OpenCV 3 Computer Vision with Python Cookbook

How it works...

Using fast Fourier transform, we convert the image from the spatial domain to the frequency domain. Then, we create a mask with zeros everywhere except a rectangle at the center. Using that mask, we set amplitudes for high frequencies to zero and convert the image back to spatial representation.

The following output is expected:

For readers interested in more applications of the frequency domain filtering technique, we refer you to Chapter 6, Seeing a Heartbeat with a Motion Amplifying Camera of the book OpenCV for Secret Agents (https://www.packtpub.com/application-development/opencv-secret-agents).