OpenCV (三）像素操作

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

using namespace cv;
using namespace std;

int main(int argc, char** argv) {
    cout << "hello world!" << endl;
    Mat src = imread("D:/OpenCVprj/image/test.png");
    namedWindow("input image", CV_WINDOW_AUTOSIZE);
    imshow("input image", src);

    //pixel opration
    Mat src_gray;	
    cvtColor(src, src_gray, CV_BGR2GRAY);
    int rows = src_gray.rows;
    int cols = src_gray.cols;
    int channel = src.channels();
    namedWindow("src_gray", CV_WINDOW_AUTOSIZE);
    imshow("src_gray", src_gray);

    Mat dst;
    dst.create(src.size(), src.type());

    for (int row = 0; row < rows; row++) {
        for (int col = 0; col < cols; col++) {
            if (channel == 1) {
                int gray = src_gray.at<uchar>(row, col);
                dst.at<uchar>(row, col) = 255 - gray;
            }
        else if (channel == 3) {
                int b = src.at<Vec3b>(row, col)[0];
                int g = src.at<Vec3b>(row, col)[1];
                int r = src.at<Vec3b>(row, col)[2];
                dst.at<Vec3b>(row, col)[0] = 255 - b;
                dst.at<Vec3b>(row, col)[1] = 255 - g;
                dst.at<Vec3b>(row, col)[2] = 255 - r;
            }
        }
　　}

    namedWindow("dst", CV_WINDOW_AUTOSIZE);
    imshow("dst", dst);
    waitKey(0);
    return 0;
}                
#include<opencv2/o