Master's Thesis
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2008:062 CIV MASTER'S THESIS A Concept of Using 2D Bar Codes in Retail Environments Per Jonsson Luleå University of Technology MSc Programmes in Engineering Computer Science and Engineering Department of Computer Science and Electrical Engineering Division of Computer Science 2008:062 CIV - ISSN: 1402-1617 - ISRN: LTU-EX--08/062--SE A Concept Study of Using 2D Bar Codes in Retail Environments Per Jonsson March 10, 2008 Abstract The recent popularity of camera equipped mobile phones have sparked a new field of use for machine-readable 2D bar codes. A code can be printed on everyday items and be interacted with using a camera phone. The interaction is initiated by scanning the 2D bar code with the phone’s camera. And the reaction can be anything from simply retrieving information to triggering some action. Because of the low cost of printing 2D bar codes, there many possible applications that could be based on this. One such application is examined in this thesis and aims to improve the usefulness of normal cash register receipts. The idea is to print a 2D bar code on receipts that contains the purchase information in digital form. This is as- sumed to help customers with managing their receipts or with more detailed book-keeping. This assumption is evaluated by developing a prototype imple- mentation of a receipt reader. This prototype is based on two Java libraries for decoding DataMatrix and Quick Response codes. The main conclusion from this evaluation is that the libraries used were able to store an estimate of 42 purchase items in a 2D bar code. There are trade-offs that can be implemented to increase the capacity when needed which helps to make the assumption valid. Acknowledgments I would like to thank Ericsson Research in Lule˚afor the opportunity to write this master thesis. Especially my supervisor at Ericsson, John Sandberg and also Jakob Saros for their help and guidance. Tommy Arngren, Angelina Frediksson, Xiaolei Hu and Simon Persson deserves a big acknowledgment for their inputs and for the participation in the brainstorming session. Furthermore, I would like to thank the interview respondents and finally my supervisor at the University, Jingsen Chen. Per Jonsson March 2008 Lule˚aUniversity of Technology ii Contents 1 Introduction 1 1.1 ObjectivesandScope......................... 1 1.2 RelatedWork............................. 2 1.3 Outline ................................ 2 2 Background 3 2.1 Barcodes ............................... 3 2.1.1 1Dbarcodes ......................... 3 2.1.2 2Dbarcodes ......................... 4 2.2 Examplesof2DSymbologies . 5 2.2.1 ColorCode........................... 5 2.2.2 ShotCode ........................... 6 2.2.3 Quickresponsecode . .. .. .. .. .. .. .. .. 6 2.2.4 DataMatrix.......................... 8 3 Methods 9 3.1 Implementation............................ 9 3.1.1 Generator........................... 9 3.1.2 Reader............................. 9 3.2 Evaluation............................... 10 3.2.1 Performancetests . 10 3.2.2 Interviews........................... 10 4 SelectionofFeasibleSymbologies 12 4.1 Concept ................................ 12 4.1.1 Problem............................ 12 4.1.2 Proposedsolution . 12 4.2 AnalysisofRequirements . 13 4.2.1 Variables ........................... 13 4.2.2 Conceptrequirements . 14 4.2.3 Delimitations ......................... 15 4.2.4 Finalrequirements . 16 4.3 Selection................................ 16 4.3.1 Datacapacityanddensity. 17 4.3.2 Errorcorrection . .. .. .. .. .. .. .. .. .. 17 4.3.3 Colorprint .......................... 17 4.3.4 Availablesoftware . 18 4.3.5 Result............................. 18 iii 5 Implementation 20 5.1 2DBarCodeGenerator . .. .. .. .. .. .. .. .. .. 20 5.1.1 Serialization.......................... 21 5.1.2 Compression ......................... 21 5.1.3 Visualization ......................... 21 5.2 ReceiptReaderPrototype . 21 5.2.1 Recognition.......................... 21 5.2.2 Decompression ........................ 22 5.2.3 Unserialization . 22 5.2.4 Userinteraction . .. .. .. .. .. .. .. .. .. 22 6 Evaluation of Concept 24 6.1 PerformanceTests .......................... 24 6.1.1 Resolutiontest ........................ 24 6.1.2 Capacitytest ......................... 25 6.2 Interviews............................... 27 6.2.1 Interview1 .......................... 28 6.2.2 Interview2 .......................... 28 6.2.3 Interview3 .......................... 28 6.2.4 Interviewsummary. 28 7 Discussion 30 7.1 Feasibility............................... 30 7.2 InterviewInput............................ 31 8 Conclusions 32 8.1 FutureWork ............................. 