opencv:直方图操作

示例程序：

#include <opencv.hpp>
using namespace cv;
using namespace std;
int main()
{
    Mat src, dst;
    //load img;
    src = imread("001.jpg",1);
    if (!src.data)
    {
        printf("error");
        return -1;
        
    }
    imshow("1", src);
    //分成三个通道
    vector<Mat> rgb_planes; // 保存在stl容器里
    split(src, rgb_planes);
    // 设置直方图尺寸 
    int histSize = 255;
    
    Mat histImage(400, 400, CV_8UC1, Scalar(0));
    int bin_w = cvRound((double)400 / histSize);
    //设置范围
    float range[] = { 0, 255 };
    const float * histRange = { range };
    bool uniform = true; bool accumulate = false;
    Mat r_hist, g_hist, b_hist; // 用于保存三个通道的直方图
    //计算直方图
    calcHist(&rgb_planes[1], 1,0,Mat(),r_hist,1, &histSize, &histRange, uniform, accumulate);
    normalize(r_hist, r_hist, 0, histImage.rows, NORM_MINMAX, -1, Mat());  // 直方图归一化
    for (int i = 1; i < histSize; i++)
    {
        line(histImage, Point(bin_w * (i - 1), 400 - cvRound(r_hist.at<float>(i - 1))), Point(bin_w * (i), 400 - cvRound(r_hist.at<float>(i))), Scalar(255), 1, 8, 0);
    }
    imshow("dst", histImage);
    waitKey(0);
    
    return 0;
}