输出图像的BGR三个通道的颜色直方图

#include   
#include   
using namespace cv;  

int main(  )
{
	Mat srcImage;
	srcImage=imread("8.jpg");
	imshow( "素材图", srcImage );
	int bins = 256;
	int hist_size[] = {bins};
	float range[] = { 0, 256 };
	const float* ranges[] = { range};
	MatND redHist,grayHist,blueHist;
	int channels_r[] = {0};

	//进行直方图的计算（红色分量部分）
	calcHist( &srcImage, 1, channels_r, Mat(), 
		redHist, 1, hist_size, ranges,
		true, false );

	//进行直方图的计算（绿色分量部分）
	int channels_g[] = {1};
	calcHist( &srcImage, 1, channels_g, Mat(), // do not use mask
		grayHist, 1, hist_size, ranges,
		true, // the histogram is uniform
		false );

	//进行直方图的计算（蓝色分量部分）
	int channels_b[] = {2};
	calcHist( &srcImage, 1, channels_b, Mat(), // do not use mask
		blueHist, 1, hist_size, ranges,
		true, // the histogram is uniform
		false );

	//-----------------------绘制出三色直方图------------------------
	//参数准备
	double maxValue_red,maxValue_green,maxValue_blue;
	minMaxLoc(redHist, 0, &maxValue_red, 0, 0);
	minMaxLoc(grayHist, 0, &maxValue_green, 0, 0);
	minMaxLoc(blueHist, 0, &maxValue_blue, 0, 0);
	int scale = 1;
	int histHeight=256;
	Mat histImage = Mat::zeros(histHeight,bins*3, CV_8UC3);

	//正式开始绘制
	for(int i=0;i(i); 
		float binValue_green = grayHist.at(i);
		float binValue_blue = blueHist.at(i);
		int intensity_red = cvRound(binValue_red*histHeight/maxValue_red);  //要绘制的高度
		int intensity_green = cvRound(binValue_green*histHeight/maxValue_green);  //要绘制的高度
		int intensity_blue = cvRound(binValue_blue*histHeight/maxValue_blue);  //要绘制的高度

		//绘制红色分量的直方图
		rectangle(histImage,Point(i*scale,histHeight-1),
			Point((i+1)*scale - 1, histHeight - intensity_red),
			Scalar(255,0,0));

		//绘制绿色分量的直方图
		rectangle(histImage,Point((i+bins)*scale,histHeight-1),
			Point((i+bins+1)*scale - 1, histHeight - intensity_green),
			Scalar(0,255,0));

		//绘制蓝色分量的直方图
		rectangle(histImage,Point((i+bins*2)*scale,histHeight-1),
			Point((i+bins*2+1)*scale - 1, histHeight - intensity_blue),
			Scalar(0,0,255));

	}

	//在窗口中显示出绘制好的直方图
	imshow( "图像的RGB直方图", histImage );
	waitKey(0);
	return 0;
}

程序运行结果：