32 References 35 A Format Specification 37 B Tables 39 iv Chapter 1 Introduction Bar codes are often associated with the scanning of items at the cash register in most stores. These bar codes encode data using several vertical lines with varying widths. But only using one dimension leaves a large part of the symbol unused. This thesis examines a variation called 2D bar codes. These codes are, unlike 1D bar codes, able to make use of the height of the symbol. As illustrated in Figure 1.1. Figure 1.1: (a) A 1D bar code only stores data in one direction while (b) 2D bar codes can utilize both dimensions. This is possible because of a change in the scanning process. 1D bar code scanners are based on only capturing a horizontal scan line. The 2D bar codes are designed to instead be processed from complete 2D camera images. The in- creasing availability if camera phones allows users to interact with 2D bar codes in a way that was not possible before. This introduces several opportunities for new applications. A concept of such an application is explored further in this study. The idea of this concept is to allow customers read receipts with their mobile phone. This is done by printing a 2D bar code on the receipt containing the information in digital form. As an example, having the receipt information in digital form could serve useful for personal book-keeping. 1.1 Objectives and Scope This thesis will study a concept with the goal of gaining greater knowledge of applications based upon the use of 2D bar codes. The main objective is to 1 2 CHAPTER 1. INTRODUCTION determine if the studied concept is feasible. This is done by examining the concept from a technical viewpoint and also by receiving input from potential providers of service. The feasibility is estimated on the basis of a prototype implementation illustrating the concept. To limit this thesis to the relevant parts of the previous paragraph, the scope have to be slightly narrowed to not include: • A comparison between implementations of decoding libraries. The selec- tion of 2D bar codes only depends on requirements posed on the capa- bilities in specifications and no further selection will be made on basis of performance. The results will only tell that there exists libraries so that at least those results could be reached. • Tests, surveys or interviews with users. This is a subject of later evaluation and not included in this introductory assessment. Furthermore, the implementation is dependent on the available hardware, in this case a Java enabled mobile phone. This restricts the software used to the Java ME1 platform. 1.2 Related Work Kato and Tan did a study[1] on 2D bar codes in 2005. Their study tried to determine which bar code was the most suitable for mobile phone applications in general. Based on a set of requirements, they selected the VS Code specification as the most flexible. This study is more specific toward a certain concept and also have to take construction of a prototype into consideration and will lead to a different end-result than Kato and Tan’s. Even though many of the requirements concurs, no Java ME decoding library was found for the VS Code. This is seen as required in this study. 1.3 Outline This introduction is followed by a background chapter introducing bar codes. Chapter 3 describes the methods used. Chapter 4 provides the concept and also the analysis and selection of two feasible bar codes. With the help of these results, the implementation process is described in Chapter 5 where a prototype bar code reader is described. The evaluation of the prototype is presented in Chapter 6 before the discussion and some concluding points in Chapters 7 and 8. Two appendices follows the report and lists additional information about implementation details and tables. 1Micro Edition. A subset of Java for resource-constrained devices, such as mobile phones. Chapter 2 Background This chapter will begin by introducing bar codes in general and will then con- tinue focusing on describing 2D bar codes. The background will also present some examples of what different 2D bar codes are capable of. 2.1 Bar codes Bar codes are basically a way of cheaply printing machine readable information on objects. There are many different kinds of bar codes, ranging from only being able to store a small number to several thousand bytes. The terms symbology and symbol will be used extensively in this report. Even though the terms in some cases can be used interchangeably, there is a subtle difference. The symbology is the bar code specification and the symbol is the, often printed, bar code itself. The symbology specifies a symbol’s appearance, how it store its data and other attributes. This section will continue to briefly introduce 1D bar code symbologies and then move on to explain the properties of 2D bar code symbologies. 2.1.1 1D bar codes 1D, or linear, bar codes is the code type most