Book Image

OpenCV By Example

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

OpenCV By Example

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

Overview of this book

Open CV is a cross-platform, free-for-use library that is primarily used for real-time Computer Vision and image processing. It is considered to be one of the best open source libraries that helps developers focus on constructing complete projects on image processing, motion detection, and image segmentation. Whether you are completely new to the concept of Computer Vision or have a basic understanding of it, this book will be your guide to understanding the basic OpenCV concepts and algorithms through amazing real-world examples and projects. Starting from the installation of OpenCV on your system and understanding the basics of image processing, we swiftly move on to creating optical flow video analysis or text recognition in complex scenes, and will take you through the commonly used Computer Vision techniques to build your own Open CV projects from scratch. By the end of this book, you will be familiar with the basics of Open CV such as matrix operations, filters, and histograms, as well as more advanced concepts such as segmentation, machine learning, complex video analysis, and text recognition.
Table of Contents (18 chapters)
OpenCV By Example
Credits
About the Authors
About the Reviewers
www.PacktPub.com
Preface
Index

The preprocessing step


Software that identifies letters do so by comparing text with a previously recorded data. Classification results can be improved greatly if the input text is clear, if the letters are in a vertical position, and if there are no other elements, such as images that are sent to the classification software. In this section, we'll learn how to adjust text. This stage is called preprocessing.

Thresholding the image

We usually start the preprocessing stage by thresholding the image. This eliminates all the color information. Most OpenCV functions require information to be the written in white and the background to be black. So, let's start with creating a threshold function to match this criterion:

#include <opencv2/opencv.hpp>
#include <vector>

using namespace std;
using namespace cv;

Mat binarize(Mat input)
{
  //Uses otsu to threshold the input image
  Mat binaryImage;
  cvtColor(input, input, CV_BGR2GRAY);
  threshold(input, binaryImage, 0, 255, THRESH_OTSU...