The imaged could be seemed to the approximation of the polygons

so it was important to the image match that researched the polygon match method.It is based the combination of the axis of least inertia and the chain

this method was capable of preserving both contour as well as region information

and it utilized the degree of triangular membership which computed by the feature triangular to compute the similarity between the two objects.This method was invariant to image transformations

and robust to concave polygons.The experimental results show that this method’s performance and retrieval efficiency is well.