sift算法是用来提取图像特征点的算法，性能优越，被广泛用于特征提取和图像匹配，自提出起，算法一直在更新，此为最新版本的sift算法，在matlab上测试可用。(The SIFT algorithm is used to extract the image feature points algorithm, superior performance, is widely used for feature extraction and image matching, since the propo