Three-dimensional linear trajectory filtering using the DWT and the mixed-domain approach

A method is proposed which combines the two-dimensional (2-D) orthogonal discrete-wavelet transform (DWT) and mixed-domain (Mixed-D) filtering to selectively enhance or attenuate a 2-D signal moving along a linear trajectory at a constant velocity. Such signals are common in video coding applications. The 2-D DWT is applied separately to each frame of the three-dimensional (3-D) input sequence, resulting in a set of multiresolution (subband) image sequences. Mixed-D filtering is then used to enhance or reject linear trajectory signals within each subband image sequence. The output for each frame is formed by inverting the wavelet transform using the Mixed-D processed sequences. This method or filtering lends itself to use in subband video coding systems, which are becoming increasingly popular, and permits selective Mixed-D filtering of the subband signals depending upon the energy content within the subbands. In this contribution, we present an overview of the proposed algorithm and present preliminary results which compare favourably in terms of arithmetic complexity, storage requirements, and the subjective quality of output, to those obtained using the Mixed-D technique