image conversion opencv 5

Edge detection

The general steps

canny operator

step

canny function

Color canny

#include<opencv2/opencv.hpp>
#include<opencv2/highgui/highgui.hpp>
#include<opencv2/imgproc/imgproc.hpp>
using namespace cv;

int main()
{
    Mat dst, edge, gray;
    Mat src = imread("G://2.jpg");
    Mat src1 = src.clone();
    imshow("原始图", src);
    dst.create(src1.size(), src1.type());
    cvtColor(src1, gray, COLOR_BGR2GRAY);
    blur(gray, edge, Size(3,3));
    Canny(edge, edge, 3, 9, 3);
    dst = Scalar::all(0);
    src1.copyTo(dst, edge);
    
    imshow("效果图",dst);

    waitKey(0);
    return 0;
}

copyTo function
image.copyTo (imageROI). Action is to copy the contents of the image pasted to the imageROI;

image.copyTo (imageROI, mask). Role of the mask image and overlapping the mask after the pixel value of 0 (black) corresponding to a point in the image point becomes transparent, leaving other points.

sobel operator

calculation process

Sobel function ()