caffe.proto源码分析

分析caffe源码，看首先看caffe.proto，是明智的选择。好吧，我不是创造者，只是搬运工。

原文地址：http://blog.csdn.net/qq_16055159/article/details/45115359
引言

要看caffe源码，我认为首先应该看的就是caffe.proto。
它位于…\src\caffe\proto目录下，在这个文件夹下还有一个.pb.cc和一个.pb.h文件，这两个文件都是由caffe.proto编译而来的。
在caffe.proto中定义了很多结构化数据，包括：

BlobProto
Datum
FillerParameter
NetParameter
SolverParameter
SolverState
LayerParameter
ConcatParameter
ConvolutionParameter
DataParameter
DropoutParameter
HDF5DataParameter
HDF5OutputParameter
ImageDataParameter
InfogainLossParameter
InnerProductParameter
LRNParameter
MemoryDataParameter
PoolingParameter
PowerParameter
WindowDataParameter
V0LayerParameter

正文

一：什么是protocol buffer

以下内容摘自：Google Protocol Buffer 的使用和原理
强烈推荐另外一篇极好的博文是：Protocol Buffer技术详解(C++实例)
简介

什么是 Google Protocol Buffer？ 假如您在网上搜索，应该会得到类似这样的文字介绍：
Google Protocol Buffer( 简称 Protobuf) 是 Google 公司内部的混合语言数据标准，目前已经正在使用的有超过 48,162 种报文格式定义和超过 12,183 个 .proto 文件。他们用于 RPC 系统和持续数据存储系统。
Protocol Buffers 是一种轻便高效的结构化数据存储格式，可以用于结构化数据串行化，或者说序列化。它很适合做数据存储或 RPC 数据交换格式。可用于通讯协议、数据存储等领域的语言无关、平台无关、可扩展的序列化结构数据格式。目前提供了 C++、Java、Python 三种语言的 API。
或许您和我一样，在第一次看完这些介绍后还是不明白 Protobuf 究竟是什么，那么我想一个简单的例子应该比较有助于理解它。
一个简单的例子

安装 Google Protocol Buffer
在网站 http://code.google.com/p/protobuf/downloads/list上可以下载 Protobuf 的源代码。然后解压编译安装便可以使用它了。
安装步骤如下所示：

tar -xzf protobuf-2.1.0.tar.gz
cd protobuf-2.1.0
./configure –prefix=$INSTALL_DIR
make
make check
make install
关于简单例子的描述

我打算使用 Protobuf 和 C++ 开发一个十分简单的例子程序。
该程序由两部分组成。第一部分被称为 Writer，第二部分叫做 Reader。
Writer 负责将一些结构化的数据写入一个磁盘文件，Reader 则负责从该磁盘文件中读取结构化数据并打印到屏幕上。
准备用于演示的结构化数据是 HelloWorld，它包含两个基本数据：

ID，为一个整数类型的数据
Str，这是一个字符串

书写 .proto 文件

首先我们需要编写一个 proto 文件，定义我们程序中需要处理的结构化数据，在 protobuf 的术语中，结构化数据被称为 Message。proto 文件非常类似 java 或者 C 语言的数据定义。代码清单 1 显示了例子应用中的 proto 文件内容。

清单 1. proto 文件

package lm; 
 message helloworld 
 { 
    required int32     id = 1;  // ID 
    required string    str = 2;  // str 
    optional int32     opt = 3;  //optional field 
 }

一个比较好的习惯是认真对待 proto 文件的文件名。比如将命名规则定于
packageName.MessageName.proto
在上例中，package 名字叫做 lm，定义了一个消息 helloworld，该消息有三个成员，类型为 int32 的 id，另一个为类型为 string 的成员 str。opt 是一个可选的成员，即消息中可以不包含该成员。
编译 .proto 文件

写好 proto 文件之后就可以用 Protobuf 编译器将该文件编译成目标语言了。本例中我们将使用 C++。
假设您的 proto 文件存放在 $SRC_DIR 下面，您也想把生成的文件放在同一个目录下，则可以使用如下命令：

protoc -I=$SRC_DIR --cpp_out=$DST_DIR $SRC_DIR/addressbook.proto

命令将生成两个文件：
lm.helloworld.pb.h ， 定义了 C++ 类的头文件
lm.helloworld.pb.cc ， C++ 类的实现文件
在生成的头文件中，定义了一个 C++ 类 helloworld，后面的 Writer 和 Reader 将使用这个类来对消息进行操作。诸如对消息的成员进行赋值，将消息序列化等等都有相应的方法。
编写 writer 和 Reader

如前所述，Writer将把一个结构化数据写入磁盘，以便其他人来读取。假如我们不使用 Protobuf，其实也有许多的选择。一个可能的方法是将数据转换为字符串，然后将字符串写入磁盘。转换为字符串的方法可以使用sprintf()，这非常简单。数字123可以变成字符串“123”。
这样做似乎没有什么不妥，但是仔细考虑一下就会发现，这样的做法对写 Reader 的那个人的要求比较高，Reader 的作者必须了 Writer 的细节。比如”123”可以是单个数字 123，但也可以是三个数字 1,2 和 3，等等。这么说来，我们还必须让 Writer 定义一种分隔符一样的字符，以便 Reader 可以正确读取。但分隔符也许还会引起其他的什么问题。最后我们发现一个简单的 Helloworld 也需要写许多处理消息格式的代码。
如果使用 Protobuf，那么这些细节就可以不需要应用程序来考虑了。
使用 Protobuf，Writer 的工作很简单，需要处理的结构化数据由 .proto 文件描述，经过上一节中的编译过程后，该数据化结构对应了一个 C++ 的类，并定义在 lm.helloworld.pb.h 中。对于本例，类名为 lm::helloworld。
Writer 需要 include 该头文件，然后便可以使用这个类了。
现在，在 Writer 代码中，将要存入磁盘的结构化数据由一个 lm::helloworld 类的对象表示，它提供了一系列的 get/set 函数用来修改和读取结构化数据中的数据成员，或者叫 field。
当我们需要将该结构化数据保存到磁盘上时，类 lm::helloworld 已经提供相应的方法来把一个复杂的数据变成一个字节序列，我们可以将这个字节序列写入磁盘。
对于想要读取这个数据的程序来说，也只需要使用类 lm::helloworld 的相应反序列化方法来将这个字节序列重新转换会结构化数据。这同我们开始时那个“123”的想法类似，不过 Protobuf 想的远远比我们那个粗糙的字符串转换要全面，因此，我们不如放心将这类事情交给 Protobuf 吧。

程序清单 2 演示了 Writer 的主要代码，您一定会觉得很简单吧？
清单 2. Writer 的主要代码

#include "lm.helloworld.pb.h"
…

 int main(void) 
 { 

  lm::helloworld msg1; 
  msg1.set_id(101); 
  msg1.set_str(“hello”); 

  // Write the new address book back to disk. 
  fstream output("./log", ios::out | ios::trunc | ios::binary); 

  if (!msg1.SerializeToOstream(&output)) { 
      cerr << "Failed to write msg." << endl; 
      return -1; 
  }         
  return 0; 
 }

Msg1 是一个 helloworld 类的对象，set_id() 用来设置 id 的值。SerializeToOstream 将对象序列化后写入一个 fstream 流。

代码清单 3 列出了 reader 的主要代码。
清单 3. Reader

#include "lm.helloworld.pb.h" 
…
 void ListMsg(const lm::helloworld & msg) { 
  cout << msg.id() << endl; 
  cout << msg.str() << endl; 
 } 

 int main(int argc, char* argv[]) { 

  lm::helloworld msg1; 

  { 
    fstream input("./log", ios::in | ios::binary); 
    if (!msg1.ParseFromIstream(&input)) { 
      cerr << "Failed to parse address book." << endl; 
      return -1; 
    } 
  } 

  ListMsg(msg1); 
  … 
 }

同样，Reader 声明类 helloworld 的对象 msg1，然后利用 ParseFromIstream 从一个 fstream 流中读取信息并反序列化。此后，ListMsg 中采用 get 方法读取消息的内部信息，并进行打印输出操作。
运行结果
运行 Writer 和 Reader 的结果如下：

\>writer 
\>reader 
101 
Hello

Reader 读取文件 log 中的序列化信息并打印到屏幕上。本文中所有的例子代码都可以在附件中下载。您可以亲身体验一下。
这个例子本身并无意义，但只要您稍加修改就可以将它变成更加有用的程序。比如将磁盘替换为网络 socket，那么就可以实现基于网络的数据交换任务。而存储和交换正是 Protobuf 最有效的应用领域。

二、caffe.proto中的几个重要数据类型

看完了上面关于protocol buffer的介绍，大家应该可以知道其实caffe.pb.cc里面的东西都是从caffe.proto编译而来的，无非就是一些关于这些数据结构（类）的标准化操作，比如

 void CopyFrom();
  void MergeFrom();
  void CopyFrom();
  void MergeFrom;
  void Clear();
  bool IsInitialized() const;
  int ByteSize() const;
  bool MergePartialFromCodedStream();
  void SerializeWithCachedSizes() const;
  SerializeWithCachedSizesToArray() const;
  int GetCachedSize()
  void SharedCtor();
  void SharedDtor();
  void SetCachedSize() const;

<0> BlobProto

message BlobProto {//blob的属性以及blob中的数据(data\diff)
  optional int32 num = 1 [default = 0];
  optional int32 channels = 2 [default = 0];
  optional int32 height = 3 [default = 0];
  optional int32 width = 4 [default = 0];
  repeated float data = 5 [packed = true];
  repeated float diff = 6 [packed = true];
}

<1> Datum

message Datum {
  optional int32 channels = 1;
  optional int32 height = 2;
  optional int32 width = 3;
  optional bytes data = 4;//真实的图像数据，以字节存储(bytes)
  optional int32 label = 5;
  repeated float float_data = 6;//datum也能存float类型的数据(float)
}

