Block/object-based algorithm for estimating true motion fields

Abstract

A hybrid algorithm for estimating true motion fields is proposed in this paper. This algorithm consists of three steps: block-based initial motion estimation, image segmentation, and wrong motion vector correction based on objects. The hierarchical block-matching algorithms are improved for the initial motion estimation. The improved algorithm uses an adaptive technique to propagate motion vectors between hierarchical levels. It produces accurate motion field everywhere, except in the areas of motion occlusion. In order to correct wrong motion vectors in the areas of motion occlusion, the current image is segmented into objects and an object-based method is proposed to process the estimated motion fields. With the object-based method, wrong motion vectors are detected by approximating the estimated motion field in each object with a motion model, and are corrected using an object-adaptive interpolator. The object-adaptive interpolator is also used to increase the density of the motion field. Experimental results show that the improved hierarchical block-matching algorithm outperforms the conventional hierarchical block- matching algorithms. The proposed algorithm results in dense motion fields that are smooth within every object, discontinuous between objects of different motion, and very close to the true motion fields.