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

Image cropping for face alignment


Having learnt about cropping, we would now want to continue our discourse on face alignment. The cropping is to happen on the rotated images that we generated in one of our previous sections. So, ideally the implementation for image rotation and cropping are part of the same code snippet/function/module. However, for the purpose of illustrating and focusing on scaling/cropping separately in this section, we will first demonstrate the working of the same independent to the image rotation code. Then, in the next section, we integrate them together so that you get an idea of how these two operations can be coupled together to complete our facial alignment pipeline.

The main problem that we are going to deal with in this section is how to come up with suitable parameters that help us define our ROI. Note that in contrast to the previous section, we have a definite goal for the ROI in mind. We are cropping images so that the unnecessary background distractions...