臺灣博碩士論文加值系統

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.

中文摘要………………………………………………………………...I
英文摘要………………………………………………………………...II
總目錄……………………………………………………………….….III
圖目錄…………………………………………………………………..V
表目錄……………………………………………………………..….VIII
第一章 緒論………………………...……….……………….………….1
1.1研究動機與背景…………………………………………………1
1.2研究目的………………………………………………….……...2
1.3研究方法………………………………….…………………..….3
1.4研究步驟…………………….…………..……………………….3
第二章 自動對焦理論………………..…..…………..……………...….6
2.1成像公式與對焦原理…………..…………………………….….6
2.2清晰度運算法…………………………...…………….……....…7
2.2.1清晰度運算法相關研究文獻……………………...…….....7
2.2.2清晰度演算法…………………………………...…..……...8
2.3景深與光圈大小對成像的影響……...…………….……....…..10
2.3.1光圈對景深的影響與景深對成像的意義………...……...10
2.3.2景深的數學公式推導…………………………...…..…….12
2.3.3景深與對焦曲線的關係………………………...…..…….13
2.4自動對焦系統架構……...…………….……....………………..15
第三章 對焦搜尋演算法及預測模型…………………………………18
3.1搜尋運算法…………………………...…………….……....…..18
3.1.1對焦點搜尋運算法的功用………………………...……...18
3.1.2數學上的搜尋運算法…………………………..…..……..18
3.2 預測模型…………………………………………….….……..20
3.2.1灰色預測模型…………………….………………….……20
3.2.2離散差分方程預測模型……………….……………….…25
第四章 自動對焦系統設計….……...……….…………..………….…31
4.1對焦曲線與離散差分方程預測模型.……………………….…31
4.2對焦搜尋演算法之設計..………………………………………36
4.3對焦搜尋演算法離線測試………..…...……………………….38
第五章 自動對焦系統之線上測試與實作..…...………..………….…44
5.1離散差分方程預測模型與粗搜尋….……………………….…44
5.2自動對焦搜尋演算法線上測試………………………..………51
5.3自動對焦搜尋演算法線上測試與相關效能數值統計..………55
第六章 研究結論與建議………...…………..…………..………….…63
6.1研究結論…………………………….……………………….…63
6.2研究建議…..………………………….……………………...…63
參考文獻………………………………………..…………………………….65
附錄………………………………………………………………………67
作者簡介………………………………………..…………………………….69

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