[1] C. Tang, L. Wang, H. Yan, and C. Li, Opt. Lasers Eng. 50, 1036 (2012).
[2] X. Yang, Q. Yu, and S. Fu, Opt. Commun. 273, 60 (2007).
[3] J. Villa, J. A. Quiroga, and I. D. L. Rosa, Opt. Lett. 34, 1741 (2009).
[4] C. Tang, L. Han, H. Ren, D. Zhou, Y. Chang, X. Wang, and X. Cui, Opt. Lett. 33, 2179 (2008).
[5] D. Szolgay and T. Sziranyi, Electron. Lett. 47, 442 (2011).
[6] S. Chikkerur, A. N. Cartwright, and V. Govindaraju, Pattern Recogn. 40, 198 (2007).
[7] L. Hong, Y. Wan, and A. Jain, IEEE Trans. Pattern Anal. Machine Intell. 20, 777 (1998).
[8] F. Zhang, W. Liu, L. Xia, J. Wang, and Y. Zhu, Chin. Opt. Lett. 7, 210 (2009).
[9] P. Mrazek, "Nonlinear Diffusion for Image Filtering and onotonicity Enhancement", PhD. Thesis (Czech Technical University, 2001).
[10] A. Da'vila, G. H. Kaufmann and D. Kerr, Opt. Eng. 35, 3549 (1996).
[11] X. Zhou, J. P. Baird, and J. F. Arnold, Appl. Opt. 38, 795 (1999).
[12] P. Zhou and K. E. Goodson, Opt. Eng. 40, 1613 (2001).
[13] Z. Xiao, Z. Xu, and F. Zhang, Chin. Opt. Lett. 11, 101101 (2013)
[14] H. Cui, W. Liao, N. Dai, and X. Cheng, Chin. Opt. Lett. 10, 031201 (2012)
