研究生: |
莊漢鈞 Chuang Han-Chun |
---|---|
論文名稱: |
離散差分預測模型用於數位相機自動對焦搜尋演算法之設計與應用 Design and Application of the Auto-Focus Search Algorithm Based on Discrete Difference Equation Prediction Model for Digital Camera |
指導教授: |
洪欽銘
Hong, Chin-Ming |
學位類別: |
碩士 Master |
系所名稱: |
機電工程學系 Department of Mechatronic Engineering |
論文出版年: | 2005 |
畢業學年度: | 93 |
語文別: | 中文 |
論文頁數: | 69 |
中文關鍵詞: | 自動對焦 、離散差分預測模型 、數位相機 |
英文關鍵詞: | auto-focus(AF), Discrete Difference Equation Prediction Model, DDEPM, digital camera |
論文種類: | 學術論文 |
相關次數: | 點閱:338 下載:59 |
分享至: |
查詢本校圖書館目錄 查詢臺灣博碩士論文知識加值系統 勘誤回報 |
本研究藉由離散差分預測模型與區間二分法設計一自動對焦搜尋演算法。隨著數位相機產業的發展,現今消費市場對數位相機的要求為-「輕、薄、短、小」、「高解析度」且「反應時間快」。就現今對焦技術而言,唯有被動式對焦技術能達到此一要求。被動式對焦技術係利用清晰度尺度來作為移動鏡頭位置的依據,然而高解析度所代表的意義為更大量的數位化資料處理,所以一般的搜尋演算法處理此一對焦問題所花費的時間往往過於冗長,但自動對焦搜尋演算法在使用上的先決條件則是它的「即時性」。
為此,本論文將運用離散差分預測模型的預測特性,提前預測對焦曲線的走勢,用以克服一般搜尋演算法因為過度伸縮鏡頭而造成搜尋時間過於冗長的問題,且由於可事先預知對焦曲線的走勢,更可以減少鏡頭在反轉時因鏡頭馬達齒輪間隙所造成反衝(backlash)的問題,如此可達到加快對焦速度的目的。最後,將離散差分預測模型搭配區間二分法,實際用於數位相機對焦模組的測試以驗證其可行性。
This paper presents a new auto-focus search algorithm based on Discrete Difference Equation Prediction Model (DDEPM) and Bisection Method. Now, mainstream market of digital camera is “light”, “thin”, “small size”, and “mega-pixels level”. To achieving these requests, the passive auto-focus technique should be adopted. In passive auto-focus technique, the lens will move to the highest focus-value position which is calculated by sharpness measure, so that the CCD layer will be in the image plane. In “mega-pixels level” digital camera, it will spend much time to compute a lot of digital image data. The common search algorithm for searching focus point will spend a lot of time, because the lens moves eternally, so that it can limit the focus region.
Actually, the auto-focus search algorithm for digital camera must be “real-time”. For this purpose, we will use DDEPM method to forecast the tendency of focus-curve, so that we can shorten the searching time by reducing the backlash times.
Finally, we will design an auto-focus algorithm based on DDEPM and Bisection Method and we will realize it by coding into digital camera, actually. The final experiment result can show the performance of this algorithm and it will prove that this algorithm is useful for reducing the backlash times.
[1] Kesseler W. and Fischer J. “Analytical Model of Autofocus Systems with CCD Camera”, Proceedings of the International Society of Optical Engineering, International Conference on Sensors, Camera Systems for Scientific, Industrial and Digital Photography Applications, vol.3965, pp.396-380, May 2000.
[2] Baina J. and Dublet J. “Automatic Focus and Iris Control for Video Cameras”, Fifth International Conference on Image Processing and its Applications, pp.232-235, 1995.
[3] Chen C.M., Hong C.M. and Hsieh Y.R. “A Modeling Technique of Grey Prediction Model Using Discrete Difference Equation”, The Journal of Grey System, vol.12, No.1, pp.65-72, 2000.
