Python Opencv实践 - 轮廓特征（最小外接圆，椭圆拟合）

亦枫Leonlew2023-09-06 23:14
import cv2 as cv
import numpy as np
import matplotlib.pyplot as plt

img = cv.imread("../SampleImages/stars.PNG")
plt.imshow(img[:,:,::-1])

#轮廓检测
img_gray = cv.cvtColor(img, cv.COLOR_BGR2GRAY)
ret,thresh = cv.threshold(img_gray, 127, 255, 0)
contours,hierarchy = cv.findContours(thresh, cv.RETR_TREE, cv.CHAIN_APPROX_NONE)
#显示轮廓
img_contours = img.copy()
img_contours = cv.drawContours(img_contours, contours, -1, (0,255,0), 2)
plt.imshow(img_contours, cmap=plt.cm.gray)

for contour in contours:
    #轮廓最小外接圆
    #(x,y),radius = cv.minEnclosingCircle(cnt)
    #cnt: 轮廓信息
    #(x,y):最小外接圆的圆心
    #radius: 最小外接圆的半径
    #参考资料：https://geek-docs.com/opencv/python-opencv/t_how-to-find-the-minimum-enclosing-circle-of-an-object-in-opencv-python.html
    (x,y),radius = cv.minEnclosingCircle(contour)
    center = (int(x), int(y))
    radius = int(radius)
    cv.circle(img, center, radius, (0,255,0), 2)
    #椭圆拟合
    #ellips = cv.fitEllipse(cnt)
    #ellipse: 椭圆信息((x,y),(a,b),angle) (x,y)椭圆中心点;(a,b) 椭圆长短轴的直径（注意：非半径）;angle中心旋转角度
    #参考资料：https://blog.csdn.net/Other_stone/article/details/111186254?spm=1001.2101.3001.6650.5&utm_medium=distribute.pc_relevant.none-task-blog-2%7Edefault%7EBlogCommendFromBaidu%7ERate-5-111186254-blog-111409635.235%5Ev38%5Epc_relevant_default_base&depth_1-utm_source=distribute.pc_relevant.none-task-blog-2%7Edefault%7EBlogCommendFromBaidu%7ERate-5-111186254-blog-111409635.235%5Ev38%5Epc_relevant_default_base&utm_relevant_index=10
    ellipse = cv.fitEllipse(contour)
    cv.ellipse(img, ellipse, (0,0,255), 2)

plt.imshow(img[:,:,::-1])