DENSE ESTIMATION OF OPTICAL FLOW FIELD WITHIN THE MPEG-2 COMPRESSED DOMAIN

A dense estimation of optical flow field within the MPEG-2 compressed domain is proposed, which utilizes only the compressed-domain information, i.e. motion vectors and DCT coefficients. First, motion vectors are pre-processed to estimate the DCT coefficients for P and B frames. Second, initial optical flow is estimated with Black's optical flow estimation framework, in which DC image is substituted by DC+2AC image to provide more intensity information. Third, high confidence test is exploited to generate the dense and accurate motion vector field by removing false and noisy motion vectors. It preserves the advantages of compressed domain processing and improves the existent MPEG velocity field in terms of accuracy and density. Experimental results demonstrate that the proposed approach can provide a satisfactory motion analysis for compressed-domain video object extraction.