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

Applying LBP to aligned facial images


Now that we have an intuition as to what the LBP captures in our image, let's try to apply this to the facial images that we have been working with. But, we aren't simply going to create the histogram of the (uniform pattern) LBP codes like we have been doing so far. We are going to make use of the spatial information that is inherent in faces.

What does exploiting spatial information in faces really mean? When you look at the image of a face, you expect to see some facial features at some distinct locations of the face. For example, the nose will almost be at the center, with the eyes on either side, the chin would cover the lower part of the face image, and so on. Now, when you create a histogram (of the LBP codes) out of the entire face image, you lose such spatial information. And how exactly are we losing spatial information? Consider two pixels-one of which is present near the left eye and the other near the center of the lower lip. If they have...