  We propose a novel motion estimation/compensation (ME/MC) method for
wavelet-based (in-band) motion compensated temporal filtering (MCTF), with
application to low-bitrate video coding. Unlike the conventional in-band MCTF
algorithms, which require redundancy to overcome the shift-variance problem of
critically sampled (complete) discrete wavelet transforms (DWT), we perform
ME/MC steps directly on DWT coefficients by avoiding the need of
shift-invariance. We omit upsampling, the inverse-DWT (IDWT), and the
calculation of redundant DWT coefficients, while achieving arbitrary subpixel
accuracy without interpolation, and high video quality even at very
low-bitrates, by deriving the exact relationships between DWT subbands of input
image sequences. Experimental results demonstrate the accuracy of the proposed
method, confirming that our model for ME/MC effectively improves video coding
quality.
