[1] T. Sun and Y. Neuvo, Pattern Recognit. Lett. 15, 341 (1994).
[2] H. Hwang and R. A Haddad, IEEE Trans. Image Process. 4, 499 (1995).
[3] R. C. Gonzalez and R. E. Woods, Digital Image Processing, 2nd ed., Upper Saddle River, NJ: Prentice Hall, 2002.
[4] H. L. Eng and K. K. Ma, IEEE Trans. Image Process. 10, 242 (2001).
[5] K. S. Srinivasan and D. Ebenezer, IEEE Signal Process. Lett. 14, 189 (2007).
[6] Y. Q. Dong and S. F. Xu, IEEE Signal Process. Lett. 14, 193 (2007).
[7] C. T. Lu and T. C. Chou, Pattern Recognit. Lett. 33, 1287 (2012).
[8] P. E. Ng and K. K. Ma, IEEE Trans. Image Process. 15, 1506 (2006).
[9] F. Duan and Y. J. Zhang, IEEE Signal Process. Lett. 17, 647 (2010).
[10] I. Pitas and A. N. Venetsanopoulos, Nonlinear Digital Filter: Principles and Application, Kluwer, Boston, MA, 1990.