Temporal symmetry constraints in block-matching.

Video processing applications such as picture rate conversion depend on accurate and consistent motion estimation. Most motion estimation and optical flow algorithms use some form of spatial regularization to improve consistency, but few perform a temporal regularization based on the symmetry between successive vector fields. Methods that do improve temporal symmetry are often computationally complex. This paper describes a simple implementation of symmetry constraints in a real-time block matching motion estimation algorithm and shows the effect on related occlusion detection methods that are based on forward-backward consistency checks.