<2> LayerParameter

message LayerParameter {
  repeated string bottom = 2; //输入的blob的名字(string)
  repeated string top = 3; //输出的blob的名字(string)
  optional string name = 4; //层的名字
  enum LayerType { //层的枚举（enum，和c++中的enum一样）
    NONE = 0;
    ACCURACY = 1;
    BNLL = 2;
    CONCAT = 3;
    CONVOLUTION = 4;
    DATA = 5;
    DROPOUT = 6;
    EUCLIDEAN_LOSS = 7;
    ELTWISE_PRODUCT = 25;
    FLATTEN = 8;
    HDF5_DATA = 9;
    HDF5_OUTPUT = 10;
    HINGE_LOSS = 28;
    IM2COL = 11;
    IMAGE_DATA = 12;
    INFOGAIN_LOSS = 13;
    INNER_PRODUCT = 14;
    LRN = 15;
    MEMORY_DATA = 29;
    MULTINOMIAL_LOGISTIC_LOSS = 16;
    POOLING = 17;
    POWER = 26;
    RELU = 18;
    SIGMOID = 19;
    SIGMOID_CROSS_ENTROPY_LOSS = 27;
    SOFTMAX = 20;
    SOFTMAX_LOSS = 21;
    SPLIT = 22;
    TANH = 23;
    WINDOW_DATA = 24;
  }
  optional LayerType type = 5; // 层的类型
  repeated BlobProto blobs = 6; //blobs的数值参数
  repeated float blobs_lr = 7; //学习速率(repeated)，如果你想那个设置一个blob的学习速率，你需要设置所有blob的学习速率。
  repeated float weight_decay = 8; //权值衰减(repeated)

  // 相对于某一特定层的参数(optional)
  optional ConcatParameter concat_param = 9;
  optional ConvolutionParameter convolution_param = 10;
  optional DataParameter data_param = 11;
  optional DropoutParameter dropout_param = 12;
  optional HDF5DataParameter hdf5_data_param = 13;
  optional HDF5OutputParameter hdf5_output_param = 14;
  optional ImageDataParameter image_data_param = 15;
  optional InfogainLossParameter infogain_loss_param = 16;
  optional InnerProductParameter inner_product_param = 17;
  optional LRNParameter lrn_param = 18;
  optional MemoryDataParameter memory_data_param = 22;
  optional PoolingParameter pooling_param = 19;
  optional PowerParameter power_param = 21;
  optional WindowDataParameter window_data_param = 20;
  optional V0LayerParameter layer = 1;
}

<3> NetParameter

message NetParameter {
  optional string name = 1;//网络的名字
  repeated LayerParameter layers = 2; //repeated类似于数组
  repeated string input = 3;//输入层blob的名字
  repeated int32 input_dim = 4;//输入层blob的维度，应该等于(4*#input)
  optional bool force_backward = 5 [default = false];//网络是否进行反向传播。如果设置为否，则由网络的结构和学习速率来决定是否进行反向传播。
}

<4> SolverParameter

message SolverParameter {
  optional string train_net = 1; // 训练网络的proto file
  optional string test_net = 2; // 测试网络的proto file
  optional int32 test_iter = 3 [default = 0]; // 每次测试时的迭代次数
  optional int32 test_interval = 4 [default = 0]; // 两次测试的间隔迭代次数
  optional bool test_compute_loss = 19 [default = false];
  optional float base_lr = 5; // 基本学习率
  optional int32 display = 6; // 两次显示的间隔迭代次数
  optional int32 max_iter = 7; // 最大迭代次数
  optional string lr_policy = 8; // 学习速率衰减方式
  optional float gamma = 9; // 关于梯度下降的一个参数
  optional float power = 10; // 计算学习率的一个参数
  optional float momentum = 11; // 动量
  optional float weight_decay = 12; // 权值衰减
  optional int32 stepsize = 13; // 学习速率的衰减步长
  optional int32 snapshot = 14 [default = 0]; // snapshot的间隔
  optional string snapshot_prefix = 15; // snapshot的前缀
  optional bool snapshot_diff = 16 [default = false]; // 是否对于 diff 进行 snapshot
  enum SolverMode {
    CPU = 0;
    GPU = 1;
  }
  optional SolverMode solver_mode = 17 [default = GPU]; // solver的模式，默认为GPU
  optional int32 device_id = 18 [default = 0]; // GPU的ID
  optional int64 random_seed = 20 [default = -1]; // 随机数种子
  optional bool debug_info = 7 [default = false]; // 调试网络很好用,可以打印出前向传播的数据以及反向传播的数据, 在网络出问题时,可以用来看看网络
}

三、caffe.proto源码

以下转载自（http://blog.csdn.net/langb2014/article/details/50395466）

//  
caffe.proto文件注释，  
caffe版本:MS-caffe-master github 2016.8.20  
caffe版本:BVLC-caffe-master github 2016.8.20  
//  
syntax = "proto2";  
package caffe;    
// 数据块形状{指定Blob的形状或维度-4D}  
message BlobShape {  
  //数据块形状定义为Num×Channel×Height×Wight原因在于caffe基于容器的多维嵌套  
  //来实现高维数据的封装。即vector(N)>。  
  repeated int64 dim = 1 [packed = true];  
}  

// 数据块{形状，数据，微分}  
message BlobProto {  
  optional BlobShape shape = 7;  
  repeated float data = 5 [packed = true];  
  repeated float diff = 6 [packed = true];  
  repeated double double_data = 8 [packed = true];  
  repeated double double_diff = 9 [packed = true];  

  //数据4D形状 -- 旧版本，已使用"BlobShape shape"代替：  
  optional int32 num = 1 [default = 0]; //样本  
  optional int32 channels = 2 [default = 0];  
  optional int32 height = 3 [default = 0];  
  optional int32 width = 4 [default = 0];  
}  

// 存放多个BlobProto实例的对应Index，易于引用  
message BlobProtoVector {  
  repeated BlobProto blobs = 1;  
}  

// 数据:{C,H,W,data(uchar&float),label} 图像样本  
message Datum {  
  optional int32 channels = 1;  
  optional int32 height = 2;  
  optional int32 width = 3;  
  // the actual image data, in bytes  
  optional bytes data = 4;  
  optional int32 label = 5;  
  // Optionally, the datum could also hold float data.  
  repeated float float_data = 6;  
  // If true data contains an encoded image that need to be decoded  
  optional bool encoded = 7 [default = false];  
}  

//滤波器参数{Type(const|uniform|gauss),}  
message FillerParameter {  
  // The filler type.  
  optional string type = 1 [default = 'constant'];  
  optional float value = 2 [default = 0]; // the value in constant filler  
  optional float min = 3 [default = 0]; // the min value in uniform filler  
  optional float max = 4 [default = 1]; // the max value in uniform filler  
  optional float mean = 5 [default = 0]; // the mean value in Gaussian filler  
  optional float std = 6 [default = 1]; // the std value in Gaussian filler  
  // 给定输入与权值相乘后应该得到非零输出，默认值-1意为不稀疏化高斯模板。  
  optional int32 sparse = 7 [default = -1];  
  // Normalize the filler variance by fan_in, fan_out, or their average.  
  // Applies to 'xavier' and 'msra' fillers.（扇入，扇出）  
  // 通过fanIn,fanOut,及其均值来归一化填充值的方差，有“xavier法”或“msra法”  
  enum VarianceNorm {  
    FAN_IN = 0;  
    FAN_OUT = 1;  
    AVERAGE = 2;  
  }  
  optional VarianceNorm variance_norm = 8 [default = FAN_IN];  
}  

//网络参数{网名，输入参数，数据块形状，forceBack，NetState,debugInfo,}  
message NetParameter {  
  optional string name = 1; // consider giving the network a name  
  // 旧版--输入网络的数据块Blobs; 改为新版--InputParameter  
  repeated string input = 3;  
  // DEPRECATED. See InputParameter. The shape of the input blobs.  
  // 旧版--输入的Blobs的形状； 改为新版--InputerParameter  
  repeated BlobShape input_shape = 8;  

  // 指定Blobs的4D输入形状 -- 已改为新版：input_shape代替  
  // 如要使用旧版，对每个输入的blob都需要指定4个参数，Num×Cha×H×W  
  // 因此 input_dim需要重复4次  
  repeated int32 input_dim = 4;  

  //确定网络是否要让每个层都强制反向传播。  
  //如果设置为false,将根据网络结构和学习率来自动确定是否需要反向传播。  
  //网络的当前状态"state"包括"phase","level","stage"。(???)  
  //某些层需要设置phase属性，使其跳过网络运行时的某些状态.  
  optional NetState state = 6;  

  // 当运行Net::Forward/Backward/Update时，打印调试信息，默认false.  
  optional bool debug_info = 7 [default = false];  

  // 构成net的layers。每个layer的链接和行为通过LayerParameter配置。  
  repeated LayerParameter layer = 100;  // ID 100 so layers are printed last.  

  // DEPRECATED: use 'layer' instead.  
  repeated V1LayerParameter layers = 2;  
}  

// NOTE：注意  
// Update the next available ID when you add a new SolverParameter field.  
// 当你添加一个新的SolverParameter属性时，需要更新下一个可获得的ID  
// SolverParameter next available ID: 41 (last added: type)  

//求解器参数{网络，}  
message SolverParameter {  
  //  
  // Specifying the train and test networks  
  //  
  // Exactly one train net must be specified using one of the following fields:  
  //     train_net_param, train_net, net_param, net  
  // One or more test nets may be specified using any of the following fields:  
  //     test_net_param, test_net, net_param, net  
  // If more than one test net field is specified (e.g., both net and  
  // test_net are specified), they will be evaluated in the field order given  
  // above: (1) test_net_param, (2) test_net, (3) net_param/net.  
  // A test_iter must be specified for each test_net.  
  // A test_level and/or a test_stage may also be specified for each test_net.  
  //  
  //指定网络，可有以下的多种形式  
  // Proto filename for the train net, possibly combined with one or more  
  // test nets.  
  optional string net = 24;  
  // Inline train net param, possibly combined with one or more test nets.  
  optional NetParameter net_param = 25;  

  optional string train_net = 1; // Proto filename for the train net.  
  repeated string test_net = 2; // Proto filenames for the test nets.  
  optional NetParameter train_net_param = 21; // Inline train net params.  
  repeated NetParameter test_net_param = 22; // Inline test net params.  

