用c++语言和opencv绘制直方图

好的，下面是用 C++ 和 OpenCV 绘制直方图的基本步骤：

1. 导入 OpenCV 库和其他必要的头文件：

#include <opencv2/opencv.hpp>
#include <iostream>

using namespace cv;
using namespace std;

2. 读取图像并转换为灰度图像：

Mat image = imread("path/to/image.jpg");
cvtColor(image, image, COLOR_BGR2GRAY);

3. 定义直方图的参数：

int histSize = 256; // 直方图的 bin 数量
float range[] = { 0, 256 }; // 像素值的范围
const float* histRange = { range };
bool uniform = true, accumulate = false;

4. 计算直方图：

Mat hist;
calcHist(&image, 1, 0, Mat(), hist, 1, &histSize, &histRange, uniform, accumulate);

5. 绘制直方图：

int hist_w = 512, hist_h = 400;
int bin_w = cvRound((double)hist_w / histSize);

Mat histImage(hist_h, hist_w, CV_8UC1, Scalar(0, 0, 0));

normalize(hist, hist, 0, histImage.rows, NORM_MINMAX, -1, Mat());

for (int i = 1; i < histSize; i++) {
    line(histImage, Point(bin_w * (i - 1), hist_h - cvRound(hist.at<float>(i - 1))),
         Point(bin_w * (i), hist_h - cvRound(hist.at<float>(i))),
         Scalar(255, 255, 255), 2, 8, 0);
}

imshow("Histogram", histImage);

完整代码如下：

#include <opencv2/opencv.hpp>
#include <iostream>

using namespace cv;
using namespace std;

int main()
{
    Mat image = imread("path/to/image.jpg");
    cvtColor(image, image, COLOR_BGR2GRAY);

    int histSize = 256;
    float range[] = { 0, 256 };
    const float* histRange = { range };
    bool uniform = true, accumulate = false;

    Mat hist;
    calcHist(&image, 1, 0, Mat(), hist, 1, &histSize, &histRange, uniform, accumulate);

    int hist_w = 512, hist_h = 400;
    int bin_w = cvRound((double)hist_w / histSize);

    Mat histImage(hist_h, hist_w, CV_8UC1, Scalar(0, 0, 0));

    normalize(hist, hist, 0, histImage.rows, NORM_MINMAX, -1, Mat());

    for (int i = 1; i < histSize; i++) {
        line(histImage, Point(bin_w * (i - 1), hist_h - cvRound(hist.at<float>(i - 1))),
             Point(bin_w * (i), hist_h - cvRound(hist.at<float>(i))),
             Scalar(255, 255, 255), 2, 8, 0);
    }

    imshow("Histogram", histImage);
    waitKey(0);

    return 0;
}

注意：在运行程序前，需要将 "path/to/image.jpg" 替换成你自己的图像路径。