Feature-based image matching algorithms play an indispensable role in automatic target recognition(ATR).In this work,a fast image matching algorithm(FIMA)is proposed which utilizes the geometry feature of extended centroid(EC)to build affine invariants.Based on affine invariants of the length ratio of two parallel line segments,FIMA overcomes the invalidation problem of the state-of-the-art algorithms based on affine geometry features,and increases the feature diversity of different targets,thus reducing misjudgment rate during recognizing targets.However,it is found that FIMA suffers from the parallelogram contour problem and the coincidence invalidation.An advanced FIMA is designed to cope with these problems.Experiments prove that the proposed algorithms have better robustness for Gaussian noise,gray-scale change,contrast change,illumination and small three-dimensional rotation.Compared with the latest fast image matching algorithms based on geometry features,FIMA reaches the speedup of approximate 1.75 times.Thus,FIMA would be more suitable for actual ATR applications.
