Model-based facial image coding has received extensive attention due to its high subjective image quality and low bit-rates. But the estimation of object motion parameters is still a difficult problem. In this paper

head motion characteristics is analyzed

and it can be classified into three motion types

head rigid motion

simple motion of facial expression and complex motion of facial expression. A motion parameter estimation algorithm based on corresponding feature points is utilized to extract head rigid motion. A linear implementation algorithm is suggested. The key works to improve the accuracy of motion parameter estimation are the selecting of some proper feature points and the building of an exactly 3D wire-frame corresponding to specified face. A deformable matrix is constructed to extract simple motion parameter of facial expression. At last

the error of motion parameter is evaluated by the area-error function.