opencv 绘制三通道的直方图

 

 

#include <opencv\cv.h>

#include <opencv\highgui.h>

#include <opencv\cxcore.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;

 

}