摘要(英) |
In this thesis, we develop a fast autofocus technique for microscope imaging, In order to solve the problem of focusing automatically in automatic optics inspection machine (AOI) and laser repair machine (LR) that used in TFT-LCD and color filter panel industry, we will offer a fast, steady, and reliable autofocus technique.
We follow the principle of the geometric optics model of image formation and the concept of the image processing, use Fast Fourier Transform (FFT), Discrete Cosine Transform (DCT), Discrete Wavelet Transform (DWT), frequency domain filter (Ideal high pass filter, IHPF),(Butterworth high pass filter, BHPF),(Gaussian high pass filter, GHPF),(Ideal low pass filter, ILPF),(Butterworth low pass filter, BLPF),(Gaussian low pass filter, GLPF), and spacial domain filter (energy of gradient magnitude, EOGM),(energy of image Laplacian, EOIL) technologies to analyze the focusing degree of the image of microscopes. Also, we combine above-mentioned technologies to the quadratic curve fitting approximate, the cubic curve fitting approximate and gaussian curve fitting approximate etc, autofocus searching algorithm. Probe into the moving step, sampling times, focus speed, and focus stability and reliability.
In order to reach characteristics such as fast, steady and reliable, we propose two kinds of good and bad criteria of judging focusing criterion: (i) Ability of resisting of the noise; (ii) Calculating complexity; Propose two kinds of good and bad criteria of judging autofocus searching algorithm: (i) Move and sampling times; (ii) Stability and reliability of the correct focusing. We think the focus criterion has apparent dependence to autofocus searching algorithm, therefore we compare the focus criterion base on the ability of resisting of the noise, calculating complexity, and the sampling times of autofocus searching algorithm. Finally, we use a large number of focus experiment to prove we develop a fast autofocus technique for microscope imaging, which can reach fast, steady and reliable results. |
參考文獻 |
[1] Baina, J. and J. Dublet,“Automatic focus and iris control for video cameras,”in Proc. of the Fifth Int. Conf. on Image Processing and its Applications, Edinburgh, Jul.4-6, 1995, pp.232-235.
[2] Boddeke, F., V. L. Van, H. Netten, and L. Toung, “Autofocusing in microscopy based on the OTF and sampling,” Bioimaging, vol.2, pp.193-203, 1994.
[3] Chern, N. K., P. A. Neow, and M. H. Ang Jr., “Practical issues in pixel-based autofocusing for machine vision,”in Proc. of the IEEE Int. Conf. on Robotics and Automation, Seoul, Korea, May 21-26, 2001, pp2791-2796.
[4] Gonzalez, R. C. and R. E. Woods, Digital Image Processing, 2nd edition, Prentice-Hall, Upper Saddle River, NJ, 2002.
[5] He, J., R. Zhou and Z. Hong,“Modified fast climbing serach auto-focus algorithm with adaptive step size searching technique for digital camera,” IEEE Trans. on Consumer Electronics, vol.49, pp257-262, May 2003.
[6] Hecht, E., Optics, Addison-Wesley Publishing Company, 1987.
[7] Kesseler, W. and F. Jan,“Analytical model of autofocus system with CCD camera,”in Proc. Int. Conf. on Sensor Camera System for Scientific, Industrial and Digital Photography Application, vol.3965, pp396-380, May 2000.
[8] Kim, Y., June-Sok Lee, A. W. Morales, and Sung-Jea Ko, “A video camera system with enhanced zoom tracking and auto white balance,”IEEE Trans. on Consumer Electronics, vol.48, no.3, pp428-434, Aug. 2002.
[9] Krotkov, E. P.,“Focusing,”International Journal of Computer Vision, vol.1, pp.223-237, 1987.
[10] Li, F. and H. Lin,“A fast auto focusing method for digital still camera,”in Proc. Int. Conf. on Mechine Learning and Cybernetics, Aug.18-21, 2005, vol.8, pp5001- 5005.
[11] Ligthart, G. and F. Groen,“A comparison of different autofocus algorithms”, in Proc. Int. Conf. on Pattern Recognition, Munich, Oct. 19-22, 1982, pp.597-600.
[12] Mallat, S., ”A compact multiresolution representation: The wavelet model.”in Proc. IEEE Int. Conf. on Computer Vision, Washington DC, 1987, pp.2-7.
[13] Nayar, S. K. and Y. Nakagawa,“Shape from focus,” in Proc. IEEE Int. Conf. on Robotics and automation, May 13-18, 1990, vol.2, pp.218-225.
[14] Schlag, J. F., A. C. Sanderson, C. P. Neuman, and F. C. Wimberly, Implementation of automatic focusing algorithms for a computer vision system with camera control, CMU-RI-TR-83-14, Robotics Institute, Carnegie-mellon University, 1983.
[15] Shen, Chun-Hung and H. H. Chen,“Robust focus measure for low-contrast images,”in Proc. Int. Conf. on Consumer Electronics, Jan. 7-11, 2006, pp.69-70.
[16] Song, Yu, and L. Mantian,”Research on SUSAN based auto-focusing algorithm for optical microscope application,”in Proc. IEEE Int. Conf. on Mechatronics and Automation, Luoyang, China, June 25-28, 2006, pp1237-1241.
[17] Subbarao, M. and J. K. Tyan,“Selecting the optimal focus measure for autofocusing and depth-from-focus,”in Proc. IEEE Trans. on Pattern Analysis and Machine Intelligence, vol. 20, no.8, pp864-870, Aug. 1998.
[18] Subbarao, M., T.S. Choi, and A. Nikzad,“Focusing techniques”, Journal of Optical Engineering, vol.32, no.11, pp.2824-2836, Nov. 1993.
[19] Subbarao, M.,“Parallel depth recovery by changing camera parameters,”in Proc. The 2nd Int. Conf. on Computer Vision, Florida, Dec.5-8, 1986, pp.149-155.
[20] Tenenbaum, J. M., Accommodation in computer vision, Ph.D. Dissertation, Stanford University, Stanford, CA, 1970.
[21] Tseng, Din-Chang, Image Processing, Lecture Note, Institute of Computer Science and Information Engineering, National Central Univ., 2007.
[22] Widjaja, J. and S. Jutamulia,“Wavelet transform-based autofocus camera systems,”in Proc. of the IEEE Asia-Pacific Conf. on Circuits and Systems, Chiangmai, Nov.24-27, 1998, pp.49-51.
[23] Xiong,Y. and S. A. Shafer,“ Depth from focusing and defocusing,”in Proc. IEEE Conf. on Computer Vision and Pattern Recognition, New York, June 15-17, 1993, pp.68-73.
[24] Yang, G. and B.J Nelson,“Wavelet-based autofocusing and unsupervised segmentation of microscopic images,”in Proc. Int. Conf. on Intelligent Robots and Systems, Minneapolis, MN, Oct.27-31, 2003, vol.3, pp.2143-2148.
[25] Yeo T., S. O. Jayasooriah, and R. Sinniah, “Autofocusing for tissues microscopy,”Image and Vision Computing, vol.11, no.10, pp.629-639, 1993. |