VS+Opencv3.3下用HOG+SVM实现INRIA行人检测

利用SVM训练一个分类器，用训练好的分类器对测试集里的数据进行检测。

这里是数据下载地址：INRIA行人数据集

点击页面下方的蓝色here即可下载。

下载完成之后，解压缩（为方便操作，建议放于项目目录下或者是根目录下，我这里是放在了D盘下面），进入文件夹，打开Train，有neg负样本，pos正样本。负样本的尺寸是437X292的，所以需要先处理一下，才能够进行训练。下面是处理代码（这里默认你已经配置好了opencv环境）。

#include <iostream>  #include <fstream>  #include <stdlib.h> //srand()和rand()函数  #include <time.h> //time()函数  #include <opencv2/core/core.hpp>  #include <opencv2/highgui/highgui.hpp>  #include <opencv2/imgproc/imgproc.hpp>  #include <opencv2/objdetect/objdetect.hpp>  #include <opencv2/ml/ml.hpp>    using namespace std;  using namespace cv;    int CropImageCount = 0; //裁剪出来的负样本图片个数    int main()  {      Mat src;      string ImgName;        char saveName[256];//裁剪出来的负样本图片文件名      ifstream fin("D:/INRIAPerson/Train/neg.lst");//打开原始负样本图片文件列表        //一行一行读取文件列表      while(getline(fin,ImgName))      {          cout<<"处理："<<ImgName<<endl;          ImgName = "D:/INRIAPerson" + ImgName;                src = imread(ImgName,1);//读取图片          //cout<<"宽："<<src.cols<<"，高："<<src.rows<<endl;                //图片大小应该能能至少包含一个64*128的窗口          if(src.cols >= 64 && src.rows >= 128)          {              srand(time(NULL));//设置随机数种子  time(NULL)表示当前系统时间              //从每张图片中随机采样10个64*128大小的不包含人的负样本              for(int i=0; i<10; i++)              {                  int x = ( rand() % (src.cols-64) ); //左上角x坐标                  int y = ( rand() % (src.rows-128) ); //左上角y坐标                  //cout<<x<<","<<y<<endl;                  Mat imgROI = src(Rect(x,y,64,128));                   sprintf(saveName,"D:/INRIAPerson/negphoto/noperson%06d.jpg",++CropImageCount);//生成裁剪出的负样本图片的文件名                  imwrite(saveName, imgROI);//保存文件              }          }      }        system("pause");  }  

