OpenCV Android Programming By Example

Amgad Muhammad

• Publisher: Packt Publishing
• Year: 2015
• eBook ISBN: 9781783550593
• Edition: 1
• Topic: Computer Science
• Subtopic: Computer Science General
• Index: Computer Science

Develop vision-aware and intelligent Android applications with the robust OpenCV library

About This Book

• This is the most up-to-date book on OpenCV Android programming on the market at the moment. There is no direct competition for our title.
• Based on a technology that is increasing in popularity, proven by activity in forums related to this topic.
• This book uniquely covers applications such as the Panoramic viewer and Automatic Selfie, among others.

Who This Book Is For

If you are an Android developer and want to know how to implement vision-aware applications using OpenCV, then this book is definitely for you.

It would be very helpful if you understand the basics of image processing and computer vision, but no prior experience is required

What You Will Learn

• Identify and install all the elements needed to start building vision-aware Android applications
• Explore image representation, colored and gray scale
• Recognize and apply convolution operations and filtering to deal with noisy data
• Use different shape analysis techniques
• Extract and identify interest points in an image
• Understand and perform object detection
• Run native computer vision algorithms and gain performance boosts

In Detail

Starting from the basics of computer vision and OpenCV, we'll take you all the way to creating exciting applications. You will discover that, though computer vision is a challenging subject, the ideas and algorithms used are simple and intuitive, and you will appreciate the abstraction layer that OpenCV uses to do the heavy lifting for you. Packed with many examples, the book will help you understand the main data structures used within OpenCV, and how you can use them to gain performance boosts. Next we will discuss and use several image processing algorithms such as histogram equalization, filters, and color space conversion. You then will learn about image gradients and how they are used in many shape analysis techniques such as edge detection, Hough Line Transform, and Hough Circle Transform. In addition to using shape analysis to find things in images, you will learn how to describe objects in images in a more robust way using different feature detectors and descriptors.

By the end of this book, you will be able to make intelligent decisions using the famous Adaboost learning algorithm.

Style and approach

An easy-to-follow tutorial packed with hands-on examples. Each topic is explained and placed in context, and the book supplies full details of the concepts used for added proficiency.

OpenCV Android Programming By Example

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Table of Contents

OpenCV Android Programming By Example

Credits

About the Author

About the Reviewers

www.PacktPub.com

Support files, eBooks, discount offers, and more

Why subscribe?

Free access for Packt account holders

Preface

What this book covers

What you need for this book

Who this book is for

Conventions

Reader feedback

Customer support

Downloading the example code

Downloading the color images of this book

Errata

Piracy

Questions

1. Getting Yourself Ready

Installing Tegra Android Development Pack

Downloading and installing TADP

TADP post-installation configuration

Installing emulator system images

Configuring Eclipse to work with NDK

NDK verification

Installing the OpenCV and Android development environment manually

Java SE Development Kit 6

Android Studio

Android SDK

Eclipse IDE

ADT and CDT plugins for Eclipse

Android NDK

Downloading Android NDK

Installing and configuring Android NDK

Building native code using Eclipse

OpenCV4Android SDK

Understanding how NDK works

An overview of NDK

A simple example of NDK

Android.mk

Building your first Android project with OpenCV

HelloVisionWorld Android application

Creating a project in Eclipse

Creating a project in Android Studio

Summary

2. App 1 - Building Your Own Darkroom

Digital images

Color spaces

The Mat class

Basic Mat operations

Processing the images stored on your phone

Loading an image to a Mat object

UI definitions

Reading an image using OpenCV

Calculating an image histogram

What are histograms?

Understanding histogram components

UI definitions

Calculating an image histogram

Enhancing the image contrast

Understanding histogram equalization

Enhancing grayscale images

UI definitions

Converting an image to grayscale

Equalizing a histogram for a grayscale image

Enhancing an HSV image

UI definitions

Equalizing a histogram for the image saturation and value

Enhancing an RGB image

UI definitions

Equalizing a histogram for the image color channels

Summary

3. App 2 - Software Scanner

Spatial filtering

Understanding convolution and linear filtering

Removing noise

The averaging filter

The Gaussian filter

The median filter

UI definitions

Applying filters to reduce image noise

Finding edges

The Sobel edge detector

The Canny edge detector

UI definitions

Applying the Sobel filter to find edges

Using the Canny edge detector

Detecting shapes

Understanding the Hough line transform

Detecting lines using Hough transform

UI definitions

Detecting and drawing lines

Detecting circles using Hough transform

UI definitions

Detecting and drawing circles

Summary

4. App 2 - Applying Perspective Correction

Image transformations and perspective correction

Translation

Rotation and translation

Scaled rotation

Affine

Perspective transformation

Rigid perspective correction

UI definitions

Estimating the perspective transformation using the object bounding box

Flexible perspective correction

UI definitions

Applying flexible perspective correction

Manual perspective correction

UI definitions

Selecting the corners manually

Summary

5. App 3 - Panoramic Viewer

Image features

Feature detectors

Understanding the Harris corner detector

UI definitions

Using the Harris corner detector

Calling a native Harris corner detector

Using the native OpenCV library within Eclipse

Using the native OpenCV library within Android Studio

Working on the native part

Understanding the FAST corner detector

UI definitions

Using the FAST corner detector

Using native FAST

Understanding the ORB feature detector

UI definitions

Using the ORB feature detector

Using native ORB

Feature description and matching

Understanding BRIEF and ORB feature descriptors

Understanding the BRISK feature descriptor

Understanding the FREAK feature descriptor

Matching the features

Working with feature matching

UI definitions

Finding an object in a scene

Native feature matching

UI definitions

The native matching process

Stitching two images

UI definitions

The native stitcher

Summary

6. App 4 – Automatic Selfie

Cascade classifiers

Haar-like features

The integral image

Adaptive Boosting

Cascading

Using cascade classifiers to detect objects

Accessing your phone's camera using OpenCV

A camera preview

UI definitions

Previewing the camera frames

Detecting closed palms in the camera frames

Using the Java-based cascade classifier

Summary

Index

OpenCV Android Programming By Example

Copyright © 2015 Packt Publishing

All rights reserved. No part of this book may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, without the prior written permission of the publisher, except in the case of brief quotations embedded in critical articles or reviews.

Every effort has been made in the preparation of this book to ensure the accuracy of the information presented. However, the information contained in this book is sold without warranty, either express or implied. Neither the author, nor Packt Publishing, and its dealers and distributors will be held liable for any damages caused or alleged to be caused directly or indirectly by this book.

Packt Publishing has endeavored to provide trademark information about all of the companies and products mentioned in this book by the appropriate use of capitals. However, Packt Publishing cannot guarantee the accuracy of this information.

First published: December 2015

Production reference: 1071215

Published by Packt Publishing Ltd.

Livery Place

35 Livery Street

Birmingham B3 2PB, UK.

ISBN 978-1-78355-059-3

www.packtpub.com

Credits

Author

Amgad Muhammad

Reviewers

Noritsuna Imamura

André Moreira

Commissioning Editor

Neil Alexander

Acquisition Editor

Meeta Rajani

Content Development Editor

Mayur Pawanikar

Technical Editor

Manthan Raja

Copy Editor

Tasneem Fatehi

Project Coordinator

Nidhi Joshi

Proofreader

Safis Editing

Indexer

Monica Ajmera Mehta

Graphics

Ahmed H. Alley

Kirk D'Penha

Jason Monteiro

Production Coordinator

Arvindkumar Gup...

Table of contents

• OpenCV Android Programming By Example