 // 指定网络状态  
 // The states for the train/test nets. Must be unspecified or  
  // specified once per net.  
  //  
  // By default, all states will have solver = true;  
  // train_state will have phase = TRAIN,  
  // and all test_state's will have phase = TEST.  
  // Other defaults are set according to the NetState defaults.  
  optional NetState train_state = 26;  
  repeated NetState test_state = 27;  

  //测试迭代批次数：  
  //合理设置可使得测试遍历完全部测试样本  
  //合理值 = 测试样本总数/每批次测试数 = totalTestSamples/batchSize  
  repeated int32 test_iter = 3;  

  //训练迭代批次数：  
  //两次测试之间所经历的训练迭代次数:合理设置可使得训练遍历完全部训练样本  
  //合理值 = 训练样本总数/每批次训练数 = totalTrainSamples/batchSize  
  optional int32 test_interval = 4 [default = 0];  
  //训练test_interval个批次，再测试test_iter个批次，为一个回合(epoch)  
  //合理设置应使得每个回合内，遍历覆盖到全部训练样本和测试样本  

  //默认不计算测试时损失  
  optional bool test_compute_loss = 19 [default = false];  

  // 如设置为真，则在训练前运行一次测试，以确保内存足够，并打印初始损失值  
  optional bool test_initialization = 32 [default = true];  
  // 基本学习速率  
  optional float base_lr = 5; // The base learning rate  
  // 打印信息的遍历间隔，遍历多少个批次打印一次信息。设置为0则不打印。  
  optional int32 display = 6;  
  // Display the loss averaged over the last average_loss iterations  
  // 打印最后一个迭代批次下的平均损失（？）  
  optional int32 average_loss = 33 [default = 1];  
  // 训练最大迭代次数  
  optional int32 max_iter = 7;  
  // accumulate gradients over `iter_size` x `batch_size` instances  
  // 累积梯度误差基于“iter_size×batchSize”个样本实例  
  // “批次数×批量数”=“遍历的批次数×每批的样本数”个样本实例  
  optional int32 iter_size = 36 [default = 1];  

  //学习率衰减策略(7种)  
  // The learning rate decay policy. The currently implemented learning rate  
  // policies are as follows:  
  //    - fixed: always return base_lr.  
  //    - step: return base_lr * gamma ^ (floor(iter / step))  
  //    - exp: return base_lr * gamma ^ iter  
  //    - inv: return base_lr * (1 + gamma * iter) ^ (- power)  
  //    - multistep: similar to step butallows non uniform steps defined by  
  //      stepvalue  
  //    - poly: the effective learning rate follows a polynomial decay, to be  
  //      zero by the max_iter. return base_lr (1 - iter/max_iter) ^ (power)  
  //    - sigmoid: the effective learning rate follows a sigmod decay  
  //      return base_lr ( 1/(1 + exp(-gamma * (iter - stepsize))))  
  //  
  // 在上述参数中，base_lr, max_iter, gamma, step, stepvalue and power 被定义  
  // 在solver.prototxt文件中，iter是当前迭代次数。  
  optional string lr_policy = 8; //学习率调节策略  
  optional float gamma = 9; // The parameter to compute the learning rate.  
  optional float power = 10; // The parameter to compute the learning rate.  
  optional float momentum = 11; // The momentum value.动量  
  optional float weight_decay = 12; // The weight decay.权值衰减系数  
  //由权值衰减系数所控制的正则化类型：L1或L2范数，默认L2  
  optional string regularization_type = 29 [default = "L2"];  
  //"step"策略下，学习率的步长值  
  optional int32 stepsize = 13;  
  //"multistep"策略下的步长值  
  repeated int32 stepvalue = 34;  

  //设置梯度裁剪阈值为>=0，当其实际L2范数超出此值时(?)  
  optional float clip_gradients = 35 [default = -1];  

  //快照间隔，遍历多少次对模型和求解器状态保存一次  
  optional int32 snapshot = 14 [default = 0]; // The snapshot interval  
  optional string snapshot_prefix = 15; // The prefix for the snapshot.  
  //是否对diff快照，有助调试，但最终的protocol buffer尺寸会很大  
  optional bool snapshot_diff = 16 [default = false];  
  //快照数据保存格式{hdf5,binaryproto(默认)}  
  enum SnapshotFormat {  
    HDF5 = 0;  
    BINARYPROTO = 1;  
  }  
  optional SnapshotFormat snapshot_format = 37 [default = BINARYPROTO];  
  // the mode solver will use: 0 for CPU and 1 for GPU. Use GPU in default.  
  enum SolverMode {  
    CPU = 0;  
    GPU = 1;  
  }  
  求解模式{GPU(device_id),CPU}  
  optional SolverMode solver_mode = 17 [default = GPU];  
  optional int32 device_id = 18 [default = 0];  
  //随机数种子，设为正则表示Solver会以此为随机数初始化caffe,可产生重复随机  
  //数，易于重复试验；设为默认-1代表使用系统时钟作为种子。  
  optional int64 random_seed = 20 [default = -1];  

  //求解器类型=SGD(默认)  
  optional string type = 40 [default = "SGD"];  

  // numerical stability for RMSProp, AdaGrad and AdaDelta and Adam  
  optional float delta = 31 [default = 1e-8];  
  // parameters for the Adam solver  
  optional float momentum2 = 39 [default = 0.999];  

  // RMSProp decay value  
  // MeanSquare(t) = rms_decay*MeanSquare(t-1) + (1-rms_decay)*SquareGradient(t)  
  optional float rms_decay = 38;  

  //若真，则打印网络状态信息，有助于调试问题  
  optional bool debug_info = 23 [default = false];  

  //若假，则不会在训练后保存快照  
  optional bool snapshot_after_train = 28 [default = true];  

  // DEPRECATED: old solver enum types, use string instead  
  enum SolverType {  
    SGD = 0;  
    NESTEROV = 1;  
    ADAGRAD = 2;  
    RMSPROP = 3;  
    ADADELTA = 4;  
    ADAM = 5;  
  }  
  // DEPRECATED: use type instead of solver_type  
  optional SolverType solver_type = 30 [default = SGD];  
}  

//对求解器状态进行快照的消息  
message SolverState {  
  optional int32 iter = 1; // The current iteration  
  optional string learned_net = 2; // The file that stores the learned net.  
  repeated BlobProto history = 3; // The history for sgd solvers  
  optional int32 current_step = 4 [default = 0]; // The current step for learning rate  
}  

enum Phase {  
   TRAIN = 0;  
   TEST = 1;  
}  
//NetState{phase,level,stage}  
message NetState {  
  optional Phase phase = 1 [default = TEST];  
  optional int32 level = 2 [default = 0];  
  repeated string stage = 3;  
}  

//网络状态规则{phases,levels,stages}  
message NetStateRule {  
  //在NetState中设置phase值(TRAIN|TEST)，使其符合此规则  
  optional Phase phase = 1;  

  //设置layer中所使用的最小最大levels。使其不定义以满足忽视level的规则。  
  optional int32 min_level = 2;  
  optional int32 max_level = 3;  

  // Customizable sets of stages to include or exclude.  
  // The net must have ALL of the specified stages and NONE of the specified  
  // "not_stage"s to meet the rule.  
  // (Use multiple NetStateRules to specify conjunctions of stages.)  
  //可定制的stages集合，用于include或exclude在网络中。网络必须包含全  
  //部制定的"stages"或不包含全部制定的"not_stage"  
  repeated string stage = 4;  
  repeated string not_stage = 5;  
}  

// Specifies training parameters (multipliers on global learning constants,  
// and the name and other settings used for weight sharing).  
//指定训练参数(乘数及全局学习率常数)和其名称，以及其他用于权值共享的设置。  
message ParamSpec {  
  // 设定参数blobs的名称--用于在层间共享参数，若无此需求则不用设计。  
  optional string name = 1;  

  //共享权重时是否需要其形状相同或仅仅数量相同，默认为形状相同  
  optional DimCheckMode share_mode = 2;  
  enum DimCheckMode {  
    // STRICT (default) 形状相同(num, channels, height, width)都匹配.  
    STRICT = 0;  
    // PERMISSIVE 数量相同  
    PERMISSIVE = 1;  
  }  

  // The multiplier on the global learning rate for this parameter.  
  // 全局学习率的乘数  
  optional float lr_mult = 3 [default = 1.0];  

  // The multiplier on the global weight decay for this parameter.  
  // 全局权值衰减系数的乘数  
  optional float decay_mult = 4 [default = 1.0];  
}  

//注意：  
//当在LayerParameter中新增字段时，需要为其更新下一个可用ID。  
//比如，最近新增了smooth_l1_loss_param层，则为其指定层专属ID:149。  
//层参数{名称，类型，输入底，输出顶，阶段，损失加权系数，全局乘数，}  
message LayerParameter {  
  optional string name = 1; // 类名称  
  optional string type = 2; // 类类型  
  repeated string bottom = 3; // the name of each bottom blob 输入blob名称  
  repeated string top = 4; // the name of each top blob 输出blob名称  

  // The train / test phase for computation. //阶段，运行时状态  
  optional Phase phase = 10;  

  //每层输出blob在目标损失函数中的加权系数，每层默认为0或1  
  repeated float loss_weight = 5;  

  //指定训练参数(全局学习率上的乘数lr_mrlt)  
  repeated ParamSpec param = 6;  


  // The blobs containing the numeric parameters of the layer.  
  //包含每层数值参数的blobs  
  repeated BlobProto blobs = 7;  

