Book Image

OpenCV 4 Computer Vision Application Programming Cookbook - Fourth Edition

By : David Millán Escrivá, Robert Laganiere
Book Image

OpenCV 4 Computer Vision Application Programming Cookbook - Fourth Edition

By: David Millán Escrivá, Robert Laganiere

Overview of this book

OpenCV is an image and video processing library used for all types of image and video analysis. Throughout the book, you'll work with recipes to implement a variety of tasks. With 70 self-contained tutorials, this book examines common pain points and best practices for computer vision (CV) developers. Each recipe addresses a specific problem and offers a proven, best-practice solution with insights into how it works, so that you can copy the code and configuration files and modify them to suit your needs. This book begins by guiding you through setting up OpenCV, and explaining how to manipulate pixels. You'll understand how you can process images with classes and count pixels with histograms. You'll also learn detecting, describing, and matching interest points. As you advance through the chapters, you'll get to grips with estimating projective relations in images, reconstructing 3D scenes, processing video sequences, and tracking visual motion. In the final chapters, you'll cover deep learning concepts such as face and object detection. By the end of this book, you'll have the skills you need to confidently implement a range of computer vision algorithms to meet the technical requirements of your complex CV projects.
Table of Contents (17 chapters)

Segmenting images using watersheds

The watershed transformation is a popular image-processing algorithm that is used to segment an image into homogenous regions quickly. It relies on the idea that when the image is seen as a topological relief, the homogeneous regions correspond to relatively flat basins, delimited by steep edges. As a result of its simplicity, the original version of this algorithm tends to over-segment the image, which produces multiple small regions. This is why OpenCV proposes a variant of this algorithm that uses a set of predefined markers that guide the definition of the image segments.

How to do it...

The watershed segmentation is obtained through the use of the cv::watershed function. The input for...