在這篇論文中，我們提出了兩個物體偵測方法，一個是對固定不變的影像樣式做搜尋，主要用於工業檢測中的自動影像檢測定位，另一個是無固定形狀的物體搜尋，我們把重點放在人臉偵測上。
在工業檢測上，我們發展一個能在不平均光源下做影像定位的演算法，在這個演算法中，我們先以邊緣偵測法取得影像中物體邊緣的強度，再取得區域中最大的邊緣強度值將整個影像中的邊緣強度做補償，所得到的影像稱為相對性的邊緣對映圖。我們的演算法中的兩個階段，以學習為基礎的樣式比對搜尋與以能量最小化為基礎的影像自動定位，皆使用由上述方法所取得的相對邊緣對映圖來做影像定位。我們所實做出來的系統除了擁有對光源不平均的強固性之外，另一優點為搜尋時非常快速。

我們的人臉偵測演算法分四個部份，分別是膚色過濾，人臉樣板比對，人臉確認與重疊人臉整合。在做偵測時，先利用色彩資訊將膚色的區域找出，再針對膚色的區域做搜尋。我們利用收集到的大量的人臉資料，取其影像特徵，再做群聚分類，每個群集的中心值向量即為我們的標準人臉樣板。將欲搜尋的影像區域取同樣的特徵向量，再與已訓練好的人臉樣板做比對，當兩者比對的值小於某個門檻值，此塊區域可能包含人臉。我們應用兩個步驟的人臉影像確認方法在可能包含人臉的影像區域上來做進一步的確認。最後，我們將重疊的人臉影像區塊做整合以得到最後的結果。

In this thesis, we proposed two new algorithms for object detection. One is the image localization algorithm for invariant or rigid objects, which are very common in automatic visual inspection. The other algorithm is used to detect variant objects. We focus on the problem of face detection.
In industrial inspection, we developed a new algorithm that can localize the object under non-uniform illuminations. In this algorithm, we first apply Sobel edge detection on an image to get the gradient map, and then we compute the local maximal gradient values to normalize the gradient map. The two stages of our alignment algorithm, i.e. the learning based pattern search and the energy minimization based alignment, perform alignment on this relative gradient map. The alignment system is not only robust against non-uniform illumination changes but also very efficient for image alignment.

Our face detection algorithm consists of four steps, i.e. the skin-color filtering, template matching, verification and overlap merging. We used skin-color information to extract skin-color region from input image, and then detected face on skin-color regions. Our face detection algorithm extract features from face images and classify the features into several clusters in the training process. The means of these clusters are face templates. Our system calculates the minimal distance between the feature vector extracted from an image region and the face templates to determine if it is a face candidate. We apply two verification steps on the detected face candidates. The first one is the complete face comparison verification and the second is the combination of criteria from local face region analysis. At last, we merge the overlapped face candidate regions to obtain the final results.

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