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

Vignetting


So far, we have introduced the concept of image filtering and discussed a couple of important filtering techniques, namely box filtering and Gaussian filtering. We also implemented the same using OpenCV and demonstrated the blurring effects that it produced on images. You can now experiment with the extent or degree of blurring by playing around with the size (and the standard deviation in the case of Gaussian filtering) of the image filters.

In this section, we are going to do something even more exciting! We are going to implement a basic version of a very cool image editing technique called Vignetting. For those of you who have come across this term in the context of popular image processing apps (such as Instagram), you will have seen it being referred to as the Vignetting filter or Vignette filter. However, since we are computer vision enthusiasts, we know that the term filter holds a very special meaning in our literature. Hence, we refrain from using the term filter for...