This is illustrated in the example of the three-level decomposition shown in Figure
"Three-Level 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.