Figure 2

Separable implementation of dual-tree filterbank. The four 2D filterbanks give two interpretations: (1) decomposition by three quaternionic wavelets oriented in horizontal, vertical, and diagonal directions. The sub-bands are A + i B + j C + k D. (2) Decomposition by six complex Gabor-type wavelets oriented in nπ/6 directions. The sub-bands are (A + D) + i (B - C) and (A - D) + i (C - B).