The key point of the global motion estimation is how to select a global motion model. In this paper

integrating with a rate distortion optimization algorithm

an adaptive global motion estimation method to optimize the coding is proposed. The scheme of the algorithm is as follows: for the same image

using the translated motion model

affine motion model and quadratic motion model to estimate the inter frame motion and calculating their Lagrangian costs respectively. The motion model which yields least Lagrangian cost is selected as the best motion mode for current frame coding. Simulated results show that the proposed technique is robust and have better performance for various resolutions of video sequences.