2D Bar Code Reader System Based On Hough Transform Rectangle Detection

With higher capacity, higher density, more powerful error-correction ability and higher security ability, two-dimensional Bar Code has played an important role gradually in the information automatic field. Firstly, based on digital image processing and combined coding theory, two-dimensional matrix bar code is a symbol system processed automatically using image recognition technology. Because two-dimensional bar codes relatively higher density information, its re cognition technology is more complex than that of one-dimensional bar. So recognizing 2D bar code fleetly and effectively becomes an important field.After the 2D bar code is printed on the surface of product, it will be influenced by the circumstance, background, light, dirty and deformity will influence the quality of bar code image, therefore, it will disturb the successful recognition of 2D bar code. How to get over the disturbing of noise and locate the bar code precisely from the background and read the information quickly is the research point of this paper, as well as the whole reader system based on that technology.The main contents of this paper are as follows:1) Take QR Code as example, we discuss the locating algorithm of 2D bar code. Based on the characteristic of QR code image, we use Canny edge detection algorithm and rectangle detection algorithm based on Hough transformation to separate the bar code area form the background effectively.2) Because 2d bar code is much more difficult than 1d bar code, it takes several steps to get character information from code symbol. We analyze the coding theory of QR code, then propose a complete decoding algorithm.3) Bar code reader based on image is quite different from traditional reader base on scanning, we analyze the recognition flow of the 2D bar code and propose a simple QR code reader system and implemented on computer.The experimental results on Visual C++ show that the performance of the algorithms proposed in this paper are so excellent that they can be applied effectively and can be consulted on recognizing other kinds of 2D bar codes.