N stage non-separable two dimensional wavelet transform for reduction of rounding errors

This paper proposes an N stage "non-separable" two-dimensional (2D) wavelet transform (WT) for lossless/lossy unified coding of digital images. The proposed method achieves better coding performance especially at high bit rate since it has fewer rounding operations. We convert the conventional "separable" 2D WT into a "non-separable" one without changing its frequency characteristics so that the number of rounding operations is reduced and the proposed method is compatible with the conventional one. The effectiveness of the proposed coding system is confirmed experimentally and theoretically.