank Tree

Usage

wt = wfbtinit(wtdef);

Input parameters

Output parameters

Description

wfbtinit({w,J,flag}) creates a filterbank tree of depth J. The parameter w defines a basic wavelet filterbank. For all possible formats see fwt. The following optional flags (still inside of the cell-array) are recognized:

'dwt','full','doubleband','quadband','octaband'

Type of the tree to be created.

wfbtinit({w,J,flag,'mod',mod}) creates a filterbank tree as before, but modified according to the value of mod. Recognized options:

'powshiftable'

Changes subsampling factors of the root to 1. This results in redundant near-shift invariant representation.

The returned structure wt has the following fields:

.nodes

Cell-array of structures obtained from fwtinit. Each element define a basic wavelet filterbank.

.children

Indexes of children nodes

.parents

Indexes of a parent node

.forder

Frequency ordering of the resultant frequency bands.

The structure together with functions from the wfbtmanip subdirectory acts as an abstract data structure tree.

Regular wfbtinit flags:

'freq','nat'

Frequency or natural ordering of the coefficient subbands. The direct usage of the wavelet tree ('nat' option) does not produce coefficient subbans ordered according to the frequency. To achieve that, some filter shuffling has to be done ('freq' option).