Structurally regular biorthogonal filter banks: theory, designs, and applications

The paper studies how regularity of a desired degree can be imposed onto the dyadic-based building blocks of a class of M-channel (M ≥ 2) causal biorthogonal filter banks (BOFBs) having anti-causal inverses, without necessarily constraining the phase responses of the filters. Structural conditions for regularity are derived in terms of the elements of the dyadic-based building blocks, and regular BOFBs are designed accordingly and evaluated using a transform-based image coder. They are found to provide better objective performance and improved perceptual quality of the decompressed images, with reduced blocking artifacts and better preserved texture details.