[1] 欧氏距离. 百度百科. http://baike.baidu.com/.
[2] 余弦相似度. 百度百科. http://baike.baidu.com/.
[3] 感知哈希算法PHash的OpenCV实现. http://blog.csdn.net/eternity1118_/article/details/51088019.
[4] 主成分分析. http://blog.csdn.net/dahuacai/article/details/50503246.
[5] PCA的数学原理. http://blog.codinglabs.org/articles/pca-tutorial.html.
[6] 初识PCA数据降维. http://www.cnblogs.com/hxsyl/p/4548264.html.
[7] David G. Lowe. Distinctive Image Features from Scale-Invariant Keypoints.IJCV2004. http://www.cs.ubc.ca/~lowe/papers/ijcv04.pdf.
[8] OpenCV, BoF-SIFT. http://www.codeproject.com/Articles/619039/Bag-of-Features-Descriptor-on-SIFT- Features-with-O.
[9] FLANN. https://github.com/jlblancoc/nanoflann.
[10] Gabor滤波器学习. http://blog.csdn.net/jinshengtao/article/details/17797641.
[11] Gabor filter. Wikipedia. https://en.wikipedia.org/wiki/Gabor_filter.
[12] 图像的Gabor小波变换. http://download.csdn.net/download/CPFZZ/1976739.
[13] OpenCV—HoG特征. http://blog.csdn.net/loadstar_kun/article/details/7728463.
[14] 利用OpenCV提取HOG特征需要了解的参数. http://blog.sciencenet.cn/blog-702148-762019.html.
[15] HOG：从理论到OpenCV实践. http://www.tuicool.com/articles/fM3Mvu.
[16] Extracting HoG Features using OpenCV. http://stackoverflow.com/questions/11626140/extracting-hog-features-using-opencv.
[17] ImageNet深度卷积神经网络笔记. http://www.gageet.com/2014/09140.php.