We achieve this effect using an operation called erosion. This is the operation that makes a shape thinner by peeling the boundary layers of all the shapes in the image:
Let's look at the function that performs morphological erosion:
Mat performErosion(Mat inputImage, int erosionElement, int erosionSize)
{
Mat outputImage;
int erosionType;
if(erosionElement == 0)
erosionType = MORPH_RECT;
else if(erosionElement == 1)
erosionType = MORPH_CROSS;
else if(erosionElement == 2)
erosionType = MORPH_ELLIPSE;
// Create the structuring element for erosion
Mat element = getStructuringElement(erosionType, Size(2*erosionSize + 1, 2*erosionSize + 1), Point(erosionSize, erosionSize));
// Erode the image using the structuring element
erode(inputImage, outputImage, element);
// Return the output image
return outputImage;
}You can check out the full code in the .cpp files to understand how to use this function. We basically...