  // Specifies whether to backpropagate to each bottom. If unspecified,  
  // Caffe will automatically infer whether each input needs backpropagation  
  // to compute parameter gradients. If set to true for some inputs,  
  // backpropagation to those inputs is forced; if set false for some inputs,  
  // backpropagation to those inputs is skipped.  
  //  
  // The size must be either 0 or equal to the number of bottoms.  

  repeated bool propagate_down = 11;  

  // Rules控制每层是否被包含在网络中，基于当前的NetState. 可使用非0数规则来  
  // include或exclude，但不能兼有。如果未指定include或exclude规则，则该层总是  
  // 被包含在内。  
  repeated NetStateRule include = 8;  
  repeated NetStateRule exclude = 9;  

  // 用于数据预处理的参数  
  optional TransformationParameter transform_param = 100;  

  // 由loss层共享的参数.  
  optional LossParameter loss_param = 101;  

  // Layer type-specific parameters.  
  //  
  // Note: certain layers may have more than one computational engine  
  // for their implementation. These layers include an Engine type and  
  // engine parameter for selecting the implementation.  
  // The default for the engine is set by the ENGINE switch at compile-time.  
  // 层类型指定参数  
  // 注意：  
  optional AccuracyParameter accuracy_param = 102;  
  optional ArgMaxParameter argmax_param = 103;  
  optional BatchNormParameter batch_norm_param = 139;  
  optional BiasParameter bias_param = 141;  
  optional ConcatParameter concat_param = 104;  
  optional ContrastiveLossParameter contrastive_loss_param = 105;  
  optional ConvolutionParameter convolution_param = 106;  
  optional CropParameter crop_param = 144;  
  optional DataParameter data_param = 107;  
  optional DropoutParameter dropout_param = 108;  
  optional DummyDataParameter dummy_data_param = 109;  
  optional EltwiseParameter eltwise_param = 110;  
  optional ELUParameter elu_param = 140;  
  optional EmbedParameter embed_param = 137;  
  optional ExpParameter exp_param = 111;  
  optional FlattenParameter flatten_param = 135;  
  optional HDF5DataParameter hdf5_data_param = 112;  
  optional HDF5OutputParameter hdf5_output_param = 113;  
  optional HingeLossParameter hinge_loss_param = 114;  
  optional ImageDataParameter image_data_param = 115;  
  optional InfogainLossParameter infogain_loss_param = 116;  
  optional InnerProductParameter inner_product_param = 117;  
  optional InputParameter input_param = 143;  
  optional LogParameter log_param = 134;  
  optional LRNParameter lrn_param = 118;  
  optional MemoryDataParameter memory_data_param = 119;  
  optional MVNParameter mvn_param = 120;  
  optional ParameterParameter parameter_param = 145;  
  optional PoolingParameter pooling_param = 121;  
  optional PowerParameter power_param = 122;  
  optional PReLUParameter prelu_param = 131;  
  optional PythonParameter python_param = 130;  
  optional RecurrentParameter recurrent_param = 146;  
  optional ReductionParameter reduction_param = 136;  
  optional ReLUParameter relu_param = 123;  
  optional ReshapeParameter reshape_param = 133;  
  optional ROIPoolingParameter roi_pooling_param = 147;  
  optional ScaleParameter scale_param = 142;  
  optional SigmoidParameter sigmoid_param = 124;  
  optional SmoothL1LossParameter smooth_l1_loss_param = 148;  
  optional SoftmaxParameter softmax_param = 125;  
  optional SPPParameter spp_param = 132;  
  optional SliceParameter slice_param = 126;  
  optional TanHParameter tanh_param = 127;  
  optional ThresholdParameter threshold_param = 128;  
  optional TileParameter tile_param = 138;  
  optional WindowDataParameter window_data_param = 129;  
  optional MILDataParameter mil_data_param = 0x004d4944; //"MID"  
  optional MILParameter mil_param = 0x004d494c; //"MIL"  
}  

// 对数据层进行转换的参数  
message TransformationParameter {  
  // 对data执行预处理，比如简单缩放,去均值。  
  optional float scale = 1 [default = 1];  
  // Specify if we want to randomly mirror data.//镜像  
  optional bool mirror = 2 [default = false];  
  // Specify if we would like to randomly crop an image.//随机裁剪  
  optional uint32 crop_size = 3 [default = 0];  
  // 指定均值文件或均值，二者不可兼有；在对应通道上减去此均值；  
  optional string mean_file = 4;  
  repeated float mean_value = 5;  
  // 强制转换图像为3通道彩色  
  optional bool force_color = 6 [default = false];  
  // 强制转换为灰度图  
  optional bool force_gray = 7 [default = false];  
}  

// Loss层参数  
message LossParameter {  
  // 如果被指定，则忽略给定label的实例  
  optional int32 ignore_label = 1;  
  // 如何对loss层损失归一化，使其跨越"batches,spatial(H*W)"或其他维度。  
  // 目前仅仅在SoftmaxWithLoss层中实现。  
  // 归一化模式  
  enum NormalizationMode {  
    // 基于batchSize×spatialDim归一化.所设定的忽略标签将不被忽略。  
    FULL = 0;  
    // 基于输出位置的总数量(batchSize×H×W)归一化，不包括被忽视的标签。  
    // 若未设置被忽视标签，则其行为与FULL相同。  
    VALID = 1;  
    // Divide by the batch size.基于batchSize进行归一化。  
    BATCH_SIZE = 2;  
    // Do not normalize the loss.不归一化损失  
    NONE = 3;  
  }  
  optional NormalizationMode normalization = 3 [default = VALID];  
  // 旧版--新版如上所述。  
  // 若"normalization"被指定则忽略此参数；若未被指定，可设置下值为false  
  // 则基于batchSize归一化。  
  optional bool normalize = 2;  
}  

// Messages that store parameters used by individual layer types follow, in  
// alphabetical order.  

message AccuracyParameter {  
  // When computing accuracy, count as correct by comparing the true label to  
  // the top k scoring classes.  By default, only compare to the top scoring  
  // class (i.e. argmax). //Topk正确率计算  
  optional uint32 top_k = 1 [default = 1];  

  // The "label" axis of the prediction blob, whose argmax corresponds to the  
  // predicted label -- may be negative to index from the end (e.g.,-1 for the  
  // last axis).  For example, if axis == 1 and the predictions are  
  // (N x C x H x W), the label blob is expected to contain N*H*W ground truth  
  // labels with integer values in {0, 1, ..., C-1}.  
  // 预测blob的"label"轴--其最大值才对应于预测标签--的索引有可能从负值开始。  
  // 即: predicted_labels=argmax(predictions blob,label_axis)  
  // 比如axis==1,其预测blob为(N x C x H x W), 而标签blob被期望包含(N×H×W)个  
  // 真实标签，且标签值为{0,1,2...C-1}。  
  optional int32 axis = 2 [default = 1];  

  // If specified, ignore instances with the given label.  
  // 如果指定，则忽略给定标签的对应实例  
  optional int32 ignore_label = 3;  
}  
//输出最大化参数，对预测标签进行最大化  
message ArgMaxParameter {  
  // If true produce pairs (argmax, maxval)  
  // 如果真，则产生(argmax,maxval)对  
  optional bool out_max_val = 1 [default = false];  
  optional uint32 top_k = 2 [default = 1];  
  // The axis along which to maximise -- may be negative to index from the  
  // end (e.g., -1 for the last axis).  
  // By default ArgMaxLayer maximizes over the flattened trailing dimensions  
  // for each index of the first / num dimension. ??  
  //  
  optional int32 axis = 3;  
}  
//拼接参数  
message ConcatParameter {  
  // The axis along which to concatenate -- may be negative to index from the  
  // end (e.g., -1 for the last axis).  Other axes must have the  
  // same dimension for all the bottom blobs.  
  // By default, ConcatLayer concatenates blobs along the "channels" axis (1).  
  optional int32 axis = 2 [default = 1];  

  // DEPRECATED: alias for "axis" -- does not support negative indexing.  
  optional uint32 concat_dim = 1 [default = 1];  
}  
//BatchNormParameter参数，源于论文batchNorm  
message BatchNormParameter {  
  // If false, accumulate global mean/variance values via a moving average. If  
  // true, use those accumulated values instead of computing mean/variance  
  // across the batch.  
  optional bool use_global_stats = 1;  
  // How much does the moving average decay each iteration?  
  optional float moving_average_fraction = 2 [default = .999];  
  // Small value to add to the variance estimate so that we don't divide by  
  // zero.  
  optional float eps = 3 [default = 1e-5];  
}  
//偏置参数  
message BiasParameter {  
  // The first axis of bottom[0] (the first input Blob) along which to apply  
  // bottom[1] (the second input Blob).  May be negative to index from the end  
  // (e.g., -1 for the last axis).  
  //  
  // For example, if bottom[0] is 4D with shape 100x3x40x60, the output  
  // top[0] will have the same shape, and bottom[1] may have any of the  
  // following shapes (for the given value of axis):  
  //    (axis == 0 == -4) 100; 100x3; 100x3x40; 100x3x40x60  
  //    (axis == 1 == -3)          3;     3x40;     3x40x60  
  //    (axis == 2 == -2)                   40;       40x60  
  //    (axis == 3 == -1)                                60  
  // Furthermore, bottom[1] may have the empty shape (regardless of the value of  
  // "axis") -- a scalar bias.  
  optional int32 axis = 1 [default = 1];  

  // (num_axes is ignored unless just one bottom is given and the bias is  
  // a learned parameter of the layer.  Otherwise, num_axes is determined by the  
  // number of axes by the second bottom.)  
  // The number of axes of the input (bottom[0]) covered by the bias  
  // parameter, or -1 to cover all axes of bottom[0] starting from `axis`.  
  // Set num_axes := 0, to add a zero-axis Blob: a scalar.  
  optional int32 num_axes = 2 [default = 1];  

