Introduction
In this tutorial, we will show you how to rotate the image by any angle with the help of OpenCV and imutils libraries. We are going to cover the following functions in the post with examples –
- OpenCV function cv2.rotate() to rotate the image by 90 degrees and 180 degrees
- imutils function rotate_bound() and rotate() to rotate the image by any angle
Rotate Image using OpenCV : cv2.rotate()
Syntax
cv2.rotate(src, rotateCode)
- src – Input Image on which rotation has to be applied
- rotateCode – Its a code to specify how to rotate the image
Examples of cv2.rotate() in Python OpenCV
First of all, let us import the OpenCV library as shown below-
In [0]:
import cv2
Read Sample Image and Display
Next, we will read a sample image for our example and display it
In [1]:
window_name='Dog Image' cv2.namedWindow(window_name, cv2.WINDOW_NORMAL) cv2.imshow(window_name,img) cv2.waitKey(0) cv2.destroyAllWindows()
Output
Example – 1: Rotate the Image 90 degree clockwise with cv2.rotate()
To rotate the image 90 degree clockwise, use the rotateCode = cv2.ROTATE_90_CLOCKWISE as shown below.
In [3]:
rotate_image = cv2.rotate(img, cv2.ROTATE_90_CLOCKWISE) window_name='OpenCV Rotate Image 90 degree Clockwise' cv2.namedWindow(window_name, cv2.WINDOW_NORMAL) cv2.imshow(window_name,rotate_image) cv2.waitKey(0) cv2.destroyAllWindows()
Output
Example – 2: Rotate the Image 180 degree with cv2.rotate()
To rotate the image 90 degree clockwise, use the rotateCode = cv2.ROTATE_180 as shown in the below example. There is no concept of rotating the image clockwise or counterclockwise here because the rotation of the image by 180 brings the transformed image to the same state in both cases.
In [4]:
rotate_image = cv2.rotate(img, cv2.ROTATE_180) window_name='OpenCV Rotate Image 180 degree' cv2.namedWindow(window_name, cv2.WINDOW_NORMAL) cv2.imshow(window_name,rotate_image) cv2.waitKey(0) cv2.destroyAllWindows()
Output
Example – 3: Rotate the Image 90 degree counterclockwise or 270 degrees clockwise
To rotate the Image 90 degree counterclockwise or 270 degrees clockwise (which is the same thing) we use rotateCode= ROTATE_90_COUNTERCLOCKWISE as shown in the below example.
In [5]:
rotate_image = cv2.rotate(img, cv2.ROTATE_90_COUNTERCLOCKWISE) window_name='OpenCV Rotate Image 90 degree anticlockwise' cv2.namedWindow(window_name, cv2.WINDOW_NORMAL) cv2.imshow(window_name,rotate_image) cv2.waitKey(0) cv2.destroyAllWindows()
Output
Rotate Image by Angle in Python using imutils Library
The out of the box OpenCV function cv2.rotate() only lets us rotate the image in multiple of 90 degrees. However, there is no direct function to rotate the image by any degree in OpenCV, it is a multistep process. This is where imutils library can be useful.
imutils library consists of many convenient wrapper functions on top of OpenCV. It contains two useful functions imutils.rotate() and imutils.rotate_bound() to rotate the image by any given angle.
The difference between the two functions is that imutils.rotate() may end up cropping the image while rotating it whereas imutils.rotate_bound() does not crop the image and preserves the entire image within the bound.
Syntax for imutils.rotate()
imutils.rotate(image, angle)
- image – Input Image on which rotation has to be applied
- angle – The angle at which the image has to be rotated
Syntax for imutils.rotate_bound()
imutils.rotate_bound(image, angle)
- image – Input Image on which rotation has to be applied
- angle – The angle at which the image has to be rotated
Example to Rotate Image by Angle using imutils.rotate()
In the below example we have used imutils.rotate() to rotate the image by 32 degrees. It can be noticed the image is cropped after rotation is applied.
In [6]:
import imutils rotate_image = imutils.rotate(img, 32) window_name='Rotate Image by Angle in Python' cv2.namedWindow(window_name, cv2.WINDOW_NORMAL) cv2.imshow(window_name,rotate_image) cv2.waitKey(0) cv2.destroyAllWindows()
Output
Example to Rotate Image by Angle using imutils.rotate_bound()
In the below example we have used imutils.rotate_bound() to rotate the image by 32 degrees. This time it can be seen that the image is not cropped and is preserved in entirety within the bounds.
In [7]:
import imutils rotate_image = imutils.rotate_bound(img, 32) window_name='Rotate Image by Angle in Python' cv2.namedWindow(window_name, cv2.WINDOW_NORMAL) cv2.imshow(window_name,rotate_image) cv2.waitKey(0) cv2.destroyAllWindows()
Output
