Fast gradient methods based global motion estimation for video compression

This paper presents a fast global motion estimation (GME) algorithm based on gradient methods (GM), which can be used for real-time applications, such as MPEG-4 video compression. Our approach improves existing state-of-the-art GME algorithms by introducing two major modifications: first, only a small subset (down-to 3%) of the original image pixels is used in the estimation process. Second, a warp-free formulation of the basic GM is derived, further decreasing the computational complexity. Experimental results show that a 20 fold computation complexity reduction is achieved, without compromising the GME accuracy and compression efficiency.