von Ahn L, Blum M, Hopper N J, et al. CAPTCHA: Using Hard AI Problems for Security // Proc of the 22nd International Conference on Theory and Applications of Cryptographic Techniques. Warsaw, Poland, 2003: 294-311
[2]
Rusu A, Thomas A, Govindaraju V. Generation and Use of Handwritten CAPTCHAs. International Journal on Document Analysis and Recognition, 2010, 13(1): 49-64
[3]
Rusu A, Govindaraju V. Handwritten CAPTCHA: Using the Difference in the Abilities of Humans and Machines in Reading Handwritten Words // Proc of the 9th International Workshop on Frontiers in Handwriting Recognition. Tokyo, Japan, 2004: 226-231
[4]
von Ahn L, Maurer B, McMillen C, et al. reCAPTCHA: Human-Based Character Recognition via Web Security Measures. Science, 2008, 321(5895): 1465-1468
[5]
Xu Ming. Recognition and Anti-Recognition of Verification Code. Master Dissertation. Nanjing, China: Nanjing University of Science and Technology. College of Computer Science and Technology, 2007 (in Chinese) (许 明.验证码的识别和反识别.硕士学位论文.南京:南京理工大学.计算机科学与技术学院, 2007)
[6]
Chellapilla K, Simard P. Using Machine Learning to Break Visual Human Interaction Proofs (HIPs) // Weiss Y, Schlkopf B, Platt J, eds. Advances in Neural Information Processing Systems. Cambridge, USA: MIT Press, 2004, 17: 265-272
[7]
Jiang Peng. Investigation on Verification Code and Its Implementation as Web Service. Master Dissertation. Nanjing, China: Nanjing University of Science and Technology. College of Computer Science and Technology, 2007 (in Chinese) (姜 鹏.验证码识别及其Web Service的实现研究.硕士学位论文.南京:南京理工大学.计算机科学与技术学院, 2007)
[8]
Hocevar S. PWNTCHA-Pretend Were Not a Turing Computer But a Human Antagonist [EB/OL]. [2010-02-15]. http://sam.zoy.org/wiki/PWNtcha
[9]
Hochreiter S, Schmidhuber J. Long Short-Term Memory. Neural Computation, 1997, 9(8): 1735-1780
[10]
Graves A. Supervised Sequence Labelling with Recurrent Neural Networks. Ph.D Dissertation. Manno, Switzerland: Technical University of Munich. Dalle Molle Institute for Artificial Intelligence, 2008
[11]
Graves A, Liwicki M. A Novel Connectionist System for Unconstrained Handwriting Recognition. IEEE Trans on Pattern Analysis and Machine Intelligence, 2009, 31(5): 855-868
[12]
Varga T. Off-line Cursive Handwriting Recognition Using Synthetic Training Data. Ph.D Dissertation. Bern, Switzerland: University of Bern. Institute of Computer Science and Applied Mathematics (IAM), 2006
[13]
Su Tonghua. Off-line Recognition of Chinese Handwriting: From Isolated Character to Realistic Text. Ph.D Dissertation. Harbin, China: Harbin Institute of Technology. School of Computer Science and Technology, 2008 (in Chinese) (苏统华.脱机中文手写识别——从孤立汉字到真实文本.博士学位论文.哈尔滨:哈尔滨工业大学.计算机科学与技术学院, 2008)
[14]
Zhao Wei, Liu Jiafeng, Tang Xianglong, et al. Cascaded HMM Training Algorithm for Continuous Character Recognition. Chinese Journal of Computers, 2007, 30(12): 2142-2150 (in Chinese) (赵 巍,刘家锋,唐降龙,等.连续字符识别的级联HMM训练算法.计算机学报, 2007, 30(12): 2142-2150)
[15]
Gers F A, Schmidhuber J. LSTM Recurrent Networks Learn Simple Context-Free and Context-Sensitive Languages. IEEE Trans on Neural Networks, 2001, 12(6): 1333-1340
[16]
Mitchell T M. Machine Learning. New York, USA: McGraw Hill, 1997
[17]
Yang Jian, Zhang D, Alejandro F, et al. Two-Dimensional PCA: A New Approach to Appearance-Based Face Representation and Recognition. IEEE Trans on Pattern Analysis and Machine Intelligence, 2004, 26(1): 117-129
[18]
Wachenfeld S, Klein H V, Jiang Xiaoyi. Recognition of Screen-Rendered Text // Proc of the 18th International Conference on Pattern Recognition. Hongkong, China, 2006, Ⅱ: 1086-1089
[19]
Li Ying. Investigation on Generation and Recognition of Verification Code. Master Dissertation. Nanjing, China: Nanjing University of Science and Technology. College of Computer Science and Technology, 2008 (in Chinese) (李 颖.Web验证码的生成与识别.硕士学位论文.南京:南京理工大学.计算机科学与技术学院, 2008)
