vitruvius's profile - activity

Hello,

I would like to remove holes in an object after I apply threshold function. Right now, I am applying dilate function a few times, then the erode function. It does okay, but in some cases, it changes the shape of the object.

I also tried to use the MORPH_CLOSE, but I guess it is no good against big holes.

I tried with different element size and shape but none of them helped.

#include <opencv2/core/core.hpp>
#include <opencv2/imgproc/imgproc.hpp>
#include <opencv2/highgui/highgui.hpp>

using namespace cv;
using namespace std;

Mat src, srcGray, srcSmooth, srcThresh;

int morpho_elem = 1; // 0: MORPH_RECT, 1: MORPH_CROSS, 2: MORPH_ELLIPSE
int morpho_size = 3;
int morpho_qty = 9;

int const smooth_kernel = 11;

int main()
{   
    src = imread("source.png", 1);

    cvtColor(src, srcGray, CV_BGR2GRAY);

    for (int i = 1; i < smooth_kernel; i = i + 2)
    {
        medianBlur(srcGray, srcSmooth, i);
    }

    threshold(srcSmooth, srcThresh, 0, 255, CV_THRESH_BINARY | CV_THRESH_OTSU);

    int dilation_type;
    if (morpho_elem == 0){ dilation_type = MORPH_RECT; }
    else if (morpho_elem == 1){ dilation_type = MORPH_CROSS; }
    else if (morpho_elem == 2) { dilation_type = MORPH_ELLIPSE; }

    Mat dilationDst, erosionDst;

    Mat element = getStructuringElement(dilation_type,
        Size(2 * morpho_size + 1, 2 * morpho_size + 1),
        Point(morpho_size, morpho_size));

    // Apply the dilation operation
    dilate(srcThresh, dilationDst, element);
    for (int i = 1; i < morpho_qty; i++)
    {
        dilate(dilationDst, dilationDst, element);
    }

    // Apply the erosion operation
    erode(dilationDst, erosionDst, element);
    for (int i = 1; i < morpho_qty; i++)
    {
        erode(erosionDst, erosionDst, element);
    }

    imshow("Final", erosionDst);

    cvWaitKey(0);

    return 0;
}

Source image:

Binary image with holes:

Output of my attempt:

Hi,

I would like to use approxPoly to close contours. But I am not quite sure about how it works.

I am using OpenCV 2.4.11.

So I have two images:

And I apply canny, then find contours.

How can I close those contour curves?

#include "opencv2/imgproc/imgproc.hpp"
#include "opencv2/highgui/highgui.hpp"
#include <stdlib.h>
#include <stdio.h>

using namespace cv;
RNG rng(12345);

int main()
{
    Mat src, srcGray, srcBlur, srcThresh, srcCanny;

    src = imread("source.png", 1);
    cvtColor(src, srcGray, CV_BGR2GRAY);
    blur(srcGray, srcBlur, Size(3, 3));

    double otsu;    
    otsu = threshold(srcBlur, srcThresh, 0, 255, CV_THRESH_BINARY | CV_THRESH_OTSU);    
    Canny(srcBlur, srcCanny, otsu, otsu * 2, 3, true);

    vector<vector<Point> > contours;
    vector<Vec4i> hierarchy;

    findContours(srcCanny, contours, hierarchy, CV_RETR_EXTERNAL, CV_CHAIN_APPROX_SIMPLE, Point(0, 0));
    Mat drawing = Mat::zeros(srcCanny.size(), CV_8UC3);
    for (int i = 0; i< contours.size(); i++)
    {
        Scalar color = Scalar(rng.uniform(0, 255), rng.uniform(0, 255), rng.uniform(0, 255));
        drawContours(drawing, contours, i, color, 2, 8, hierarchy, 0, Point());
    }

    imshow("Contours", drawing);

    cvWaitKey();
    return 0;
}

I tried something like this but it made it didn't help at all.

vector<vector<Point> > approx;

    approx.resize(contours.size());
    for (intk = 0; k < contours.size(); k++)
        approxPolyDP(Mat(contours[k]), approx[k], 3, true);

Hello,

I would like to get some user input after I show an image. But even though imshow() is being executed, it waits till the user input to show the image. I get an empty window until scanf_s() is done. Why is this happening?

I am using Visual Studio 2013, and OpenCV 2.4.11.

Here is a little demo:

#include <iostream>
#include <opencv2/core/core.hpp>
#include <opencv2/highgui/highgui.hpp>

using namespace cv;
using namespace std;

int main()
{   
    char in[15];
    namedWindow("Source", 1);

    Mat src = imread("toy.png");

    imshow("Source", src);

    scanf_s("%s", in, sizeof in);

    waitKey();
    return 0;
}

toy.png: