由於數位影音資料庫的日益增加，如何有效的管理就顯得更加重要。CBIR（content based image retrieval）是以影像內容為基礎的影像擷取系統。它會根據圖片的特徵與使用者的輸入來自動搜尋相關的圖片。MPEG-7是對於多媒體內容描述子的一個整合標準，而且它對於CBIR的發展是非常重要不可或缺的一部分。

在這篇論文之中，我們使用一種紀錄主要顏色描述特質的方法，來當我們的顏色描述子。主要顏色描述子是一個嚴謹而且有效率的顏色描述子，它主要是為了達到需求較低的儲存容量與高速的擷取系統而開發設計的。利用少數擁有代表性的顏色來表示一張圖片。這些代表性的顏色取得方法來自於群聚與量化圖片的特徵而完成。此描述子的內容包含了代表性的顏色與它們在圖片中所佔得比例。我們將改善過後的相似比對方法，套用在原本的影像擷取系統，如此，對於影像擷取的結果將會有較好的準確性。

In recent year, for dealing the increasing of image database, develop an efficient image retrieval system becomes more and more important. Content based image retrieval (CBIR) is the most widely used retrieval techniques based on image content and is an automatic process for searching relevant images based on image features and user inputs. MPEG-7 is an international standard for multimedia content description, and it is an important achievement for CBIR.

In this work we use dominant color descriptor (DCD) as our color descriptor. DCD is a compact and efficient descriptor, designed for small storage and high speed retrieval. Image feature is formed by a small number of represent colors. These colors are normally obtained by using clustering and color quantization. The descriptor consists of the representative colors, their percentages in a region. We improve the original similarity measure to integrate with an existent retrieval system. Hence, well accuracy is demonstrated in the results of image retrieval.

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