Book Image

Learn OpenCV 4 By Building Projects - Second Edition

By : David Millán Escrivá, Vinícius G. Mendonça, Prateek Joshi
Book Image

Learn OpenCV 4 By Building Projects - Second Edition

By: David Millán Escrivá, Vinícius G. Mendonça, Prateek Joshi

Overview of this book

OpenCV is one of the best open source libraries available, and can help you focus on constructing complete projects on image processing, motion detection, and image segmentation. Whether you’re completely new to computer vision, or have a basic understanding of its concepts, Learn OpenCV 4 by Building Projects – Second edition will be your guide to understanding OpenCV concepts and algorithms through real-world examples and projects. You’ll begin with the installation of OpenCV and the basics of image processing. Then, you’ll cover user interfaces and get deeper into image processing. As you progress through the book, you'll learn complex computer vision algorithms and explore machine learning and face detection. The book then guides you in creating optical flow video analysis and background subtraction in complex scenes. In the concluding chapters, you'll also learn about text segmentation and recognition and understand the basics of the new and improved deep learning module. By the end of this book, you'll be familiar with the basics of Open CV, such as matrix operations, filters, and histograms, and you'll have mastered commonly used computer vision techniques to build OpenCV projects from scratch.
Table of Contents (14 chapters)

Basic graphical user interface with OpenCV

We are going to create a basic user interface with OpenCV. The OpenCV user interface allows us to create windows, add images to it, and move, resize, and destroy it. The user interface is in OpenCV's highui module. In the following code, we are going to learn how to create and show two images by pressing a key to display multiple windows with the image moving in the window on our desktop.

Don't worry about reading the full code; we are going to explain it in small chunks:

#include <iostream> 
#include <string> 
#include <sstream> 
using namespace std; 
 
// OpenCV includes 
#include <opencv2/core.hpp> 
#include <opencv2/highgui.hpp> 
using namespace cv; 
 
int main(int argc, const char** argv) 
{ 
   // Read images 
   Mat lena= imread("../lena.jpg"); 
# Checking if Lena image has been...