大概经过几十秒就能生成12000多张负样本的图片了。

接下来就是训练分类器以及对测试样本进行测试了。

#include "opencv2/core/core.hpp"  #include "opencv2/objdetect.hpp"#include "opencv2/core/cuda.hpp"#include "opencv2/highgui/highgui.hpp"  #include "opencv2/imgproc/imgproc.hpp"  #include "opencv2/video/video.hpp"  #include "opencv2/ml.hpp"#include "opencv2/opencv.hpp"#include <opencv2/objdetect/objdetect.hpp>  #include <opencv2/imgcodecs.hpp>#include <stdlib.h>#include <time.h>#include <algorithm>#include <math.h>#include <iostream>  #include <vector>#include <fstream>#include <cstdlib>using namespace std;using namespace cv;using namespace cv::ml;//函数声明void get_svm_detector(const Ptr< SVM > & svm, vector< float > & hog_detector);void convert_to_ml(const std::vector< Mat > & train_samples, Mat& trainData);void load_images(const String & dirname, vector< Mat > & img_lst, bool showImages);void sample_neg(const vector< Mat > & full_neg_lst, vector< Mat > & neg_lst, const Size & size);void computeHOGs(const Size wsize, const vector< Mat > & img_lst, vector< Mat > & gradient_lst);int test_trained_detector(String obj_det_filename, String test_dir, String videofilename);//函数定义void get_svm_detector(const Ptr< SVM >& svm, vector< float > & hog_detector){// get the support vectorsMat sv = svm->getSupportVectors();const int sv_total = sv.rows;// get the decision functionMat alpha, svidx;double rho = svm->getDecisionFunction(0, alpha, svidx);CV_Assert(alpha.total() == 1 && svidx.total() == 1 && sv_total == 1);//括号中的条件不满足时，返回错误CV_Assert((alpha.type() == CV_64F && alpha.at<double>(0) == 1.) ||(alpha.type() == CV_32F && alpha.at<float>(0) == 1.f));CV_Assert(sv.type() == CV_32F);hog_detector.clear();hog_detector.resize(sv.cols + 1);memcpy(&hog_detector[0], sv.ptr(), sv.cols * sizeof(hog_detector[0]));//memcpy指的是c和c++使用的内存拷贝函数，memcpy函数的功能是从源src所指的内存地址的起始位置开始拷贝n个字节到目标dest所指的内存地址的起始位置中。hog_detector[sv.cols] = (float)-rho;}/** Convert training/testing set to be used by OpenCV Machine Learning algorithms.* TrainData is a matrix of size (#samples x max(#cols,#rows) per samples), in 32FC1.* Transposition of samples are made if needed.*/void convert_to_ml(const vector< Mat > & train_samples, Mat& trainData){//--Convert dataconst int rows = (int)train_samples.size();//行数等于训练样本个数const int cols = (int)std::max(train_samples[0].cols, train_samples[0].rows);//列数取样本图片中宽度与高度中较大的那一个Mat tmp(1, cols, CV_32FC1); //< used for transposition if neededtrainData = Mat(rows, cols, CV_32FC1);for (size_t i = 0; i < train_samples.size(); ++i){CV_Assert(train_samples[i].cols == 1 || train_samples[i].rows == 1);if (train_samples[i].cols == 1){transpose(train_samples[i], tmp);tmp.copyTo(trainData.row((int)i));}else if (train_samples[i].rows == 1){train_samples[i].copyTo(trainData.row((int)i));}}}void load_images(const String & dirname, vector< Mat > & img_lst, bool showImages = false){//载入目录下的图片样本vector< String > files;glob(dirname, files);//返回一个包含有匹配文件/目录的数组。出错则返回falsefor (size_t i = 0; i < files.size(); ++i){Mat img = imread(files[i]); // load the imageif (img.empty())            // invalid image, skip it.{cout << files[i] << " is invalid!" << endl;continue;}if (showImages){imshow("image", img);waitKey(1);}img_lst.push_back(img);//将Img压入img_lst}}void sample_neg(const vector< Mat > & full_neg_lst, vector< Mat > & neg_lst, const Size & size){//该函数对每一个负样本采样出一个随机的64*128尺寸的样本，由于之前已经采样过了，所以main函数中没有使用该函数Rect box;box.width = size.width;//等于检测器宽度box.height = size.height;//等于检测器高度const int size_x = box.width;const int size_y = box.height;srand((unsigned int)time(NULL));//生成随机数种子for (size_t i = 0; i < full_neg_lst.size(); i++){//对每个负样本进行裁剪，随机指定x,y,裁剪一个尺寸为检测器大小的负样本box.x = rand() % (full_neg_lst[i].cols - size_x);box.y = rand() % (full_neg_lst[i].rows - size_y);Mat roi = full_neg_lst[i](box);neg_lst.push_back(roi.clone());}}void computeHOGs(const Size wsize, const vector< Mat > & img_lst, vector< Mat > & gradient_lst){//计算HOG特征HOGDescriptor hog;hog.winSize = wsize;Rect r = Rect(0, 0, wsize.width, wsize.height);r.x += (img_lst[0].cols - r.width) / 2;//正样本图片的尺寸减去检测器的尺寸，再除以2r.y += (img_lst[0].rows - r.height) / 2;Mat gray;vector< float > descriptors;for (size_t i = 0; i< img_lst.size(); i++){cvtColor(img_lst[i](r), gray, COLOR_BGR2GRAY);hog.compute(gray, descriptors, Size(8, 8), Size(0, 0));//Size(8,8)为窗口移动步长，gradient_lst.push_back(Mat(descriptors).clone());}}int test_trained_detector(String obj_det_filename, String test_dir, String videofilename){//当videofilename为空，则只检测图片中的行人cout << "Testing trained detector..." << endl;HOGDescriptor hog;hog.load(obj_det_filename);vector< String > files;glob(test_dir, files);int delay = 0;VideoCapture cap;if (videofilename != ""){cap.open(videofilename);}obj_det_filename = "testing " + obj_det_filename;namedWindow(obj_det_filename, WINDOW_NORMAL);for (size_t i = 0;; i++){Mat img;if (cap.isOpened()){cap >> img;delay = 1;}else if (i < files.size()){img = imread(files[i]);}if (img.empty()){return 0;}vector< Rect > detections;vector< double > foundWeights;hog.detectMultiScale(img, detections, foundWeights);for (size_t j = 0; j < detections.size(); j++){if (foundWeights[j] < 0.5) continue;//清楚权值较小的检测窗口Scalar color = Scalar(0, foundWeights[j] * foundWeights[j] * 200, 0);rectangle(img, detections[j], color, img.cols / 400 + 1);}imshow(obj_det_filename, img);if (27 == waitKey(delay)){return 0;}}return 0;}int main(int argc, char** argv){const char* keys ={"{help h|     | show help message}""{pd    |  D:/INRIAPerson/96X160H96/Train/pos   | path of directory contains possitive images}""{nd    |  D:/INRIAPerson/negphoto   | path of directory contains negative images}""{td    |  D:/INRIAPerson/Test/pos   | path of directory contains test images}""{tv    |     | test video file name}""{dw    |  64   | width of the detector}""{dh    |  128   | height of the detector}""{d     |false| train twice}""{t     |true| test a trained detector}""{v     |false| visualize training steps}""{fn    |D:/my_detector.yml| file name of trained SVM}"};CommandLineParser parser(argc, argv, keys);//命令行函数，读取keys中的字符， 其中key的格式为:名字 简称| 内容 |提示字符。if (parser.has("help")){parser.printMessage();exit(0);}String pos_dir = parser.get< String >("pd");//正样本目录String neg_dir = parser.get< String >("nd");//负样本目录String test_dir = parser.get< String >("td");//测试样本目录String obj_det_filename = parser.get< String >("fn");//训练好的SVM检测器文件名String videofilename = parser.get< String >("tv");//测试视频int detector_width = parser.get< int >("dw");//检测器宽度int detector_height = parser.get< int >("dh");//检测器高度bool test_detector = parser.get< bool >("t");//测试训练好的检测器bool train_twice = parser.get< bool >("d");//训练两次bool visualization = parser.get< bool >("v");//训练过程可视化（建议false，不然爆炸)if (test_detector)//若为true，测对测试集进行测试{test_trained_detector(obj_det_filename, test_dir, videofilename);exit(0);}if (pos_dir.empty() || neg_dir.empty())//检测非空{parser.printMessage();cout << "Wrong number of parameters.\n\n"<< "Example command line:\n" << argv[0] << " -pd=/INRIAPerson/96X160H96/Train/pos -nd=/INRIAPerson/neg -td=/INRIAPerson/Test/pos -fn=HOGpedestrian96x160.yml -d\n"<< "\nExample command line for testing trained detector:\n" << argv[0] << " -t -dw=96 -dh=160 -fn=HOGpedestrian96x160.yml -td=/INRIAPerson/Test/pos";exit(1);}vector< Mat > pos_lst,//正样本图片向量full_neg_lst,//负样本图片向量neg_lst,//采样后的负样本图片向量gradient_lst;//HOG描述符存入到该梯度信息里面vector< int > labels;//标签向量clog << "Positive images are being loaded...";load_images(pos_dir, pos_lst, visualization);//加载图片 pos正样本的尺寸为96*160if (pos_lst.size() > 0){clog << "...