Extraction of high-resolution video stills from MPEG image sequences

The Bayesian high-resolution video stills (HRVS) algorithm has been embedded within the MPEG video compression standard, such that an MPEG-1 intra-coded frame (I-picture) can be enhanced by temporally integrating the neighboring motion-compensated P- and B-pictures. Super-resolution enhancement is achievable if objects within the image sequence move with subpixel increments; thus, the Bayesian HRVS algorithm requires subpixel-resolution motion fields estimated with respect to the I-picture. Half-pel resolution motion fields are provided by the MPEG encoder in the compressed bit stream. These motion vectors are used as initial conditions to a reduced-search block matching algorithm which calculates higher-resolution motion fields with acceptable accuracy. The computation time required to estimate the subpixel motion fields in the Bayesian HRVS algorithm is reduced by a factor of approximately 30 when lower-resolution motion vectors are already available from the MPEG decoder, with little degradation in video still quality