On the aliasing effect of the finer directional wavelet transform

The 2D separable wavelet transform offers limited directionality because it can only provide three directional subbands. The finer directional wavelet transform has been proposed to improve the directionality of the 2D separable wavelet transform. The finer directional wavelet transform employs quadrant filters on subband outputs of the 2D separable wavelet transform. It divides the three directional subband of wavelet transform into six finer directional subbands. Even though the finer directional wavelet transform has advantages of being non redundant and has efficient separable implementation, it suffers in performance due to aliasing. The aliasing occurs due to the quadrant filters´ inherent frequency response characteristics and thus cannot be eliminated. This paper addresses the aliasing involved in the implementation of the finer directional wavelet transform and recommends ways to reduce the aliasing.