Non separable 2D factorization of separable 2D DWT for lossless image coding

In this report, we propose a reversible two dimensional (2D) discrete wavelet transform (DWT) compatible to the irreversible 9-7 DWT for lossy coding in the JPEG 2000. All the filters and scalings are factorized into lifting steps, and signals are rounded into integers, so that the proposed DWT becomes reversible and applicable to lossless coding. Furthermore, we factorize the separable 2D transfer function of the 2D DWT into non separable 2D functions to reduce the lifting steps and rounding operations. As a result, errors due to the rounding operations are reduced and the compatibility to the irreversible 9-7 DWT is improved.