This paper shows that performance improvements are possible if different filter banks in the different levels, even in the nodes, of a subband tree are used. A progressive optimization technique is proposed for fine tuning of the product subband filters in a tree structure. The time and frequency properties of product subband filters are evaluated and comparisons made.
Mehmet V. Tazebay,
Ali Naci Akansu,
"Progressive optimization in subband trees", Proc. SPIE 2308, Visual Communications and Image Processing '94, (16 September 1994); doi: 10.1117/12.185869; https://doi.org/10.1117/12.185869