Study On Algorithm Of Two-dimensional Bar Code Generation And Recognition And Its Realization With Portable C Program

Barcode technology based on computer and information technology is an emerging technology integrating encoding, printing, image capturing and processing, error correcting and image recognition. Barcode is playing an important part in the automatic identification field at present, because it can not only improve work efficiency effectively, but also realize scientific and modernization management. PDF417 is a kind of two-dimension barcode which has been a national stander. It break the limitation of one-dimension barcode and will improve work efficiency and reliability greatly.According to the subject background and research status, this paper carries on systematic deep research to the encoding and decoding algorithm of PDF417 using the software Visual C++ 6. 0 , and make the algorithm come true with C language. The main work of this paper includes: (1)analysis and implementation of PDF417 encoding algorithm, including generation of codewords, data compress, generation of error correction codewords and so on; make a data file to search symbol character and codeword based on the table of symbol character-codeword. (2) use the scanner to get barcode image and realize the algorithm of image processing on PC, including image binaryzation, image enhancement, image orientation; especially puts forward a technique of Hough transform specific to PDF417; at last, generate a new bmp image for further decoding treatment on PC after intelligent repair based on special structure of PDF417. (3)realize the image decoding algorithm with barcode image after treatment to be the research target, including determination of starting position, getting levels of barcode, query of codewords, calling subroutines of decoding. (4)study some methods of writing portable C program, and discuss the development and composition of PDF417 application system based of PC and embedded system.This paper also gives examples to verify the feasibility of the above algorithm. In the case of low noise interference the algorithm can decode the barcode correctly, although it is difficult in decoding heavy noise bar code image.