Image rotation 

In this section, we will learn how we can perform a rotation by using OpenCV and the rotation matrix, M. A rotation matrix is a matrix that is used to perform a rotation in Euclidean space. It rotates points in the xy plane counterclockwise through an angle, 𝜃, around the origin.

Now we will implement image rotation using OpenCV: 

1. We will first import the matplotlib (mpimg and pyplot), numpy, and openCV libraries:

In[1]: import cv2
In[2]: import numpy as np
In[3]: import matplotlib.image as mpimg
In[4]: from matplotlib import pyplot as plt
In[5]: %matplotlib inline

2. Next, we will read the input image:

In[5]: image = cv2.imread('test_image.jpg')
In[6]: cv2.imshow('Original Image', image)
In[7]: cv2.waitKey()
In[8]: cv2.destroyAllWindows()

The input image looks like this:

Fig 4.55: Input image

3. The height and width of the image are as follows:

In[9]: height, width = image.shape[:2] 
In[10]: height
579
In[11]: width
530

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