Rotations

cv2.getRotationMatrix2D(rotation_center_x, rotation_center_y, angle of rotation, scale)



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import cv2
import numpy as np

image = cv2.imread('images/input.jpg')
height, width = image.shape[:2]

# Divide by two to rototate the image around its centre
rotation_matrix = cv2.getRotationMatrix2D((width/2, height/2), 90, .5)

rotated_image = cv2.warpAffine(image, rotation_matrix, (width, height))

cv2.imshow('Rotated Image', rotated_image)
cv2.waitKey()
cv2.destroyAllWindows()

Notice all the black space surrounding the image.

We could now crop the image as we can calculate it's new size (we haven't learned cropping yet!).

But here's another method for simple rotations that uses the cv2.transpose function



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#Other Option to Rotate
img = cv2.imread('images/input.jpg')

rotated_image = cv2.transpose(img)

cv2.imshow('Rotated Image - Method 2', rotated_image)
cv2.waitKey()
cv2.destroyAllWindows()



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# Let's now to a horizontal flip.
flipped = cv2.flip(image, 1)
cv2.imshow('Horizontal Flip', flipped) 
cv2.waitKey()
cv2.destroyAllWindows()



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