Research Of Image Restoration In Barcode Recognition

With the development of computer technology, two-dimensional bar code has been widely applied to logistics industry, automated production, international trade, electronic commerce and so on. Two dimensional barcode has large information capacity, small area, anti-counterfeit and contamination resistance, which demonstrates the superiority in the area of the information acquisition, the information storage and the information reading.In this thesis, lots of exploratory research work has been done around restoration algorithm of DataMatrix and PDF417 bar code. The main work of this dissertation is summarized as follows.1. This paper introduces the code system standard, graphic symbols as well as the characteristics of two-dimensional bar code, especially for DataMatrix and PDF417. And before recognition, the bar code image preprocessing and detection algorithm are discussed. Many image preprocessing methods, such as gray level transformation and gray-scale equalization are used. And the bar code image detection algorithm and anti-perspective transformation algorithm are maily focused on.2. In the area of barcode restoration, for DataMatrix bar code a parameter estimation algorithm of Gaussian PSF is proposed. Then the degradated image of DataMatrix bar code can be restored. A lot of experiments find that the estimation algorithm works well.3. For PDF417 bar code, an estimation algorithm based on EM (Expectation Maximization) to the bar code signal that is got from horizontal scanning of PDF417 bar code is used. Some analysis and comparisons through experiments for bar code recognition rate are made. Facts show that the algorithm has advantages and practical value.4. An application system is designed using C++ programming language to complete bar code image acquisition from camera and decoding based on windows platform. The system has already been used in experimental unit. The results show its excellent performance.