上一讲：【opencv4】opencv视频教程 C++（opencv教程）2、加载，修改，保存图像
矩阵的掩膜操作
获取图像像素指针
像素范围处理saturate_cast<uchar>
函数调用filter2D功能
代码示例
#include <opencv2/opencv.hpp>
#include <iostream>
using namespace cv;
int main(int argc, const char* argv[]) {
Mat src, dst;
src = imread("./test.jpg");
//if (src.empty()) {
if (!src.data){
printf("could not load image...\n");
return -1;
}
namedWindow("input img"); //默认自动窗口大小
imshow("input img", src);
/*
//看不懂啊！20220201 大年初一
int cols = (src.cols - 1) * src.channels(); //src分辨率是580×326的，src.cols=580是列数，src.channels()=3是通道数，最终计算cols=1737（579×3）
int offsetx = src.channels(); //3
int rows = src.rows; //326
dst = Mat::zeros(src.size(), src.type()); //第二个参数是位深度，目前值为16
for (int row = 1; row < (rows - 1); row++) {
const uchar* previous = src.ptr<uchar>(row - 1);
const uchar* current = src.ptr<uchar>(row);
const uchar* next = src.ptr<uchar>(row + 1);
uchar* output = dst.ptr<uchar>(row);
for (int col = offsetx; col < cols; col++) {
output[col] = saturate_cast<uchar>(5 * current[col] - (current[col - offsetx] + current[col + offsetx] + previous[col] + next[col]));
}
}
*/
//投机取巧调包侠上线！也看不太懂
Mat kernel = (Mat_<char>(3, 3) << 0, -1, 0, -1, 5, -1, 0, -1, 0); //默认
//Mat kernel = (Mat_<char>(3, 3) << -1, -1, -1, -1, 5, -1, -1, -1, -1); //没效果，一片黑
//Mat kernel = (Mat_<char>(3, 3) << 0, -1, 0, -1, 10, -1, 0, -1, 0); //感觉有种曝光过度感觉
//Mat kernel = (Mat_<char>(3, 3) << 0, -2, 0, -2, 16, -2, 0, -2, 0); //明显曝光过度
//Mat kernel = (Mat_<char>(3, 3) << 0, -2, 0, -2, 8, -2, 0, -2, 0); //直接变白素描了
//Mat kernel = (Mat_<char>(3, 3) << 0, -2, 0, -2, 9, -2, 0, -2, 0); //貌似跟（0, -1, 0, -1, 5, -1, 0, -1, 0）相同
//Mat kernel = (Mat_<char>(3, 3) << 0, -10, 0, -10, 41, -10, 0, -10, 0); //这。。。
filter2D(src, dst, src.depth(), kernel);
namedWindow("output img"); //默认自动窗口大小
imshow("output img", dst);
waitKey(0);
return 0;
}
vs编译运行结果：
