Here is an example using opencv you can draw rectangle over an object:
By giving the template image of the source image you can draw the shape over the image
# 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)
Source Image

Template Image

Result Image
