【caffe】Layer解读之：Date

痛定思痛。 2022-05-16 06:07 80阅读 0赞

*  Layer type: Date
 *  头文件位置：./include/caffe/layers/data\_layer.hpp
 *  CPU 执行源文件位置:./src/caffe/layers/data\_layer.cpp
 *  Date层的功能：读取LevelDB，LMDB，并进行一系列前处理。

layer { name: "cifar" type: "Data" top: "data" top: "label" include { phase: TRAIN }
    
      transform_param { scale:0.0078125 mirror:true crop_size:32 mean_value: 128 mean_value: 128 mean_value: 128 }
      data_param { source: "examples/cifar10/cifar10_train_lmdb" batch_size: 32 backend: LMDB }
    }

mean\_value和scale的作用：这两个操作都是像素级的操作mean\_value就是对所有像素减均值，而scale一般是在mean\_value之后对每个像素乘以scale，如：0.0078125 = 1/128。  
crop\_size的作用：[crop\_size对图像增强][crop_size]  
[caffe源码之ImageDataLayer解析][caffe_ImageDataLayer]  
[caffe源码解读(5)－image\_data\_layer.cpp][caffe_5_image_data_layer.cpp]  
[LMDB][]  
[Blob][]  
[Blob源码][Blob 1]  
[protobuf解释][protobuf]

#### 参数定义 ####

message DataParameter {
      enum DB {
       LEVELDB = 0;
       LMDB = 1;
      }
      // Specify the data source.
      optional string source = 1;
      // Specify the batch size.
      optional uint32 batch_size = 4;
      // The rand_skip variable is for the data layer to skip a few data points
      // to avoid all asynchronous sgd clients to start at the same point. The skip
      // point would be set as rand_skip * rand(0,1). Note that rand_skip should not
      // be larger than the number of keys in the database.
      // DEPRECATED. Each solver accesses a different subset of the database.
      //在开头跳过这个数量的输入; 对异步sgd很有用
      optional uint32 rand_skip = 7 [default = 0];
      optional DB backend = 8 [default = LEVELDB];
      // DEPRECATED. See TransformationParameter. For data pre-processing, we can do
      // simple scaling and subtracting the data mean, if provided. Note that the
       // 数据比例缩放，注意该操作处于减均值操作之后
      optional float scale = 2 [default = 1];
      // 指定均值文件路径，注意不能同时指定mean_file 和 mean_value
      optional string mean_file = 3;
      // DEPRECATED. See TransformationParameter. Specify if we would like to randomly
      // 指定从原图随机crop的尺寸
      optional uint32 crop_size = 5 [default = 0];
      // 是否要对输入图像采用随机水平镜像See TransformationParameter. 
      optional bool mirror = 6 [default = false];
      // 强制将图片转为三通道彩色图片
      optional bool force_encoded_color = 9 [default = false];
      // 预先存取多少个batch到host memory
      // (每次forward完成之后再全部重新取一个batch比较浪费时间), 
      optional uint32 prefetch = 10 [default = 4];
    }

##### transform\_param #####

// transform 参数
    message TransformationParameter {
      // 数据比例缩放，注意该操作处于减均值操作之后
      optional float scale = 1 [default = 1];
    
      // 是否要对输入图像采用随机水平镜像
      optional bool mirror = 2 [default = false];
    
      // 指定从原图随机crop的尺寸
      optional uint32 crop_size = 3 [default = 0];
    
      // 指定均值文件路径，注意不能同时指定mean_file 和 mean_value
      optional string mean_file = 4;
    
      // 指定均值，如果只指定一个均值，则所有通道均减去该均值；如果指定了多个，则每个通道减去对应均值
      repeated float mean_value = 5;
    
      // 是否强制转为三通道图像
      optional bool force_color = 6 [default = false];
    
      // 强制转为单通道图像
      optional bool force_gray = 7 [default = false];
    }

##### data\_param #####

message ImageDataParameter {
      // Specify the data source.
      optional string source = 1;
      // Specify the batch size.
      optional uint32 batch_size = 4 [default = 1];
    
      // The rand_skip variable is for the data layer to skip a few data points
      // to avoid all asynchronous sgd clients to start at the same point. The skip
      // point would be set as rand_skip * rand(0,1). Note that rand_skip should not
      // be larger than the number of keys in the database.
      optional uint32 rand_skip = 7 [default = 0];
    
      // 每一个 epoch是否打乱数据.
      optional bool shuffle = 8 [default = false];
    
      // 如果new_height or new_width 不等于0，则会resize图像.
      optional uint32 new_height = 9 [default = 0];
      optional uint32 new_width = 10 [default = 0];
    
      // 指定图片为彩色还是灰度图
      optional bool is_color = 11 [default = true];
    
      // 数据比例缩放，注意该操作处于减均值操作之后
      optional float scale = 2 [default = 1];
    
      //均值文件路径
      optional string mean_file = 3;
    
      //图片数据根目录
      optional string root_folder = 12 [default = ""];
    }

[crop_size]: https://blog.csdn.net/qiu931110/article/details/81746787
[caffe_ImageDataLayer]: https://blog.csdn.net/paranoid_cnn/article/details/53172030
[caffe_5_image_data_layer.cpp]: https://blog.csdn.net/weixin_37970694/article/details/79192778
[LMDB]: https://blog.csdn.net/jyl1999xxxx/article/details/53942824
[Blob]: https://blog.csdn.net/jyl1999xxxx/article/details/53981813
[Blob 1]: https://www.cnblogs.com/xiangfeidemengzhu/p/7094995.html
[protobuf]: http://alanse7en.github.io/caffedai-ma-jie-xi-2/