smooth a curve in images

This is from a post in stackoverflow.com . I make a copy here so that it’s easy to access.

#!/usr/bin/env python3
# -*- coding: utf-8 -*-
# @Time    : 2019-03-09 01_17_59 Sat
# @Author  : yusisc (yusisc@gmail.com)
 
import matplotlib
matplotlib.use('TkAgg')
import numpy as np
from scipy import interpolate
from matplotlib import pyplot as plt
 
 
x = np.array([23, 24, 24, 25, 25])
y = np.array([13, 12, 13, 12, 13])
 
# append the starting x,y coordinates
x = np.r_[x, x[0]]
y = np.r_[y, y[0]]
 
# fit splines to x=f(u) and y=g(u), treating both as periodic. also note that s=0
# is needed in order to force the spline fit to pass through all the input points.
ret = interpolate.splprep([x, y], s=0, per=True)
tck = ret[0]
 
# evaluate the spline fits for 1000 evenly spaced distance values
xi, yi = interpolate.splev(np.linspace(0, 1, 1000), tck)
 
# plot the result
fig, ax = plt.subplots(1, 1)
ax.plot(x, y, 'or')
ax.plot(xi, yi, '-b')
plt.show()

ref

python - Interpolating a closed curve using scipy - Stack Overflow
https://stackoverflow.com/questions/33962717/interpolating-a-closed-curve-using-scipy

python - Fitting a closed curve to a set of points - Stack Overflow
https://stackoverflow.com/questions/31464345/fitting-a-closed-curve-to-a-set-of-points

How to fit curve through cloud of points? OpenCV/C++ - Stack Overflow
https://stackoverflow.com/questions/32595265/how-to-fit-curve-through-cloud-of-points-opencv-c