The Research Of Decoding Two Dimensional Bar Code In Image Mode

It is the wide application of one-dimensional codes that speeds up the data collection and ink~rmation processing, and it provides the great contribution for the modernization and scientization of administration. Due to the limit of the information capacity, one-dimensional bar codes is just a label tbr goods. They must be used with database. With the development of high technology, it is pressed for using bar code to express more information within the limited printing space, which could realize the description for goods. Two-dimensional bar codes appeared just about to meet upwards requirement. 1vo-dimensional bar codes have many types, however, PDF4I7 have already become national criterion in China. Therefore, PDF417 bar code is our research oblect. In threign countries, 2-D bar codes technology have already been applied in many fields, and they have produced 2-D bar code identify system in good property. In China, this technology is just in research phase, so we have dropped behind the teign countries greatly. The main factor that restricts to develop 2-D bar code technology in our country is that the 2-D bar code identify systems in current market are sold too expensively. Because of the characters of 2-D bar code, we must take measures to reduce the cost of system to develop this technology. The main reason of high price in system is the part of decoding, therefore, our research focus on auto-identify of PDF4 17, namely, the research of decoding arithmetic. Difference to traditional decoding process, we adopt the method based on a mode of image, that is to say, the image of bar-code collected by the camera is decoded though the arithmetic process. So, the method of decoding is different from traditional mode of decoding. One-off collecting of bar-code image by taking picture avoid the problems that produced by linear scanner. At the same time, it simplify to the operation of scanning of bar-code image. In order to research bar code technology effectively, we start to research for one dimensional bar code, because it is simpler than 2-D bar code, and its technology is very perfect. So it will be easier to implement. If one dimensional bar code is able to be decoded ideally by the mode of image process and analysis, well then, we could use this decoding method for the 2-D bar code on the basis of its characters. The decoding arithmetic mainly have two parts, the first part is to pretreatment the image collected, namely, the reform of image. This will ground for the correct decoding afterwards. The second part is to decode the bar-code image after pretreatment. The last result that the bar-code represents the text information is obtained. According to the results of the experiments, this decoding arithmetic is able to implement to decode PDF417 bar code correctly, and it meets basically the technical requirement.