  // (filler is ignored unless just one bottom is given and the bias is  
  // a learned parameter of the layer.)  
  // The initialization for the learned bias parameter.  
  // Default is the zero (0) initialization, resulting in the BiasLayer  
  // initially performing the identity operation.  
  optional FillerParameter filler = 3;  
}  
//对比度损失参数  
message ContrastiveLossParameter {  
  // margin for dissimilar pair  
  optional float margin = 1 [default = 1.0];  
  // The first implementation of this cost did not exactly match the cost of  
  // Hadsell et al 2006 -- using (margin - d^2) instead of (margin - d)^2.  
  // legacy_version = false (the default) uses (margin - d)^2 as proposed in the  
  // Hadsell paper. New models should probably use this version.  
  // legacy_version = true uses (margin - d^2). This is kept to support /  
  // reproduce existing models and results  
  optional bool legacy_version = 2 [default = false];  
}  
//卷积参数  
message ConvolutionParameter {  
  optional uint32 num_output = 1; // The number of outputs for the layer  
  optional bool bias_term = 2 [default = true]; // whether to have bias terms  

  // Pad, kernel size, and stride are all given as a single value for equal  
  // dimensions in all spatial dimensions, or once per spatial dimension.  
  repeated uint32 pad = 3; // The padding size; defaults to 0  
  repeated uint32 kernel_size = 4; // The kernel size  
  repeated uint32 stride = 6; // The stride; defaults to 1  
  // Factor used to dilate the kernel, (implicitly) zero-filling the resulting  
  // holes. (Kernel dilation is sometimes referred to by its use in the  
  // algorithme 脿 trous from Holschneider et al. 1987.)  
  repeated uint32 dilation = 18; // The dilation; defaults to 1  

  // For 2D convolution only, the *_h and *_w versions may also be used to  
  // specify both spatial dimensions.  
  optional uint32 pad_h = 9 [default = 0]; // The padding height (2D only)  
  optional uint32 pad_w = 10 [default = 0]; // The padding width (2D only)  
  optional uint32 kernel_h = 11; // The kernel height (2D only)  
  optional uint32 kernel_w = 12; // The kernel width (2D only)  
  optional uint32 stride_h = 13; // The stride height (2D only)  
  optional uint32 stride_w = 14; // The stride width (2D only)  

  optional uint32 group = 5 [default = 1]; // The group size for group conv  

  optional FillerParameter weight_filler = 7; // The filler for the weight  
  optional FillerParameter bias_filler = 8; // The filler for the bias  
  enum Engine {  
    DEFAULT = 0; //CPU  
    CAFFE = 1;   //GPU-CUDA  
    CUDNN = 2;   //GPU-CUDA-CUDNN  
  }  
  optional Engine engine = 15 [default = DEFAULT];  

  // The axis to interpret as "channels" when performing convolution.  
  // Preceding dimensions are treated as independent inputs;  
  // succeeding dimensions are treated as "spatial".  
  // With (N, C, H, W) inputs, and axis == 1 (the default), we perform  
  // N independent 2D convolutions, sliding C-channel (or (C/g)-channels, for  
  // groups g>1) filters across the spatial axes (H, W) of the input.  
  // With (N, C, D, H, W) inputs, and axis == 1, we perform  
  // N independent 3D convolutions, sliding (C/g)-channels  
  // filters across the spatial axes (D, H, W) of the input.  
  optional int32 axis = 16 [default = 1];  

  // Whether to force use of the general ND convolution, even if a specific  
  // implementation for blobs of the appropriate number of spatial dimensions  
  // is available. (Currently, there is only a 2D-specific convolution  
  // implementation; for input blobs with num_axes != 2, this option is  
  // ignored and the ND implementation will be used.)  
  optional bool force_nd_im2col = 17 [default = false];  
}  
//裁剪参数  
message CropParameter {  
  // To crop, elements of the first bottom are selected to fit the dimensions  
  // of the second, reference bottom. The crop is configured by  
  // - the crop `axis` to pick the dimensions for cropping  
  // - the crop `offset` to set the shift for all/each dimension  
  // to align the cropped bottom with the reference bottom.  
  // All dimensions up to but excluding `axis` are preserved, while  
  // the dimensions including and trailing `axis` are cropped.  
  // If only one `offset` is set, then all dimensions are offset by this amount.  
  // Otherwise, the number of offsets must equal the number of cropped axes to  
  // shift the crop in each dimension accordingly.  
  // Note: standard dimensions are N,C,H,W so the default is a spatial crop,  
  // and `axis` may be negative to index from the end (e.g., -1 for the last  
  // axis).  
  optional int32 axis = 1 [default = 2];  
  repeated uint32 offset = 2;  
}  
//数据参数  
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.  
  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  
  // mean subtraction is always carried out before scaling.  
  optional float scale = 2 [default = 1];  
  optional string mean_file = 3;  
  // DEPRECATED. See TransformationParameter. Specify if we would like to randomly  
  // crop an image.  
  optional uint32 crop_size = 5 [default = 0];  
  // DEPRECATED. See TransformationParameter. Specify if we want to randomly mirror  
  // data.  
  optional bool mirror = 6 [default = false];  
  // Force the encoded image to have 3 color channels  
  optional bool force_encoded_color = 9 [default = false];  
  // Prefetch queue (Number of batches to prefetch to host memory, increase if  
  // data access bandwidth varies).  
  optional uint32 prefetch = 10 [default = 4];  
}  
//DropoutParameter参数  
message DropoutParameter {  
  optional float dropout_ratio = 1 [default = 0.5]; // dropout ratio  
  optional bool scale_train = 2 [default = true];  // scale train or test phase  
}  

// DummyDataLayer fills any number of arbitrarily shaped blobs with random  
// (or constant) data generated by "Fillers" (see "message FillerParameter").  
message DummyDataParameter {  
  // This layer produces N >= 1 top blobs.  DummyDataParameter must specify 1 or N  
  // shape fields, and 0, 1 or N data_fillers.  
  //  
  // If 0 data_fillers are specified, ConstantFiller with a value of 0 is used.  
  // If 1 data_filler is specified, it is applied to all top blobs.  If N are  
  // specified, the ith is applied to the ith top blob.  
  repeated FillerParameter data_filler = 1;  
  repeated BlobShape shape = 6;  

  // 4D dimensions -- deprecated.  Use "shape" instead.  
  repeated uint32 num = 2;  
  repeated uint32 channels = 3;  
  repeated uint32 height = 4;  
  repeated uint32 width = 5;  
}  

message EltwiseParameter {  
  enum EltwiseOp {  
    PROD = 0;  
    SUM = 1;  
    MAX = 2;  
  }  
  optional EltwiseOp operation = 1 [default = SUM]; // element-wise operation  
  repeated float coeff = 2; // blob-wise coefficient for SUM operation  

  // Whether to use an asymptotically slower (for >2 inputs) but stabler method  
  // of computing the gradient for the PROD operation. (No effect for SUM op.)  
  optional bool stable_prod_grad = 3 [default = true];  
}  

// Message that stores parameters used by ELULayer  
message ELUParameter {  
  // Described in:  
  // Clevert, D.-A., Unterthiner, T., & Hochreiter, S. (2015). Fast and Accurate  
  // Deep Network Learning by Exponential Linear Units (ELUs). arXiv  
  optional float alpha = 1 [default = 1];  
}  

// Message that stores parameters used by EmbedLayer  
message EmbedParameter {  
  optional uint32 num_output = 1; // The number of outputs for the layer  
  // The input is given as integers to be interpreted as one-hot  
  // vector indices with dimension num_input.  Hence num_input should be  
  // 1 greater than the maximum possible input value.  
  optional uint32 input_dim = 2;  

  optional bool bias_term = 3 [default = true]; // Whether to use a bias term  
  optional FillerParameter weight_filler = 4; // The filler for the weight  
  optional FillerParameter bias_filler = 5; // The filler for the bias  

}  

// Message that stores parameters used by ExpLayer  
message ExpParameter {  
  // ExpLayer computes outputs y = base ^ (shift + scale * x), for base > 0.  
  // Or if base is set to the default (-1), base is set to e,  
  // so y = exp(shift + scale * x).  
  optional float base = 1 [default = -1.0];  
  optional float scale = 2 [default = 1.0];  
  optional float shift = 3 [default = 0.0];  
}  

/// Message that stores parameters used by FlattenLayer  
message FlattenParameter {  
  // The first axis to flatten: all preceding axes are retained in the output.  
  // May be negative to index from the end (e.g., -1 for the last axis).  
  optional int32 axis = 1 [default = 1];  

  // The last axis to flatten: all following axes are retained in the output.  
  // May be negative to index from the end (e.g., the default -1 for the last  
  // axis).  
  optional int32 end_axis = 2 [default = -1];  
}  

// Message that stores parameters used by HDF5DataLayer  
message HDF5DataParameter {  
  // Specify the data source.  
  optional string source = 1;  
  // Specify the batch size.  
  optional uint32 batch_size = 2;  

