connected components in OpenCV

Question

I am looking for an OpenCV function that can find connected components and perform a few tasks on them ( like getting the number of pixels, contour, list of pixels in the ob

Answer 1

You can use cv::connectedComponentsWithStats() function.

Here is an example.

    // ...
    cv::Mat labels, stats, centroids;
    int connectivity = 8; // or 4
    int label_count = cv::connectedComponentsWithStats(src, labels, stats, centroids, connectivity);
    for (int i = 0; i < label_count; i++)
    {
        int x = stats.at(i, cv::CC_STAT_LEFT);
        int y = stats.at(i, cv::CC_STAT_TOP);
        int w = stats.at(i, cv::CC_STAT_WIDTH);
        int h = stats.at(i, cv::CC_STAT_HEIGHT);
        int area = stats.at(i, cv::CC_STAT_AREA);
        double cx = centroids.at(i, 0);
        double cy = centroids.at(i, 1);

        // ...
    }