直线检测

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

using namespace cv;
using namespace std;

int max_count = 255;
int threshold_value = 100;
const char* output_lines = "Hough Lines";
Mat src, roiImage, dst;
void detectLines(int, void*);
void morhpologyLines(int, void*);
int main(int argc, char** argv) {
    src = imread("直线检测.jpg", IMREAD_GRAYSCALE);
    if (src.empty()) {
        printf("could not load image...
");
        return -1;
    }
    namedWindow("input image", CV_WINDOW_AUTOSIZE);
    imshow("input image", src);
    namedWindow(output_lines, CV_WINDOW_AUTOSIZE);
    Rect roi = Rect(10, 10, src.cols - 20, src.rows - 20);
    roiImage = src(roi);
    imshow("ROI image", roiImage);
    // createTrackbar("threshold:", output_lines, &threshold_value, max_count, detectLines);
    // detectLines(0, 0);
    morhpologyLines(0, 0);

    waitKey(0);
    return 0;
}

//直接使用霍夫变换
void detectLines(int, void*) {
    Canny(roiImage, dst, threshold_value, threshold_value * 2, 3, false);
    //threshold(roiImage, dst, 0, 255, THRESH_BINARY | THRESH_OTSU);
    vector<Vec4i> lines;
    HoughLinesP(dst, lines, 1, CV_PI / 180.0, 30, 30.0, 0);
    cvtColor(dst, dst, COLOR_GRAY2BGR);
    for (size_t t = 0; t < lines.size(); t++) {
        Vec4i ln = lines[t];
        line(dst, Point(ln[0], ln[1]), Point(ln[2], ln[3]), Scalar(0, 0, 255), 2, 8, 0);
    }
    imshow(output_lines, dst);
}


//先形态学
void morhpologyLines(int, void*) {
    // binary image
    Mat binaryImage, morhpImage;
    threshold(roiImage, binaryImage, 0, 255, THRESH_BINARY_INV | THRESH_OTSU);//取反再二值化
    imshow("binary", binaryImage);

    // morphology operation
    //用直线的结构元素，开操作去掉除直线以外的对象
    Mat kernel = getStructuringElement(MORPH_RECT, Size(20, 1), Point(-1, -1));//用直线型的结构元素
    morphologyEx(binaryImage, morhpImage, MORPH_OPEN, kernel, Point(-1, -1));//开操作
    imshow("morphology result", morhpImage);

    // dilate image
    //膨胀操作，使得直线变得明显
    kernel = getStructuringElement(MORPH_RECT, Size(3, 3), Point(-1, -1));
    dilate(morhpImage, morhpImage, kernel);
    imshow("morphology lines", morhpImage);

    // hough lines
    vector<Vec4i> lines;
    HoughLinesP(morhpImage, lines, 1, CV_PI / 180.0, 30, 20.0, 0);
    Mat resultImage = roiImage.clone();
    cvtColor(resultImage, resultImage, COLOR_GRAY2BGR);
    for (size_t t = 0; t < lines.size(); t++) {
        Vec4i ln = lines[t];
        line(resultImage, Point(ln[0], ln[1]), Point(ln[2], ln[3]), Scalar(0, 0, 255), 2, 8, 0);
    }
    imshow(output_lines, resultImage);
    return;
}