[1] Darrell T, Wohn K. Pyramidbased depth from focus [C]// Proc Computer Vision and Pattern Recognition, Ann Arbor, MI, USA, Jun 5-9, 1988: 504-509.

[2] Nayar S K. Shape from focus system for rough surface [C]// Proc Computer Vision and Pattern Recognition, Champaign, Illinois, USA, 1992: 539-606.

[3] Nayar S K, Nakagawa Y. Shape from focus [J]. IEEE Transactions on Pattern Analysis and Machine Intelligence(S0162-8828), 1994, 16: 824-831.

[4] Xiong Y, Shafer S A. Depth from focusing and defocusing [C]// Proc Computer Vision and Pattern Recognition, New York, NY, USA, June 15-17, 1993: 68-73.

[5] Helmli F S, Scherer S. Adaptive shape from focus with an error estimation in light microscopy [C]// Proceedings of the 2nd International Symposium on Image and Signal Processing and Analysis, Pula, Croatia, June 21, 2001: 188-193.

[6] Niederoest M, Niederoest J, Scucka J. Shape From Focus: Fully Automated 3D Reconstruction and Visualization of Microscopic Objects [C]// 6th International Conference on Optical 3-D Measurement Techniques, Zurich, Switzerland. September 22-25, 2003: 236-243.

[8] Nourbakhsh R, Dvid Andre, Carlo Tomasi, et al. Mobile robot obstacle avoidance via depth from focus [J]. Robotics and Autonomous Systems(S0921-8890), 1997, 22(6): 151-158.

[9] Subbarao M, Choi T S. Accurate recovery of three-dimensional shape from image focus [J]. IEEE Trans. Pattern Anal. Machine Intelligence(S0162-8828), 1995, 17: 266-274.

[12] Choi T, Yun J. Three-dimensional shape recovery from focused image surface [J]. Optical Engineering(S0091-3286), 2000, 39: 1321-1326.