  // Specify whether to shuffle the data.  
  // If shuffle == true, the ordering of the HDF5 files is shuffled,  
  // and the ordering of data within any given HDF5 file is shuffled,  
  // but data between different files are not interleaved; all of a file's  
  // data are output (in a random order) before moving onto another file.  
  optional bool shuffle = 3 [default = false];  
}  

message HDF5OutputParameter {  
  optional string file_name = 1;  
}  

message HingeLossParameter {  
  enum Norm {  
    L1 = 1;  
    L2 = 2;  
  }  
  // Specify the Norm to use L1 or L2  
  optional Norm norm = 1 [default = L1];  
}  
//数据集参数  
message ImageDataParameter {  
  // 指定数据源文件  
  optional string source = 1;  
  // 指定批量大小batchSize  
  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.  
  // 随机跳过rand_skip * rand(0,1)个样本，以使得SGD从不同状态点启动  
  optional uint32 rand_skip = 7 [default = 0];  
  // Whether or not ImageLayer should shuffle the list of files at every epoch.是否在每个回合都混排图片，默认否  
  optional bool shuffle = 8 [default = false];  
  // It will also resize images if new_height or new_width are not zero.  
  // 若以下2个值不为0，则将图片缩放为下面的形状  
  optional uint32 new_height = 9 [default = 0];  
  optional uint32 new_width = 10 [default = 0];  
  // Specify if the images are color or gray指明是彩色还是灰度图  
  optional bool is_color = 11 [default = true];  
  // DEPRECATED. See TransformationParameter. For data pre-processing, we can do  
  // simple scaling and subtracting the data mean, if provided. Note that the  
  // mean subtraction is always carried out before scaling.  
  // 旧版--图片预处理参数，新版用TransformationParameter  
  optional float scale = 2 [default = 1];  
  optional string mean_file = 3;  
  // DEPRECATED. See TransformationParameter. Specify if we would like to randomly  
  // crop an image.  
  optional uint32 crop_size = 5 [default = 0];  
  // DEPRECATED. See TransformationParameter. Specify if we want to randomly mirror  
  // data.  
  optional bool mirror = 6 [default = false];  
  optional string root_folder = 12 [default = ""];  
}  
//信息增益损失参数  
message InfogainLossParameter {  
  // Specify the infogain matrix source.  
  optional string source = 1;  
}  
//内积参数  
message InnerProductParameter {  
  optional uint32 num_output = 1; // The number of outputs for the layer  
  optional bool bias_term = 2 [default = true]; // whether to have bias terms  
  optional FillerParameter weight_filler = 3; // The filler for the weight  
  optional FillerParameter bias_filler = 4; // The filler for the bias  

  // The first axis to be lumped into a single inner product computation;  
  // all preceding axes are retained in the output.  
  // May be negative to index from the end (e.g., -1 for the last axis).  
  optional int32 axis = 5 [default = 1];  
  // Specify whether to transpose the weight matrix or not.  
  // If transpose == true, any operations will be performed on the transpose  
  // of the weight matrix. The weight matrix itself is not going to be transposed  
  // but rather the transfer flag of operations will be toggled accordingly.  
  optional bool transpose = 6 [default = false];  
}  
//输入参数  
message InputParameter {  
  // This layer produces N >= 1 top blob(s) to be assigned manually.  
  // Define N shapes to set a shape for each top.  
  // Define 1 shape to set the same shape for every top.  
  // Define no shape to defer to reshaping manually.  
  // 此层管理输入(top)blobs，当输入blob个数N≥1，可使其自动分配。  
  // 设定N个shapes为N个输入blob；设定1个shape使得全部输入blob形状相同；  
  // 不设定，可手动调整。  
  // 可查看.\models\bvlc_reference_caffenet\deploy.prototxt中指定1个shape  
  repeated BlobShape shape = 1;  
}  

// LogLayer的参数  
message LogParameter {  
  // LogLayer computes outputs y = log_base(shift + scale * x), for base > 0.  
  // Or if base is set to the default (-1), base is set to e,  
  // so y = ln(shift + scale * x) = log_e(shift + scale * x)  
  optional float base = 1 [default = -1.0];  
  optional float scale = 2 [default = 1.0];  
  optional float shift = 3 [default = 0.0];  
}  

// LRNLayer层参数  
message LRNParameter {  
  optional uint32 local_size = 1 [default = 5];  
  optional float alpha = 2 [default = 1.];  
  optional float beta = 3 [default = 0.75];  
  enum NormRegion {  
    ACROSS_CHANNELS = 0;  
    WITHIN_CHANNEL = 1;  
  }  
  optional NormRegion norm_region = 4 [default = ACROSS_CHANNELS];  
  optional float k = 5 [default = 1.];  
  enum Engine {  
    DEFAULT = 0;  
    CAFFE = 1;  
    CUDNN = 2;  
  }  
  optional Engine engine = 6 [default = DEFAULT];  
}  

//数据内存占用参数  
message MemoryDataParameter {  
  optional uint32 batch_size = 1;  
  optional uint32 channels = 2;  
  optional uint32 height = 3;  
  optional uint32 width = 4;  
}  
//MVN参数{均值，方差，跨通道}(mean-varance-normalization)  
message MVNParameter {  
  // This parameter can be set to false to normalize mean only  
  // 设定为false时仅归一化均值，否则包括方差  
  optional bool normalize_variance = 1 [default = true];  

  // This parameter can be set to true to perform DNN-like MVN  
  // 执行跨通道归一化,类似于DNN的MVN；默认否，只执行Spatial内归一化。  
  optional bool across_channels = 2 [default = false];  

  // Epsilon for not dividing by zero while normalizing variance  
  // 防止除0的极小数  
  optional float eps = 3 [default = 1e-9];  
}  

//？？  
message ParameterParameter {  
  optional BlobShape shape = 1;  
}  
//池化层参数  
message PoolingParameter {  
  enum PoolMethod {  
    MAX = 0;  
    AVE = 1;  
    STOCHASTIC = 2;  
  }  
  optional PoolMethod pool = 1 [default = MAX]; // The pooling method  
  // Pad, kernel size, and stride are all given as a single value for equal  
  // dimensions in height and width or as Y, X pairs.  
  optional uint32 pad = 4 [default = 0]; // The padding size (equal in Y, X)  
  optional uint32 pad_h = 9 [default = 0]; // The padding height  
  optional uint32 pad_w = 10 [default = 0]; // The padding width  
  optional uint32 kernel_size = 2; // The kernel size (square)  
  optional uint32 kernel_h = 5; // The kernel height  
  optional uint32 kernel_w = 6; // The kernel width  
  optional uint32 stride = 3 [default = 1]; // The stride (equal in Y, X)  
  optional uint32 stride_h = 7; // The stride height  
  optional uint32 stride_w = 8; // The stride width  
  enum Engine {  
    DEFAULT = 0;  
    CAFFE = 1;  
    CUDNN = 2;  
  }  
  optional Engine engine = 11 [default = DEFAULT];  
  // If global_pooling then it will pool over the size of the bottom by doing  
  // kernel_h = bottom->height and kernel_w = bottom->width  
  optional bool global_pooling = 12 [default = false];  
}  

message PowerParameter {  
  // PowerLayer computes outputs y = (shift + scale * x) ^ power.  
  optional float power = 1 [default = 1.0];  
  optional float scale = 2 [default = 1.0];  
  optional float shift = 3 [default = 0.0];  
}  
//Python参数  
message PythonParameter {  
  optional string module = 1;  
  optional string layer = 2;  
  // This value is set to the attribute `param_str` of the `PythonLayer` object  
  // in Python before calling the `setup()` method. This could be a number,  
  // string, dictionary in Python dict format, JSON, etc. You may parse this  
  // string in `setup` method and use it in `forward` and `backward`.  
  optional string param_str = 3 [default = ''];  
  // Whether this PythonLayer is shared among worker solvers during data parallelism.  
  // If true, each worker solver sequentially run forward from this layer.  
  // This value should be set true if you are using it as a data layer.  
  optional bool share_in_parallel = 4 [default = false];  
}  

// RecurrentLayer参数  
message RecurrentParameter {  
  // 输出表示的维度必须是非0的  
  optional uint32 num_output = 1 [default = 0];  

  optional FillerParameter weight_filler = 2; //weight权值参数  
  optional FillerParameter bias_filler = 3;   //bias偏置参数  

  // Whether to enable displaying debug_info in the unrolled recurrent net.  
  // 在展开RCNN时是否打印deuginfo  
  optional bool debug_info = 4 [default = false];  

  // Whether to add as additional inputs (bottoms) the initial hidden state  
  // blobs, and add as additional outputs (tops) the final timestep hidden state  
  // blobs.  The number of additional bottom/top blobs required depends on the  
  // recurrent architecture -- e.g., 1 for RNNs, 2 for LSTMs.  
  // 是否添加初始化的隐藏blobs作为额外输入(bottoms)，以及添加最终的timestep隐  
  // 藏blobs作为额外输出（tops）。  
  optional bool expose_hidden = 5 [default = false];  
}  

// ReductionLayer参数  
message ReductionParameter {  
  enum ReductionOp {  
    SUM = 1;  
    ASUM = 2;  
    SUMSQ = 3;  
    MEAN = 4;  
  }  

  optional ReductionOp operation = 1 [default = SUM]; // reduction operation  

  // The first axis to reduce to a scalar -- may be negative to index from the  
  // end (e.g., -1 for the last axis).  
  // (Currently, only reduction along ALL "tail" axes is supported; reduction  
  // of axis M through N, where N < num_axes - 1, is unsupported.)  
  // Suppose we have an n-axis bottom Blob with shape:  
  //     (d0, d1, d2, ..., d(m-1), dm, d(m+1), ..., d(n-1)).  
  // If axis == m, the output Blob will have shape  
  //     (d0, d1, d2, ..., d(m-1)),  
  // and the ReductionOp operation is performed (d0 * d1 * d2 * ... * d(m-1))  
  // times, each including (dm * d(m+1) * ... * d(n-1)) individual data.  
  // If axis == 0 (the default), the output Blob always has the empty shape  
  // (count 1), performing reduction across the entire input --  
  // often useful for creating new loss functions.  
  optional int32 axis = 2 [default = 0];  

  optional float coeff = 3 [default = 1.0]; // coefficient for output  
}  

// ReLULayer参数  
message ReLUParameter {  
  // 允许非0斜率可以加速优化:  
  // Maas, A. L., Hannun, A. Y., & Ng, A. Y. (2013). Rectifier nonlinearities  
  // improve neural network acoustic models. In ICML Workshop on Deep Learning  
  // for Audio, Speech, and Language Processing.  
  optional float negative_slope = 1 [default = 0];  
  enum Engine {  
    DEFAULT = 0;  
    CAFFE = 1;  
    CUDNN = 2;  
  }  
  optional Engine engine = 2 [default = DEFAULT];  
}  

message ReshapeParameter {  
  // Specify the output dimensions. If some of the dimensions are set to 0,  
  // the corresponding dimension from the bottom layer is used (unchanged).  
  // Exactly one dimension may be set to -1, in which case its value is  
  // inferred from the count of the bottom blob and the remaining dimensions.  
  // For example, suppose we want to reshape a 2D blob "input" with shape 2 x 8:  
  //  
  //   layer {  
  //     type: "Reshape" bottom: "input" top: "output"  
  //     reshape_param { ... }  
  //   }  
  //  
  // If "input" is 2D with shape 2 x 8, then the following reshape_param  
  // specifications are all equivalent, producing a 3D blob "output" with shape  
  // 2 x 2 x 4:  
  //  
  //   reshape_param { shape { dim:  2  dim: 2  dim:  4 } }  
  //   reshape_param { shape { dim:  0  dim: 2  dim:  4 } }  
  //   reshape_param { shape { dim:  0  dim: 2  dim: -1 } }  
  //   reshape_param { shape { dim:  0  dim:-1  dim:  4 } }  
  //  
  optional BlobShape shape = 1;  

