Nicolas Modrzyk
Java Image Processing RecipesWith OpenCV and JVM
Nicolas Modrzyk
Tokyo, Japan
ISBN 978-1-4842-3464-8e-ISBN 978-1-4842-3465-5
https://doi.org/10.1007/978-1-4842-3465-5
Library of Congress Control Number: 2018936912
© Nicolas Modrzyk 2018
This work is subject to copyright. All rights are reserved by the Publisher, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed.
Trademarked names, logos, and images may appear in this book. Rather than use a trademark symbol with every occurrence of a trademarked name, logo, or image we use the names, logos, and images only in an editorial fashion and to the benefit of the trademark owner, with no intention of infringement of the trademark. The use in this publication of trade names, trademarks, service marks, and similar terms, even if they are not identified as such, is not to be taken as an expression of opinion as to whether or not they are subject to proprietary rights.
While the advice and information in this book are believed to be true and accurate at the date of publication, neither the authors nor the editors nor the publisher can accept any legal responsibility for any errors or omissions that may be made. The publisher makes no warranty, express or implied, with respect to the material contained herein.
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Introduction

My father is a dentist. When I was in my early childhood, he used to repeat the same sentence over and over again, which as far as I can remember and translate properly now was something like:

“Son, get the right tool for the job.”

And as he was looking at me trying to wash the car with the wrong washing product and spending twice the amount of time that I should have, I knew somewhere deep inside of me that he was right.

He did not use a screwdriver to pull out teeth from his patients, and he had what seemed like twenty different brushes to clean each type of tooth. I even thought it was funny at the time.

Fast-forward thirty years later; I was talking about this book with him and he added:

“Well, son, you know, it’s not only about the right tool, it’s about the right tool at the right time.”

And so, this is the philosophy guiding this book.

OpenCV, the computer vision library, has always been one of the tools to work on imaging- and vision-related projects, even more so with every improvement in AI and neural networks. But OpenCV was always taking some time to get the right libraries, and the right build tools, and the right build settings, and so forth.

The vision of the Clojure wrapper Origami is to bring you all the power of OpenCV to your hands almost instantly, along with a pleasurable syntax. This way we hope you can focus and spend your time entirely on the job, not on the tool.

Chapter 1 will introduce you to pure OpenCV on the JVM using Java, Scala, and Kotlin and present some of their shortcomings.

Chapter 2 will present Origami, the Clojure wrapper, and how to use it to perform simple image manipulation.

Chapter 3 will get you up to speed with more advanced concepts of image manipulation, like shape finding, but still in a pleasant syntax.

Finally, Chapter 4 moves to video analysis, with shape finding, transformations, and various techniques to analyze real-time streams with ease.

Acknowledgments

It’s been the most amazing typing race of my life to get this book out on time, and to beat time and the odds, I got support from so many people that it would take another book just to write the list of names. So …

Thank you to all my family, brother, sister, friends, Abe-san, all my soccer friends, people still having Guinness pints in Ireland (keep one for me!), the awesome people in America (who sometimes send LP records… when I need them the most), Sawada-san, Chris and the Biners, my French friends (always there for support even when not being asked for it), publisher Apress, Divya for never being impressed and kicking my butt on a regular basis, and … the people deep in my heart for your NEVER-ENDING support. I never could have finished this without you. I appreciate it so much.

And, of course… thank you to my two beautiful daughters, Mei and Manon, for keeping up and always doing their best even during hard times. You simply rock! I love you.

