本文首先提出一種新的定量方法，利用電腦的影像特徵分析來定量系統的靈敏度，不再以視覺感受來比較圖像的對比度，而是利用數據去進行分析，這裡使用灰階差分統計法與灰階共生矩陣法來分析圖像對比度，再配合溫度計得到系統的靈敏度，最後是灰階共生矩陣法比較適合。
實驗利用三原色光源進行分析，在三原色光源中的綠光會比其他色光有更高靈敏度，推論是主要受到相機靈敏度的影響，故未來只要分析三原色光的靈敏度，可以依照顏色的混和比例得出不同光的靈敏度。
為了提升系統的靈敏度，我們仿效前人進行紋影成像系統的改進，在系統中添加一面凹面鏡，將紋影成像直接投影在測量物旁，雖然數據顯示沒有提升系統的靈敏度，但改進後的實驗架構能夠量測出從室溫到40度之間的變化，適合溫度變化不大的實驗，運用在風速的測量上也有不錯的成果，風速5m/s前誤差只有11%。此外，改進的架構也避免雷射損害相機感光元件，有助於長期使用雷射觀測紋影的研究，同時也讓研究者更容易觀測實驗過程。

This study proposes a new quantitative method, which using computerized image analysis to quantify the sensitivity of the system; therefore, we no longer weigh the pros and cons of different systems by visual perception. Instead, using data to explain. Here, we use the gray level difference statistics and the gray-level co-occurrence matrix to analyze image contrast, with thermometer to get the sensitivity of the system, and finally the gray-level co-occurrence matrix is relatively accurate.
Experiment using the RGB color light to analysis, the green light has higher sensitivity than other color . The inference is mainly affected by the sensitivity of the camera, so if the sensitivity of the RGB color light can be analyzed, and the sensitivity of different lights can be obtained according to the color mixing ratio.
In order to improve the sensitivity of the system, we imitate the predecessors to improve the schlieren imaging system. Add a concave mirror to the system, and then the schlieren image is projected directly beside the observation object, although the results show that the sensitivity doesn’t improve, but it can measure the change from 20℃ to 40℃, which is suitable for experiments with little temperature change. It also has good results in the measurement of wind speed which the error is only 11%. Beside, the improved system reduce the damage by laser to the camera photosensitive elements, which is helpful to researchers who use lasers to observe schlieren image for a long time, and also makes it convenient for researchers to observe the experimental process.

摘要 i
Abstract iii
誌謝 v
目錄 vii
圖目錄 xi
表目錄 xv
第1章 序論 1
1.1 前言 1
1.2 研究動機 2
第2章 文獻回顧與基本理論 3
2.1 紋影成像的原理 3
2.1.1 氣體密度 3
2.1.2 光的折射 4
2.1.3 遮光的影響 5
2.1.4 紋影成像幾何理論 6
2.1.5 靈敏度 8
2.1.6 凹面鏡的反射性質 9
2.2 紋影系統的演進 10
2.2.1 背景紋影系統 11
2.2.2 August Toepler紋影系統 12
2.2.3 雙凹面鏡紋影系統 13
2.2.4 單凹面鏡紋影系統 14
2.3 人眼與相機視覺 15
2.3.1 人眼視覺 15
2.3.2 相機視覺 16
2.4 影像特徵分析 17
2.4.1 灰階差分統計法 17
2.4.2 灰階共生矩陣 18
2.5 速度分析 20
2.5.1 PIVlab 20
2.5.2 Tracker 20
2.6 影像處理 21
2.6.1 對比度受限的直方圖均衡化(CLAHE) 21
2.6.2 二維自適應去噪濾波(Wiener2 Denoise) 22
2.6.3 強度上限(Intensity Capping) 24
第3章 實驗架構 25
3.1 光學系統 25
3.1.1 單凹面鏡紋影成像系統 25
3.1.2 改良後的紋影成像系統 25
3.2 實驗設備介紹 26
第4章 實驗測試與系統調整 29
4.1 定量靈敏度 29
4.2 相機參數設定 29
4.2.1 幀率 29
4.2.2 快門速度 29
4.2.3 感光度ISO 29
4.2.4 相機光圈 30
4.3 影像分析程式測試 31
4.3.1 灰階差分統計法與灰階共生矩陣程式測試 31
4.3.2 分析法選擇 32
4.4 PIVlab作業流程 34
4.4.1 分析前處理 34
4.4.2 分析 36
4.4.3 分析後處理 36
4.4.4 數據分析 37
4.5 PIVlab分析誤差與調整 38
4.5.1 PIVlab軟體誤差 38
4.5.2 設定偵詢區 40
4.5.3 實驗數據誤差 41
第5章 實驗結果與討論 43
5.1 三原色光的影響 43
5.2 不同架構的影響 48
5.3 風速分析 53
第6章 結論與未來方向 55
參考文獻 57

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