拟合圆：

#! /usr/bin/env python
# -*- coding: utf-8 -*-
import cv2
from numpy import *
from scipy import optimize
import functools

def countcalls(fn):
    @functools.wraps(fn)
    def wrapped(*args):
        wrapped.ncalls +=1
        return fn(*args)

    wrapped.ncalls = 0
    return wrapped

def calc_R(xc, yc):
    return sqrt((xx - xc) ** 2 + (yy - yc) ** 2)
@countcalls
def f_2(c):
    Ri = calc_R(*c)
    return Ri - Ri.mean()

def nihe(xx,yy):
    # 质心坐标
    x_m = mean(xx)
    y_m = mean(yy)
    #圆心估计
    center_estimate = x_m, y_m
    center_2, _ = optimize.leastsq(f_2, center_estimate)

    xc_2, yc_2 = center_2
    Ri_2  = calc_R(xc_2, yc_2)
    #拟合圆的半径
    R_2 = Ri_2.mean()
    residu_2 = sum((Ri_2 - R_2)**2)
    residu2_2 = sum((Ri_2**2-R_2**2)**2)
    ncalls_2= f_2.ncalls

    #输出列表
    # fmt = '%-22s %10.5f %10.5f %10.5f %10d %10.6f %10.6f %10.