caffe中负责整个网络输入的datalayer是从leveldb里读取数据的，是一个google实现的很高效的kv数据库。

因此我们训练网络必须先把数据转成leveldb的格式。

这里我实现的是把一个目录的全部图片转成leveldb的格式。

工具使用命令格格式：convert_imagedata src_dir dst_dir attach_dir channel width height

例子：./convert_imagedata.bin /home/linger/imdata/collar_train/ /home/linger/linger/testfile/crop_train_db/ /home/linger/linger/testfile/crop_train_attachment/ 3 50 50

源码：

#include <google/protobuf/text_format.h>
#include <glog/logging.h>
#include <leveldb/db.h>

#include <stdint.h>
#include <fstream>  // NOLINT(readability/streams)
#include <string>
#include <set>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <dirent.h>
#include <sys/stat.h>
#include <unistd.h>
#include <sys/types.h>
#include "caffe/proto/caffe.pb.h"
#include <opencv2/highgui/highgui.hpp>
#include <opencv2/highgui/highgui_c.h>
#include <opencv2/imgproc/imgproc.hpp>

using std::string;
using namespace std;


set<string> all_class_name;
map<string,int> class2id;


/**
 * path:文件夹
 * files：用于保存文件名称的vector
 * r：是否须要遍历子文件夹
 * return:文件名称，不包括路径
 */
void list_dir(const char *path,vector<string>& files,bool r = false)
{
	DIR *pDir;
	struct dirent *ent;
	char childpath[512];
	pDir = opendir(path);
	memset(childpath, 0, sizeof(childpath));
	while ((ent = readdir(pDir)) != NULL)
	{
		if (ent->d_type & DT_DIR)
		{

			if (strcmp(ent->d_name, ".") == 0 || strcmp(ent->d_name, "..") == 0)
			{
				continue;
			}
			if(r) //假设须要遍历子文件夹
			{
				sprintf(childpath, "%s/%s", path, ent->d_name);
				list_dir(childpath,files);
			}
		}
		else
		{
			files.push_back(ent->d_name);
		}
	}
	sort(files.begin(),files.end());//排序

}

string get_classname(string path)
{
	int index = path.find_last_of('_');
	return path.substr(0, index);
}


int get_labelid(string fileName)
{
	string class_name_tmp = get_classname(fileName);
	all_class_name.insert(class_name_tmp);
	map<string,int>::iterator name_iter_tmp = class2id.find(class_name_tmp);
	if (name_iter_tmp == class2id.end())
	{
		int id = class2id.size();
		class2id.insert(name_iter_tmp, std::make_pair(class_name_tmp, id));
		return id;
	}
	else
	{
		return name_iter_tmp->second;
	}
}

void loadimg(string path,char* buffer)
{
	cv::Mat img = cv::imread(path, CV_LOAD_IMAGE_COLOR);
	string val;
	int rows = img.rows;
	int cols = img.cols;
	int pos=0;
	for (int c = 0; c < 3; c++)
	{
		for (int row = 0; row < rows; row++)
		{
			for (int col = 0; col < cols; col++)
			{
				buffer[pos++]=img.at<cv::Vec3b>(row,col)[c];
			}
		}
	}

}
void convert(string imgdir,string outputdb,string attachdir,int channel,int width,int height)
{
	leveldb::DB* db;
	leveldb::Options options;
	options.create_if_missing = true;
	options.error_if_exists = true;
	caffe::Datum datum;
	datum.set_channels(channel);
	datum.set_height(height);
	datum.set_width(width);
	int image_size = channel*width*height;
	char buffer[image_size];

	string value;
	CHECK(leveldb::DB::Open(options, outputdb, &db).ok());
	vector<string> filenames;
	list_dir(imgdir.c_str(),filenames);
	string img_log = attachdir+"image_filename";
	ofstream writefile(img_log.c_str());
	for(int i=0;i<filenames.size();i++)
	{
		string path= imgdir;
		path.append(filenames[i]);//算出绝对路径

		loadimg(path,buffer);

		int labelid = get_labelid(filenames[i]);

		datum.add_label(labelid);
		datum.set_data(buffer,image_size);
		datum.SerializeToString(&value);
		snprintf(buffer, image_size, "%05d", i);
		printf("\nclassid:%d classname:%s abspath:%s",labelid,get_classname(filenames[i]).c_str(),path.c_str());
		db->Put(leveldb::WriteOptions(),string(buffer),value);
		//printf("%d %s\n",i,fileNames[i].c_str());

		assert(writefile.is_open());
		writefile<<i<<" "<<filenames[i]<<"\n";

	}
	delete db;
	writefile.close();

	img_log = attachdir+"image_classname";
	writefile.open(img_log.c_str());
	set<string>::iterator iter = all_class_name.begin();
	while(iter != all_class_name.end())
	{
		assert(writefile.is_open());
		writefile<<(*iter)<<"\n";
		//printf("%s\n",(*iter).c_str());
		iter++;
	}
	writefile.close();

}

int main(int argc, char** argv)
{
	if (argc < 6)
	{
	    LOG(ERROR) << "convert_imagedata src_dir dst_dir attach_dir channel width height";
	    return 0;
	}
//./convert_imagedata.bin  /home/linger/imdata/collarTest/ /home/linger/linger/testfile/dbtest/  /home/linger/linger/testfile/test_attachment/ 3 250 250
	//   ./convert_imagedata.bin /home/linger/imdata/collar_train/ /home/linger/linger/testfile/crop_train_db/ /home/linger/linger/testfile/crop_train_attachment/ 3 50 50
	google::InitGoogleLogging(argv[0]);
	string src_dir = argv[1];
	string src_dst = argv[2];
	string attach_dir = argv[3];
	int channel = atoi(argv[4]);
	int width = atoi(argv[5]);
	int height = atoi(argv[6]);

	//for test
	/*
	src_dir = "/home/linger/imdata/collarTest/";
	src_dst = "/home/linger/linger/testfile/dbtest/";
	attach_dir = "/home/linger/linger/testfile/";
	channel = 3;
	width = 250;
	height = 250;
	 */

	convert(src_dir,src_dst,attach_dir,channel,width,height);



}