Image resolution enhancement using undecimated double density dual tree wavelet transform

Abstract

In this paper, an undecimated double density dual tree discrete wavelet transform (UDDDT-DWT) based image resolution enhancement technique is proposed. The critically sampled discrete wavelet transform (DWT) suffers from the drawbacks of being shift-variant and lacking the capacity to process directional information in images. The double density dual tree wavelet transform (DDDT-WT) is an approximately shift-invariant transform capturing directional information. The UDDDT-DWT is an improvement of the DDDT-DWT, making it exactly shift-invariant. The method uses a forward and inverse (UDDDT-DWT) to construct a high-resolution (HR) image from the given lower-resolution (LR) image. The HR image is reconstructed from the LR image using the inverse UDDDT-DWT. Results are presented and discussed through comparisons between state-of-the-art resolution enhancement methods.