Downsampling an image using OpenCV

In this program, we will down sample an image. Downsampling is decreasing the spatial resolution while keeping the 2D representation of an image. It is typically used for zooming out of an image. We will use the pyrdown() function in the openCV library to complete this task.

Original Image

Algorithm

Step 1: Fead the image.
Step 2: Pass the image as a parameter to the pyrdown() function.
Step 3: Display the output.

Example Code

import cv2

image = cv2.imread('testimage.jpg')
print("Size of image before pyrDown: ", image.shape)

image = cv2.pyrDown(image)
print("Size of image after pyrDown: ", image.shape)
cv2.imshow('DownSample', image)

Output

Size of image before pyrDown:  (350, 700, 3)
Size of image after pyrDown:  (175, 350, 3)

Explanation

If we observe the size of the image before and after using the pyrDown function, we see that the size is decreased, i.e., we have downsampled the image.