如下图所示，想要取出图像上的红色印记，我们可以采用通道分离的方法，具体如下：

#include<opencv2\opencv.hpp>
#include<string>
#include <vector>using namespace cv;
using namespace std;int main()
{Mat src = imread("234.png");//resize(src, src, Size(700, 500));Mat gray;cvtColor(src, gray, CV_RGB2GRAY);if (src.empty()){printf("fail to open image!\n");return -1;}// 全局二值化int th = 180; //阈值要根据实际情况调整Mat binary;threshold(gray, binary, th, 255, CV_THRESH_BINARY);vector<Mat>channels;split(src, channels);Mat red = channels[2];//按照BGR的顺序Mat blue = channels[0];Mat green = channels[1];Mat red_binary;threshold(red, red_binary, th, 255, CV_THRESH_BINARY);imshow("src", src);imshow("gray", gray);imshow("binary", binary);imshow("red channel", red);imshow("blue channel", blue);imshow("green channel", green);imshow("red+binary", red_binary);waitKey();return 0;
}