傳統條碼辨識在光照不均的環境下，會造成條碼影像分割錯誤及辨識率不足的問題。本研究應用迭代式Otsu方法來改善影像的二值化，利用迭代搜索的分割影像的子區域，對於所採集的條碼影像，計算不同光照區域的最佳閾值，以增進影像分割的可靠度，從而提升條碼辨識率。我們實作了此方法，並以一組取樣品質不佳的條碼影像資料庫進行測試，測試結果表明，該方法確實對不同光照環境的影像能夠獲得更好的二值化結果。此一結果將能被應用到真實工業生產條碼的辨識。

Traditionally, barcode recognition rate will be affected by uneven illumination since it may cause the faults of image segmentation and then raise the error rate of recognition. In this paper, we try to use an iterative triclass thresholding technique proposed by Cai to improve the thresholding. The method uses iterative search for image segmentation and computes the optimal threshold values for different illumination regions. Thus, the reliability of image segmentation is increased and the rate of barcode recognition is improved. We implemented this method and tested it with a group of inferior sampling quality barcode images. The experiment data shows that the method actually obtains a better result of thresholding on images under the uneven illumination. The result will be applied to actually industrial barcode recognition.

[1] T. Sun, and D. Zhou, "Automatic Identification Technology- Application Of Two-Dimensional Code," 2011 IEEE International Conference on Automation and Logistics (ICAL), pp. 164-168, Aug 2011.
[2] C. H. Chu, D. N. Yang, and M. S. Chen, "Image Stabilization for 2D Barcode in Handheld Devices," Proceedings of International Conference on Multimedia, Augsburg, Bavaria, pp. 697-706, 2007
[3] T. Kanungo, and P. Resnik, "The Bible, Truth, and Multilingual OCR Evaluation," In Proceedings of SPIE Conference on Document Recognition and Retrieval VI, San Jose, Jan 1999.
[4] C. Chen, and Y. F. Zheng, "Passive and active stereo vision for smooth surface detection of deformed plates, " IEEE Transactions on Industrial Electronics, Volume:42, Issue: 3, pp. 300-306, 1995
[5] M. B. Holte, T. Cuong, M. M. Trivedi, and T. B. Moeslund, " Human Pose Estimation and Activity Recognition From Multi-View Videos: Comparative Explorations of Recent Developments," IEEE Journal of Selected Topics in Signal Processing, Volume:6, Issue: 5, pp. 538-552, Aug 2012.
[6] W. Liu, and D. Hu, "Application of surface fitting in two-dimension barcode image segmentation," Information Technology, pp. 46-48, 2006.
[7] T. G. Stockham, "Image processing in the context of a visual model," Proc. IEEE, vol. 60, pp. 828-842, 1972.
[8] Y. Liu, M. Y. Liu, and M. J. Liu, "Design of automatic recognition algorithm of quick response code," Computer Systems & Applications, pp. 51-54, Jun 2006.
[9] N. Otsu, "A Threshold Selection Method from Gray-Level Histogram," IEEE Trans. Systems, Man, and Cybernetics, vol. 9, Pages 62-66, 1979
[10] H. Cai, Z. Yang, X Cao, W. Xia, and X. Xu, " A New Iterative Triclass Thresholding Technique in Image Segmentation," IEEE Trans on Image Processing, vol. 23, no. 3, March 2014
[11] X. P. Hu, Q. Dong, and Z. Q. Yu, "QR code recognition based on image processing," Aeronautical Computing Technique, pp. 99-102, 2007.
[12] ISO/IEC 18004 Information technology - Automatic identification and data capture techniques - QR Code bar code symbology specification, 2006
[13] X. D. Hu, and J. M. He, "On the recognition of Data Matrix techniques," Journal of Hangzhou Dianzi University, pp. 124-126, 2008.
[14] ISO/IEC 16022 Information technology - Automatic identification and data capture techniques - Data Matrix bar code symbology specification, 2006
[15] L. K. Huang, and M. J. Wang, "Image thresholding" by minimizing the measures of fuzziness," Pettern Recognition, Vol. 28, No. 1, pp.41-51, Jan 1995.
[16] J. N. Kapur, P. K. Sahoo, and A. K. C. Wong, "a new method for gray-level picture thresholding using the entropy of the histogram," Computer Vision Graphice, and I mage Processing, 29(3), p.273-285, 1985.
[17] J. Starck, M. Elad, and D. Donoho, "Image Decomposition Via The Combination of Sparse Representations and A Variational Approach", IEEE Trans. on Image Processing, vol. 14, no. 10, pp. 1570-1582, 2005.
[18] C. H. Chen, C. M. Kuo, C. Y. Chen, and J. H. Dai, "The design and synthesis using hierarchical robotic discrete-event modeling," Journal of Vibration and Control, vol.19, no.11, pp.1603–1613, December 2013.
[19] R. J. Mayer, "IDEF0 Function Modeling," Air Force Systems Command, 1992.
[20] X. Fan, and G. Fan, "Graphical Models for Joint Segmentation and Recognition of License Plate Characters," IEEE Signal Processing Letters, Vol. 16, No. 1, pp. 10-13. 2009