Method and apparatus for calculating interatively for a picture or a picture sequence a set of global motion parameters from motion vectors assigned to blocks into which each picture is divided

Global motion estimation techniques play an important role in advanced video coding. Global motion estimation is useful for increasing the coding efficiency. However, it is of high complexity due to using a multiple parameters model and an iterative processing. The invention is based on a four-parameter linear global motion estimation model. From particular block motion vectors of a frame a set of global motion parameters is calculated in an iterative process. In each iteration loop, the motion vector outliers in symmetrical motion vector blocks are processed according to a given set of rules in order to keep the symmetrical structure during the iterative process.