  // axis and num_axes control the portion of the bottom blob's shape that are  
  // replaced by (included in) the reshape. By default (axis == 0 and  
  // num_axes == -1), the entire bottom blob shape is included in the reshape,  
  // and hence the shape field must specify the entire output shape.  
  //  
  // axis may be non-zero to retain some portion of the beginning of the input  
  // shape (and may be negative to index from the end; e.g., -1 to begin the  
  // reshape after the last axis, including nothing in the reshape,  
  // -2 to include only the last axis, etc.).  
  //  
  // For example, suppose "input" is a 2D blob with shape 2 x 8.  
  // Then the following ReshapeLayer specifications are all equivalent,  
  // producing a blob "output" with shape 2 x 2 x 4:  
  //  
  //   reshape_param { shape { dim: 2  dim: 2  dim: 4 } }  
  //   reshape_param { shape { dim: 2  dim: 4 } axis:  1 }  
  //   reshape_param { shape { dim: 2  dim: 4 } axis: -3 }  
  //  
  // num_axes specifies the extent of the reshape.  
  // If num_axes >= 0 (and axis >= 0), the reshape will be performed only on  
  // input axes in the range [axis, axis+num_axes].  
  // num_axes may also be -1, the default, to include all remaining axes  
  // (starting from axis).  
  //  
  // For example, suppose "input" is a 2D blob with shape 2 x 8.  
  // Then the following ReshapeLayer specifications are equivalent,  
  // producing a blob "output" with shape 1 x 2 x 8.  
  //  
  //   reshape_param { shape { dim:  1  dim: 2  dim:  8 } }  
  //   reshape_param { shape { dim:  1  dim: 2  }  num_axes: 1 }  
  //   reshape_param { shape { dim:  1  }  num_axes: 0 }  
  //  
  // On the other hand, these would produce output blob shape 2 x 1 x 8:  
  //  
  //   reshape_param { shape { dim: 2  dim: 1  dim: 8  }  }  
  //   reshape_param { shape { dim: 1 }  axis: 1  num_axes: 0 }  
  //  
  optional int32 axis = 2 [default = 0];  
  optional int32 num_axes = 3 [default = -1];  
}  

// ROIPoolingLayer参数  
message ROIPoolingParameter {  
  // Pad, kernel size, and stride are all given as a single value for equal  
  // dimensions in height and width or as Y, X pairs.  
  optional uint32 pooled_h = 1 [default = 0]; // The pooled output height  
  optional uint32 pooled_w = 2 [default = 0]; // The pooled output width  
  // Multiplicative spatial scale factor to translate ROI coords from their  
  // input scale to the scale used when pooling  
  optional float spatial_scale = 3 [default = 1];  
}  
//ScaleParameter参数  
message ScaleParameter {  
  // The first axis of bottom[0] (the first input Blob) along which to apply  
  // bottom[1] (the second input Blob).  May be negative to index from the end  
  // (e.g., -1 for the last axis).  
  // ？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？  
  // 第一个输入Blob的首axis，被应用到第二个输入Blob。但第2个Blob的形状可能不同  
  // For example, if bottom[0] is 4D with shape 100x3x40x60, the output  
  // top[0] will have the same shape, and bottom[1] may have any of the  
  // following shapes (for the given value of axis):  
  //    (axis == 0 == -4) 100; 100x3; 100x3x40; 100x3x40x60  
  //    (axis == 1 == -3)          3;     3x40;     3x40x60  
  //    (axis == 2 == -2)                   40;       40x60  
  //    (axis == 3 == -1)                                60  
  // Furthermore,bottom[1]may have the empty shape (regardless of the value of  
  // "axis") -- a scalar multiplier.  
  optional int32 axis = 1 [default = 1];  

  // (num_axes is ignored unless just one bottom is given and the scale is  
  // a learned parameter of the layer.  Otherwise, num_axes is determined by the  
  // number of axes by the second bottom.)  
  // The number of axes of the input (bottom[0]) covered by the scale  
  // parameter, or -1 to cover all axes of bottom[0] starting from `axis`.  
  // Set num_axes := 0, to multiply with a zero-axis Blob: a scalar.  
  optional int32 num_axes = 2 [default = 1];  

  // (filler is ignored unless just one bottom is given and the scale is  
  // a learned parameter of the layer.)  
  // The initialization for the learned scale parameter.  
  // Default is the unit (1) initialization, resulting in the ScaleLayer  
  // initially performing the identity operation.  
  optional FillerParameter filler = 3;  

  // Whether to also learn a bias (equivalent to a ScaleLayer+BiasLayer, but  
  // may be more efficient).  Initialized with bias_filler (defaults to 0).  
  optional bool bias_term = 4 [default = false];  
  optional FillerParameter bias_filler = 5;  
}  
//SigmoidParameter参数  
message SigmoidParameter {  
  enum Engine {  
    DEFAULT = 0;  
    CAFFE = 1;  
    CUDNN = 2;  
  }  
  optional Engine engine = 1 [default = DEFAULT];  
}  
//SliceParameter参数  
message SliceParameter {  
  // The axis along which to slice -- may be negative to index from the end  
  // (e.g., -1 for the last axis).  
  // By default, SliceLayer concatenates blobs along the "channels" axis (1).  
  optional int32 axis = 3 [default = 1];  
  repeated uint32 slice_point = 2;  

  // DEPRECATED: alias for "axis" -- does not support negative indexing.  
  optional uint32 slice_dim = 1 [default = 1];  
}  
//SmoothL1LossParameter参数  
message SmoothL1LossParameter {  
  // SmoothL1Loss(x) =  
  //   0.5 * (sigma * x) ** 2    -- if x < 1.0 / sigma / sigma  
  //   |x| - 0.5 / sigma / sigma -- otherwise  
  optional float sigma = 1 [default = 1];  
}  

//SoftmaxLayer, SoftmaxWithLossLayer的参数  
message SoftmaxParameter {  
  enum Engine {  
    DEFAULT = 0;  
    CAFFE = 1;  
    CUDNN = 2;  
  }  
  optional Engine engine = 1 [default = DEFAULT];  

  // The axis along which to perform the softmax -- may be negative to index  
  // from the end (e.g., -1 for the last axis).  
  // Any other axes will be evaluated as independent softmaxes.  
  // 沿着哪一个轴运用softmax，该轴上必须是相互独立的分量。  
  // eg.预测时对类标签运用，计算损失时对每个类的对数损失运用。  
  optional int32 axis = 2 [default = 1];  
}  
//TanHParameter参数  
message TanHParameter {  
  enum Engine {  
    DEFAULT = 0;  
    CAFFE = 1;  
    CUDNN = 2;  
  }  
  optional Engine engine = 1 [default = DEFAULT];  
}  

// TileLayer参数  
message TileParameter {  
  // The index of the axis to tile.  
  optional int32 axis = 1 [default = 1];  

  // The number of copies (tiles) of the blob to output.  
  optional int32 tiles = 2;  
}  

// ThresholdLayer参数  
message ThresholdParameter {  
  optional float threshold = 1 [default = 0]; // Strictly positive values  
}  

// MILLayer参数  
message MILParameter {  
  enum MILType {  
    MAX = 0;  
    NOR = 1;  
  }  
  optional MILType type = 1 [default = MAX]; // The MIL method  
}  

//窗口数据参数：专用于目标检测或分割  
message WindowDataParameter {  
  // Specify the data source.指定数据源  
  optional string source = 1;  
  // 数据预处理：尺度缩放，去均值等。去均值应在缩放前执行。  
  optional float scale = 2 [default = 1];  
  optional string mean_file = 3;  
  // 指定批处理的数据量  
  optional uint32 batch_size = 4;  
  // 是否随机裁剪  
  optional uint32 crop_size = 5 [default = 0];  
  // 是否镜像变换  
  optional bool mirror = 6 [default = false];  
  // Foreground (object) overlap threshold 前景目标重合阈值  
  optional float fg_threshold = 7 [default = 0.5];  
  // Background (non-object) overlap threshold背景重合阈值  
  optional float bg_threshold = 8 [default = 0.5];  
  // Fraction of batch that should be foreground objects  
  // 前景目标在batch中的比例  
  optional float fg_fraction = 9 [default = 0.25];  
  // Amount of contextual padding to add around a window  
  // (used only by the window_data_layer)  
  // 窗口周边需要添加的上下文padding  
  optional uint32 context_pad = 10 [default = 0];  
  // Mode for cropping out a detection window  
  // warp: cropped window is warped to a fixed size and aspect ratio  
  // square: the tightest square around the window is cropped  
  // mode:裁剪出一个检测窗口的模式  
  // warp:裁剪窗口被扭曲为某个固定尺寸和形状  
  // square:裁剪窗口周边最紧？的方框  
  optional string crop_mode = 11 [default = "warp"];  
  // cache_images: will load all images in memory for faster access  
  //将全部图像(裁剪得到的小图像)放入内存以便快速存取  
  optional bool cache_images = 12 [default = false];  
  // append root_folder to locate images  
  // 添加根文件夹以定位文件  
  optional string root_folder = 13 [default = ""];  
}  
//MILDataParameter参数  
message MILDataParameter {  
  // Specify the data source.  
  optional string source = 1;  

