Directional Wavelet Bases Constructions with Dyadic Quincunx Subsampling

TL;DR

This paper develops directional wavelet systems with dyadic quincunx subsampling, extending previous work to biorthogonal wavelets, and provides an algorithm for their construction with optimized dual wavelets.

Contribution

It extends orthonormal wavelet constructions to biorthogonal wavelets with similar frequency irregularity constraints and offers a numerical algorithm for biorthogonal wavelet design.

Findings

Supports of wavelets are discontinuous in frequency domain.

Irregularity constraints can be relaxed in frames with redundancy.

Numerical algorithm enables optimization of dual wavelets.

Abstract

We construct directional wavelet systems that will enable building efficient signal representation schemes with good direction selectivity. In particular, we focus on wavelet bases with dyadic quincunx subsampling. In our previous work, We show that the supports of orthonormal wavelets in our framework are discontinuous in the frequency domain, yet this irregularity constraint can be avoided in frames, even with redundancy factor less than 2. In this paper, we focus on the extension of orthonormal wavelets to biorthogonal wavelets and show that the same obstruction of regularity as in orthonormal schemes exists in biorthogonal schemes. In addition, we provide a numerical algorithm for biorthogonal wavelets construction where the dual wavelets can be optimized, though at the cost of deteriorating the primal wavelets due to the intrinsic irregularity of biorthogonal schemes.