A wavelet domain half-pixel motion compensation process that reduces aliasing
effects
that down sampling causes in the wavelet transform uses an H-transform and provides
motion estimation and compensation in wavelet domain without requiring an inverse
wavelet transform. For encoding, a q-dimensional (e.g., q=2) H-transform is applied
in a conventional manner to non-overlapping qq matrices in a first frame.
When determining motion vectors for a second frame, "half-pixel" interpolation
of the wavelet data of the first frame determines generates half-pixel data corresponding
to qq space-domain matrices that are offset (e.g., 1 pixel) horizontally
and/or vertically from the qq matrices that were transformed. Motion estimation
techniques can then identify object motion by comparing wavelet domain object data
in one frame to actual and interpolated wavelet domain data for another frame.
Half-pixel interpolation or data generation can be combined with multi-resolution
motion estimation in a high-performance wavelet video encoder.
