OpenCV之图像处理case(六) 对象提取与测量

代码

#include "../common/common.hpp"

void main(int argc, char** argv) {
    Mat src = imread(getCVImagesPath("images/case3-6.png"));
    imshow("src3-6", src);

    // 降噪(二值分割THRESH_TRIANGLE 的效果会更好)   二值分割+图像形态学+轮廓提取
    Mat blurImage;
    GaussianBlur(src, blurImage, Size(15, 15), 0, 0);
    imshow("blur", blurImage);

    Mat gray_src, binary;
    cvtColor(blurImage, gray_src, COLOR_BGR2GRAY);
    threshold(gray_src, binary, 0, 255, THRESH_BINARY | THRESH_TRIANGLE); // 颜色单一，所以使用 THRESH_TRIANGLE
    imshow("binary", binary);

    // 形态学操作
    Mat morphImage;
    Mat kernel = getStructuringElement(MORPH_RECT, Size(3, 3), Point(-1, -1));
    morphologyEx(binary, morphImage, MORPH_CLOSE, kernel, Point(-1, -1), 2);
    imshow("morphology", morphImage);

    // 获取最大轮廓
    vector<vector<Point>> contours;
    vector<Vec4i> hireachy;
    findContours(morphImage, contours, hireachy, CV_RETR_EXTERNAL, CHAIN_APPROX_SIMPLE, Point());
    cout << "contours.size=" << contours.size() << endl; // contours.size=31
    Mat connImage = Mat::zeros(src.size(), CV_8UC3);
    for (size_t t = 0; t < contours.size(); t++) {
        Rect rect = boundingRect(contours[t]);
        if (rect.width < src.cols / 2) continue;
        if (rect.width >(src.cols - 20)) continue;
        double area = contourArea(contours[t]); // 轮廓面积，求面积的时候需要将轮廓中的区域变成黑色，否则面积会求的不正确?
        double len = arcLength(contours[t], true); // 轮廓弧长
        drawContours(connImage, contours, static_cast<int>(t), Scalar(0, 0, 255), 1, 8, hireachy);
        printf("area  of star could : %f\n", area); // area  of star could : 148728.000000
        printf("length  of star could : %f\n", len); // length  of star could : 2386.708920
    }
    imshow("result", connImage);

    waitKey(0);
}

效果图