Barcodes were developed in 1950 and have been widely used in a variety of applications due to their high reliability, efficiency and cost-effectiveness. However, barcodes can only record limited information about items. The 2D-barcode was devised to be capable of including a brief description in addition to assigning a number to an item. Moreover, sound, pictures and even traditional Chinese characters, etc., can be recorded as 2D-barcodes. There are many forms of 2D-barcodes in accordance with various commercial applications. For example, in 1994, the Japan Densoe company [11] developed a rapid reaction barcode (Quick Response code, QR-code) for the array code, shown in Figure 11. The QR-code design is very clever. The most important features of aQR-code are the position marks of the top left, bottom left corner and the upper right corner. Positioning marks are triple concentric
