Overlay a rectangle on an image

overlay.py

%matplotlib inline
import matplotlib.pyplot as plt
import matplotlib.patches as mpatches
from skimage import data

# get image
img = data.astronaut()
print('image size', img.shape)
fig, ax = plt.subplots()
ax.imshow(img)

# define patch
patch_loc = (150, 15)
width = 150
height = 170
patch = mpatches.Rectangle(patch_loc, width, height, fill=False, color='blue')

# show
ax.add_patch(patch)
plt.tight_layout()
plt.show()

Results