用不变矩和边界方向进行形状检索

基于形状的图像检索一直以来是图像内容检索的一个难点问题，而目前采用周长、面积、边角率等描述形状的方法不能使形状检索达到理想的效果．本文提出了一种新的针对图像形状的检索方法．首先，用Canny算子对图像进行平滑处理，提取图像边界方向直方图特征、其次，用不变矩来描述图像形状的区域特征，不变矩特征不受图像的缩放、平移和旋转的影响．最后，为了克服不变矩只关心对象区域，而对图像边界忽视的缺点，提出了不变矩与边界方向特征相结合的方法，使得检索取得更好的效果．本文通过对医学图像的形状检索实验，给出了实验结果和结论．

Shape-based Retrieve Using Invariant Moments and Edge Direction

Shape based retrieve is always a difficult side in content based image retrieve fields. There are some shape based image retrieve methods ,such as using perimeter, area to describe shape feature, but they can't make shape based retrieve efficiently. We propose a new method based on object shape information. First of all we smooth the source image by Canny operator and get the feature of the edge direction histogram, then we use 7 Invariant Moments describing shape feature. These features are invariant under rotation, scale, translation and reflection of images and have been widely used in a number of application due to their invariance properties. At last in order to get over that invariant moments only takes into consideration the region of the objects while ignores the boundary of the objects, we propose an integrating the invariant moments and edge direction method. The experiment of shape based retrieve methods in medical images has been done and the result is satisfactory, which verifies the effect of this method.