#include "opencv2/opencv.hpp"

 #include<iostream>

 using namespace cv;

 using namespace std;

 void main()

 {

     Mat img = imread("E://0.jpg", );  //以灰度方式打开，灰度图和彩色图直方图结果不同

     imshow("src", img);

     Mat dstHist;  //定义存储直方图变量

     int dims = ;  //需要统计的特征数目(只统计灰度值)

     float hranges[] = {, };  //范围[0,256),注意是最大值加1

     const float* ranges[] = {hranges};

     int bins = ;//组距：简单理解为直方图分为几个柱子

     int channels = ;

     //计算直方图

     calcHist(&img, , &channels, Mat(), dstHist, dims, &bins, ranges);

     int scale = ;

     Mat dstImg(bins * scale, bins*, CV_8UC3, Scalar());  //定义直方图输出图像,长×宽

     double minValue = ;

     double maxValue = ;

     minMaxLoc(dstHist, &minValue, &maxValue);//统计直方图dstHist的最小最大值,并返回该值位置

     int hpt = saturate_cast<int>(0.9*bins);  //设置最大值并防止溢出

     int j=;

     //绘制直方图

     for(int i=; i<; i++)

     {

         float binValue = dstHist.at<float>(i);

         //if(i>250)

             cout<<"i="<<i<<"---Value="<<binValue<<endl;

         int realValue = saturate_cast<int>(binValue*hpt/maxValue);  //归一化数据

             //cout<<"i="<<i<<"---Value="<<realValue<<endl;

         line(dstImg, Point(i*scale, bins-), Point(i*scale, bins-realValue), Scalar(, , ), , );//左上角和右下角坐标，坐标系如下图所示

         //rectangle(dstImg, Point(i*scale, bins-1), Point(i*scale+1, bins-realValue), Scalar(0, 255, 0), 1);

         //rectangle(dstImg, Point(j*scale, bins-1), Point(j*scale+1, bins-realValue), Scalar(rand()%255, rand()%255, rand()%255), -1);

         //rectangle(dstImg, Point(j*scale, bins-1), Point(j*scale+1, bins-realValue), Scalar(rand()%255, rand()%255, rand()%255), -1);

         //j=j+3;

     }

     imshow("Histogram", dstImg);

     waitKey();

     destroyAllWindows();

 }

 #include "opencv2/opencv.hpp"

 #include<iostream>

 using namespace cv;

 using namespace std;

 void main()

 {

     Mat img = imread("E://0.jpg",);

     imshow("src", img);

     Mat dstHist;

     int channels = ;

     int histSize[]={};

     float hranges[]={,,,,,};

     const float* ranges[]={hranges};

     int size=;

     //计算直方图

     calcHist(&img,,&channels,Mat(),dstHist,,histSize,ranges,false);

     int scale=;

     Mat dstImg(size*scale,size,CV_8UC3,Scalar());

     double minValue=;

     double maxValue=;

     minMaxLoc(dstHist,&minValue,&maxValue,,);

     int hpt=saturate_cast<int>(0.9*size);//设置最大值并防止溢出

     int j=;

     for (int i = ; i < ; i++)

     {

         float binValue=dstHist.at<float>(i);

         cout<<"i="<<i<<"---Value="<<binValue<<endl;

         int realValue=saturate_cast<int>(binValue*hpt/maxValue);

         rectangle(dstImg,Point(j*scale,size-),Point((j+)*scale-,size-realValue),Scalar(, , ), -);

         j+=;

     }

     imshow("Histogram", dstImg);

     waitKey();

     destroyAllWindows();

 }

 #include "opencv2/opencv.hpp"

 using namespace cv;

 void main()

 {

     Mat src=imread("E://0.jpg");

     int bins = ;

     int hist_size[] = {bins};

     float range[] = { ,  };

     const float* ranges[] = { range};

     Mat hist_r,hist_g,hist_b;

     int channels_r[] = {};

     calcHist( &src, , channels_r, Mat(), // do not use mask

         hist_r, , hist_size, ranges,

         true, // the histogram is uniform

         false );

     int channels_g[] = {};

     calcHist( &src, , channels_g, Mat(),hist_g, , hist_size, ranges,true,false);

     int channels_b[] = {};

     calcHist( &src, , channels_b, Mat(),hist_b, , hist_size, ranges,true,false);

     double max_val_r,max_val_g,max_val_b;

     minMaxLoc(hist_r, , &max_val_r, , );

     minMaxLoc(hist_g, , &max_val_g, , );

     minMaxLoc(hist_b, , &max_val_b, , );

     int scale = ;

     int hist_height=;

     Mat hist_img = Mat::zeros(hist_height, bins*+, CV_8UC3);

     for(int i=;i<bins;i++)

     {

         float bin_val_r = hist_r.at<float>(i);

         float bin_val_g = hist_g.at<float>(i);

         float bin_val_b = hist_b.at<float>(i);

         int intensity_r = cvRound(bin_val_r*hist_height/max_val_r);  //要绘制的高度

         int intensity_g = cvRound(bin_val_g*hist_height/max_val_g);  //要绘制的高度

         int intensity_b = cvRound(bin_val_b*hist_height/max_val_b);  //要绘制的高度

         rectangle(hist_img,Point(i*scale,hist_height-),

             Point((i+)*scale - , hist_height - intensity_r),

             CV_RGB(,,));

         rectangle(hist_img,Point((i+bins)*scale,hist_height-),

             Point((i+bins+)*scale - , hist_height - intensity_g),

             CV_RGB(,,));

         rectangle(hist_img,Point((i+bins*)*scale,hist_height-),

             Point((i+bins*+)*scale - , hist_height - intensity_b),

             CV_RGB(,,));

     }

     imshow( "src", src );

     imshow( "RGB Histogram", hist_img );

     waitKey();

     destroyAllWindows();

 }

 #include "opencv2/opencv.hpp"

 using namespace cv;

 void main()

 {

     Mat src=imread("E://0.jpg");

     Mat hsv;

     int Bbins = , Gbins = ;

     int histSize[] = {Bbins, Gbins};

     float hranges[] = { ,  };

     float sranges[] = { ,  };

     const float* ranges[] = { hranges, sranges };

     Mat hist;

     int channels[] = {, };

     calcHist( &src, , channels, Mat(), hist, , histSize, ranges);

     double maxVal=;

     minMaxLoc(hist, , &maxVal, , );

     int scale = ;

     Mat histImg = Mat::zeros(Bbins*(scale), Bbins*(scale), CV_8UC3);

     for( int h = ; h < Bbins; h++ )

         for( int s = ; s < Bbins; s++ )

         {

             float binVal = hist.at<float>(h, s);

             //cout<<"h="<<h<<"s="<<s<<"binValue="<<binVal<<endl;

             //int intensity = cvRound(binVal*255/maxVal);

             int intensity = int(binVal*/maxVal);

             rectangle( histImg, Point(h*scale, s*scale),

                 Point((h+)*scale - , (s+)*scale - ),

                 Scalar::all(intensity),CV_FILLED );

         }

     namedWindow( "Source",  );

     imshow( "Source", src );

     namedWindow( "B-G Histogram",  );

     imshow( "B-G Histogram", histImg );

     waitKey();

     destroyAllWindows();

 }