This is illustrated in the example of the three-level
decomposition shown in Figure
Discrete Wavelet Decomposition"
. Assume that for transformation
the biorthogonal set of spline filters with respective filter length of 6 and 2 is
used. Since group delay definitely needs to be synchronized, for the last level
select additional filter delays
= 1. Total delay at the last stage of decomposition for
this set of filters is two samples. This value corresponds to the time scale of the
input of the last stage of decomposition. In order to ensure an equivalent delay of
the “detail” part on the second level, the delay must be increased by 2*2 samples.
Respective values of additional delays for the second level is equal to
+ 4 = 5. A greater
value of the “high frequency” component delay needs to be selected for the first
level of decomposition,
+ 2*4 = 13.