Image coding using 2-D anisotropic dual-tree discrete wavelet transform

We propose an image coding scheme using 2-D anisotropic dual-tree discrete wavelet transform (DDWT). First, we extend 2-D DDWT to anisotropic decomposition, and obtain more directional subbands. Second, an iterative projection-based noise shaping algorithm is employed to further sparsify anisotropic DDWT coefficients. At last, the resulting coefficients are rearranged to preserve zero-tree relationship so that they can be efficiently coded with SPIHT. Experimental results show that our proposed scheme outperforms JPEG2000 and SPIHT at low bit rates despite the redundancy of DDWT.