[4] Chen C.M. and Lee H.M., “An Efficient Gradient Forecasting Search Method Utilizing the Discrete Difference Equation Prediction Model”, Applied Intelligence, vol. 16, No. 1, pp. 43-58, 2002.
[5] Deng J.L., “Control Problems of Grey System,” Systems & Control Letters, vol. 1, pp. 288-294, 1982.
[6] Harris B, “University Physics”, John Wiley & Sons, INC.
[7] Yoshida Y., Shinohara S., Ikeda H., Tada K., Yoshida H., Nishide K. and Sumi M., “Control of Lens Position in Auto-Focus Cameras Using Semiconductor Laser Range Finder”, Proceedings of the 34th Midwest Symposium, vol. 1, pp. 395-398, May 1991.
[8] Adams J., Parulski K. and Spaulding K.,” Color processing in digital cameras”, Micro IEEE, vol. 18, Issue 6, pp.20-30, Nov 1998.
[9] Kawamura S., “Capturing images with digital still cameras”, Micro IEEE, vol. 18, Issue 6, pp.14-19, Dec. 1998.
[10] Chan W.H. and Youe C.T., “Video CCD based portable digital still camera”, Consumer Electronics on IEEE Transactions, vol. 41, Issue 3, pp.455-459 Aug. 1995.
[11] Nayar S.K. and Nakagawa Y., “Shape from Focus”, Proceedings of the IEEE Transactions on Pattern Analysis and Machine Intelligence, vol. 41, Issue 3, pp.455-459 Aug. 1995.
[12] Zhang X., Kubo N., Obuchi Y. and Kanbe T., “An approach to detect defective CCD in digital cameras”, The 25th Annual Conference of the IEEE, vol. 2, pp.552-558 Dec. 1999.
[13] Widjaja J., Jutamulia S. “Wavelet Transform-Based Auto-focus Camera Systems”, Proceedings of the IEEE Asia-Pacific Conference on Circuits and Systems, pp.49-51, 1998.
[14] Schlag J. F., Sanderson A. C., Neumann C. P. and Wimberly F. C. “Implementation of Automatic Focusing Algorithms for a Computer Vision System with Camera Control”, Technical Report CMU-RI-TR-83-14, Carnegie Mellon University, Aug. 1983.
[15] Tenenbaum J. M., “Accomodation in Computer Vision”, Stanford University, Nov. 1970.
[16] Krotkov E. P., “Active Computer Vision by Cooperative Focus and Stereo”, Springer-Verlag, New York, 1989.
[17] Horn B. K. P., “Focusing”, Technical Report AIM-160, Massachusetts Institute of Technology, May 1968.
[18] Davies E. R., “Machine Vision: Theory, Algorithms, Practicalities”, Academic Press Limited, 1990.
[19] J. F. Brenner, B. S. Dew and J. B. Horton, “An automated microscope for cytological research”, Journal Histochem Cytochem, Vol.24, pp.100-111, 1976.
[20] B. Ferren, “Spatial image system”, U.S. Patent 4,584,704 Apr. 1986.
[21] J. R. Bergen, “Method and apparatus for extended depth of field imaging”, U.S. Patent 6,201,899 B1 Mar. 2001.
[22] Kreyszig E., “Advanced Engineering Mathematics”, John Wiley & Sons,Inc. 1993.
[23] Arieh I., “A First Course in the Numerical Analysis of Differential Equations”, 2002.
[24] R. L. Burden and J. D. Faires, “Numerical Analysis”, Brooks/Cole, 2001.
[25] Ng Kuang Chern, N. Poo Aun Neow, and Ang M.H. Jr., “Practical Issues in Pixel-Based Autofocusing for Machine Vision,” Proceedings of the IEEE International Conference on Robotics and Automation, vol.3, pp.2791-2796, 2001.
[26] Beveridge G. S., and Schechter R. S., “Optimization: Theory and Practice”, McGraw-Hill, New York, 1970.
[27] Deng J.L., “Introduction to Grey System Theory,” The Journal of Grey System, vol. 1, pp. 1-24, 1989.