凸形测试

import cv2
o=cv2.imread('C:/Users/xpp/Desktop/Finger.png')#原始图像
cv2.imshow("original",o)
gray=cv2.cvtColor(o,cv2.COLOR_BGR2GRAY)#将彩色图片转换为灰度图
ret,thresh=cv2.threshold(gray,235,255,cv2.THRESH_BINARY)#将灰度图片转换为二值图片
contours,hierarchy=cv2.findContours(thresh,2,1)#计算图像轮廓
for cnt in contours:
    hull=cv2.convexHull(cnt)#计算凸包
    length=len(hull)
    if length>5:
        for i in range(length):
            cv2.line(gray,tuple(hull[i][0]),tuple(hull[(i+1)%length][0]),(0,0,255),2)#绘制凸包
print("函数cv2.convexHull()构造的多边形是否是凸形的：",cv2.isContourConvex(hull))#凸形测试
cv2.imshow("result1",gray)
epsilon=0.01*cv2.arcLength(cnt,True)#计算轮廓长度
approx=cv2.approxPolyDP(cnt,epsilon,True)#计算逼近多边形
image2=cv2.drawContours(gray,[approx],0,(0,0,255),2)#绘制图像轮廓
print("函数cv2.approxPolyDP()构造的多边形是否是凸形的：",cv2.isContourConvex(approx))#凸形测试
cv2.imshow("result2",image2)
cv2.waitKey()
cv2.destroyAllWindows()