Lattice structure for regular paraunitary linear-phase filterbanks and M-band orthogonal symmetric wavelets

Paraunitary linear-phase (PULP) -channel uniform filterbanks, which are also known as the generalized lapped orthogonal transforms (GenLOTs), can be designed and implemented using lattice structures. This paper discusses how to impose regularity constraints onto the lattice structure of PULP filterbanks. These conditions are expressed in term of the rotation angles of the lattice components by which the resulting filterbanks are guaranteed to have one or two degrees of regularity. Iterating these new regular filterbanks on the lowpass subband generates a large family of symmetric -band orthonormal wavelets. Design procedures with many design examples are presented. Smooth interpolation using regular PULP filterbanks is illustrated through image coding experiments where the novel -band wavelets consistently yield smoother reconstructed images and better perceptual quality.