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

Multidimensional histograms in OpenCV


All the histograms that we have seen being computed and/or plotted in this chapter so far have been one-dimensional histograms. This is because the pixel intensities were the only entities that were being aggregated into bins. Also, if you recall the parameters that we discussed for OpenCV's calcHist() function, you would remember that one of them explicitly specified the number of dimensions that the function is supposed to work with (we have passed the integer 1 as the parameter for all the invocations in the chapter so far). In this section, we will take a brief look at the concept of multidimensional image histograms and also see how we can modify the code that we have been working with to enable the calcHist() function to return a multidimensional histogram.

Before we dive into the code, let's understand what multidimensional histograms are and what they represent. If you think of the one-dimensional histograms that we have been dealing with so far...