opencv3画出一幅图像的HSV直方图_c#opencv图像hsv直方图

直方图的计算在OpenCV中可以使用calcHist()函数，计算完成后可以采用OpenCV中的绘图函数，如绘制矩形的rectangle()函数，绘制线段的line()函数来完成。

所用函数：1.计算直方图：calcHist()
2.找寻最值：minMaxLoc()

以下附上画出图像HSV直方图的代码

#include<opencv.hpp>
#include<highgui.hpp>
#include<imgproc.hpp>
using namespace cv;
using namespace std;



int main()

{
	Mat srcimage = imread("1.bmp");
	imshow("原图", srcimage);
	Mat srcimageHSV;
	//图像转化HSV颜色空间图像
	cvtColor(srcimage, srcimageHSV, COLOR_BGR2HSV);
	imshow("HSV空间图像", srcimageHSV);

	int channels = 0;
	int histsize[] = { 256 };
	float midranges[] = { 0,255 };
	const float *ranges[] = { midranges };
	MatND  dsthist;

	calcHist(&srcimageHSV, 1, &channels, Mat(), dsthist, 1, histsize, ranges, true, false);
	Mat drawImage = Mat::zeros(Size(256 * 3, 256), CV_8UC3);
	double g_dhistmaxvalue;
	minMaxLoc(dsthist, 0, &g_dhistmaxvalue, 0, 0);

	//画出h色调通道
	for (int i = 0; i < 256; i++) {
		int value = cvRound(256 * 0.9 *(dsthist.at<float>(i) / g_dhistmaxvalue));
		line(drawImage, Point(i, drawImage.rows - 1), Point(i, drawImage.rows - 1 - value), Scalar(255, 0, 0));
	}


	//画出s饱和度通道
	channels = 1;
	calcHist(&srcimageHSV, 1, &channels, Mat(), dsthist, 1, histsize, ranges, true, false);
	for (int i = 0; i < 256; i++) {
		int value = cvRound(256 * 0.9 *(dsthist.at<float>(i) / g_dhistmaxvalue));
		line(drawImage, Point(i + 256, drawImage.rows - 1), Point(i + 256, drawImage.rows - 1 - value), Scalar(0, 255, 0));
	}


	//画出v亮度通道
	channels = 2;
	calcHist(&srcimageHSV, 1, &channels, Mat(), dsthist, 1, histsize, ranges, true, false);
	for (int i = 0; i < 256; i++) {
		int value = cvRound(256 * 0.9 *(dsthist.at<float>(i) / g_dhistmaxvalue));
		line(drawImage, Point(i + 256 * 2, drawImage.rows - 1), Point(i + 256 * 2, drawImage.rows - 1 - value), Scalar(0, 0, 255));
	}

	imshow("HSV直方图", drawImage);
	waitKey(0);
	return 0;
}
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结果如下