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How to Draw Rectangle on Image in Matplotlib?

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Prerequisites: Matplotlib

Given an image the task here is to draft a python program using matplotlib to draw a rectangle on it. Matplotlib comes handy with rectangle() function which can be used for our requirement.

Syntax: Rectangle(xy, width, height, angle=0.0, **kwargs)

Parameters:

  • xy: Lower left point to start the rectangle plotting
  • width : width of the rectangle
  • height: Height of the rectangle.
  • angle: Angle of rotation of the rectangle.

Approach

  • Import the necessary libraries. 
  • Insert and display the image.
  • Create the figure and axes of the plot 
  • Add the patch to the Axes
  • Display the image

Example 1: Draw a rectangle on an image

Python3




import matplotlib.pyplot as plt
import matplotlib.patches as patches
from PIL import Image
import numpy as np
  
x = np.array(Image.open('geek.png'), dtype=np.uint8)
plt.imshow(x)
  
# Create figure and axes
fig, ax = plt.subplots(1)
  
# Display the image
ax.imshow(x)
  
# Create a Rectangle patch
rect = patches.Rectangle((50, 100), 40, 30, linewidth=1,
                         edgecolor='r', facecolor="none")
  
# Add the patch to the Axes
ax.add_patch(rect)
plt.show()


Output:

original image

image with rectangle

Example 2: Draw a filled rectangle

Python3




import matplotlib.pyplot as plt
import matplotlib.patches as patches
from PIL import Image
import numpy as np
  
x = np.array(Image.open('geek.png'), dtype=np.uint8)
plt.imshow(x)
  
# Create figure and axes
fig, ax = plt.subplots(1)
  
# Display the image
ax.imshow(x)
  
# Create a Rectangle patch
rect = patches.Rectangle((50, 100), 40, 30, linewidth=1,
                         edgecolor='r', facecolor="g")
  
# Add the patch to the Axes
ax.add_patch(rect)
plt.show()


Output:

original image

image with rectangle



Last Updated : 17 Dec, 2020
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