Organization of optimal nonuniform lapped biorthogonal transforms based on coding efficiency
In this paper, we present optimal nonuniform lapped biorthogonal transforms for image compression. Subband coding using wavelet transforms have received a lot of attention because of multiresolution representation. The wavelet transform is regarded as a nonuniform filter bank and is constructed using the tree structure of a two-channel filter bank. However, it may not be optimal in the sense of energy compaction. If we can design nonuniform filter banks directly, it is possible to overcome the conventional wavelet transform. We then design a direct-structured nonuniform filter bank with a lapping window, called NULBT. Finally we show some examples and confirm the validity of our method.