下面是一个使用opencv在对象上绘制矩形的示例：通过给出源图像的模板图像，您可以在图像上绘制形状

# importing needed libraries
import cv2
import numpy as np

img_rgb = cv2.imread(source image)     # opening the source image
img_gray = cv2.cvtColor(img_rgb, cv2.COLOR_BGR2GRAY)   # converting to the gray scale
template = cv2.imread(template image,0)   # opening the template image
w, h = template.shape[::-1]     # giving the sape of template image

res = cv2.matchTemplate(img_gray,template,cv2.TM_CCOEFF_NORMED)   # matching both the image using the opencv methods for matching object
threshold = 0.9
loc = np.where( res >= threshold)
for pt in zip(*loc[::-1]):
    cv2.rectangle(img_rgb, pt, (pt[0] + w, pt[1] + h), (0,0,255), 1)
cv2.imshow('screen',img_rgb)
cv2.waitKey(0)

源图像

模板图像

结果图像