Closing | Morphological Transformations in OpenCV in C++

In this article, a Morphological Operation called Closing is discussed.

• It helps to reduce the internal noise present inside an image.
• In this article, another operator is elaborated called closing which is just the reverse of Opening and applies dilation followed by erosion.
• Just like the Opening operator it also uses a structuring element but it is used for removing small holes instead of pertusions.

Syntax:

morphologyEx (src, dst, op, kernel, anchor, iterations, borderType, borderValue)

Parameters:

• src: It is the input image.
• dst: It is the output image.
• op: Type of morphological operation.
• kernel: Structuring element used for Closing.
• anchor: Anchor position inside the structuring element. The default value is [-1, -1} signifying position as the center of the structuring element.
• iterations: Number of times Closing is applied.
• borderType: Type of border ( BORDER_CONSTANT, BORDER_REPLICATE, etc.)
• borderValue: Border value
• Return: Output Image (Mat Object)

The closing operation is given by the expression:

• The expression represents the fact that A is a sub-image of A^.B.
• This operator is used to remove small holes from the image.
• It also helps in smoothening the contours and fusion of narrow breaks and long thin gulfs.

Below is the program demonstrating the Closing Morphological Operator:

C++

// C++ program for demonstrating the
// closing morphological operator

// For drawing shapes
#include <opencv2/highgui/highgui.hpp>
#include <opencv2/imgproc.hpp>
using namespace cv;
using namespace std;

// Function to demonstrate the
// closing morphological operator
void closingMorphological()
{
    // Reading the Image
    Mat image = imread(
        "C:/Users/harsh/Downloads/geeks.png",
        IMREAD_GRAYSCALE);

    // Check if the image is
    // created successfully
    if (!image.data) {
        cout << "Could not open or "
             << "find the image\n";
        return 0;
    }

    int morph_size = 2;

    // Create structuring element
    Mat element = getStructuringElement(
        MORPH_RECT,
        Size(2 * morph_size + 1,
             2 * morph_size + 1),
        Point(morph_size, morph_size));
    Mat output;

    // Closing
    morphologyEx(image, output,
                 MORPH_CLOSE, element,
                 Point(-1, -1), 2);

    // Displays the source and
    // the closing image formed
    imshow("source", image);
    imshow("Closing", output);
    waitKey();
}

// Driver Code
int main(int argc, char** argv)
{
    // Function Call
    closingMorphological();

    return 0;
}

Output: