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Machine Vision Algorithms in Java Springer-Verlag London Ltd. Paul F. Whelan and Derek Molloy Machine Vision Algorithms in Java Techniques and Implementation With 183 Figures Springer Paul F. Whelan, BEng, MEng, PhD Derek Molloy, BEng Vision Systems Laboratory, School of Electronic Engineering, Dublin City University, Dublin 9, Republic of lreland ISBN 978-1-4471-1066-8 ISBN 978-1-4471-0251-9 (eBook) DOI 10.1007/978-1-4471-0251-9 British Library Cataloguing in Publicat ion Data Whelan, Paul Machine vis ion algorithms in java : techniques and implementation 1.Computer vis ion 2. java (Computer program language) 3.Computer algorithms I.Titiie II. Molloy, Derek 006.3'7 ISBN 978-1-4471-1066-8 Library of Congress Cataloging-in-Publication Data Whelan, Paul E, 1963- Machine vision algorithms in java: techniques and implementation / Paul E Whelan and Derek Molloy. p.cm. ISBN 978-1-4471-1066-8 (alk. paper) 1. Computer vis ion. 2. Computer algorithms. 3. java (Computer program language) 1. Molloy, Derek, 1973-II. Title TA1634.w542000 006.3 '7 -dc21 00-030072 Apart from any fair dealing for the purposes of research or private study, or criticism or review, as per mitted under the Copyright, Designs and Patents Act 1988, this publication may only be reproduced, stored or transmitted, in any form or by any means, with the prior permis sion in writing of the publishers, or in the case of reprographic reproduction in accordance with the terms of licences issued by the Copy right Licensing Agency. Enquiries concerning reproduction outside those terms should be sent to the publishers. © Springer-Verlag London 2001 Originally published by Springer-Verlag London Berlin Heidelberg in 2001 Softcover reprint of the hardcover 1s t edition 2001 The use of registered names, trademarks etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant laws and regulations and therefore free for general use. The publisher makes no representation, express or implied, with re gard to the accuracy of the informa tion contained in this book and cannot accept any legal responsibility or liability for any errors or omis sions that may be made. Typesetting: PostScript files by authors 34/3830-543210 Printed on acid-free paper SPIN 10743121 To Caroline, Hannah and Sean. (PFW) To Sally and parents. (DM) Preface For many novices to the world of machine vision, the development of auto mated vision solutions may seem like a relatively easy task as it only requires a computer to understand basic elements such as shape, colour and texture. Of course this is not the case. Extracting useful information from images in a lab oratory environment is a difficult process at the best of times, but to develop imaging systems with the reliability and repeatability required for industrial, medical and associated imaging applications increases the complexity of the design task. The aim of this book was to produce a self contained software reference source for machine vision designers which takes such issues into ac count. To that end Machine Vision Algorithms in Java contains explanations of key machine vision techniques and algorithms, along with the Java source code for a wide range of real-world image processing and analysis functions. A number of texts have been written over the last few years, which have focused on implementing image processing and to a lesser extent image anal ysis functions, through coded examples (i.e. for a range of software languages and environments). So, why do we need another book on the subject? Firstly, Machine Vision Algorithms in Java concentrates on examining these issues from a machine vision perspective. It focuses on the image analysis and gen eral machine vision design task, as well as discussing the key concepts relating to image processing. In addition, we have made available (via the Internet) a comprehensive machine vision development environment, Neat Vision, which allows the algorithms and techniques discussed throughout this book to be implemented by the reader. The range of machine vision techniques and applications has grown sig nificantly over the last decade and as such it would be difficult for a single text to cover them all. Therefore, this book concentrates on those algorithms and techniques that have found acceptance within the machine vision com munity. As is in the nature of putting a book like this together, certain areas receive greater attention reflecting our experience and the nature of our own research. This book has grown from a number of different elements. Many of the ideas outlined are based on the postgraduate modules Computer and Machine Vision (EE544) and Object-oriented Programming (EE553) developed by Dr. Paul Whelan and Derek Molloy respectively. Both modules are available in Vlll Preface traditional form and via the Internet as part of Dublin City University's Remote Access to Continuing Engineering Education (RA CeE) initiativel . Another key element was the development of Neat Vision, a Java based visual programming environment for machine vision. It provides an intuitive interface which is achieved using a "drag and drop" block diagram approach, where each image analysis/processing operation is represented by a graphical block with inputs and outputs that can be interconnected, edited and deleted as required. NeatVision was designed to allow the user to focus on the ma chine vision design task rather than concerns about the subtlety of a given programming language. It allows students of machine vision to implement their ideas in a dynamic and easy to use way, thus reinforcing one of the key elements of the educational experience, interaction. In conjunction with the publication of this book a fully functional 'shareware' version of NeatVision has been made available via the Internet2. We have also included an introduction to Object-oriented Programming (OOP) and the Java programming language, with particular reference to its imaging capabilities. This was done for those readers who may be un familiar with OOP and the Java programming language. It includes details relating to the design of a Java based visual programming environment for machine vision along with an introduction to the Java 2D imaging and the Java Advanced Imaging (JAI) Application Programming Interface (API). A wide range of illustrative examples are also included. Having successfully digested the ideas outlined in this book the reader will: • Be familiar with the essential elements of machine VlSlOn software and have an understanding of the problems involved in the development and implementation of machine vision systems from a software perspective. • Have the ability to design and implement image processing and analysis techniques. • Be able to evaluate emerging