A direction-adaptive image coding using two-dimensional direct lifting wavelet transform

In this paper, a novel direction-adaptive image coding scheme is introduced by using two-dimensional adaptive directional lifting-based wavelet transform (2D-ADLWT). Conventionally, one-dimensional ADLWT (1D-ADLWT) has been proposed. However, it requires large amount of computational cost for optimal lifting direction decision and image transformation. In this work, adaptive directional lifting is implemented by using 2D direct lifting wavelet transform and directional downsampling matrices. Direct 2D lifting structure can reduce the computational cost for image transformation and optimal lifting direction decision significantly. Moreover, in the simulation, it is shown that the proposed method is comparable to the 1D-ADLWT in terms of image coding efficiency. Thus, an effective ADLWT with low computational cost can be provided.