A new lifting structure of non separable 2D DWT with compatibility to JPEG 2000
Masahiro Iwahashi, Hitoshi Kiya · 2010
In this report, we reduce the number of lifting steps of the two dimensional (2D) discrete wavelet transform (DWT) in JPEG 2000 by introducing a factorization of the separable 2D transfer function into some non separable 2D (NS-2D) functions. The order of the 1D lifting steps in vertical and in horizontal are properly replaced so that all of them are synthesized into NS-2D functions. As a result, the number of the lifting steps of the 2D 9/7 DWT is reduced to 75 [%] maintaining compatibility to the JPEG 2000. Since the number of the lifting steps is essentially proportional to a delay of output signals, it contributes to construct a low latency DWT under the assumption that direct accessing to a 2D intermediate memory is permitted.