Book Image

OpenCV 4 Computer Vision Application Programming Cookbook - Fourth Edition

By : David Millán Escrivá, Robert Laganiere
Book Image

OpenCV 4 Computer Vision Application Programming Cookbook - Fourth Edition

By: David Millán Escrivá, Robert Laganiere

Overview of this book

OpenCV is an image and video processing library used for all types of image and video analysis. Throughout the book, you'll work with recipes to implement a variety of tasks. With 70 self-contained tutorials, this book examines common pain points and best practices for computer vision (CV) developers. Each recipe addresses a specific problem and offers a proven, best-practice solution with insights into how it works, so that you can copy the code and configuration files and modify them to suit your needs. This book begins by guiding you through setting up OpenCV, and explaining how to manipulate pixels. You'll understand how you can process images with classes and count pixels with histograms. You'll also learn detecting, describing, and matching interest points. As you advance through the chapters, you'll get to grips with estimating projective relations in images, reconstructing 3D scenes, processing video sequences, and tracking visual motion. In the final chapters, you'll cover deep learning concepts such as face and object detection. By the end of this book, you'll have the skills you need to confidently implement a range of computer vision algorithms to meet the technical requirements of your complex CV projects.
Table of Contents (17 chapters)

Reading video sequences

In order to process a video sequence, we need to be able to read each of its frames. OpenCV has put in place an easy-to-use framework that can help us perform frame extraction from video files or even from USB or IP cameras. This recipe shows you how to use it.

How to do it...

Basically, all you need to do in order to read the frames of a video sequence is create an instance of the cv::VideoCapture class. You then create a loop that will extract and read each video frame. Here, we are going to explain how to code the main function to show each frame. The following steps will help us to read video sequences:

  1. Open a video capture with the following code:
int main() 
{ 
  // Open the video file 
  cv...