本文提出了一個可供輪椅使用者使用的手勢辨識系統，大多數的手勢辨識相關文獻只探討如何提升手勢辨識的準確度，但是在這篇論文中除了手勢辨識之外，還有許多的問題需要解決，例如偵測手什麼時候進入影片當中或者手掌的區域是不是有超出影片的周圍。本文提出的系統之流程可以分為四個步驟，首先要先判斷手何時出現在影片中，接下來是如何把手從背景中擷取出來，然後判斷手掌是否超出影片的四周圍，最後則是手勢辨識。在擷取手部區域方面，我們從統計學的離群值(outlier)觀念做延伸應用到膚色偵測上，不同於大多數的手勢辨識系統只對膚色做了單一階段的偵測，我們做了兩階段的膚色偵測，藉由此方法去除跟手相連的膚色雜訊。至於判斷手掌是否超出影片的四周圍的階段，我們利用人體工學的概念來判斷手掌是否超出影片範圍外。從實驗結果可發現本文提出的系統除了背景的膚色雜訊過大或者手跟攝影機的距離太過接近無法克服之外，整體而言是相當成功的，如果把本文所提出的系統搭配硬體或者晶片加以實現，將有助於提升輪椅使用者單獨在家時候的便利性。

In this study, a hand gesture recognition system is proposed for users on wheelchairs. Unlike other studies that focus on the stage of hand gesture recognition, many problems are considered, such as detection of when a hand reaches in the field of the camera view or detection of a full palm. There are 4 stages in the proposed system, detection of the appearance of hands, segmentation of hand regions, detection of full palm and hand gesture recognition. Detection of the appearance of hands is to find out when a hand appears in the front of the camera. The hand region is then obtained in the next stage. In this stage, some morphological techniques, along with 2 stage skin color detection, are used to alleviate the effect of noise. The 2 stage skin color detection approach is adopted from the idea of handling outliers to extract the palm from complicated backgrounds. Following that, detection of full palm is conducted to know whether the hand reaches beyond the field of the camera view. The concept of ergonomics is employed to determine whether the hand is beyond the field of the camera view. Finally, hand gesture recognition is performed. Experimental results show that the proposed system is quite promising except that a very small number of frames are misjudged because the system cannot deal with some problems such as the area of the noise being too large or the hand being too close to the camera.

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