本論文提出一個指尖行為分析系統，此系統能分辨放大、縮小、左右移與拍照的手勢，並以此做為人機互動的方式。
　　系統一開始使用背景相減搭配膚色偵測進行手部區域提取，此方法在複雜的背景下能初步濾除不必要的雜訊。取出手部區域後，進行手指指尖定位，我們以粒子隨機擴散讓粒子分佈於手部邊緣，接著保留位於指尖上的粒子，剩下的粒子再進行分群以區分不同指尖上的粒子，每一群粒子的平均位置即是手指指尖定位的結果。最後，利用指尖定位結果分析指尖的行為，系統共區分為單指指尖行為分析、雙指指尖行為分析、四指指尖行為分析，藉由此系統，使用者可以在不需配戴任何指套或標記的情況下自然的操作達到人機互動的目的。由實驗結果顯示本系統指尖偵測率為84.58%，且處理速度為每秒29張影像，能準確與即時的分析手勢。

A fingertip-movement analysis system is proposed in this paper. This system can distinguish the gesture like flick-right, flick-left, pinching to zoom in and out and taking picture to be a way for human-computer interaction.
We combine background subtraction and skin detection to extract hand region. This method can remove most noise in the complex background. After hand extraction we use particle random diffusion algorithm to position fingertip. The algorithm uses particles to diffuse to the contour of hand randomly. Then keep the particles which are located in fingertip. After that, a particle grouping algorithm is applied to distinguish each fingertip. Fingertip position is the average position of each group’s particles. The system will analyze fingertip in three different ways which are single fingertip-movement analysis, double fingertip-movement analysis and four fingertip-movement analysis. By this system, user can easily interact with computer without any fingertip marker. The experimental results show that our system can operate in real-time at a frame rate of 29fps and with 84.58% fingertips detection rate.

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