opencv：全局阈值

图像的二值化分割，最重要的就是计算阈值

阈值的计算方法很多，基本分为两类，全局阈值与自适应阈值

OTSU、Triangle

#include <opencv2/opencv.hpp>
#include <iostream>
using namespace cv;
using namespace std;
int main(int argc, char** argv)
{
    Mat src = imread("f:/images/shuang001.jpg");
    if (src.empty())
    {
        printf("Could not find the image!\n");
        return -1;
    }
    namedWindow("input", WINDOW_AUTOSIZE);
    imshow("input", src);
    Mat gray, binary;
    cvtColor(src, gray, COLOR_BGR2GRAY);
    imshow("gray", gray);
    // 均值分割
    Scalar m = mean(gray);
    printf("means: %.2f\n", m[0]);
    threshold(gray, binary, m[0], 255, THRESH_BINARY);
    imshow("binary", binary);
    // 直方图
    threshold(gray, binary, 0, 255, THRESH_BINARY | THRESH_OTSU);
    imshow("THRESH_OTSU", binary);
    threshold(gray, binary, 0, 255, THRESH_BINARY | THRESH_TRIANGLE);
    imshow("THRESH_TRIANGLE", binary);
    waitKey(0);
    destroyAllWindows();
    return 0;
}