One of the advantages of barcode technology is its fast, accurate and reliable operation. Most one-dimensional (1D) barcodes only use a checksum to ensure that the data are correctly decoded. The data of 1D barcodes are vertically redundant. This allows correct data retrieval even when the symbol has been partially damaged. When at least one horizontal path across the barcode is readable, a code with printing defects can be correctly read. Furthermore, human-readable characters are also printed below most 1D barcodes (see Figure 2.12). This allows users to input the data manually in the worst-case scenario. Hence, a checksum for error detection may be sufficient for a 1D barcode.

Moreover, two-dimensional (2D) barcodes do not have such vertical redundancy. Furthermore, they are not accompanied by human-readable characters, often because of the limitation in printing area for the data encoded in 2D barcodes. Printing the encoded data near the symbol may be possible when using index 2D barcodes with limited data capacity. However, considering the space efficiency advantage of 2D barcodes, it is reasonable not to print human-readable characters along with the 2D barcode symbols. In some cases, it might be impossible owing to space restrictions. This prevents users from correcting data manually if an error should occur. Hence, 2D barcodes need a means of not only detecting errors but also correcting them.

Error detection and correction codes

Among the many error detection and/or correction techniques, the one most commonly used for 2D barcodes is the Reed–Solomon code. Nearly all database 2D barcodes have adopted this technique.

Overview of barcode technology

First of all, it is important to know the relationship between a ‘code’ and a ‘symbol’ in this context:

Definition of barcode

The definition of a barcode is given in the International Organization for Standardization and the International Electrotechnical Commission (ISO/IEC 1976 2–2): Information technology –Automatic identification and data capture (AIDC) techniques – Harmonised vocabulary – Part 2: Optically readable media (ORM). Since it only includes onedimensional barcodes, the definition given by the Japanese Standards Association (JSA) is preferred.

Abarcode is a machine-readable representation of information that is formed by combinations of high and low reflectance regions of the surface of an object [2], which are converted to ‘1’ s and ‘0’ s. This definition includes both one-dimensional and twodimensional barcodes. Originally, information was encoded into an array of adjacent bars and spaces of varying width and that is where the word ‘barcode’ is derived from. This type of barcode is called a linear one-dimensional (1D) barcode. The 1D barcode symbologies can be read by a scanner that sweeps a beam of light across the barcode symbol in a straight line [2].

The improvement in capability of barcode technology

Two decades have passed since the first two-dimensional (2D) barcode was introduced in 1988. Over this period, barcode technology, especially that for 2D barcodes, has evolved continuously from its original tasks for automatic identification and data capture to a tool for realising augmented reality (AR) and/or ubiquitous computing. The focus of early researchers was on the capability of 2D barcodes as a whole, in comparison with the traditional one-dimensional (1D) barcodes, and the effect of their emergence on certain sectors of industry.

Taxonomic research on 2D barcodes and a comparison with 1D barcodes

Noting the potential of this new technology, Barnes et al. [15], for example, conducted thorough taxonomic research on the 2D barcodes available at the time. They first introduced 2D barcodes in comparison with 1D barcodes and then analysed, compared and contrasted the existing 2D barcodes with each other in terms of their capability (especially data capacity and accuracy), distinctive features and applications. As a result, Barnes et al. concluded that 2D barcode technology is more advantageous than its 1D counterpart in terms of physical size, storage capability and data accuracy, despite the cost of the increase in data density. These advantageous features allow a 2D barcode to be a robust portable database, while a 1D barcode can only work as a key to access a backend database for which network connectivity must be guaranteed.

Barnes et al. [15] also referred to the trends in certain industries towards standardisation of the use of 2D barcodes that have occurred at various times.

Since the first barcode system was first introduced in a Cincinnati supermarket in the United States of America (USA) 40 years ago, this technology has co-evolved together with printing and scanning techniques. The printed tags are inexpensively produced as the costs of papers and printing devices have never had a dramatic increase. This has fostered the inexpensive operation of barcode systems and, in turn, their widespread adoption. The scanning technology has also had a great impact on the development of barcode technology, as without effective scanning barcode systems cannot operate. In fact, the lack of feasible scanning systems delayed the development of early barcode systems.

Different types of barcode technology, namely, one-dimensional (1D), two-dimensional (2D) and three-dimensional (3D), have been developed to meet user needs, along with numerous barcode symbologies. Each barcode symbology has unique features to meet specific requirements. As a result, a wide variety of barcode technologies is currently available, which not only meet user needs but have become a necessity in our daily lives.

In this chapter the history of barcode technology is introduced, and this is followed by a detailed explanation of how 2D and 3D barcodes have evolved since the birth of 1D barcodes (also called linear barcodes). Next, the barcode systems and symbologies that are commonly used at present are described. Finally, we forecast how each barcode technology will progress, taking into account how their interactiveness has promoted their advancement. Furthermore, the adoption of other emerging technologies such as radio frequency identification (RFID) is also predicted.

This book was written for scientists, researchers and those who are interested in the science and development of barcode technology for mobile devices. It is a comprehensive work covering the history and evolution of this technology. The book also presents a substantial compilation of different barcodes used or designed for mobile devices and mobile applications. Nonetheless, this collection will never stay complete for long as this is a rapidly evolving field, with new mobile barcodes being invented on almost a yearly basis. In fact, within this book, we have presented our very own novel two-dimensional (2D) barcode, designed especially for mobile devices such as camera mobile phones.

Also presented herein are the techniques and development process for our novel 2D barcode, the Mobile Multi-Colour Composite (MMCC™). Hence, we envision that this book will be a useful reference for those who are interested in designing and developing barcodes for mobile devices.

Finally, we do hope that this book will be the first of many to come that will fill the current gap in the publications in this area of interest.

Acknowledgements

Any substantial work of substance would not be possible without the kind contributions and supports of others. For continuous support and encouragements from Cambridge University Press, we wish to thank especially Dr Phil Meyler and Ms Sabine Koch.

For the personal support of our loved ones, our respective acknowledgements are as follows.

Dr Hiroko Kato wishes to thank her husband, Hisanori, for his continued support and patience and her children, Masanori and Yukino, for their constant support and understanding and all the help they gave with household chores while she focused on completing this book.

Aims of the prototype colour 2D barcode development

As mentioned in Chapter 2, most 2D barcodes were developed to meet special requirements. For example, QR Code was invented in response to the demand for a barcode with greater data capacity than the traditional linear barcodes so that it could collect information about products without accessing a backend database and hence improve the productivity in assembly lines. Visual Code was developed to implement applications for human–computer interaction.

To design a barcode, first of all the purpose of barcode development and the target applications must be determined. The ultimate goal of our barcode development was to implement a 2D barcode system that can provide applications and services ubiquitously, regardless of time, place and occasion. To implement such a system, a barcode must be flexible in both data capacity and network connectivity. Consider, for example, a ringtone downloading service advertised in a magazine. If an index 2D barcode were used, the only option for a user would be to connect his camera phone to the designated Web page and download ringtones via the Internet. Continuous network connectivity has to be guaranteed for this type of service always to be available. Conversely, no network connectivity leads to no service.

With a database 2D barcode with high data capacity, however, it is possible to provide other options. For example, a user can save the uniform resource locators (URLs) of Web sites directly encoded in the barcode in his or her mobile camera phone for later use.