A LOCALLY QUADRATIC MODEL OF THE MOTION ESTIMATION ERROR CRITERION FUNCTION AND ITS APPLICATION TO SUBPIXEL INTERPOLATIONS

It is observed that around the optimum point of the motion estimation process the error criterion function is well modeled as a quadratic fu nction with respect to the motion vector offsets. This locally quadrat ic functional model decomposes the motion estimation optimization at s ubpixel resolutions into a two-stage pipelinable processes: full-searc h at full-pixel resolution and interpolation at any subpixel resolutio n. Practical approximation formulas lead to the explicit computations of both motion vectors and error criterion functional values at subpix el resolutions.