Design&Implementation Of PDF417Two Dimensional Barcode Encoding And Decoding

The barcode technology has been used in various application fields and developing rapidly since its advent. With an increasing demand, such as people’s intention to include more information within a same limited space, while the capacity of the One-dimensional barcode is restricted, which can only be used to mark items but without detail descriptions. In our daily life, one dimensional barcode cannot meet the needs of many people in fields such as transportation and storage of information. Taking into account of the advantages of two dimensional barcode, such as the capacity to include more information, high reliability, good confidentiality performance, the emergence of the two dimensional barcode solves the problem of one dimensional barcode which cannot describe items due to its limited capacity. At the same time, in terms of error control, the two-dimensional barcode adopts the RS error correction code, which improves the read capability of barcode. In this paper, the research object is PDF417barcode which is a stacked two dimensional barcode, and to recognize the barcode image captured with ordinary camera in the natural environment. In this topic, the encoding of the barcode and its recognition process is studied in details. At the same time, the specific encoding process and the decoding algorithm and steps of the barcode image is displayed in specific manners by utilizing the Visual C++software to realize the encoding and decoding of the PDF417barcode. The main content of this paper is as follows:(1) The encoding rule of the PDF417two dimensional barcode has been analyzed and studied in detail and the whole process of the encoding is demonstrated. At the same time, the encoding principle of Reed-Solomon error-correcting code has been studied in detail as well. According to the principle of encoding, the Visual C++software is used to realize the encoding of the PDF417barcode.Problems which appeared in encoding process, such as data overflow for high grade of error correction, are all solved, and put forward the optimization algorithm.(2) The paper stated the pretreatment process of the barcode image which is captured with ordinary camera in the natural environment:graying, filtering the noise of the barcode image, edge detection, column boundary acquisition, the unit module calculation, identifying the level of the barcode and the code word. Pretreatment process lays the foundation role for the eventually identify of the barcode. In the whole pretreatment process, given the characteristics of PDF417barcode, optimization is applied to edge detection algorithm by using the differential diminishing boundary method to process the barcode image. Compared with the traditional edge detection algorithm,optimization is applied to edge detection algorithm to process the barcode image, the boundary of the image is more clearly, and the effect of the image is better.(3)The recognition and decoding process of the PDF417two dimensional barcode have been analyzed and studied in detail. The process of barcode image recognition after pretreatment process is exhibited. At the same time, the decoding principle of Reed-Solomon error-correcting code has been studied in detail as well. At last, the Visual C++software is used for decoding of the PDF417barcode.