opencv 绘制三通道的直方图

#include <opencvcv.h>
#include <opencvhighgui.h>
#include <opencvcxcore.h>
#include <stdlib.h>
#include <stdio.h>
 

//绘制直方图
IplImage* DrawHistogram(CvHistogram* hist , float scaleX = 1 , float scaleY = 1)
{
        //获取直方图中极大值
        float histMax = 0;
 
        cvGetMinMaxHistValue(hist , 0 ,&histMax ,0 ,0);
 
        //创建图像 该图像用于显示直方图
        IplImage* imgHist = cvCreateImage(cvSize(256*scaleX , 64*scaleY) , 8 ,1);

        //图像置零
        cvZero(imgHist);
 
        //依次绘制直方图的bin
        for(int i=0;i<255;i++)
        {
                //获取直方图的值
                float histValue = cvQueryHistValue_1D(hist , i);
                float nextValue = cvQueryHistValue_1D(hist , i+1);

                //获取四边形的四个点的坐标  详情请观看视频的讲解
                CvPoint pt1 = cvPoint(      i*scaleX , 64*scaleY);
                CvPoint pt2 = cvPoint(  (i+1)*scaleX , 64*scaleY);
                CvPoint pt3 = cvPoint(  (i+1)*scaleX , (64 - (nextValue/histMax)*64) *scaleY );
                CvPoint pt4 = cvPoint (      i*scaleX , (64 - (histValue/histMax)*64) *scaleY );
 
                int numPts = 5;
                CvPoint pts[5];
 
                pts[0] = pt1;
                pts[1] = pt2;
                pts[2] = pt3;
                pts[3] = pt4;
                pts[4] = pt1;

                //填充四边形
                cvFillConvexPoly(imgHist , pts ,numPts , cvScalar(255));
        }
        return imgHist;
}
 


int main(int argc, char* argv[])
{
        //加载图像
        IplImage* src = cvLoadImage("D:\1.jpg");
 
        cvNamedWindow("sr");
        cvShowImage("sr" , src);

        int dims = 1;  // 一维直方图
        int size =256; //bin的个数 每一位的直放个数
        float range[] = {0,255}; //取值范围
        float* ranges[] = {range};

        CvHistogram* hist;
 
        //创建直方图
 
        hist = cvCreateHist(dims , &size , CV_HIST_ARRAY ,  ranges , 1 );

        //清空直方图
 
        cvClearHist(hist);
 
        //给B  G  R 三个通道的图像分配空间
 
        IplImage* imgRed = cvCreateImage(cvGetSize(src) , 8 ,1);
        IplImage* imgGreen = cvCreateImage(cvGetSize(src) , 8 ,1);
        IplImage* imgBlue = cvCreateImage(cvGetSize(src) , 8 ,1);

        //将图像src  分解成B   G   R 三个通道
		//cvSplit最后一个通道为NULL
        cvSplit(src , imgBlue , imgGreen , imgRed , NULL);
		 
        //计算B通道 直方图
 
        cvCalcHist(&imgBlue , hist , 0 , 0 );
 
        //绘制B通道直方图  结果保存在histBlue
 
        IplImage* histBlue = DrawHistogram(hist);
 
        //将B通道的直方图数据清空
 
        cvClearHist(hist);
 
        //计算G通道直方图
 
        cvCalcHist(&imgGreen , hist , 0 , 0 );
 
        //绘制G通道直方图  histGreen
 
        IplImage* histGreen = DrawHistogram(hist);
 
        //将G通道的直方图数据清空
 
        cvClearHist(hist);
 
        //计算R通道 直方图
 
        cvCalcHist(&imgRed , hist , 0 , 0 );
 
        //绘制R通道直方图  histRed
 
        IplImage* histRed = DrawHistogram(hist);
 
        //将R通道的直方图数据清空
 
        cvClearHist(hist);

        cvNamedWindow("B");
        cvNamedWindow("G");
        cvNamedWindow("R");

        cvShowImage("B"  , histBlue);
        cvShowImage("G"  , histGreen);
        cvShowImage("R"  , histRed);

        cvWaitKey(0);
 
        //释放资源

        //(1) 释放源图像
        cvReleaseImage(&src);

        //(2) 释放三个通道的图像
        cvReleaseImage(&imgRed);
        cvReleaseImage(&imgGreen);
        cvReleaseImage(&imgBlue);

        //(3)释放三个通道直方图
        cvReleaseImage(&histBlue);
        cvReleaseImage(&histGreen);
        cvReleaseImage(&histRed);

        //(4)释放直方图空间
        cvReleaseHist(&hist);

        return 0;
 
}