Fast motion vector re-estimation for arbitrary video downsizing using spatial-variant filter

To downsize a compressed video to a lower resolution, the straightforward method is to decompress the compressed video, downsample the video in spatial domain and then re-compress the downsampled video. This process can be computationally expensive unless fast motion vector re-estimation methods are used. In this paper, the use of a spatial-variant filter (SVF) as a fast motion vector re-estimation method for arbitrary downsizing factor is investigated. Simulation results suggest that the SVF can improve the quality of the existing fast algorithms in terms of PSNR. With a little bit of local search, its PSNR can be close to the full search