Arithmetic Operations on Images using Python OpenCV

In this article, you will learn about different arithmetic operations performed on images using Python OpenCV. We have performed several arithmetic operations on numbers. But, these arithmetic operations can also be performed on images, like addition, subtraction, multiplication, and division.

First, we need to install the OpenCV module. Here is the command to install the OpenCV module with the pip tool.

pip install opencv-contrib-python

The above command installs some other modules along with OpenCV. Those modules are generally used with OpenCV.

Addition of Images Python OpenCV

Python OpenCV provides the cv2.addWeighted() method to add two images. This method calculates the weighted sum of two arrays. It returns an image in the output, which is a combination of the corresponding pixel values of the input images. It has the following syntax-

cv.addWeighted(src1, alpha, src2, beta, gamma[, dst[, dtype]])

src1- first input array,
alpha- weight of the first array elements,
src2- second input array of the same size and channel number as src1,
beta- weight of the second array elements,
gamma- scalar added to each sum,
dst- output array that has the same size and number of channels as the input arrays,
dtype- optional depth of the output array.

Example of Images Addition

Suppose we have the following two images-

import cv2
import numpy as np

img1 = cv2.imread('nature.jpg')
img2 = cv2.imread('ocean.jpg')
dst = cv2.addWeighted(img1, 0.7, img2, 0.6, 0)

cv2.imshow('Blended Image',dst)

cv2.waitKey(0)
cv2.destroyAllWindows()

The above code returns the following output-

Subtraction of Images Python OpenCV

In Python OpenCV, the cv2.subtract() method is used to subtract two images. Both images should be of the same size and type.

import cv2
import numpy as np

img1 = cv2.imread('nature.jpg')
img2 = cv2.imread('ocean.jpg')
result_image = cv2.subtract(img1, img2)
cv2.imshow('Subtracted Image', result_image)

cv2.waitKey(0)
cv2.destroyAllWindows()

Multiplication of images Python OpenCV

The addition and subtraction of the images are generally used. It is also possible to multiply and divide the images, which are not generally used. In Python OpenCV, cv2.multiply() method is used to multiply two images. Suppose we have the following two images-

import cv2
import numpy as np

img1 = cv2.imread('nature.jpg')
img2 = cv2.imread('night.jpg')
result_image = cv2.multiply(img1, img2)
cv2.imshow('Multiply Image', result_image)

cv2.waitKey(0)
cv2.destroyAllWindows()

The above code returns the following output-

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