本研究利用原子力顯微鏡(Atomic Force Microscope, AFM)量測去氧核醣核酸(deoxy- ribonucleicacid, DNA)影像，再將DNA影像進行影像處理後，利用一種由8連通費 里曼鏈碼(Freeman chain code)延伸出來的切向量估測進行曲線擬合，估算DNA的 輪廓切向量。持久長度(Persistence Length)是一種力學性質，可用來表示DNA分子 鏈的剛性，能夠預估DNA的輪廓彎曲情形。在計算DNA的持久長度時，需要精 準的曲線輪廓長度(Contour Length)以及精準的輪廓切向量，才能有準確的估測結 果。原子力顯微鏡被使用在長條狀高分子生物(Long Chain Biopolymer)樣本的成像 上，例如:DNA，但在不同的影像解析度下，計算輪廓切向量會產生誤差。為了修 正DNA的輪廓切向量誤差，本研究利用AFM攫取的DNA影像，經過一系列的影像 處理，將二值化影像細線化至單一像素寬後，針對單一像素寬的DNA影像，進行 輪廓切向量的估測，再對應原始DNA輪廓切向量估測結果進行修正，最後可得到 準確的DNA輪廓切向量。

A tangent vector estimator extended from the 4-pixel 8-connected Freeman chain code is used to fit the curve of DNA image taken by AFM in this research. Persistence length is a kind of physical property that is able to represent the rigidity of molecule chain of DNA. Precise contour length and accurate contour tangent are both required for estimation of accurate persistence length. However, because of the different image resolutions, the calculation of the contour tangent will have the error. In order to eliminate the contour tangent error of the curve of the DNA image, an estimation method of contour tangent for digitized images is developed in this study. Using this method can effectively eliminate the error of contour tangent which caused by the image resolution, and measure the precise contour tangent.

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