Book Image

Learning OpenCV 3 Application Development

By : Samyak Datta
Book Image

Learning OpenCV 3 Application Development

By: Samyak Datta

Overview of this book

Computer vision and machine learning concepts are frequently used in practical computer vision based projects. If you’re a novice, this book provides the steps to build and deploy an end-to-end application in the domain of computer vision using OpenCV/C++. At the outset, we explain how to install OpenCV and demonstrate how to run some simple programs. You will start with images (the building blocks of image processing applications), and see how they are stored and processed by OpenCV. You’ll get comfortable with OpenCV-specific jargon (Mat Point, Scalar, and more), and get to know how to traverse images and perform basic pixel-wise operations. Building upon this, we introduce slightly more advanced image processing concepts such as filtering, thresholding, and edge detection. In the latter parts, the book touches upon more complex and ubiquitous concepts such as face detection (using Haar cascade classifiers), interest point detection algorithms, and feature descriptors. You will now begin to appreciate the true power of the library in how it reduces mathematically non-trivial algorithms to a single line of code! The concluding sections touch upon OpenCV’s Machine Learning module. You will witness not only how OpenCV helps you pre-process and extract features from images that are relevant to the problems you are trying to solve, but also how to use Machine Learning algorithms that work on these features to make intelligent predictions from visual data!
Table of Contents (16 chapters)
Learning OpenCV 3 Application Development
Credits
About the Author
About the Reviewer
www.PacktPub.com
Preface

Plotting histograms in OpenCV


Now that we are familiar with the process of computing histograms using the APIs provided by OpenCV, we turn our attention to the problem of representing the information inside a histogram. In the previous section, we saw that we could easily traverse the Mat object representing our histogram to get a glimpse of the values (frequency counts). Also, in the section on the basics of histogram processing, we saw that a visual representation of a histogram in the form of a bar chart has the advantage of possessing a greater visual appeal. This section essentially attempts to the answer this question: Given a histogram that has been computed by the calcHist() function (or any other method for that matter), how do we represent the same graphically using OpenCV/C++? The key thing to note here is that we are trying to plot the histogram graphically using the same framework of OpenCV and C++ that we have been working with throughout this book. If we relax this restriction...