在基于內容的圖像檢索中，不同圖像對形狀細節的要求不同及形狀特征對旋轉的敏感
性，影響檢索性能。對此，本文提出了一種基于邊緣梯度方向直方圖的圖像檢索算法：利用B樣條小波的多尺度變換模極大值進行邊緣檢測，實現不同圖像對形狀細節不同要求；用邊緣梯度方向直方圖表示物體的形狀，采用循環移位最小值計算直方圖的相關性進行圖像匹配，使其具有旋轉不變性。實驗證明，算法對圖像的亮度變化、縮放、旋轉具有不變性，有較高的檢索性能。
關鍵詞：基于內容的圖像檢索；邊緣檢測；直方圖；小波分析
Abstract：In content_based image retrieval, different details are requied by different images and shape is more sensitive to circumrotation than color and texture ,which decrease image retrieva performance. An algorithm for image retrieval based on edge gradient direction histogram is proposed.Image edge is detected by B-Spline wavelet transform based on maximum model in order for resulting that different details are requied by different images and represented by the histogram of gradient directions at edge pixels.The relativity of histogram which results from itertative rotation minimum matching is used to avoid the sensitivity of rotated image. Experimental results show that the algorithm has the robustness against illumination changes, position translation, scale and rotated image and a superior image-retrieving performance.
Keywords:Content_based image retrieval; Edge Detection; Histogram;Wavelet