WFBT Wavelet FilterBank Tree
Usage: c=wfbt(f,wt);
c=wfbt(f,wt,ext);
[c,info]=wfbt(...);
Input parameters:
f : Input data.
wt : Wavelet filterbank tree definition.
Output parameters:
c : Coefficients stored in a cell-array.
info : Transform parameters struct.
WFBT(f,wt) returns coefficients c obtained by applying a wavelet
filterbank tree defined by wt to the input data f.
[c,info]=WFBT(f,wt) additionally returns struct. info containing
transform parameters. It can be conviniently used for the inverse
transform IWFBT e.g. fhat = iWFBT(c,info). It is also required by
the PLOTWAVELETS function.
wt defines a tree shaped filterbank structure build from the
elementary two (or more) channel wavelet filters. The tree can have any
shape and thus provide a flexible frequency covering. The outputs of the
tree leaves are stored in c.
The wt parameter can have two formats:
1) Cell array containing 3 elements {w,J,treetype}, where w is
the basic wavelet filterbank definition as in FWT function, J*
stands for the depth of the tree and the flag treetype defines
the type of the tree to be used. Supported options are:
'dwt'
Plain DWT tree (default). This gives one band per octave freq.
resolution when using 2 channel basic wavelet filterbank and
produces coefficients identical to the ones in FWT.
'full'
Full filterbank tree. Both (all) basic filterbank outputs are
decomposed further up to depth J achieving linear frequency band
division.
'doubleband','quadband','octaband'
The filterbank is designed such that it mimics 4-band, 8-band or
16-band complex wavelet transform provided the basic filterbank
is 2 channel. In this case, J is treated such that it defines
number of levels of 4-band, 8-band or 16-band transform.
2) Structure returned by the WFBTINIT function and possibly
modified by WFBTPUT and WFBTREMOVE.
Please see WFBTINIT for a detailed description and more options.
If f is row/column vector, the coefficient vectors c{jj} are columns.
If f is a matrix, the transformation is by default applied to each of
W columns [Ls, W]=size(f).
In addition, the following flag groups are supported:
'per'(default),'zero','odd','even'
Type of the boundary handling. Please see the help on FWT for a
description of the boundary condition flags.
'freq'(default),'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).
Examples:
---------
A simple example of calling the WFBT function using the "full
decomposition" wavelet tree:
f = gspi;
J = 7;
[c,info] = wfbt(f,{'sym10',J,'full'});
plotwavelets(c,info,44100,'dynrange',90);
Url: http://ltfat.github.io/doc/wavelets/wfbt.html
See also: iwfbt, wfbtinit.
Package: ltfat