openCV学习笔记（四）：绘制直方图和calcHist()函数、normalize()函数的解析

openCV学习笔记（4）：绘制直方图和calcHist()函数、normalize()函数的解析

opencv版本：2.3.1

配置环境：openCV学习笔记（一）：opencv2.3.1与vs2010安装配置

#include <opencv2/highgui/highgui.hpp>
#include <opencv2/imgproc/imgproc.hpp>
#include <iostream>
#include <conio.h>

using namespace cv;
using namespace std;

int main()
{
	char *imageSrc = "I:\\OpenCV Learning\\picture\\sumpalace.jpg";

	Mat image = imread(imageSrc,1);
	/**********************************/
	//Mat grayImage = imread(imageSrc,0);
	/**********************************/
	if(!image.data)
	{
		cout<<"error"<<endl;
		return -1;
	}
	imshow("原始图像",image);

	vector<Mat> rgbPlanes;
	split(image,rgbPlanes);
	/**********************************/
	/*rgbPlanes矢量（可增长数组），通过split()函数，将image的R,G,B通道分别加入到rgbPlanes[0]、rgbPlanes[1]、rgbPlanes[2]
	/**********************************/
	//Mat *grayImage = &grayImage0;
	/**********************************/
	int histSize = 256;
	//R、G、B值范围为[0,255]
	float range[] = {0,255};
	const float *histRange = {range};
	//三个矩阵，分别保存R、G、B直方图
	Mat redHist,greenHist,blueHist;
	/**********************************/
	//Mat grayHist;
	/**********************************/
	//计算R、G、B直方图，calcHist()函数的参数解析见后面
	calcHist( &rgbPlanes[0], 1, 0, Mat(), redHist, 1, &histSize, &histRange,true,false);
	calcHist( &rgbPlanes[1], 1, 0, Mat(), greenHist, 1, &histSize, &histRange,true,false);
	calcHist( &rgbPlanes[2], 1, 0, Mat(), blueHist, 1, &histSize, &histRange,true,false);
	/**********************************/
	//calcHist(&grayImage,1,0,Mat(), grayHist, 1, &histSize, &histRange,true,false);
	/**********************************/
	//定义显示直方图的画布
	int histWidth = 400;
	int histHeight = 400;
	int binWidth = cvRound((double)histWidth/histSize);

	Mat histImage(histWidth,histHeight,CV_8UC3,Scalar(0,0,0));
	//归一化处理normalize()函数的参数解析见后面
	normalize(redHist,redHist,0,histImage.rows,NORM_MINMAX,-1,Mat());
	normalize(greenHist,greenHist,0,histImage.rows,NORM_MINMAX,-1,Mat());
	normalize(blueHist,blueHist,0,histImage.rows,NORM_MINMAX,-1,Mat());
	/**********************************/
	//normalize(grayHist,grayHist,0,histImage.rows,NORM_MINMAX,-1,Mat());
	/**********************************/
	//画直方图
	for( int i = 1; i < histSize; i++ )
   {
     line( histImage, Point( binWidth*(i-1), histHeight - cvRound(redHist.at<float>(i-1)) ) ,
                      Point( binWidth*(i), histHeight - cvRound(redHist.at<float>(i)) ),
                      Scalar( 0, 0, 255), 2, 8, 0  );
	// rectangle(histImage,Point( binWidth*(i-1), histHeight),
    //                  Point( binWidth*(i-1), histHeight - cvRound(redHist.at<float>(i))), Scalar(0,0,255), CV_FILLED);
     line( histImage, Point( binWidth*(i-1), histHeight - cvRound(greenHist.at<float>(i-1)) ) ,
                      Point( binWidth*(i), histHeight - cvRound(greenHist.at<float>(i)) ),
                      Scalar( 0, 255, 0), 2, 8, 0  );
     line( histImage, Point( binWidth*(i-1), histHeight - cvRound(blueHist.at<float>(i-1)) ) ,
                      Point( binWidth*(i), histHeight - cvRound(blueHist.at<float>(i)) ),
                      Scalar( 255, 0, 0), 2, 8, 0  );
	 /**********************************/
	 /*line( histImage, Point( binWidth*(i-1), histHeight - cvRound(grayHist.at<float>(i-1)) ) ,
                      Point( binWidth*(i), histHeight - cvRound(grayHist.at<float>(i)) ),
                      Scalar( 255, 255, 255), 2, 8, 0  );*/
	 /**********************************/

	 
    }

    // 显示直方图
	imshow("直方图", histImage );

	waitKey();

	return 0;
}

运行结果：

直方图-

原图-

解释(此部分来自http://www.opencv.org.cn/opencvdoc/2.3.2/html/doc/tutorials/imgproc/histograms/histogram_calculation/histogram_calculation.html)

——calcHist()函数

参数说明如下:

——normalize()函数

该函数接受下列参数: