How to Display an OpenCV image in Python with Matplotlib?

How to Draw Rectangle on Image in Matplotlib?

Last Updated : 17 Dec, 2020

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

How to Display an OpenCV image in Python with Matplotlib?

yashisrivastav

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