Lifting-based directional lapped transforms

Abstract

A 'directional lapped transform coder' ('DLT Coder') provides various techniques for designing directional lapped transforms. In general, lapped transforms are factorized into lifting steps. A “directional operator” is then introduced into each lifting step in order to construct the directional lapped transform by selecting data elements from a data signal along a path corresponding to the directional operator. The resulting directional lapped transform preserves the advantages of conventional lapped transforms while also providing more efficient representation directional signals. In various embodiments, the resulting directional lapped transform is used to enable an image/video coding scheme that provides significant improvement over conventional state-of-the-art image lapped transform based coding schemes for images with strong directional correlations.