我需要突出显示在Python上使用OpenCV呈现的所有图像的轮廓

我尝试了代码，但它在第二个图像上无法正常工作

import cv2
import numpy as np

# Input image and make it gray
image = cv2.imread("img2.jpg")
gray = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)

# Blur
gray = cv2.GaussianBlur(gray, (5, 5), 0)

thresh = cv2.threshold(gray, 120, 255, cv2.THRESH_BINARY_INV)[1]

# Find contours
cnts = cv2.findContours(thresh, cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_SIMPLE)
cnts = cnts[0] if len(cnts) == 2 else cnts[1]
c = max(cnts, key=cv2.contourArea)

# Draw dots onto image
cv2.drawContours(image, [c], -1, (0, 255, 0), 1)

cv2.imshow('Image', image)
cv2.WaitKey(0)

它应该是这样的