图像特征提取的四种算法，花了很大的力气才弄来的！和大家分享！-Four types of image feature extraction algorithm, to spend a great deal of effort to get the! To share with you all!

用于进行特征选择的方法，可以对数据进行降维，减少冗余。(For the method of feature selection, the data can be reduced and redundant.)