Weighted-Median Refinement of Motion Vectors in H.263-based Video Coding

In this paper, the impact of a refinement of motion vectors (MV) on the performance of a block-DCT based video coder (H.263) is addressed. Postprocessing is accomplished by exploiting both the spatial correlation of the vector field and the confidence of the estimated block vectors. A recently proposed adaptive scheme for MV smoothing, based on the theory of vector median filters, is adjusted and embedded into an H.263 video coder. With a bit stream that is perfectly compatible with an H.263 decoder, results are improved, especially for very low bit rates and complex motion of the scene.