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題名 Efficient Auto-Focus Algorithm Utilizing Discrete Difference Equation Prediction Model for Digital Still Cameras
作者 Chen, Chih-ming ; Hong, Chin-Ming ; Chuang, Han-Chun
Chen, Chih-ming
陳志銘
關鍵詞 Difference equations;
      Predictive models;
      Digital cameras;
      Lenses;
      Focusing;
      Search methods;
      Particle measurements;
      Image resolution;
      Turning;
      Software algorithms
日期 2006-12
上傳時間 5-十二月-2008 12:03:18 (UTC+8)
摘要 Most digital still cameras employ the passive auto-focus scheme to achieve these goals. Measuring the sharpness of an image using passive auto-focus is time-consuming, particularly for digital still cameras with mega-pixels resolutions. However, the auto-focus search algorithm for digital still cameras needs to be fast and real-time. This study presents an efficient real-lime auto-focus (AF) algorithm combining the discrete difference equation prediction model (DDEPM) and bisection search method for digital still cameras. The proposed auto-focus algorithm uses both the coarse search procedure with DDEPM and the fine search procedure with bisection search method to perform the auto-focus process for digital still cameras. The coarse search procedure utilizes the precise forecasting ability of the DDEPM model to determine the turning points of the focus value curve, thus skipping some unnecessary detection points on the focus value curve. This procedure can be used to move the lens quickly to the neighborhood region of the best-focused lens position during AF processes. After the coarse search is finished, the fine search procedure is used to find the best-focused lens position according to the coarse search result. The proposed scheme increases the auto-focus speed since it reduces the number of detection points required for the focus value curve when searching the neighboring region of the best-focused lens position, and also reduces the lens backlash times. The proposed algorithm is implemented herein on an HP digital camera including control software. The experimental results indicate that the proposed AF algorithm is very reliable and requires few focusing iterations
關聯 IEEE Transactions on Consumer Electronics, 52(4), 1135-1143
資料類型 article
DOI http://dx.doi.org/10.1109/TCE.2006.273125
dc.creator (作者) Chen, Chih-ming ; Hong, Chin-Ming ; Chuang, Han-Chunzh_TW
dc.creator (作者) Chen, Chih-ming-
dc.creator (作者) 陳志銘-
dc.date (日期) 2006-12en_US
dc.date.accessioned 5-十二月-2008 12:03:18 (UTC+8)-
dc.date.available 5-十二月-2008 12:03:18 (UTC+8)-
dc.date.issued (上傳時間) 5-十二月-2008 12:03:18 (UTC+8)-
dc.identifier.uri (URI) https://nccur.lib.nccu.edu.tw/handle/140.119/12671-
dc.description.abstract (摘要) Most digital still cameras employ the passive auto-focus scheme to achieve these goals. Measuring the sharpness of an image using passive auto-focus is time-consuming, particularly for digital still cameras with mega-pixels resolutions. However, the auto-focus search algorithm for digital still cameras needs to be fast and real-time. This study presents an efficient real-lime auto-focus (AF) algorithm combining the discrete difference equation prediction model (DDEPM) and bisection search method for digital still cameras. The proposed auto-focus algorithm uses both the coarse search procedure with DDEPM and the fine search procedure with bisection search method to perform the auto-focus process for digital still cameras. The coarse search procedure utilizes the precise forecasting ability of the DDEPM model to determine the turning points of the focus value curve, thus skipping some unnecessary detection points on the focus value curve. This procedure can be used to move the lens quickly to the neighborhood region of the best-focused lens position during AF processes. After the coarse search is finished, the fine search procedure is used to find the best-focused lens position according to the coarse search result. The proposed scheme increases the auto-focus speed since it reduces the number of detection points required for the focus value curve when searching the neighboring region of the best-focused lens position, and also reduces the lens backlash times. The proposed algorithm is implemented herein on an HP digital camera including control software. The experimental results indicate that the proposed AF algorithm is very reliable and requires few focusing iterations-
dc.format application/en_US
dc.language enen_US
dc.language en-USen_US
dc.language.iso en_US-
dc.relation (關聯) IEEE Transactions on Consumer Electronics, 52(4), 1135-1143en_US
dc.subject (關鍵詞) Difference equations;
      Predictive models;
      Digital cameras;
      Lenses;
      Focusing;
      Search methods;
      Particle measurements;
      Image resolution;
      Turning;
      Software algorithms		-
dc.title (題名) Efficient Auto-Focus Algorithm Utilizing Discrete Difference Equation Prediction Model for Digital Still Camerasen_US
dc.type (資料類型) articleen
dc.identifier.doi (DOI) 10.1109/TCE.2006.273125en_US
dc.doi.uri (DOI) http://dx.doi.org/10.1109/TCE.2006.273125en_US