[done]" << endl;}else{clog << "no image in " << pos_dir << endl;return 1;}Size pos_image_size = pos_lst[0].size(); //令尺寸变量pos_image_size=正样本尺寸//检测所有正样本是否具有相同尺寸for (size_t i = 0; i < pos_lst.size(); ++i){if (pos_lst[i].size() != pos_image_size){cout << "All positive images should be same size!" << endl;exit(1);}}pos_image_size = pos_image_size / 8 * 8;//令pos_image_size的尺寸为检测器的尺寸if (detector_width && detector_height){pos_image_size = Size(detector_width, detector_height);}labels.assign(pos_lst.size(), +1);              //assign()为labels分配pos_lst.size()大小的容器，用+1填充 表示为正样本const unsigned int old = (unsigned int)labels.size();//旧标签大小clog << "Negative images are being loaded...";load_images(neg_dir, neg_lst, false);//加载负样本图片//sample_neg(full_neg_lst, neg_lst, pos_image_size);  clog << "...[done]" << endl;labels.insert(labels.end(), neg_lst.size(), -1);//在labels向量的尾部添加neg_lst.size()大小的容器，用-1填充 表示为负样本CV_Assert(old < labels.size());//CV_Assert()作用：CV_Assert（）若括号中的表达式值为false，则返回一个错误信息。clog << "Histogram of Gradients are being calculated for positive images...";computeHOGs(pos_image_size, pos_lst, gradient_lst);//计算正样本图片的HOG特征clog << "...[done]" << endl;clog << "Histogram of Gradients are being calculated for negative images...";computeHOGs(pos_image_size, neg_lst, gradient_lst);//计算负样本图片的HOG特征clog << "...[done]" << endl;Mat train_data;convert_to_ml(gradient_lst, train_data);//转化为ml所需的训练数据形式clog << "Training SVM...";Ptr< SVM > svm = SVM::create();/* Default values to train SVM */svm->setCoef0(0.0);svm->setDegree(3);svm->setTermCriteria(TermCriteria(CV_TERMCRIT_ITER + CV_TERMCRIT_EPS, 1000, 1e-3));svm->setGamma(0);svm->setKernel(SVM::LINEAR);//采用线性核函，其他的sigmoid 和RBF 可自行设置，其值由0-5。svm->setNu(0.5);svm->setP(0.1); // for EPSILON_SVR, epsilon in loss function?svm->setC(0.01); // From paper, soft classifiersvm->setType(SVM::EPS_SVR); // C_SVC; // EPSILON_SVR; // may be also NU_SVR; // do regression tasksvm->train(train_data, ROW_SAMPLE, Mat(labels));clog << "...[done]" << endl;//训练两次if (train_twice){clog << "Testing trained detector on negative images. This may take a few minutes...";HOGDescriptor my_hog;my_hog.winSize = pos_image_size;// Set the trained svm to my_hogvector< float > hog_detector;get_svm_detector(svm, hog_detector);my_hog.setSVMDetector(hog_detector);vector< Rect > detections;vector< double > foundWeights;for (size_t i = 0; i < full_neg_lst.size(); i++){my_hog.detectMultiScale(full_neg_lst[i], detections, foundWeights);for (size_t j = 0; j < detections.size(); j++){Mat detection = full_neg_lst[i](detections[j]).clone();resize(detection, detection, pos_image_size);neg_lst.push_back(detection);}if (visualization){for (size_t j = 0; j < detections.size(); j++){rectangle(full_neg_lst[i], detections[j], Scalar(0, 255, 0), 2);}imshow("testing trained detector on negative images", full_neg_lst[i]);waitKey(5);}}clog << "...[done]" << endl;labels.clear();labels.assign(pos_lst.size(), +1);labels.insert(labels.end(), neg_lst.size(), -1);gradient_lst.clear();clog << "Histogram of Gradients are being calculated for positive images...";computeHOGs(pos_image_size, pos_lst, gradient_lst);clog << "...[done]" << endl;clog << "Histogram of Gradients are being calculated for negative images...";computeHOGs(pos_image_size, neg_lst, gradient_lst);clog << "...[done]" << endl;clog << "Training SVM again...";convert_to_ml(gradient_lst, train_data);svm->train(train_data, ROW_SAMPLE, Mat(labels));clog << "...[done]" << endl;}vector< float > hog_detector;//定义hog检测器get_svm_detector(svm, hog_detector);//得到训练好的检测器HOGDescriptor hog;hog.winSize = pos_image_size;//窗口大小hog.setSVMDetector(hog_detector);hog.save(obj_det_filename);//保存分类器test_trained_detector(obj_det_filename, test_dir, videofilename);//检测训练集return 0;}

检测效果如下。这里使用的是线性核，有兴趣的可以自己改用其他核函数以及相关参数，感兴趣的可以在评论区一起讨论。