machine vision algorithms and techniques. • Be familiar with the Java programming language and its application to image analysis. • Be able to develop machine vision solutions using a Java based visual pro gramming environment (i.e. Neat Vision). This book is aimed at senior undergraduate and postgraduate students in engineering and computer science as well as practitioners in machine vision, who may wish to update or expand their knowledge in the field. We have tried to present the techniques and algorithms of machine vision in a way 1 http://www.racee.ie/ 2 See http://www.NeatVision.com/ for further details on downloading and in stalling this software. This web site also contains details of the NeatVision envi ronment along with a summary of its techniques. A number of working examples along with sample files and associated visual workspaces are also available. Preface IX that it will be understood not only by specialists familiar with the field, but also by those who are less familiar with the topic. Care has also been taken to ensure that we have provided adequate references to supporting work. This should aid readers who wish to examine the topics covered in more detail. The organisation of the book is as follows. Chap. 1 introduces the general field of machine vision systems engineering. Chap. 2 outlines the key concepts behind the Java programming language. As well as giving a brief history, de scription and layout of the Java language, this chapter outlines the properties of Java that make it useful for image processing and analysis. The purpose of Chap. 3 is to detail some of the basic techniques and algorithms used in the development of machine vision systems. Key elements of the image process ing and analysis functions introduced in this section are also implemented in Java and form the basis of the NeatVision visual programming environment. Chap. 4 follows on from this basic introduction by examining mathemati cal morphology, a key framework in which many machine vision algorithms can be placed. Chaps. 5 and 6 expand our discussion of imaging techniques to include key elements of texture and colour image analysis. Chap. 7 de tails the design and implementation of the Neat Vision visual programming environment. Appendix A outlines the graphics file formats that are used by NeatVision and Appendix B details the NeatVision imaging Application Programming Interface (API) specification. Finally, Appendix C summarises the range of operators available in the NeatVision machine vision software development environment. A range of sample applications implemented in NeatVision are highlighted throughout the book. For updates, corrections, colour images and sample visual programmes please refer to the book web site at http://www.eeng.deu.ie;-j avamv /. Dublin, June 2000 Paul F. Whelan Derek Molloy mvaj©eeng.deu.ie Acknowledgments This book has benefited from the comments and suggestions of a wide range of people, including our colleagues with whom we have had many fruitful discussions and collaborations. Numerous students have also contributed, both directly and indirectly. The most important contributions coming from members of the Vision Systems Laboratory (VSL) at Dublin City Univer sity (DCU), namely Ovidiu Ghita, Alexandru Drimbarean and Pradeep PP. We would particulary like to express our gratitude to Robert Sadleir (VSL) for a fruitful collaboration in the development of Neat Vision. Robert also contributed to our discussion on the Neat Vision development environment, specifically in Chap. 7. We would also like to thank all the members of the VSL for their comments on the various drafts of this book. We would like to thank Prof. Charles McCorkell, Head of the School of Electronic Engineering, DCU, for his support of the VSL and this book project. We would also like to acknowledge all our academic colleagues for our many discussions on computer and machine vision, especially Prof. Bruce Batchelor (machine vision systems engineering) and Dr. Pierre Soille (math ematical morphology). We would like to acknowledge Xuemei Zhang (De partment of Psychology, Stanford University), Mark Graves (Spectral Fusion Technologies) and Tim Carew (Technology Systems International) and thank them for their permission to use some of the material cited in this book. Special thanks are due to Nicholas Pinfield and Oliver Jackson of Springer Verlag for their commitment to this book and maintaining its schedule. Ma chine Vision Algorithms in Java: Techniques and Implementation was pre pared in camera-ready form using the IbTEX text processing environment and Paint Shop Pro image editing software. Finally, the authors would like to thank their families for their constant support and encouragement during this project. We would like to thank the readers in advance for comments and suggestions aimed at improving and ex tending the present book and its associated NeatVision software. Any errors, of course, remain our own responsibility. Acknowledgments XII Notice Neat Vision and its associated materials are copyrighted © 2000, by Paul F. Whelan. The software is presented "as is". While every reasonable effort has been made to ensure the reliability of this software, NeatVision and the associated algorithms outlined in this book are supplied for general reference only and should not be relied on without further specific inquiry. Neat Vision may be downloaded, stored on a hard drive or other storage device, with the following restrictions and exceptions: • Systematic or multiple-copy reproduction or republication; electronic re transmission to another location; print or electronic duplication of any NeatVision material supplied for a fee or for commercial purposes; or alter ing or recompiling any contents of NeatVision and its associated materials are not permitted. • By choosing to use Neat Vision and its associated materials, you agree to all the provisions of the copyright law protecting it and to the terms and conditions established by the copyright holder. • The authors cannot accept responsibility for any loss or damage caused by the use of the source code presented in this book. Trademarks • Sun, Sun Microsystems, Solaris, Java and all Java-based trademarks are trademarks or registered trademarks of Sun Microsystems, Inc. in the United States and other countries. • Netscape and Netscape Navigator are registered trademarks of Netscape Communications Corporation in the United States and other countries. • Microsoft, Windows, Windows NT and/or other Microsoft products refer enced herein are either trademarks or registered trademarks of Microsoft Corporation. • IBM is a registered trademark of IBM Corporation in the United States and other countries. • Paint Shop Pro is a registered trademark of Jasc Software, Inc.