在同一个根目录下有若干个文件夹，每个文件夹下有若干张图片，对这些图片提取CNN特征，生成一个文件夹名和图片对应的mat数据文件(There are several folders under the same root directory. There are several pictures under each folder. Extract CNN features from these pictures, and generate a folder name and mat data file corresponding to the picture.)