摘要
由於電腦科技、媒介存取設備及多媒體壓縮標準的日新月異，促使大量的數位資料產生，也讓這些資料無遠弗屆在使用者間相互流通。如今，人們可以很容易的獲取電子書籍、電子期刊、電子期刊、視訊串流等包含圖像的數位資訊。所以如何提供使用者一方便簡潔的圖像檢索系統是一重要的課題。目前雖然有相當多以影像為內容之檢索系統，但針對圖像的檢索系統卻相當貧乏。甚至目前的圖像檢索系統大都採用輪廓特徵而非像素點特徵，輪廓特徵的缺點是，所有組成圖像的直線及曲線都需一一處理，所以相當耗時。所以本論文之目標是提出簡單但有效的圖像及影像檢索法。 所提方法採用方向梯度直方圖當作圖像的特徵。首先將圖像切割成數個空間小區塊，並針對每一空間區塊，擷取其方向梯度直方圖，再將所有區塊之方向梯度直方圖串接成代表整個圖像之方向梯度直方圖特徵。最後根據圖像方向梯度直方圖特徵，採用卡方距離，計算檢索圖像與資料庫圖像之相似程度。檢索輸出是將所有相似圖像依卡方距離由小排到大。 在本論文中，將所提方法為基礎分別推廣於三種不同的應用，二值物件檢索、二值圖像檢索，圖像及影像綜合檢索。實驗證明所提方法在此三種應用，都較現有方法有更高的檢索正確率。
並列摘要
New computing technologies, media acquisition/storage devices, and multimedia compression standards have increased the amount of digital data generated and stored by computer users. Nowadays, it is easy to access electronic books, patents and trademarks which contain tremendous graphics. Hence, it is imperative to develop an effective method of retrieving images by using graphics as query keywords. Although many content-based retrieval methods have been proposed, few are specifically designed for graphics. Moreover, most existing graphics retrieval methods adopt contour-based rather than pixel-based approaches. A contour-based method is concerned with a lot of lines, curves and components that must be correspondingly matched, which provides accurate results but requires intensive computation. Thus, the objective of this study was to develop simple yet effective graphics/image retrieval. The proposed method adopts histograms of oriented gradient (HOG) as graphics features. The graphics are first divided into small spatial regions, i.e., blocks, from which HOGs are computed. The HOGs, one for each block, are then concatenated to form the representation for the graphics. Finally, the similarity between the query and database graphics can be computed with based on HOG. The retrieved list includes similar graphics in order of increasing . Experimental results using different databases confirm that the proposed method has higher retrieval accuracy compared to existing pixel-based methods.