Table of Contents

Chapter 1:​ OpenCV on the JavaVM 1
1-1 Getting Started with Leiningen 2
Problem 2
Solution 2
How it works 3
1-2 Writing Your First OpenCV Java Program 9
Problem 9
Solution 9
How it works 9
1-3 Automatically Compiling and Running Code 13
Problem 13
Solution 13
How it works 13
1-4 Using a Better Text Editor 15
Problem 15
Solution 16
How it works 16
1-5 Learning the Basics of the OpenCV Mat Object 21
Problem 21
Solution 21
How it works 21
1-6 Loading Images from a File 24
Problem 24
Solution 24
How it works 25
1-7 Saving Images into a File 28
Problem 28
Solution 28
How it works 28
1-8 Cropping a Picture with Submat 30
Problem 30
Solution 30
How it works 30
1-9 Creating a Mat from Submats 35
Problem 35
Solution 35
How it works 35
1-10 Highlighting Objects in a Picture 40
Problem 40
Solution 40
How it works 41
1-11 Using a Canny Result as a Mask 44
Problem 44
Solutions 45
How it works 45
1-12 Detecting Edges with Contours 47
Problem 47
Solution 47
How it works 47
1-13 Working with Video Streams 51
Problem 51
Solution 51
How it works 52
1-14 Writing OpenCV Code in Scala 57
Problem 57
Solution 58
How it works 58
1-15 Writing OpenCV Code in Kotlin 66
Problems 66
Solutions 66
How it works 66
Chapter 2:​ OpenCV with Origami 83
2-1 Starting to Code with Origami 84
Problem 84
Solution 84
How it works 85
2-2 Working with Mats 106
Problem 106
Solution 106
How it works 107
2-3 Loading, Showing, Saving Mats 117
Problem 117
Solution 117
How it works 117
2-4 Working with Colors, ColorMaps, and ColorSpaces 124
Problem 124
Solution 125
How it works 125
2-5 Rotating and Transforming Mats 138
Problem 138
Solution 138
How it works 139
2-6 Filtering Mats 148
Problem 148
Solution 148
How it works 148
2-7 Applying Simple Masking Techniques 161
Problem 161
Solution 161
How it works 161
2-8 Blurring Images 166
Problem 166
Solution 167
How it works 167
Chapter 3:​ Imaging Techniques 175
3-1 Playing with Colors 176
Problem 176
Solution 177
How it works 177
3-2 Creating Cartoons 201
Problem 201
Solution 201
How it works 201
3-3 Creating Pencil Sketches 211
Problem 211
Solution 211
How it works 212
3-4 Creating a Canvas Effect 221
Problem 221
Solution 221
How it works 221
3-5 Highlighting Lines and Circles 226
Problem 226
Solution 226
How it works 227
3-6 Finding and Drawing Contours and Bounding Boxes 239
Problem 239
Solution 240
How it works 240
3-7 More on Contours:​ Playing with Shapes 252
Problem 252
Solution 252
How it works 252
3-8 Moving Shapes 260
Problem 260
Solution 261
How it works 262
3-9 Looking at Trees 266
Problem 266
Solution 266
How it works 266
3-10 Detecting Blur 269
Problem 269
Solution 269
How it works 270
3-11 Making Photomosaics 272
Problem 272
Solution 272
How it works 273
Chapter 4:​ Real-Time Video 279
4-1 Getting Started with Video Streaming 280
Problem 280
Solution 280
How it works 281
4-2 Combining Multiple Video Streams 288
Problem 288
Solution 289
How it works 289
4-3 Warping Video 290
Problem 290
Solution 290
How it works 291
4-4 Using Face Recognition 293
Problem 293
Solution 293
How it works 294
4-5 Diffing with a Base Image 297
Problem 297
Solution 297
How it works 298
4-6 Finding Movement 302
Problem 302
Solution 302
How it works 303
4-7 Separating the Foreground from the Background Using Grabcut 308
Problem 308
Solution 308
How it works 309
4-8 Finding an Orange in Real Time 317
Problem 317
Solution 317
How it works 318
4-9 Finding an Image Within the Video Stream 323
Problem 323
Solution 323
How it works 324
Index333

About the Author and About the Technical Reviewer

About the Author

Nicolas Modrzyk
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is currently Chief Technical Officer of Karabiner Software and a leader of development teams.

He is also an active contributor to the open source software community. As a developer and technical consultant, Nico has been involved over many years in designing large-scale server applications for a video conferencing company, managing enormous clusters of databases through high-performance middleware developed from scratch, enabling Japanese leaders with content management and process management systems, and pushing the boundaries of business processes for leading Asian companies.

Nico is an ardent advocate of Agile methods and is focused on getting the job done right to satisfy clients. He also loves to push friends and team members to challenge themselves and reach their goals. He has lived by those empowering standards in various countries, including France, America, Ireland, Japan, China, and India. Nico is also the author of a few other books on the Clojure programming language, in both English and Japanese.

He is currently based in Tokyo, Japan, where he is often found after hours playing soccer, hiking, performing live concerts with his guitar, and enjoying life with friends and colleagues.

 

About the Technical Reviewer

Aakash Kag
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is an AI developer at Manacola Private Ltd. He has two years of experience in big data analytics. He is a postgraduate in Computer Science with a specialization in Big Data Analytics. Aakash has also made contributions to the Microsoft bot builder.

Currently, Aakash is working on problems related to Conversational Bots and Natural Language Understanding.

He is passionate about Machine Learning meetups, where he often presents talks.

 
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