opencv4 学习 09 使用形态学算子提取水平线和垂直线

1.提取水平线时，主要使用 w×1 形状的核，w为核的宽度，然后再进行腐蚀和膨胀操作。

2.提取垂直线时，主要使用 1×h 形状的核，h为核的高度，然后再进行腐蚀和膨胀操作。

#include <opencv2/imgcodecs.hpp>
#include <opencv2/highgui.hpp>
#include <opencv2/imgproc.hpp>
#include <iostream>

using namespace std;
using namespace cv;

void show_wait_destory(const char* winname, cv::Mat img){
    imshow(winname, img);
    moveWindow(winname,500,0);
    waitKey(0);
    destroyWindow(winname);
}

int main(int argc, char* argv[])
{
    Mat src = imread("notes.png", IMREAD_COLOR);
    imshow("src", src);
    Mat gray;
    if(src.channels()==3){
        cvtColor(src, gray, COLOR_BGR2GRAY);
    }
    else {
        gray = src;
    }
    show_wait_destory("gray",gray);

    Mat bw;
    adaptiveThreshold(~gray, bw ,255, ADAPTIVE_THRESH_MEAN_C,THRESH_BINARY,15,-2);
    show_wait_destory("binary", bw);

    Mat horizontal = bw.clone();
    Mat vertical = bw.clone();

    int horizontal_size = horizontal.cols / 30;
    Mat horizontalStructure = getStructuringElement(MORPH_RECT, Size(horizontal_size, 1));
    erode(horizontal, horizontal,horizontalStructure, Point(-1,-1));
    dilate(horizontal,horizontal,horizontalStructure, Point(-1,-1));
    show_wait_destory("horizontal", horizontal);

    int vertical_size = vertical.rows / 30;
    Mat verticalStructure = getStructuringElement(MORPH_RECT, Size(1, vertical_size));
    erode(vertical, vertical, verticalStructure, Point(-1,-1));
    dilate(vertical, vertical, verticalStructure, Point(-1,-1));
    show_wait_destory("vertical",vertical);

    bitwise_not(vertical, vertical);
    show_wait_destory("vertical_bit", vertical);

    // Extract edges
    Mat edges;
    adaptiveThreshold(vertical,edges,255,ADAPTIVE_THRESH_MEAN_C, THRESH_BINARY, 3, -2);
    show_wait_destory("edges", edges);

    Mat kernel = Mat::ones(2,2,CV_8UC1);
    dilate(edges,edges,kernel);
    show_wait_destory("dilate",edges);

    Mat smooth;
    vertical.copyTo(smooth);
    blur(smooth, smooth, Size(2,2));
    smooth.copyTo(vertical,edges);
    show_wait_destory("smooth - final", vertical);

    return 0;
}

 

参考：

https://docs.opencv.org/3.4/dd/dd7/tutorial_morph_lines_detection.html