Reduction of transients during lifting based spatial adaptation of filter banks

Spatial adaptation of filter banks (FBs) is useful for non-stationary signals/images. Lifting structure for FBs results in structural perfect reconstruction (PR) at the transition region, allowing to spatially adapt between arbitrary FBs, avoiding the need to design border FBs. Though lifting based spatial adaptation of FBs gives PR, it induces spurious transients in the resulting subbands around the point of adaptation. In this paper we study this problem in detail and propose a set of conditions on lifting steps that can greatly reduce the amount of transients. We design a linear phase 13/11 FB with the proposed conditions applied on lifting steps along with (4, 4) number of vanishing moments. We successfully show spatial adaptation between the 13/11 FB and the 5/3 FB used in JPEG2000 to reduce the ringing artifacts in images.