# 3 Ways of Image Subtraction in Python with NumPy, OpenCV and Pillow Libraries

## Introduction

In this post, we will see various ways of doing image subtraction in Python by using NumPy, OpenCV, and Pillow libraries. The subtraction of images may sound a bit strange to beginners but images consist of numeric pixels hence we can perform pixel-wise subtraction between two images.

**Subtraction of Images**

When one image is subtracted from another it does pixel-wise subtraction where the pixel of the 2nd image is subtracted from the 1st image resulting in a new 3rd image.

Mathematically, when image B is subtracted from image A, the pixel-wise subtraction operation to get the output image C can be represented as follows –

**C(x,y) = A(x,y) – B(x,y)**

Where,

- A(x,y) represents the pixel value at position (x, y) in the image A.