人脸识别，人脸图像预处理；读入人脸库，训练形成特征子空间；把训练图像和测试图像投影到上一步骤中得到的子空间上；选择一定 的距离函数进行识别。-Recognition, face image preprocessing　read into the face database, training the formation of the feature sub-space　the training images and test images were projected into the subspace obtained in the previous step　select a certain distance function to identify.