  // Number of scales for each image  
  optional uint32 num_scales = 2 [default = 1];  

  // Side length ratio between neighbouring scales  
  optional float scale_factor = 6 [default = 1];  

  // Number of channels in the image  
  optional uint32 channels = 4 [default = 3];  

  // Specify the number of images per batch  
  optional uint32 images_per_batch = 3;  
  // Specify the number of classes  
  optional uint32 n_classes = 5;  
  // specify the box_dir and label_dir  
  optional string label_file = 7;  

  // Root directory which contains all the images  
  optional string root_dir = 11;  
  // Extention for the file  
  optional string ext = 12;  

  // To randomize or not  
  optional bool randomize = 13 [default = true];  
}  

//SPP参数,源于论文SPPNet  
message SPPParameter {  
  enum PoolMethod {  
    MAX = 0;  
    AVE = 1;  
    STOCHASTIC = 2;  
  } //池化方法，获得金字塔的方法，最大/平均/随机  
  optional uint32 pyramid_height = 1; //金字塔高度  
  optional PoolMethod pool = 2 [default = MAX]; // The pooling method  
  enum Engine {  
    DEFAULT = 0;  
    CAFFE = 1;  
    CUDNN = 2;  
  }  
  optional Engine engine = 6 [default = DEFAULT];  
}  

// DEPRECATED: use LayerParameter.  
// 旧版：使用层参数。 V1可能是第一版version1的意思  
message V1LayerParameter {  
  repeated string bottom = 2;  //输入  
  repeated string top = 3;     //输出  
  optional string name = 4;    //层名称  
  repeated NetStateRule include = 32; //运行时状态：包含  
  repeated NetStateRule exclude = 33; //运行时状态：不包含  
  enum LayerType {             //层类型  
    NONE = 0;  
    ABSVAL = 35;  
    ACCURACY = 1;  
    ARGMAX = 30;  
    BNLL = 2;  
    CONCAT = 3;  
    CONTRASTIVE_LOSS = 37;  
    CONVOLUTION = 4;  
    DATA = 5;  
    DECONVOLUTION = 39;  
    DROPOUT = 6;  
    DUMMY_DATA = 32;  
    EUCLIDEAN_LOSS = 7;  
    ELTWISE = 25;  
    EXP = 38;  
    FLATTEN = 8;  
    HDF5_DATA = 9;  
    HDF5_OUTPUT = 10;  
    HINGE_LOSS = 28;  
    IM2COL = 11;  
    IMAGE_DATA = 12;  
    INFOGAIN_LOSS = 13;  
    INNER_PRODUCT = 14;  
    LRN = 15;  
    MEMORY_DATA = 29;  
    MULTINOMIAL_LOGISTIC_LOSS = 16;  
    MVN = 34;  
    POOLING = 17;  
    POWER = 26;  
    RELU = 18;  
    SIGMOID = 19;  
    SIGMOID_CROSS_ENTROPY_LOSS = 27;  
    SILENCE = 36;  
    SOFTMAX = 20;  
    SOFTMAX_LOSS = 21;  
    SPLIT = 22;  
    SLICE = 33;  
    TANH = 23;  
    WINDOW_DATA = 24;  
    THRESHOLD = 31;  
  }  
  optional LayerType type = 5;  
  repeated BlobProto blobs = 6;  
  repeated string param = 1001;  
  repeated DimCheckMode blob_share_mode = 1002;  
  enum DimCheckMode {  
    STRICT = 0;  
    PERMISSIVE = 1;  
  }  
  repeated float blobs_lr = 7;  
  repeated float weight_decay = 8;  
  repeated float loss_weight = 35;  
  optional AccuracyParameter accuracy_param = 27;  
  optional ArgMaxParameter argmax_param = 23;  
  optional ConcatParameter concat_param = 9;  
  optional ContrastiveLossParameter contrastive_loss_param = 40;  
  optional ConvolutionParameter convolution_param = 10;  
  optional DataParameter data_param = 11;  
  optional DropoutParameter dropout_param = 12;  
  optional DummyDataParameter dummy_data_param = 26;  
  optional EltwiseParameter eltwise_param = 24;  
  optional ExpParameter exp_param = 41;  
  optional HDF5DataParameter hdf5_data_param = 13;  
  optional HDF5OutputParameter hdf5_output_param = 14;  
  optional HingeLossParameter hinge_loss_param = 29;  
  optional ImageDataParameter image_data_param = 15;  
  optional InfogainLossParameter infogain_loss_param = 16;  
  optional InnerProductParameter inner_product_param = 17;  
  optional LRNParameter lrn_param = 18;  
  optional MemoryDataParameter memory_data_param = 22;  
  optional MVNParameter mvn_param = 34;  
  optional PoolingParameter pooling_param = 19;  
  optional PowerParameter power_param = 21;  
  optional ReLUParameter relu_param = 30;  
  optional SigmoidParameter sigmoid_param = 38;  
  optional SoftmaxParameter softmax_param = 39;  
  optional SliceParameter slice_param = 31;  
  optional TanHParameter tanh_param = 37;  
  optional ThresholdParameter threshold_param = 25;  
  optional WindowDataParameter window_data_param = 20;  
  optional TransformationParameter transform_param = 36;  
  optional LossParameter loss_param = 42;  
  optional V0LayerParameter layer = 1;  
}  

// DEPRECATED: V0LayerParameter is the old way of specifying layer parameters  
// in Caffe.  We keep this message type around for legacy support.  
// 旧版本：V0LayerParameter version-0版  
message V0LayerParameter {  
  optional string name = 1; // the layer name  
  optional string type = 2; // the string to specify the layer type  

  // Parameters to specify layers with inner products.  
  optional uint32 num_output = 3; // The number of outputs for the layer  
  optional bool biasterm = 4 [default = true]; // whether to have bias terms  
  optional FillerParameter weight_filler = 5; // The filler for the weight  
  optional FillerParameter bias_filler = 6; // The filler for the bias  

  optional uint32 pad = 7 [default = 0]; // The padding size  
  optional uint32 kernelsize = 8; // The kernel size  
  optional uint32 group = 9 [default = 1]; // The group size for group conv  
  optional uint32 stride = 10 [default = 1]; // The stride  
  enum PoolMethod {  
    MAX = 0;  
    AVE = 1;  
    STOCHASTIC = 2;  
  }  
  optional PoolMethod pool = 11 [default = MAX]; // The pooling method  
  optional float dropout_ratio = 12 [default = 0.5]; // dropout ratio  

  optional uint32 local_size = 13 [default = 5]; // for local response norm  
  optional float alpha = 14 [default = 1.]; // for local response norm  
  optional float beta = 15 [default = 0.75]; // for local response norm  
  optional float k = 22 [default = 1.];  

  // For data layers, specify the data source  
  optional string source = 16;  
  // For data pre-processing, we can do simple scaling and subtracting the  
  // data mean, if provided. Note that the mean subtraction is always carried  
  // out before scaling.  
  optional float scale = 17 [default = 1];  
  optional string meanfile = 18;  
  // For data layers, specify the batch size.  
  optional uint32 batchsize = 19;  
  // For data layers, specify if we would like to randomly crop an image.  
  optional uint32 cropsize = 20 [default = 0];  
  // For data layers, specify if we want to randomly mirror data.  
  optional bool mirror = 21 [default = false];  

  // The blobs containing the numeric parameters of the layer  
  repeated BlobProto blobs = 50;  
  // The ratio that is multiplied on the global learning rate. If you want to  
  // set the learning ratio for one blob, you need to set it for all blobs.  
  repeated float blobs_lr = 51;  
  // The weight decay that is multiplied on the global weight decay.  
  repeated float weight_decay = 52;  

  // 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 = 53 [default = 0];  

  // Fields related to detection (det_*)  
  // foreground (object) overlap threshold  
  optional float det_fg_threshold = 54 [default = 0.5];  
  // background (non-object) overlap threshold  
  optional float det_bg_threshold = 55 [default = 0.5];  
  // Fraction of batch that should be foreground objects  
  optional float det_fg_fraction = 56 [default = 0.25];  

  // optional bool OBSOLETE_can_clobber = 57 [default = true];  

  // Amount of contextual padding to add around a window  
  // (used only by the window_data_layer)  
  optional uint32 det_context_pad = 58 [default = 0];  

  // Mode for cropping out a detection window  
  // warp: cropped window is warped to a fixed size and aspect ratio  
  // square: the tightest square around the window is cropped  
  optional string det_crop_mode = 59 [default = "warp"];  

  // For ReshapeLayer, one needs to specify the new dimensions.  
  optional int32 new_num = 60 [default = 0];  
  optional int32 new_channels = 61 [default = 0];  
  optional int32 new_height = 62 [default = 0];  
  optional int32 new_width = 63 [default = 0];  

  // Whether or not ImageLayer should shuffle the list of files at every epoch.  
  // It will also resize images if new_height or new_width are not zero.  
  optional bool shuffle_images = 64 [default = false];  

  // For ConcatLayer, one needs to specify the dimension for concatenation, and  
  // the other dimensions must be the same for all the bottom blobs.  
  // By default it will concatenate blobs along the channels dimension.  
  optional uint32 concat_dim = 65 [default = 1];  

  optional HDF5OutputParameter hdf5_output_param = 1001;  
}  
//PReLUParameter,源于论文  
message PReLUParameter {  
  // Parametric ReLU described in K. He et al, Delving Deep into Rectifiers:  
  // Surpassing Human-Level Performance on ImageNet Classification, 2015.  

  // Initial value of a_i. Default is a_i=0.25 for all i.  
  optional FillerParameter filler = 1;  
  // Whether or not slope paramters are shared across channels.  
  optional bool channel_shared = 2 [default = false];  
}